Unusual Coolant Problem (I'm actively searching!)
 

My car:

'94 R2 with a Fluidyne radiator and stock AST.

The symptoms:

I'm driving home last night and the coolant buzzer goes off. I add coolant at the filler neck and then at the reservoir. Apparently I mis-read the reservoir stick because the coolant just overflows onto my garage floor (is this normal?).

Well, this morning I go to work and the buzzer and comes on again (after a couple of minutes). I turn around and check the filler neck and it was low again! I add more coolant at the neck and notice the coolant is dripping out from the reservoir.

WAIT, THERE'S MORE!!!

Since the temps are normal, I drive to work, and the temp level seems fine. After about 30 minutes, I'm almost at work and am sitting at a red light. The buzzer comes on again! Only now, the temp indicator is DIPPING LOWER! To below the "C" mark while at idle, and then goes back up to "normal" again.

The light turns green, I continue to work (a block away) and the buzzer goes off. I pull into the parking lot and the buzzer comes on again. I shut the car off and there's coolant dripping from the reservoir.

So, what do you guys (and gals) think? My car does smoke during a cold start, but stops after a few minutes.

Thanks for the help.

it could be that when on low coolant the sensor wont be in the coolant therefore cant read properly make shore you didn't switch the ast cap and the neck (engine) cap.

The filler neck cap is labeled "Filler," and the AST cap say "...DO NOT OPEN...", so I don't think they're switched. Thanks.

As far as the temp guage going to cold, I don't know. But I do know that I had the same problem with the coolant going to the overflow and not getting drawn back into the radiator. You need to check a couple of things.
1> make sure that the hose going from the AST to the overflow is good and has no holes. Even a pinhole is enought to break the siphon needed to pull the coolant back into the system as it cools.

2>check the surface where the cap on the AST seals to the AST itself. I nick or a piece of dirt or something in there will not allow the cap to seal properly and will thus not allow coolant to be drawn back to the AST from the overflow.

Both of these things will allow the coolant to be expelled to the overflow, but will not allow it to be drawn back to the radiator as everything cools down thus resulting in an accumulation of coolant in the overflow and a shortage of coolant in the radiator / engine.

Hope this helps.

Sounds like it could either be a bad or poor-sealing cap (letting coolant into the reservoir at too low a pressure), or it could be the dreaded O-ring problem. Both have similar symptoms.

If either the cap on the AST doesn't seal, or combustion pressure is getting into the cooling system, then you get what you are seeing: not enough coolant in the engine, and too much in the reservoir, plus loss of coolant from the engine while you are driving.

The ONLY way for coolant to come out the overflow bottle when filling at the filler neck is if the AST cap is not sealing.

Thanks guys. I'll check the AST cap when I get off of work.

SPURVO, by "overflow bottle," you mean the coolant reservoir behind the passenger side headlight right?

Is there a procedure to get the AST cap to seal properly other than "turn clockwise as tight as possible"?

I had the same problem, with the Pettit AST, due to the cap not sealing properly, and some air getting into the system, also if you've just changed the Coolant in your system, I had issues like that with the stock ast when I did my radiator hoses, sometimes air gets trapped and it slowly works its way out, not healthy for the car, but as long as you don't see the water temp shoot through the roof, probhably okay as long as you get all the air out soon, and get the system to stabelize...

check the filler neck for bubbles at a cold startup. if there are bubbles coming out you could be in for a rebuild. couldn't hurt to pressure test it too.

I would agree that you probably have cap issues - make sure you check them both. I had a problem with coolant not being drawn back into the engine - coolant buzzer came on every morning but the overflow was full. I replaced the filler cap and the problem was solved. Hopefully it is that simple for you.

Replace the water level sensor, thats what cured my headache.

Check the gasket on the AST cap.

Well, I checked both the AST and filler caps and didn't see anything obvious. So I added some water and drove home with the stupid buzzer coming on intermittenly.

I got home and the coolant reservoir (overflow bottle?) is dripping. I checked the bottle and there appears to be a crack in the rubber sleeve where the tube connects to the bottle. Could this be the cause?

Thanks for all the help!!!

This problem is pretty common on this forum. It is either what others have said. I had this problem and I did everything. Replace all my caps, overflow tank, radiator, hoses, and none of it was it. Then I decided to do the final thing and did an engine rebuild and what do I see, my o-ring was toasted. If you've done everything, just hope that your engine isn't toasted. If it is, it'll be a good time to get it ported. :)

I have the same problem, I installed a new koyo radiator and alum ast. I also put on a greddy filler cap and still have overflow issues. Sometimes I drive around the neighborhood for a half hour before it happens. Not reliable, next step new engine with porting and 3mm apex seals. I just bought this car 4 months ago with 63,000 mi on it- suprised me. Too bad I love my car so much!

cold, make sure coolant is not above the dip stick mark for full.

engine warm, pressure test system ... look for leaks.

disconnect hose at ast, and make sure u can slowly suck fluid up hose from o'flow tank.

cap with spring goes on ast

I took it to the dealer to check for leaks this morning. The service manager called me back and told me I needed a new engine!

Is he BS-ing me? The car only smokes for a couple of minutes on a cold start, and the smoke doesn't have that "sweet" smell.

I doubt he is BS-ing you. You're car is showing a lot of signs of O-ring failure. Take it to another reputable place that you trust and get a second opinion. Don't just have it "checked for leaks." Have it Pressure Tested... This will give you undeniable proof one way or the other.

If the O-rings are shot, and you don't have the $$$ for a rebuild, you can look into a block welding system like CRC (lots of threads on that).

Sorry bud, it's not sounding good,
Rob

Yes, could be. If the crack allows the tube to pull air back into cooling system after shutting down & cooling off.

The cooling system should create a vacuum to draw the coolant back. It could be pulling air as well, displacing the coolant. You keep refilling and eventually overflow.

Don't get your hopes up, though.

Here's a related question:

For all of you that had these symptoms, how long did your car go on before your engine completely failed? How much mileage passed from the appearance of the symptoms to the engine failing and what is your driving style?

I'm like a lot of people here, I upgraded to a Fluidyne radiator, Samco silicon radiator hoses, aluminum AST, and Greddy filler cap, and still I see my coolant going down by a half cup every time I drive it. My temps on my DEFI water temp gauge vary while driving from 178F to 200F, with temps rising steadily during stop and go traffic. If I keep my air con on, it keeps the temps stable at 180F. I've tried everything to try to bulletproof the cooling system but I am at the end of all possible problems, other than O-ring failure. My car pulls strong still, BUT it does smoke a little for 3 minutes in the morning start only. How long do you think I have? How long was it for you before the engine died?

Assuming I need a rebuild, any recommendations?

I've heard good things and bad things about almost every engine builder, even Pineapple Racing.

Hayes Rotary build an engine for my '91 FC and I was very happy with their work. However, their reputation on this forum is spotty also.

I'd like to find a local shop.

By local, I mean in the Seattle, WA area.

Hey, thanks again for the help.

I did the "champagne bubble" test and didn't see any bubbles. The coolant was burping and overflowing the filler neck though.

Is the "champagne bubble" test conclusive? I mean if the results are good (no bubbles), then the O-Rings are OK right?

For bubble test, I cut the top off of a sprite bottle, where the threaded cap mount fits pretty nicely into the filler neck. This will catch the overflow while the engine is running so you can look for the bubbles

Hashiriya, I drove my car for three months with the failed O-ring. Drove it hard and often. It ran fine and started fine every day. Just lost 8-10 oz coolant EVERY time I drove it (exhaust gases pushing coolant out the overflow (yes, the one behind the pass headlight))

dtn, you might try going over to Bothell Import on Bothell-Everett highway and have Steve Hayes go over the car. They can put it on a lift, pressurize the cooling system, and they have an exhaust gas sniffer that can check the coolant for unburned hydrocarbons, which is probably the definitive O-ring failure test. Just call Bothell Import (425-481-3210), talk to Nate (he's the manager), tell him your car (there's been three of them in there over the last month alone), and set up an appointment.

This is such a common problem that when I need a rebuild, I want to do something to prevent it. I've read about aftermarket o-rings, metal o-ring shields, modifying the coolant passages, etc.

Anyone have any success with any of these methods to help remedy this engineering blunder? This a bigger design error than the infamous AST, IMO of course

Here's an update:

I took the car to Hayes Rotary and they did the bubble test (with a big funnel cap filled with coolant attached to the filler neck) and it failed (easier to see the bubbles with that thing attached). So they said I need a new/rebuilt engine. Don also said that I should replace the 13 lb AST cap with a 16 lb cap. I did that and the car drove fine for a couple of days.

I still couldn't believe that I needed a new engine (Mazda reman with 28K miles!!!) so I took SPURVO's advice and made an appointment at Bothel Import to check for signs of hydrocarbons in the coolant.

Well, this morning I started the car and it idled roughly with lots of white smoke and the coolant smell. So I cancelled my appointment with Bothel Imports (no point doing the sniffer test now).

No more false hope, I need a rebuilt/new engine.

My plan is to have 3mm seals, street port, and silicon/teflon O-rings in the new engine. Will I need a new ECU since I already have a DP and CB?

Is there anything else I should have done to make the car more reliable? I also have a Fluidyne radiator (4 months new).

Actually, the 16 lb cap makes the problem worse as this forces more coolant into the engine due to the higher pressure. Read up on Hayes Rotary, if'n you haven't yet. 16 lb cap was replaced by MAZDA with the 13 for a reason. Yes, the cooling system will work marginally better at the higher pressure, but at the cost of the rest of the system, IMO. Anyways... VERY sad to hear your bad news. I remember the sphincter clutch I had when I saw the tiny bubbles... sigh.

If you are only driving short distances, you can actually drive for a while on the blown seal. Just carry coolant/water mix in your rear bin, like I did. And when people ask why your car is leaking green stuff after you shut it off, just smile and say it's drooling back!

I DO NOT reccomend the CRC block weld method, as this will clog up the radiator and heater (Majik can probably find that old thread with pictures. icky!). Save up and do it right.

Steet port with CB and DP ONLY will not necessarily need a new ECU, but you should get one to take advantage of the power increase available with the port (spark timing needs to be shifted to take advantage of the larger intake charge, or some such nonsense). If you throw an intake on there, you are asking for trouble without a tuned ECU.

When I repoped my engine, I replaced the clutch, vacuum lines (I only counted 67), coolant hoses, ALL gaskets. I had Pineapple crack open a remanufactured engine I bought from Ray Crowe at Malloy Mazda (they're on the east cosat, I had it shipped directly to Pineapple) and check that all was well. The rotor bearings showed severe use, so they replaced them and sewed the short block back up. I went down there over a weekend and picked up the engine. Got a real nice tour for free (well, I did give 'em $800 for the inspection and all...). Anyway, I'm over 7000 miles with nary a problem (a few in the beginning, coolant leak and weird tapping sound at idle that went away at 1000 miles). Total cost was in the $6K neighborhood (new alternator, new air pump, new this new that! Ray REALLY likes me :) )

I'm rambling now. 3mm seals aren't worth it unless you plan on running high boost where you expect detonation and want to save your rotor housings somewhat. For more stock application, 2mm are just fine, again IMO. Plus, why pay all that money for machining?

The improved O-rings seem to be working fine for me so far, so that is worth it. Cryo treated oil hardware seems like snake oil to me, but I had Pineapple do it anyway for the 5-year warantee (YES, I know others are having issues with those guys wrt their warantee and all that. They did right by me, so they're fine in my book, end of discussion from my POV).

Bothell Import quoted me 1K for the install. There was another guy on here the other month that had them R&R his engine after it failed as they were diagnosing a boost issue. I haven't heard from him to find out how it went. Again Steve Hayes (Don's nephew, I'm given to understand. I was politely asked to not inquire as to the familial relationship... seems Don's reputation precedeth him!) at BI knows these cars pretty well, and they're good people.

That's all from Walton corner for now. Good luck, and sorry again! It'll work out... it'll just cost more than you thought. Then it'll stop costing you.. HAHAHAHA, I crack me up. Actually, since the R&R, nothing much has been a problem. Oops, there I went and pissed off the rotary gods. sigh... I'm in for an eventful drive home, I can FEEL it!

Bye now...

I had a very similar problem. My coolant light would come on and I knew I wasn't low. There were two possible situations.

1) The old fluid had never really been filtered out well enough and had left deposits needing to be cleaned out.

-solution- Go to a mechanic that can do a power flush for your coolant.

2) Thermometer has issues, and is not picking up the right temperature even though you have coolant.

-solution- Thermometer either needs to be replaced or repaired. Might just be the sensor.

Oops, Didn't see your last comment. Hope your next one works out for you.

Fortunately, I have an extended warranty. The only snag is they want to send out an inspector to look at my engine before they approve the engine replacement.

The reason I want to get the 3mm seals is gas, I always buy 92 Octane, but I want to protect myself in case I'm in a rural area (I like to go on LONG drives) and can't find a BP or Texaco. All it takes is one crappy tank of gas and boom (again).

I was thinking about getting a new ECU, but it seems that M2's (Mostly Mazda?) ECU does not support ported engines (fine print on their web site). I'll look into Pettit's ECU.

I kinda figured that if the O-rings were broken, then the 16 lb caps would make it worse. But at the time I was still in denial (despite the bubbles) and I was hoping that the 13 lb OEM Mazda cap was not really holding 13 lbs (read that somewhere on the forum) and causing similar problems.

I have no plans to do the CRC block weld method, I'm not running 100% water in the middle of the winter in this area.

As for Hayes Rotary. I did do a search and found some negative comments, but my personal experience has always been good (through 2 RX-7s); so I'm inclined to give them my business until they prove otherwise.

Thanks for the moral (and technical) support.

Your car MUST be bone stock when inspected. They will find any reason to reject your claim. I have been down that road.

Well since we are on the topic some....here is my coolant buzzer scenario.

When I slow down sometimes at a stoplight the coolant buzzer will come on and stay on until I start moving again. It will only do this once in a while....sometimes with days/weeks in between. I have went home and checked the coolant, all is well....maybe an 1/8th of a cup low...nothing big. Could be overflow or something...not sure, but it does not use any coolant, nor does it smoke on startup, nor do I have any bubbles when I test the system. I have only had the car for a few weeks now and I have had no other problems than this annoying buzzer once in a while. I have not replaced any of the coolant lines, caps, etc..yet...still exactly the way I bought it. It does have the AST eliminated...like my last FD did...but it seems to me that I have air in the system, but I have burped it a few different times to make sure all the air was out of the system, but I can't figure out why it only comes on when I slow down or stop....and then goes right back off when I start driving again.

Could it be a loose connection, cap, cracked line, o-ring, etc....has anyone heard of a car doing this before? My last FD blew a coolant seal, so I know the signs of that....but this FD is just confusing me all together. I am going to try and replace the radiator lines, heater lines, and the cap to see if I can't find the problem....but I am just checking to see if anyone has heard of this and has any insight as to what may be causing it.

Thanks,
Scott

I'd guess loose connection, lane. Pull the Y pipe crossover (the black tube running TO the IC FROM the turbos) and it's mounting bracket (held with those two 10mm bolts). That's the first connection the sensor goes to. You can try grounding that wire and checking to see if the buzzer continues. It sounds like your coolant system is fine...

If I recall correctly, the next connection for the buzzer is inside the cabin, behind the heater, connector X-07 (I think), in case the problem is not at the engine. Happy hunting!

When the engine RPM (and the waterpump RPM) both slow to idle, you get the buzzer, according to your post. Sounds like air in your system that gets forced back around with an increase in coolant pressure. Just a guess.

At risk of starting an AST debate, you don't have one, uh, oh, nevermind...

coolant
 

I know this sounds weird but the coolant thats being pushed back out is kinda like a piston engine when your head gasket goes. it creates pressure and when you shut the car off it will push the coolant back out through the path with least resistance. it has happened to my camaro. it most likely is the o-ring or maybe a water jacket is a little blocked up try bringing the car to sts and getting a coolant flush they use some kind of high pressure technique it mught help. but if you need to rebuild your engine then instead of getting a new therm make your own fan switch. Thats what I did when I start the car both fans turn on high when I shut the car off they turn off. Also the res filler will crack alot because there is no opening on the caps most cars the filler cap has venting holes to relieve some pressure build up. hey I dont know much but I had problems with my coolant had it rebuilt and my coolant guage hasnt even hit mid way yet even in dead traffic.

- Also the res filler will crack alot because there is no opening on the caps most cars the filler cap has venting holes to relieve some pressure build up. -

The pressure relief for the overflow is on the bottle portion itself, right next to where the neck joins the body of the bottle. If you follow the neck down, you will see a little black ring on top. That's the releif, and that's also where the coolant comes from when you get the pass headlight drool.

I was on the way home from work and my coolant buzzer went off. While I was replacing the coolant I dropped and lost the filler cap. "doh" Next day I went to advanced auto and picked up a spring cap because thats all they had. I've been driving the car on and off and the car has not been low on coolant since I've done this. Questions are, What purpose does the non spring cap preform, and why has the spring cap seemed to have retarded my coolant leak?