Why am I dropping coolant?
 

I'm hoping there's someone out there with an extensive knowledge of our coolant system. I'm having a major issue with my 93 rx7. Can anyone tell me why I'm losing coolant out of my overflow? I replaced the thermostat today and that didn't change anything. Iv'e checked all hoses for leaks and I don't see anything. when the car gets warm enough I see water coming out of the overflow. What can cause this? Please help me...

How much time is on the engine? Do a search on coolant seals. :(

your water seals on your motor are broke. rebuild time.

it works like this. when your seals fail, combustion gases get into the water jackets pushing water out of the motor into your overflow.
happened to me :)

things to look for: bubbles in your coolant while car is running
also, if gas leaks out while its running, then water leaks in when its parked. car will have trouble starting, only start with one rotor, and kick out white smoke.

i went a while before rebuilding. to do this, every time before you drive, top off at the water cap.

it got to the point when i couldnt drive 30min before my coolant level sensor would go off.

The engine has about 800 miles on it. I just rebuilt the motor.
@ Futile I don't see any smoke except for the normal early morning fog. There's no white smoke at all and it seems to be running really well, slightly rich, but that's only at idle and it's probably because it hasn't been tuned since the rebuild. I also added a OMP adapter and have a reservoir too so that could make it run a little rich.

I followed the break-in instructions to a "T" and it never overheated.
also I just found out I put the thermostat with the jiggle pin down instead of up.

Opps sorry that's 800 kilometers not miles and I should mention that I am running water only right now until I figure out why it's leaking. This may be a stupid question, but could using just distilled water w/o coolant cause it to boil over or something out of the overflow? Also, it's not coming out in bubbles its just coming out straight water out of the little black hole on top and only when it gets warm enough.

well earlier I checked the coolant system again to see what it was doing and now I'm getting a lot of smoke when it's cold. Wayyyy more than I thought was coming out. And unfortunately its looking pretty white.... I'm gonna post up a video for you guys to see shortly.

Get a pressure tester and test both your fill cap and pressure cap. Pressure cap should "crack" at approximately the indicated psi, but should hold pressure fairly close to the crack pressure as well. If not, you've got a bad cap. It's possible that your rebuilder "pinched" a coolant o-ring when they rebuilt your engine. A friend of mine here in Phoenix just experienced the same thing.

P.S. How cold is it getting in Vancouver now at night? I'd be a little concerned with straight water in your engine from a freezing perspective. Is your garage heated?

I was the rebuilder, so I'm hoping it wasn't me lol. What do you mean by crack? Would a bad cap cause water to come out of the overflow? Could this be a faulty ast too? If I test my coolant system and it's not holding pressure would that point to coolant seal if I can't locate any exterior leaks? It's not getting cold enough here just yet, still raining.

Here's a video of it running from a cold start to warm-up and a little driving after. Didi this last night.

http://www.youtube.com/watch?v=nRzDEu7oTXk

http://www.youtube.com/watch?v=ubMAbWvRKi8

definitely do a pressure test. In my case, I was using a small amount of coolant, and had a *very* small amount of smoke at startup that would go away once warmed up.

One neat thing that worked for me was to use pressurize the system using the pressure tester, leave it overnight. Pull the egi fuse, and crank the engine with the spark plugs out. For me, coolant spit out of the plug bores, which was a pretty definitive sign that I was getting coolant into the combustion chamber.

Also, did you do a coolant pressure test after you put the shortblock back together?

Don't take offense but this is why I paid someone to rebuild my motor.

Hopefully you get it handled.

Do not go by the stock temp gauge in the car !! When the stock gauge moves past center, it's already to hot.
Get a aftermarket temp gauge, so you will know exactly what the temps are doing.
Yes, it looks like coolant seals, but check it with a tester.

Also, don't "push" the car hard when you're on fumes. Put some gas in that tank.

A better description than "crack" is pop. I have a better idea...

Rent a coolant system pressure test and pressure test the coolant system itself (not just the caps) by attaching it to the thermostat inlet and applying vacuum. If you don't see any visible leaks, it is possible that it is a coolant seal.

Go to the 3rd gen FAQ thread stickied in this forum and look under the "C" section for coolant to learn more about the cooling system.

A bad cap would not cause coolant to come out of the overflow.

Remove the radiator cap with the car stone cold and start the car. If coolant is shooting out, you've got a bad coolant seal and the engine is pushing air/fuel into the coolant system.

Easy test to know for sure.

I built an engine once with the aftermarket coolant seals that are basically O-rings. One of them JUST slipped out of the groove and was pinched by the iron. Engine DRANK coolant. Also, it didn't show up after assembly when I pressurized the cooling system with the Pineapple pressure tester. Had to tear the motor back down, redid it with Mazda seals that STAY PUT like they should. Never touched the aftermarket ones again.

I disagree with the "this is why I let a pro build my engine" - yes, it's complicated to build an engine, but you have to go into it knowing you could mess something up that requires you to tear it down again. That's how you learn. If we all took that attitude this would be like the BMW forums where everyone just talks about writing a check to some shop and doesn't do anything themselves.

Anyhow, sorry for the bad news. Only other possibility would be a hole in the line going from the overflow tank to the radiator cap neck - a hole there would keep the engine from pulling coolant from the overflow tank back into the cooling system. But, that typically takes many cycles to push enough coolant into the tank to overflow.

Dale

Thanks Dale. I always learn from threads like these.

Thanks Dale, and I agree, I bought this car because I wanted to enjoy it. I love to build and I am also willing to pay the consequences of making mistakes. I'm going to do what you said and take the cap off and start it. I'll also check the line from the overflow tank and get a pressure tester. It did take a while for me to see anything coming out of the overflow so I wonder if it's not being sucked back in. I'll keep you guys posted on the results.

I can get the mazda seals from Atkins and Mazdatrix if needed right?

Yeah I'm very familiar with this fact because of all the horror stories about it on this forum. I just figured I would get by until I figured out the leaking. I went and got some more fuel for it so we are sittin at 3/4 now :nod:. Any recommendations on a decent WP gauge? I kinda wanna go digital. I've heard Defi is good, but I don't think they have digital gauges. I also saw this video (http://www.youtube.com/watch?v=YjRTQapbz0s) where this guy had a digital temp readout in his dash.

so far looking good, no bubbles. I'm getting the pressure tester next wednesday. Right now I'm flushing the coolant system ad I also replaced my AST cap just for the heck of it. How do I get coolant out of my overflow? is there a drain plug or anything?

I always use a turkey baster haha.

Dale mentioned the coolant line going to the overflow from the ast make sure it is a good hose if it is weak it wont function properly and cause the overflow problem your having. I also had this problem on my car and I replaced the hose and never happened again.

As I thought about my problem Ive remembered a key difference between my situation and yours, mine overflowed after I had driven it awhile and after it was off for a few minutes it would start to overflow.

Alright I took the overflow tank out and then drained the water from the radiator. I inspected the line that's coming from the top of the AST to the top of the overflow I also did a visual on the other two lines as well. I don't have a way to test for vacuum yet, but I did blow and suck on the hose and the plastic tube in the overflow tank. I didn't hear any air releasing. I filled the car with coolant as per the FSM and am currently waiting for it to cool down so I can burp it.

so the overflow tank is sitting outside the car but still hooked up. I heated the car up and drew a line with a marker where it was when I filled it cold and where it stopped once it got hot. The water hasn't moved at all and its been about an hour and a half since I did that. I did this after my last post. What happens if you pull the cap off the fill neck and the pressure releases?

If you pull the cap off the fill neck it'll burn you really bad and you'll never do it again.

I know that, I waited about 40 minutes before I touched it and even then I used a rag and went slow. My question was whether it would make the system unable to suck coolant back in from the overflow.

Update

So last night I went back out and checked and sure enough the water still didn't drop down from the line I drew. So that tells me it's still not sucking it back in, or maybe there's just a ton of air. I put the excess coolant from the overflow into the fill neck and warmed it up again. I still can't tell if the thermostat was opening but I did warm it up for a while and again watched the overflow slowly fill to almost the top. I shut it off again and let it sit overnight.

Its now just after noon and I checked the overflow again. Nothing was sucked back in at all! Bad AST? Still has air in it? This time when I popped the fill neck cap there was no pressure whatsoever and after squeezing the upper rad hose I was able to dump most of the coolant from the overflow in using a funnel. I also pulled the TB hose. I warmed it up and there was a lot of smoke but it smelled normal to me.

I'm not sure if it smokes more because of the 2 stroked OMP or not. After it got up to normal temp. I brought the rpms to 25 hundred and held it for about 20 secs. Checked the overflow, and repeated this cycle until I finally saw the temp fall way down and then get back up to normal temp again. When this happened the add coolant light came on for about 5 secs then stopped. Also bubbles were coming out of the overflow.

Just to add I should let you guys know that when I changed the T-stat I used an OEM one but not from mazda. It does have the pin at 12 o'clock and is rated for 82C. Today when I warmed it up I turned the A/C and fan on hot so the rad fan would blow.

Here are the vids I took from the last post http://www.youtube.com/watch?v=adZ--lbohb0

and part 2 http://www.youtube.com/watch?v=rkEvs67b5uc

They are kinda long, but I hope this helps out

Also the T-stat I bought was a Stant Xactstat 48438 rated at 180F/82C

It's funny to watch your videos. This car turns the average Joe into a diagnostic expert in very short order :) Ecstacy and Agony is how I describe FD3S ownership.

Also, I hope that you're running that thing in a ventilated carport and not a garage. If in a garage, you could be headed for a shorter life than your car, so be careful :)

I think you're looking at the right things. If running the stock ECU, you can turn on the AC at any time and the fans will turn on. Did you know that? Also, I'm not a fan of those pressure caps with the red pressure relief lever. Most that I've ever tested (even brand new) would not hold pressure. Not sure why you bought a 16 lb cap. Just get a coolant tester with the adapter for testing caps, head to NAPA and start testing 13 lb caps until you find one where the pressure "cracks" between 12 and 13 psi, then holds that pressure for awhile. I did this a year or so ago when I was chasing a coolant problem similar to yours, and it ended up that my cap was BAD. Also, when I went to my local NAPA, I tested 5 caps that they had on shelf and 3 of the 5 NEW caps tested bad, so take the time to ensure that you have a good cap.

Finally, my stock temp gauge sits SIGNIFICANTLY lower on my sweep than yours, albiet I'm running a Apexi Power FC with fans set to come on at 86C. I'd recommend an aftermarket gauge sometime in your near future so you can see the "actual" operating temperature instead of the stock "weighted to the middle" one. It rarely moves higher than yours unless there is a major problem, then it sweeps up fast, but unfortunately that's usually too late to keep it from overtemping. IMO, aftermarket water temp gauge is a must!

Pics of my "non vented" Stant cap!

http://i684.photobucket.com/albums/v...CCAZ_1/011.jpg

Lol we have a love hate relationship. Yeah I knew about the fans, I kinda want to get the other switch from the FC so the fans come on earlier too. I thought that I needed a 16 lbs cap, that's what my manual says to test it for, but I kinda remember reading something about a recall changing it to 13. I am currently in the market for a water temp, boost and A/F gauge and wideband. WT is most important though. I will go ahead and change both caps on the fill neck and on the AST. Just so I know I got it right, its a sealed cap on the fill neck and 13lbs on the AST right? My pressure tester will be here on Wednesday this week, so I'll have lots more info for you guys then. Thanks for everyone's help so far

That's right. Here in AZ, you can "rent" a coolant pressure testing kit for an $80 deposit from Autozone. Bring it back and they credit your card. Keep it, and eventually they charge your credit card. That's how I ended up with mine... I can take a PIC of my setup for cap testing if you'd like, just so we're comparing apples to apples. Let me know!

maybe try bleeding the coolant system out for air if u havent already done so , and do you still have the AST all hooked up and not plugged?

just a quick comment. i didnt see anyone say this but...

i recently had coolant flowing out of my overflow pretty bad. so bad i had to fill the car with water every time i went to drive....EVERYTIME. anyway, i got the car on the lift and saw nothing. i decided to take out the overflow tank to see if it was cracked or something.

from my discovery, the overflow bottle is made of 2 separate pieces. the neck and the bottle. just so happens the previous owner broke the neck off the bottle and taped the two together. so when ever the overflow would overflow higher than where the neck was taped, it would leak out.

give yours a look if you havent already...

I have been bleeding it for the past few days, but it doesn't seem to be working. Somehow air is getting in. Yes the AST is hooked up, just got a new cap today a 13lb Stant cap and I pressure tested it first to make sure if was in spec.

I also did take the overflow out of the car to inspect it, and it has no leaks.

I'm going down to Washington on Wednesday to rent the tester. That would be cool if I could see your setup so I can make sure I got it right.

Jrexx6 no one seemed to answer your question about using just water as the coolant ..remember water will boil at 212 degrees ..and your seven can get there in a heartbeat and you will never know it especially if your using the stock temp gauge.
I reccomend you add the boil over protection. if you do add the prestone this will start to smell sweet out your exhaust if it is the water seals. Once you confirm you are leaking you can do a rebuild or spend 50 bucks. I have had excellent results using "Blue Devil" on my FC and My Freinds FD. This will last a year or longer in many cases. I watch my AEM digital temp gauge like a hawk cause before I found Blue Devil I tried several other products that lasted only weeks at a time and the temp can spike to 245 in a just a few seconds! Blue Devil has been working very well for me and I added an extension to my low coolant sensor so I reduce the amount of false alarms. good luck

Is this similar to Alumaseal? I've read some good things about that too. I'm looking for a permanent fix though as well so I'm not sure If I wanna go this route.

In addition to the lower boiling point, pure water is going to cause rust and corrosion inside of the cooling system.

Here you go! Took some quick pics this morning. Make sure you have an adapter in the test kit that securely fits your style of cap. As you can see, I'm running a larger US style cap. Good luck and report back!

http://i684.photobucket.com/albums/v...AZ_1/005-8.jpg

http://i684.photobucket.com/albums/v...AZ_1/006-8.jpg

http://i684.photobucket.com/albums/v...AZ_1/008-2.jpg

http://i684.photobucket.com/albums/v...AZ_1/009-3.jpg

http://i684.photobucket.com/albums/v...AZ_1/010-2.jpg

No Alumaseal is a powder not made to handle the high heat of compressed gas. My freind with the FD said the same thing ..but with a Seven there is no permanent fix ..your engine was just rebuilt and your having coolant problems. Several other forum members have commented they blow seals when they boost a cold engine. Do yourself a favor and research Blue Devil. It is a pure Liquid that reacts to heat and forms a permanent seal for most head gasket leaks. I thought it may help my rotary seal issue after several other products failed. it works in about 15 minutes how can that hurt? It stays in the coolant system and contiinues to work the whole year round before you change the coolant again.

I watched a youtube vid the other day on it. It seems to work really well. I'll have to do some reading on it some more. I'm going out to do my pressure test tonight, so I'll report back tomorrow with results. wish me luck!!

Well My friend with the FD did not believe me ..in fact he laughed and said he would do a rebuild if that happened to him. 6 months later his sons FD blew the coolant o rings and he was calling me and asking what was the name of that stuff?? He went out and bought the 35 dollar version ( can mix with antifreeze) and He was shocked! its been 8 mos for him and no issues. My Fc has been going on two years. good Luck!

You shouldn't really be needing to use any blue devil/k-seal/alumaseal solution with a recently rebuilt engine though!

Try bleeding it through properly, there are guides around that tell you how to do it in a foolproof way (basically involves removing the throttle body coolant line and pouring until it comes out of there - whilst making sure the ast is full). You wouldnt believe the trouble I had getting the air out of mine just by topping it up from the filler.
Hopefully the pressure test will tell you more!

Update
 

Ok I got my pressure tester and here were the results:

I tested my fill neck cap and It was holding less than 12lbs of pressure. I believe this is supposed to be unvented right?
My new AST cap was holding just over 12lbs
My old AST cap was still good lol and held around 13-15
The prestone cap I bought was a 16lb cap but it was venting from the top of the cap.
I pressure checked the system throught the fill neck and found a small leak revealing itself at about 12.5 lbs on the upper rad hose, just a loose clamp.
I wasn't able to get the pressure up to 20lbs throught the fill neck because the AST was letting the air into the overflow at around 13 or so.

I also tried throught the AST and got the same problem. Should I be blocking the passage from the AST to the overflow tank while doing the pressure test? It doesnt say anything in the shop manual about it, but I did read something on here about it the other day.

The good news is that this morning when I went to check on her again. The coolant level in the overflow got sucked back in to the engine. It was almost overflowing last night and now its about 2 inches from the bottom. So now we know that using the original caps and fixing that upper hose leak the system actually works.

Now I'm going to add coolant with the TB hose disconnected and see if she can be burped properly.

Just put coolant in it and let it get warm, heater is blowing cold air. I'm beginning to think I may have a water pump problem or the Stant T-stat I just got sucks. The upper rad hose is cold. Anyone have any ideas as to why I may not be getting flow to the heater core? Air bubble?

I put it the old T-stat and it works the car is heating up no problem. I hate the fact that everytime I do something to the coolant system I have to bleed it all over again. Putting the Overflow back in place and bringing it to Forcefed tomorrow so they can give it a once over.

Awesome. Sounds like things are starting to work out!

What AST do you have? If it is a Pettit AST, its likely that the top is warped, and no cap will seal it properly.

Stock AST but it's still in working condition. I'm looking for a good aftermarket one though.

I drove it around today my coolant light keeps coming on when the thermostat opens. I'm thinking about just taking the dang thing out. I bought a digital temp reader to check how hot it is getting and it seems to be a lot less then what I was thinking.

I need a good temp gauge though so I can see the water temp continuously. Do you guys have any recommendations?

VDO gauges

The Conclusion...
 

Well folks I took her to Forcefed today and did the funnel test on it. I have a coolant breach folks.:( Unfortunately I'm gonna have to tear her down again and put new seals in. The good thing is that while she's out I can do some other upgrades I wanted to do. I think I'll add in the gauges I wanted to and maybe even install a stand-alone. Thanks for all your help guys. I'll post up some info once I have her all taken apart so you can see where the failure was.

yes, please keep us posted on what happened!!