psreynol

I've had a persistent issue with my car and I'm starting to think it is a head gasket.

water temps creep up when in traffic but never very high

water temps get too high on the track around 110 C

when I start the car after it sits I see some water out the tail pipe. thought this might be condensation

I have a persistent oil leak that I can not seem to locate. thought it was a rear main seal but it was not, thought it was the cas seal but it was not that either. I see no oil on the front of the engine around the front main. at this point I think it must be the oil pan or the head gasket.

when I put my trans back in and resealed my reroute on the back of the block (had a small leak) I bleed the coolant system but I started seeing bubbles in the overflow tank which I had not see before when I bleed the system the first time after installing the reroute.

after driving to the track in hopes that I fixed the oil leak ( only gets bad when the car is very hot) my coolant overflow tank was almost empty and ive noticed some little brown flakes in the overflow tank but that might be just crud left over from old coolant.

at this point I can only assume I need a head gasket. what else should I check?


has anyone tried the Bars Leak stuff you add to seal a head gasket? my guess is that it will not work

SJP0tato

iTrader: (7)

Stop assuming:

psreynol

the pressure you use test leak down is very low and will not automatically show a blown head gasket though it could in some cases I guess. head gaskets fail in different ways and most that have nothing to do with leakdown. the tester can be a valuable tool if you have a major problem or a worn out engine but it does not mean anything on its own like you suggest.

thirdgen

iTrader: (26)

Does it consume water??? Pressure test the cooling system and see what happens.

Savington

iTrader: (31)

Who told you this?

There are four ways a head gasket can possibly fail (cylinder-cylinder, coolant-oil, coolant-cylinder, oil-cylinder). Three of them involve failing a leakdown test. The fourth involves immediate and catastrophic bottom end failure.

Joe Perez

iTrader: (8)

Depending upon what thermostat you are using, and how well up to par everything else in the system is, this is at the upper end of "normal" for a Miata. Ducting, reroute, bigger radiator, all the usual fixes apply.


Most cars do this.



By "leak", do you mean:

1: That oil is visible on the ground underneat the car after it's been parked,
2: That the engine, transmission, etc., are covered in a film of oil, or
3: That oil is magically vanishing without a trace?



Bubbles in the overflow tank, and an empty overflow tank after a couple of cycles, could mean a couple of things:

1: When you re-assembled and filled the system, you didn't get all the air out of it, and as the engine is heat-cycled it is purging itself of the excess air and drawing in water from the tank to replace it, or

2: You have a coolant leak, which is causing you to lose coolant during normal operation and then ingest a mixture of water (from the overflow tank) and air (from wherever it's leaking) during cooldown as the coolant (and air) inside the engine contracts.


I've never seen a car more than a few years old that didn't have flakey crud in the overflow tank. People use non-distilled water, and the minerals and crap in the water seem to wind up sticking to the body of the tank. Some of it is also probably rust and whatnot from the rest of the engine. Long story short: this is pretty normal, and fairly harmless.


A pressure test of the cooling system (at the radiator neck) would be my starting point. If there is a leak somewhere in the system, you'll find it in one of the following forms:

1: An external coolant leak will result in coolant escaping the system and winding up on the floor.

2: A coolant-cylinder leak (eg, head gasket) will result in coolant entering one of the cylinders, where it can be seen by shining a flashlight down the open spark plug hole. You may also hear the coolant entering the cylinder by putting your ear against the plug hole, though this is not a highly reliable indicator.

3: A coolant-oil leak (again, head gasket) will obviously cause coolant to wind up in the oil pan. This typically causes the oil itself to become murky/frothy, and it'll usually deposit a whipped-cream like residue in the top of the head including the oil filler cap. Drain the oil and examine it. Water is pretty obvious.


By the same token, oil in the coolant is also pretty obvious. You can draw a sample off the top of the waterline in the radiator upper tank (through the neck) and also examine the water in the overflow tank. Put it in a clear glass and just look at it. You know what happens when you have oil and water together in the same container.

psreynol

Savingtion, thanks for the insight, I'm sure you have dealt with many engine problems and have have much more experience than I. my post was based on experience and talking to mechanics whose response always seems to be blah blah.. not always.. such and such can happen... likely a bring it and and we will see. though one shop is awesome and even lends me tools sometimes at no charge. Ive been frustrated tracking down some issues and have received the link to a leakdown tester several times and I have one, and use it and the engine passes with strong numbers. my apologies to the dude to linked me to the leakdown tester perhaps that is the right call.

I hope the solution proved to be very simple on all counts. but I will know Monday, likely my last track day of the season. I belvie the oil leak was a missing AC bolt, which was on my list to check when I got the car, and it was checked, but I realized that I was not sure where this bolt was located so I could not have possibly checked it. I checked it and it was missing.

I skinned the bottom and completely sealed the radiator so mo air can pass unless it goes through the radiator..

I changed out the aftermarket fan that came on the car to a oem mazda fan and I can feel a difference. the car no longer gets hot in traffic. however we see much cooler temps now in Chicago so that could help. I am cautiously optimistic that this will take care of my issues.

I mounted a cutting board from target to the floor to help with the hot foot with my custom exhaust. my sound silly but I think it will help.

I'm going to drop the car a little in the front to help with mild throttle push in mid speed corners. I need the 14mm rear sway bar and better suspension and I hope to buy that this winter.

SJP0tato

iTrader: (7)

Apply this to the underside of the body in the transmission tunnel (outside the car). It helped with hot foot problem immensely:

psreynol

I used a similar DEI product on the tunnel but the one you linked looks a little thicker. it helped but not enough. perhaps I will order another piece.