coolant leak after shut off!
 

Hey guys... I've spent the last couple of hours on the forum trying to find out the solution to the problem using the search feature in this forum... and DAMN, rx7's seem to have quite a few of these!

My leak only occurs after the car is shut off after its been driven. THe leak seems like a half cup of fluid right under the coolant resevoir tank (underneathe the passenger side headlight). That resevoir tank is full and yet after cool down, I need to add about a half a cup of water to the filler neck.

Is this a symptom of failed water seals? (please say no, please say no!!!!) I just find it funny that coolant is not being sucked back into the cooling system.

Your help is GREATLY appreciated... thank you thank you!

Re: coolant leak after shut off!
 

Yes, it is most likely your seals. Does it start hard in the morning and blow any white smoke at startup? You'll also smell the coolant as it comes out your exhaust. A litlle puff of blue/grey smoke is normal.
Sorry to be the grim reaper. There is a possible cure
with CRC Copper Block Weld if this IS the problem and IF it is a small leak. Don't give up hope yet!
:eek:

shiet!!! Well, I don't smell coolant from the exhaust yet... but I don't want to push my luck. How does the CRC stuff work? And I would say I'd lose about a cup of coolant a day... I'm not sure if that's considered small or not... I really am hoping that it's something else, I can't afford the down time... might have to pick up a commuter car or something. What are the chances it could be a faulty radiator cap?:(

Sure it could be a bad cap, and about 15 other things. I need to know the symptoms first. So - hard starts and white smoke?
If not then we'll work backward and forget about the CRC for the time being. One thing you'll have to get is a radiator pressure tester which can be rented from AutoZone or another parts store.

I don't think that it is your seals. I would lean closer to the pressure cap going bad. You are spilling the 1/2 cup you put in the day before each time you turn you motor off. While you are moving the temps are lower and there is not as much pressure under the cap as when you are parked and not circulating the coolant. A bad cap, or too low a pressure cap would allow for the coolant to exit and not return at the same level. Replace the cap first before you worry about the seals. Replace you AST if you havn't already. They are not getting any younger and you are chancing a melt down if it cracks open.

$10 says it's your cap.

I'm with Ron, it's leaning towards your motor. At least that's one of the symptoms of a bad motor. But check for all the obvious first.


good luck,

car 53:cool:

I guess I'm hung up on the fact that my motor sounds and runs very good. No smoke, no smell of coolant from the exhaust (at least not yet)... but I think I'm in denial of the inevitable. In the mornings, the car starts as usual... the only thing odd is the coolant on the floor after I shut off the engine after a drive. And it's not a constant leak. It will leak until the engine is cool, and then stop.

I suppose I will purchase a $15 dollar radiator cap in hopes that it will solve the problem... but I'm getting more and more doubtful.
II've been reading too many posts of people blowing their water seals with the same symptoms as me.

So, if it is the seals... how much longer do I have? And how effective is that CRC stuff? Thanks guys, for all your input... much appreciated!

Brian

if you're not getting the white smoke then its probably not your seals. i had the same exact problem and you know what it was? when a new water pump was installed someone forgot to put sealant on one of the bolts. leaked all to hell...

A quick test is to remove the filler neck cap(with pressure released), start the car(some fluid may surge out), when it levels off, see if there are any bubbles coming from the coolant. If so, exhaust gas is getting through the engine seal into the coolant. Only fix then is an engine rebuild. Another symptom is oil in the coolant. You would see this at the top of the filler neck.

The theory of all this is that the exhaust gas overpressurizes the coolant which forces it into the overflow tank. When the car cools, there's not enough reverse pressure to return all the coolant back into the system. So, overtank overflows and filler neck is low.

However it could also be as simple as your filler neck cap or pressure cap. They are cheap to replace. Hopefully the caps are your problem, it was the cause of my coolant problems.

Arc Welder

It's the motor... it's going. I've had two go in 18,000 miles. I know how it goes.

Ok guys, what if I AM getting white smoke at startup and NOT losing coolant. Should I be worried about white smoke if I'm not losing coolant? Is it just condensation from the colder weather or something else I should look into? Recently my car has been producing a lot of white smoke from the exhaust for a couple of minutes in when I first start up the car in the mornings but one morning when I woke up late for work and it was already warm outside... no smoke. My exhaust doesn't smell like coolant either... more like fuel actually. I know my cooling system is pressurizing because every morning I check the AST cap and the radiator cap and both are pressurized and full of coolant. Someone had mentioned that it could be poor compression and that air is going into the motor and then condensating when I start up the car? I've never heard that before but my vacuum is around 16-17 at idle... Any advice/comments?

MILD 7 how many miles are on you engine. My waterseals are blown hence it sits in my driveway. I never smelled coolant in the exaust but the one problem was that I couldn't get the coolant to level off in the resivour no matter how many times I tried to bleed it. As a result it would push the excess coolant that was being displaced in to the overflow in pass. fender. The way in which I was able to be clear that it was the seal was to use my coolant pressure tester pressurize to 15lbs and maintain, and let it sit for an hour. While waiting remove the 2 spark plugs from motor. Be sure to watch pressure so that it doesn't drop, that could be a leak from a hose or a coolant seal. After an hour rotate the motor slowly and then look for coolant to come out of the sparkplug holes. If no coolant probably either one of the caps.
Good Luck

Chad, my motor has about 80,000 on it. I'm going to see if there's bubbles in the coolant at the filler neck as soon as my car cools down. I won't have time to investigate further until later this weekend. I'm very worried now. If worst case senario = blown seals... anyone know a good place in Socal to quickly and reasonable drop in a reman. engine? This is my only car, and use it daily to commute... this sucks!!!

Hi Brian, I'm back.

First, take a deep breath and relax a little bit. We're all totally stressed out right now and suffering from Post Traumatic Stress Syndrome - whether you know it or not.

The bubbles in the filler neck are for sure one of the signs of a "blown seal". So, you can check that easily on cold startup. Make sure you take a towel and make a "collar" around the neck to keep coolant off your belts and engine since a little will spill over. Make sure it does not hang down in your belts! Fill it to the top with DISTILLED WATER ONLY. Get a bright flashlight. When you start the engine cold, if you have "blown seals" you will see lots of little bubbles percolating up to the top - kind of like champagne bubbles. As it warms up you will probably see more. If they are small and kind of fizzy you have a small leak and one that can be repaired - MAYBE - with the CRC product. If you have big bubbles - probably not. The point is that a "blown seal" may not be a death sentence after all. But at $7.00 a bottle (and you might go through a few), some time and distilled water you have absolutely nothing to lose! The CRC product "Copper Block Weld" DOES work on small leaks. I've got over 5,000 miles on my engine with 71,000 miles on it and it does not burn any coolant since my treatment.
I was lucky since I caught mine right when it happened. If you ignore it or beat on the engine it will get worse and worse until the only cure is a rebuild. Now, if you're racing or running high boost there is no question you are just buying time - but it sounds like yours is a daily driver - and this is a relatively low stress situation compared to the way most guys on this forum drive!!

The fact that it starts easily and you are not smelling any coolant is good! Hopefully it is just a small leak. So..........check out the bubbles and report back! We're with you 100% dood, and the guys on this forum are THE BEST - they are total fanatics.
(and I mean that in a GOOD way)

Let's figure this out logically and not start guessing and throwing parts and money at it....

Ron;)

get a 20oz bottle and cut it in half. then hold it tightly upside down and look in. it wont spill.

Hey... Mine did the exact same thing... 3 things i did... noticed the upper radiator hose was getting crimped cause it should be under that bracket to hold it in place not over it :mad: stupid previous owners..... also i changed the water pump ( probablly cured all my problems ) Since i was there i also changed the thermostat. I did all of this in reverse order :D No more coolant problems. Oh yeah my coolant bubbled meaning it was boiling. Pressure problems with car running=water pump. Just my $.10

The verdict
 

Ok guys.... my worst fear has come true... started the engine with the filler cap off... and low and behold... bubbles. Here's the run down. When I first started the car (wasn't too cold... no 3,000 rpm warm up mode) and a steady flow of bubbles similar when you just open a soda. The stream of bubbles was constantly flowing for the first 30 seconds, and then began to slow. After about a minute, I counted about 5 bubbles per second. So it seems to me that my leak isn't too big.

So, now that I know that it's a water seal(s) how does this CRC stuff work? And where can I get it (autozone, etc?). Yes I do plan on replacing the motor soon, as soon as I can save up enough cash. I'm thinking the most cost effecient solution is a Mazda reman. Anyone know any qualified shops in the Socal area that could drop it in without too much down time and at a reasonable price (tri point is too pricey). Thinking about the rotary shop in Gardena. How much does labor usually cost. Not planning on doing anything else than a straight forward swap. Hoping not to spend more than 3 grand.

I really do appreciate all the help and support I 'm getting from you guys... it makes my situation easier to swallow knowing that I have fellow brothers who feel my pain.. and know what I'm gonig through. Thanks a million... you guys are the best!!!

Brian:(

Hey Brian...
I feel your pain... gone thru a engine/rear turbo/Diff as well all this year. Ouch!!! And my car is still not up to par and running
right.
However... I had leaks from the front overflow tanks area as well. It turned out to be a overfull overflow. Then bleeds out excess somewhere underneath.
If your car is not blowing white smoke in the mornings. This is a very good sign. You might have
air bubbles in your coolling system. When cold remove the rubber coolant hose on the throdle body and fill with distilled
water til you get some that flows from that disconnected hose.
Also squeeze the main rad-hose a few times to get the sir bubbles out.
Re-hook up hose to throdle body and make sure coolant is full.
I would check the AST for proper operation as well.

Best wishes.... jc.

couldn't this problem be easily decided by bringing the car to someone who can run a compression test on the engine? correct me if I am worng but a compression test can tell you if your seal are bad- correct?
-Jon
94 base

I don't know if this is it, but my friend was having a similar problem. He would shut the car off and coolant would "spill". What it ended up being was that there was a clog in the system and the coolant was backed up. So I did a hella fluch on his car for him. I took the thermostat housing off after I cleaned the entire radiator. I sprayed water in the block and ran the motor with a hose attached to it to clean it out. The water would enter through where the thermostat was and exit through the bottom of the radiator. Then I put it all back together, and it worked great. The other thing that I have heard on forum is that the cap could be bad. I would try those two things first.

I had the same problem - coolent leaking after shutdown in the same place.

I replaced the caps & it completely dissappeared. Pls do as the others on the Forum have suggested - replace the caps - its cheap & "may" fix your problem as it has with other owners.

The bubbles you refer too can be trapped air in your coolent system that gets in because there is not a strong seal - coolent leaks & air gets in.

Don't be ready to think its your seals - doubt it - do the cheap/logical fixes first & then worry about seals if its still present.

Good luck pal.

-Matt:)

When you use a pressure tester, how long should you leave it pressurized? Since changing to the SR Ultimate Rad last month, I have been pushing coolant out but not sucking it back in. But it is not always consistent - seems worse in stop and go driving than highway driving. It doesn't boil over either, just overflows the tank if you let it go on too long with out sucking some out of the tank & usually this is the same amount that I have to add back to the filler neck to top it off. No hard start or smoke or burning coolant smell and no overheating that ever saw on the guage.

I borrowed a pressure tester last week and put it on the filler cap first and pumped it up to about 16 psi, a second later the AST cap vented and let pressure down to 13 psi. So to do the 20 psi test per the FSM I put the tester on the AST and pumped it up to about 19 psi. Then left it for over 40 min. while looking around at every hose to see a leak - nothing. So I tried putting it back on the filler neck, pumped it to 16 then it vented to 13 psi and held for a while. When I started looking this time I could see coolant weeping not dripping from the lower radiator hose.

Alas, as suspected I should not have reused the Mazda spring clamps. No problem since I already had the worm clamps and new rad hoses in stock. So I replaced them and still have the same problem but now it will sometimes pull the coolant back in from the overflow tank. Last night I finally saw a coolant drip on the rad pan right below the water pump housing connections but couldn't feel around too good since it was so hot but I did feel a trace wet spot by the lower rad hose to water pump housing. Will try to tighten that clamp this evening. The only other place I suspect is the long hose than I have by-passed from the throttle body, it's been on and off a few times but I have reused the Mazda spring clamp - perhaps that one is weeping and not showing a leak.

I will try the running it with the cap off to check for bubbles just to be sure but since it sometimes pulls coolant back in now and doesn't consistently overflow I think/pray the motor is ok.

Do I need to leave the pressure tester on the system for an extended time like overnight to find these weeping type leaks since they don't spew coolant?
Help is appreciated,
Jack

whoa whoa whoa whoa!! Hang on a cotton picking second.

Ok, depending on how hot your engine was, keep this in mind - water boils. What is your water/coolant ratio? When you take off the radiator cap, you've lowered the pressure in your cooling system, thus, lowering the boiling temperature of your water/coolant. It's possible that you're just seeing the result of boiling. Were the bubbles big or were they small and foamy? Mine was doing this too - big bubbles - result of boiling because the engine wasn't COMPLETELY COLD when I was checking.

Now, take a look at a much more common problem on the 7.... the radiator. Is yours still stock? When your engine bay gets hot, everything expands. Lots of stuff in there is made out of different materials and expands at different rates. One such thing is the radiator, being that it's made out of aluminim and plastic (what were they thinking??). If your radiator's plastic tanks get small cracks, they may not leak until the aluminum core expands and makes the cracks wider.

To see if it's your radiator - take off the mazda fresh air duct if you still have it on... remove the fuse panel just below that (just move it to the side). That should be enough to see the top of your radiator. Take a flashlight and shine it down on the radiator. See any sign of liquid on it? Take a paper towel and wipe it along the plastic tank where it meets the core... any sign of coolant or water? Do the same wipe on both sides of the top and bottom tanks - right where they meet the radiator. If you find any sign of coolant in these places, there's a VERY good chance that you just need to replace your radiator.

I had the SAME THING happen to me - leaking only after shutdown when hot. Everyone told me my seals were gone too, but before jumping on a rebuild, I had the radiator checked. low and behold, my problem was fix and the car was upgraded with a $412 Fluidyne radiator as opposed to a $3K rebuild. Let's hope this is your case too.

Re: The verdict
 

Please check my above post before getting a rebuild started.

However, IF you end up needing a rebuild, I HIGHLY recommend Rotary Power in Gardena. The number is 310-516-9959. Don't get a reman, have them do a rebuild, especially if your housings aren't damaged from a blown out apex seal. I was asking him about his prices - he said that a straight rebuild with 2mm apex seals and no porting or performance mods will cost just over $2K.

Coincidently - it was Rotary Power that found my coolant leak and told me it was just the radiator, so at least you know they're honest about this sort of thing.

Good luck!

I would also first lean to a coolant system leak. As the car gets hot it expells coolant into the overflow tank. If you have a pressure leak somewhere the coolant system will run at a lower pressure and the coolant will boil when the car is turned off. When the system cools off, it is supposed to suck the coolant back into the motor. With a coolant leak this does not happen and you need to constantly refill at the coolant neck. Also, over time this causes the overflow tank to have too much coolant in it, causing more on the ground. The rotary does expell some air into the coolant even with a good motor - that's why Mazda put in the plastic air-separator tank.

If you have a bad seal, the coolant will overflow with the motor running. This happened to my 2G for a couple of years prior to losing the motor.

Just never run the car hot...make sure you keep up with the coolant until you get it fixed.

Again, thanks for all the help... I just got back from work and will be heading out to the autoparts store for a pressure tester thingy. One thing I noticed but failed to mention, was that everytime I pulled off the filler cap to add water (engine cold), there would be vaccum. It would take a little effort to pull it off and a suction sound could be heard... kinda like a cork popping sound. Does this have any significance in locating my prob? Just wondering.

Well post when I get the results of the coolant system pressure checker. Thanks again guys.

Well......there's lots of interesting hypothesis here. But frankly there is no real investigation - just " this is what happened to me"
The whole coolant system is prone to failure as it ages at a number of points.

But like I said, let's look at this from a logical standpoint.

If it is a constant stream of small bubbles it's the seals. Period.
But before we make a conclusive diagnoses let's eliminate ANY other potential causes. And it's FREE. As in NOTHING, ZIP, ZILCH.
Sure beats the hell out of $100 an hour for a "rotary expert".

The next step is to pressurize the system with a dedicated radiator pressure tester which can be rented/borrowed/purchased if need be. AutoZone and probably a few other places will sell/rent you one with a major credit card expecting you to bring it back with no problem at all. They do it as a servce to their customers.

You cannot just take your car to a "radiator shop" expecting any conclusive results since it appears your leak is minor. You need to pressurize the system when it is stone cold for at least 24 hours, sometimes more. Sure, it's a pita to keep walking outside and pumping up the tester as it slowly drops - what you are trying to do is force water out of the system and find it. You may find only a drop or two on the ground, and you'll need to observe it constantly since these drops can evaporate quickly!

If it pisses on the ground you are lucky. The leak is not your O rings, but I doubt it - especially with the miles on your engine.
BUT - it could be your:

1) RADIATOR (BTW - lots of manufacturers use plastic in their radiators - including Mercedes) BrianK's method for detecting leaks is pretty clever but frankly you have to pull it and put it under water and pressure to find out for sure if it is leaking - remember, this is a small leak. The stock radiators are a very weak link on this car.

2) HOSES - God knows there are more than a few suspects here.

3) PRESSURE CAP(s) - We can only hope this is it. With your tester accessories you can check these out in a heartbeat. Test them - don't guess!

4) WATER PUMP - unlikely but still a potential culprit at 80K miles

5) LOW COOLANT SENSOR ON THE WATER PUMP HOUSING - it's on the front of the filler neck and of course is made from plastic!

6) AST - if equipped -what a piece of ****.

7) TURBO COOLANT HOSES - Oh yeah! Last but not least and a VERY likely suspect since they are buried down low. They turn into petrified rubber and leak around the clamps.

So - where is the leak? The only way to know for sure is to pump the sucker up and OBSERVE - Not guess. This is called the scientific method - and it works every time guys........

Once we've found it we can try to fix it.

So, until you "pump it up" for a while you'll never know.

Forget about the CRC until you find the leak - it's there hiding somewhere, and they are sneaky little bastards sometimes..

Brian, if you're not willing or able to do this then you are better off taking it to someone who knows what they are doing. They are few and far between when it comes to rotaries. They also like to sell rebuilds since it is good money. You may still need to go this route but you owe it to yourself to check it out thoroughly before you whip out the ol' checkbook!

Later,

Ron:rolleyes:

Thanks Ron,

I will attempt to pick up the pressure kit tomorrow... and might as well pick up a radiator cap/AST cap as well. I purchased a filler cap already. A little more history about my car... pretty much bone stock except intake/exhaust. When I bought the car 2 years and 2 months ago, the end tanks on the radiator cracked... as the AST leaked. Fortunately, when I bought the car, it still had a year left on the extended warantee, and the radiator has been replaced free of charge. The AST was replaced as well, but I had to fork out almost 2 bills for that since it wasn't covered. So basically, the radiator and AST are relatively new. I also replaced one of the hose going to the turbos (the small 6" hose underneath the airpump) about 6 months ago, because that develped a leak back then.

I crawled underneathe the car, removed the bottom cover... and no sign of leaks or coolant on the radiator (both on top and bottom). Also inspected the larger hoses to no avail.

I'm beginning to smell a slight hint of coolant under the hood right after I drive it. I'm not sure if it's from the overflow or not.

Like you suggested, the only way to know is to get down and do it right, step by step. My lack of patience at times gets the best of me. Will keep you posted! Thanks!

Good - I forgot to mention you'll also need to buy a special plastic adaptor, about $20, to fit your AST tank top. You should replace the other turbo hose as well. I'll bet you replaced the uppermost one. The bottom one is harder to get to but you should do it as well. Once we locate the leak (hopefully not your seals) you should also consider replacing ALL your hoses and toss a new thermostat in as well for insurance. This is expensive stuff since it is all custom Mazda hose bends, but then again so are engines! Good luck!

Ron

new development
 

Well, let's see. Finally had time to drop by a Napa parts store today (unfortunately they were closed as well as tomorrow, Sunday). Autozone did not carry the domestic to import adapter for the coolant system pressure tester. I will need to go back Monday after work. Nonetheless something interesting happened today.

Got home from a 20 min... "easy" freeway drive... didn't push the engine at all. Pulled in the garage and popped the hood as usual. Notice some hissing/sizzling sound coming from the filler neck. Apparently the filler cap was leaking. Now, I had just replaced that stupid cap 3 weeks ago... so I'm wondering why it's leaking. I checked the rubber seal when the engine cooled and could not find any cracks, etc. on it. I'm wondering if my engine just got so hot that it caused it to leak. Keep in mind that I just installed a new radiator cap (the one that goes on top of the AST) last week as well.

Another interesting thing is that the aluminum housing that the filler cap sits on was extremely hot tonight. Much more than usual. The sizzling sound I heard was actually the coolant that was leaking from the filler cap boiling. There is also an Allen wrench iron bolt/plug that sits on top of the housing, right next to the filler cap that was extremely hot. Coolant was sizzling off that thing for over 10 min after I shut off the engine. I figured that the bolt/plug was made of iron, which caused that particular point to absorb much more heat, thus boil coolant on contact.

I'm wondering if this really is where my leak is. But something tells me that for some reason my engine was running extra hot tonight... which caused my filler neck cap to leak. I know that there's no sure way to tell until I get that adapter for the testor... which I will do Monday as previously mentioned. Aaaack!!! I know I'm going to lose sleep over this!

Brian

Replace the cap.......you are fine, I think, since your engine runs fine and seems to have no other ill effects.
Seems like a lot of people are confusing "smoke" with condensation, in my opinion.......
Anyway, mine did the same thing, seemed like I was always chasing coolant.....add some, leak some, add some, leak some.....
I replaced the cap with a STANT #233 from O'Reilly's and have been fine ever since.
Have hope, young Padewan.....

Mild7, I think that you have been listining to far in advance to some of the help that has poured (NPI) through this thread. Yes, everyone has a good point, but why would you go a spend the extra dough on a tester when you could by the filler, and pressure cap first? You don't know, (or didn't know) that cap's were not your issue.

Save a buck, buy the caps.

I did buy the caps... I picked up the filler cap 3 weeks ago when my car first started leaking... and the radiator cap last week. Even so, still losing coolant (up to a pint a day). That's what puzzled me last night... I'm not sure why my cap was leaking when in fact I just bought it. Like I said previously... the rubber seal on the filler cap still looks brand new and the aluminum neck looks in good condition with now visible cracks or chips. At only $15 I don't see a problem with buying another filler cap, but since it's only 3 weeks old, I'm thinking that my problem lies else where. Appreciate the feedback.

Brian

Is there any way you can tell if it is leaking into the rotorhousing buy looking at your plugs?

AdamP

Plan on looking at the plugs once I get the cooling system pressurized. I doubt I'll be able to detect coolant in the housings without leaving the system pressurized, since my coolant loss is not severe (that is, if it the culprit is the seals). Will find out soon!

coolant leak
 

mild7- I went thru the same problem you are experiencing. The advice from RonKMIller is to the point. There are a number of things that could be the problem. Start with the easiest to fix and work your way up. I replaced the AST cap, filler cap, ALL hoses (I think there are 14), low coolant sensor, pressure tested the system, before ruling out everything except bad coolant o rings. If you can find a place that does it, there is a fluorescent dye test that can find even small external coolant leaks. There is also an exhaust gas in coolant test that some shops can do. You can also do a home made exhaust gas in coolant test. Connect a length of tubing to the connection on the neck of the coolant filler cap (not AST cap). Run about 5 feet of this tubing into a clear jug of water and place the end of the tube under the water level. Start the engine when it is cold and observe for bubbles coming out of the tubing. After the engine is warmed up, there should not be any gas or bubbles coming out of the tubing. If there is a steady steam of bubbles, it indicates exhaust gas or compression air/gas mixture is getting past the coolant o rings into the coolant. If the leak is minor, you might try to seal it. I did- was not successful. Got Mazda factory rebuilt block. BTW, mine ran fine, even with the leak, it just could not go very far, cause it would start to pump the coolant into the overflow reservoir, then the low coolant light would come on and it would overheat if not stopped and coolant put back in. Good luck.

Thanks Ron,

Well, this is what I've done so far... I've replaced both caps last month. The radiator and AST have been replaced when I bought the car 2 years ago. This week, I borrowed my brother's car so that I could leave the coolant pressure testor on for more than 24 hours. This is what I have found thus far with the coolant pressure testor:

1) Pressurized system to 20lbs... as stated in the FSM
2) Checked pressure periodically to make sure system was
constantly pressurized.
3) Had noticed that pressue would not fall below 17 lbs when
left (ie when I went to work).
4) Pulled the plugs on both rotors after having the system

oops... accidently submitted reply
 

4)Pulled the plugs after having coolant system pressurized for
over 24 hours (both rotors). Noticed no coolant on any plug.
Reinstalled plugs. Started car. Car started fine, no smoke
or smell of coolant.
5)Crawled under and removed plastic bottom/cover to inspect
what I could. Looked at both hoses going to the turbos...
and other hoses... to no avail.

So... I guess I'm going to pick up a mechanics stethoscope next... and leave the pressure tester on longer. Thanks for you help... I find this fucking leak sooner or later!!!

Brian

coolant leak
 

Brian- One thing occurred to me. I think one of your posts said that when you removed the filler cap after the car had been run, then allowed to cool, that the cap seemed to be under considerable vacuum. This is strange, since if there is a lot of vacuum, it should draw the coolant back from the overflow reservoir into the engine. Did you check to make certain the hoses to the overflow tank are not obstructed or kinked and will allow coolant to be drawn out? I used a large 60 cc syringe to flush and draw coolant thru every friggin hose on the thing to make sure they were open. Since your pressure hold test was good it sounds more like there is some external leak. That's good, since it is less expensive than an engine rebuild, but frustrating to find the leak. Even a miniscule leak will interfere with the proper cycling of the coolant in and out of the overflow tank. I would try to find someone who can do the fluorescent dye leak test. They will put a dye in the coolant, let it run until the engine warms up, then shine a black light on the engine and hoses. Even a small leak will give off a fluorescent green glow. They make a kit to do this, but you would have to buy one for about $150 to use once. Hope you get this fixed. I wracked my brain for over a month before I got mine diagnosed properly- the Mazda dealer was NO help and most of the piston engine mechanics did not do much better. Ron A.

Re: oops... accidently submitted reply
 

Well, this is actually very good news and you can just about count on it not being an engine O ring! (although frustrating since it is still hiding somewhere.) Ron A's advice is excellent, and would probably be a great next step re: the dye. Try another 24 hours of pressurizing first though. I would not be surprised if your leak only happens when it is warmed up - all it takes is a pin size hole to cause this much grief, and if in a hot area it could evaporate rapidly. A couple of other places to check that might not be obvious - you'll need an inspection mirror and BRIGHT flashlight: 1) The hose that comes off the top of the block behind the thottle body next to the firewall. It goes to the back of the throttle body. It is commonly used to "burp" the system. 2) the hose UNDER the throttle body. 3) heater hoses on passenger side firewall (doubtful). 4) I still suspect that 2nd turbo hose that you didn't replace before.........it is a real hot spot. Put that stethescope on it and listen for hiss. That's how I found mine.

You may never find it but I am thinking it is definitely a hose somewhere............One sure fire way is to replace all the hoses, it needs to be done anyway with your mileage. I always hate throwing parts at a problem but it IS amazing how sometimes this is the only cure. Think of it as insurance.

I think I found it!
 

Well, came home the other day from work (about a 20 min. freeway drive) and popped the hood like usual. For the second time, coolant starts sizzling around the filler cap. I had a hard time believing it was the cap since I just replaced it a month ago. After further investigation... I noticed a a good sized nick on the lip of the filler neck, right where it meets the rubber portion of the cap.

My next question is... where would I find this piece? There's a flange right below the top of the neck. I've checked the mazdatrix catelog (which carries a lot of parts) with no luck. Would the dealer carry this piece? Or would I need to visit a parts dismantler/junk yard in search of one.

I'm pretty sure this is where my leak has been all along. Hopefully I can locate the part, and hopefully, that will cure my car's need to drink water... Thanks for everyone's help and support!

Brian

Dealer. Prepare to submit an arm and two legs.

If the nick is really small you may want to try to dress it with some emery cloth or a jewelers file. I doubt if this will work, but it's worth a try. Make sure the rubber seal hasn't been chafed or dented - you may want to look at it under a magnifying glass in bright light. Looks like you've found it at last....good for you!
Now about that second turbo hose..............

:cool:

Later.

Listen to this! I had the EXACT same problems, where my car burped up all the coolant after shut down, I did the filler neck bubble thing, and it did the same thing as you said, and then I took out my thermostat to inspect it, and all the rubber was chewed up, restricting flow a lot. I replaced the thermostat, changes the 2 caps, and 5,000 miles after it works perfect, not one problem!

Something to think about.

I'm having similar problems but I think mine has to do with a couple newbies putting too much coolant in the system during a recent oil change.

other things:
1) I had a reman put in 6,000 miles ago. (included new h2o pump and thermostat)
2) The temp gauge never goes above half way.
3) The add coolant light has never come on.
4) car starts right up
5) never see the white smoke @ startup
6) took the filler cap off and started it up cold.... coolant quickly started to overflow but before I put the cap on (40 seconds after taking it off and starting it up) I didn't see any bubbles.

symptoms:
1) noticed leaking coming from in front of passenger wheel.
2) noticed a lil' coolant near front of car under fuses near the fans.

I've bought a 13 psi filler cap and a 16 psi AST cap and will be putting those on after work today.

My questions are these:
1) If it is the thermostat are there any sites out there that describe replacing it?
2) what psi was I supposed to get?