charliegt

Before anyone says "search" - I have searched, over and over, for the past several months. I am posting this as a last resort before I start tearing the engine apart looking for a leak, or worse.

Alright. I'll start out with some background information about my coolant issue. The car is a 94, touring model, 5spd, by the way.

1. The AST was removed by the original owner.

2. After getting my car back from the body shop I had a coolant leak due to the upper radiator hose being sliced where it connects to the radiator because the airbox was pushing down on it too hard. I fixed this and was problem free for a few months.

3. My coolant buzzer started going off again and I could smell coolant. Upon investigation I found that the hose clamp on the upper radiator hose (where it connects to the filler spot (not sure of the exact name) was broken, AND coolant was leaking out around the coolant level sensor. I replaced both faulty parts.

2 weeks later the buzzer went off again. I checked the level by taking off the filler cap and was only able to add a very small amount of coolant. For the next several months I have been adding small amounts of coolant about once a week.

The strange thing is that the buzzer only comes on when the thermostat first opens, and goes off after a minute or so (once the car is warmed up).

About a week ago I noticed the smell of coolant under the hood after I had been driving. I discovered that the hose clamp I had put on (the type you adjust with a screw driver) had become loose and I coolant was squeezing up from under it. I re-tightened the clamp and added more coolant.

Now, even after topping it off, the buzzer comes on once the thermostat opens (it goes off after a minute or so and very rarely comes on any other time). This only happens during cold starts. Also, after the car had sat and cooled down I checked the filler spot and it was pretty low (I could still see the top of the coolant but it was down more than usual). However, I checked the overflow tank and it had a lot in it.

The car is obviously losing coolant somehow. The only ways I can think of are : a leak that I don't know about, burning coolant, or possibly air bubbles in the system (although I have been adding more and more for several months so I am doubting that is the case).

I am also thinking that maybe the overflow tank is not installed properly, or perhaps the return line is clogged. This was a used tank that the bodyshop installed. However, if that were the case wouldn't coolant be spilling out? It does sometimes, but usually only after I've added a lot of coolant.

Another problem, which may be unrelated is that the other day I tried burping the system (ie topping it off, starting the car for a minute, adding more, repeating) - but all I managed to do was flood the engine and couldn't get it to start for about 20 minutes. Later that day though, when I tried to start the car again it idled really rough and then quit. I started it again and it idled rough so I gave it some gas and it straightened out. Ran perfect after that.

The engine has always started right up with no trouble, warm or cold, and ran great - tons of power. It isn't my daily driver so I only drive it every other week or so - and when I start it after sitting there is some smoke but not much.

Any help or advice would be great, I'm getting really frustrated messing around with this for so long and still not being able to figure it out.

Thanks a lot,
-Charlie

DaleClark

iTrader: (55)

I'm having similar woes with the customer's car I've been working on. In his case I think it's bad coolant seals - he's overheated the car more than once, and the engine has 113,000 miles on it - it's pushing its luck.

In your case, could be a few things. First off, make sure you don't have any small leaks in the coolant system. If you can get a coolant pressure tester to pressurize the system with the car off, that makes finding leaks pretty easy. Also, if there's even a pinhole leak in the rubber hose going to the overflow tank, you'll lose coolant recovery - coolant will push into the overflow tank and never get sucked back into the engine.

I prefer to use Mazda spring clamps on all the coolant hoses - they maintain a constant pressure on the hose, even as the hose and the system expands and contracts with heat and cold. Screw clamps don't maintain a constant tension.

Dale

DaveW

You already said some of this, but...

The fact that the coolant sensor buzzer comes on only when cold COULD be a sign that the coolant is not being sucked back from the overflow tank, and the overflow tank is shedding the excess each time you run the car, requiring refilling.

Are you SURE that the line to the overflow tank is not pinched, or doesn't have a pinhole somewhere? Is the tank, itself, leaking slightly, or the nipple to the coolant-return hose cracked? Is the pressure cap working properly, allowing the air in the engine to be expelled and the coolant to be sucked back to the engine?

The worst-case scenario would be a coolant o-ring allowing some of the coolant into the combustion chambers, and some combustion gasses into the cooling system. Search for "champaign-bubble" or pressure test cooling system.

The flooding sounds like a typical situation when the car is not warmed enough after starting from cold.

charliegt

Dale,

Thanks for the response. I forgot to mention that the engine has about 60k miles on it.

Anyway, what you are saying is that there is only 1 hose going to the overflow tank? I noticed that the shop installed it incorrectly, the hose runs up over the airbox. When I had the airbox out I tried to find and alternate route but gave up because I didn't think that it mattered. Would this cause the coolant not to be sucked back in? Also, do local autoparts stores like autozone sell coolant pressure testers?

Thanks again,
-Charlie

DaleClark

iTrader: (55)

Stock, the overflow hose does run under the airbox to the overflow tank. BTW, the overflow tank is the tank down in the passenger side fender that's clear plastic, not the AST - just making sure we're talking about the same thing . The overflow hose runs across the cross bar going from left to right between the frame rails of the car - the bottom of the intercooler is attached to this bar.

Most local parts stores won't have a coolant pressure tester. I rented one from Autozone but it only worked with domestic radiator caps - that would actually work if you had, say, a Pettit AST that used the large domestic cap. I'm planning on buying one from Harbor Freight - they have one that will adapt to import-style cap use. Pricey for one tool (like $70 or so), but worth it if you have a Harbor Freight store in driving distance - ordering from them takes FOR-EV-ER to get your stuff.

Dale

charliegt

Yeah, we're talking about the same part. The bodyshop ran the hose over the airbox, which I knew wasn't correct but I didn't think it would matter. Do you think that this could be causing the coolant not to be returned to the system? I'll call around this weekend and see if I can track down a pressure tester.

Thanks again,
-Charlie

charliegt

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charliegt

bump

DaveW

Running the overflow hose over instead of under the airbox should make no difference, UNLESS the hose is collapsing or being pinched (between the hood and the airbox?) because it is on the top.

If the flow is unimpeded, then the routing will make no difference.

Power_Put

i didnt have patient reading above cos no time but let me try i had the same problem i thinks its the wire that goes to the water level on the neck trace that wire and i found mine laying around under the coil rack and if it touches the engine its going to buzz

good luck

jeremyb

If you're talking about the water-level sensor, grounding the wire causes the buzzer to stay off even when you have no coolant. Alot of people that have faulty buzzers going off all the time just connect a grounded wire to the sensors wire via T splice. Having disconnected and NOT touching ground, should make the buzzer go off.

Jeremy

charliegt

I've never taken a rotary apart before, is a coolant o-ring the same as a head gasket? What would be involved in replacing it?

Now that I'm back in town I took another look at it. The coolant overflow tank had quite a bit of fluid in it, but I had to add a lot to the filler spot to get the level up to the cap. This is making me think that there is a problem with the return of coolant to the system. However I am still having problems starting the car. Today, it had trouble starting twice - just like it was flooded, except the first time was a cold start after sitting a week, and the second time was after completely warming up and sitting for about 5 minutes. Any ideas?

Thanks,
-Charlie

DaveW

QUOTE:
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"I've never taken a rotary apart before, is a coolant o-ring the same as a head gasket? What would be involved in replacing it?

Now that I'm back in town I took another look at it. The coolant overflow tank had quite a bit of fluid in it, but I had to add a lot to the filler spot to get the level up to the cap. This is making me think that there is a problem with the return of coolant to the system. However I am still having problems starting the car. Today, it had trouble starting twice - just like it was flooded, except the first time was a cold start after sitting a week, and the second time was after completely warming up and sitting for about 5 minutes. Any ideas?"
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The coolant o-rings seal between the engine segments. To replace these, the engine needs to be disassembled, and a full rebuild should be done at that point.

The overflow tank should have a dipstick attached to the cap with a bunch of cross-slots. The tank is full when the coolant is ~8" below the top cap.

If you have trouble starting, AND there is a LOT of white smoke at start-up, AND you are losing coolant, AND a pressure test shows a loss of pressure, but there are no external leaks, then your coolant seals are probably shot. A quicky test for bad coolant seals is the "champagne-bubble test" - search for that.

charliegt

Ok, after reading through countless posts I'm convinced I need a new motor. However, when I tried the champagne test (idleing engine cool with filler cap off, I did not see any bubbles).

Today, I'm going to go under the car and pull the plugs to check for coolant in the chambers. I'm also going to do a compression test and check the oil for coolant. I checked with autozone and they don't have a coolant system pressure tester.

-Charlie

DaveW

Just in case you were thinking you could confirm seal failure with a compression test, a compression test won't detect coolant seal failure unless they are totally failed. Usually, they only seep, and that's not enough to detect by a compression test.

Also, coolant seals have been known to only seep coolant into the engine when the coolant temp and pressure builds up after the engine is shut off. Sometimes, corrosion in the seal grooves can cause some leakage even though the engine was never overheated.

charliegt

Dave,

Thanks for the info. I'll keep that in mind when I'm looking for a sign of a leak. I plan on rolling the car into the driveway to get under it, now from what I've read if there is a seal problem there should be some evidence of coolant in one of the combustion chambers right? If I pull the plugs and crank the engine shouldn't something shoot out? Or maybe the plugs will smell like coolant already.

Thanks,
-Charlie

rotorhead333

I doubt you need a new motor. Do a pressure test first, chances are you have another leak somewhere. Do you smell coolant under the hood or in the car while the system is hot? if so, there is a leak somewhere among the thirteen or so hoses. Also, the coolant level sensor is a piece of crap and likes to corrode, spend the $50 and get a new one. If the coolant system isn't syphoning back and forth between the overflow is because the system isn't holding pressure and won't flow very well either. If you are suspecting an internal o'ring failure and aren't getting white smoke out the tailpipe, there is still a way to check for that failure. Any shop that does emissions repairs and has a gas analyzer to test emissions can test for exhaust bypassed and present in the cooling ststem or excessive hydrocarbons in the coolant. This is how headgasket failures are verified also. Good luck!