Cooling system issues....long..

[breakaway500]

Please explain the head space chem test.
Either I am used to it being called something else, or this is possibly a new way to test for cross connections between the combustion chamber and cooling system?
I currently use a hydrocarbon sniffer and coolant system pressure test to determine a possible cross connection.

[TroyV]

I think that is what it is.. I'm not sure of the official name....but it sniffs the head space of the radiator for compression gas by passing the gas through a chemical. So...I called it the head space chem test to sound more.....Matrixy

[John F]

I think that is what it is.. I'm not sure of the official name....but it sniffs the head space of the radiator for compression gas by passing the gas through a chemical. So...I called it the head space chem test to sound more.....Matrixy

You sound like the marketing guys I work with

[rnoonan]

paultg - My MR2 was a normally-aspirated '85. (I really liked that car - may it rest in pieces.) The symptoms were exactly as you describe. My theory is that the pressures in the cylinder during the compression/ignition part of the cycle are much higher than the pressure in the cooling system, and the head gasket essentially operates as a one-way valve in that situation. I sure wish I had known about the "head space chem test" when it happened to my MR2, but luckily my mechanic was experienced enough to guess what was happening. I've seen this issue in other cars since then.

The funny part of the story has to do with how and when I discovered the problem. We were at an EMRA/COM event at Pocono and as often happens there, it was foggy. In fact, the fog was so thick that we couldn't even run the course at first. Eventually, the fog thinned to the point that the corner workers could see each other, so out we went. I had done about one lap of the relatively short course and glanced in my mirror as I got to the end of the part of the oval we were running on to see if anybody was coming up fast behind me. To my surprise, the fog behind me was too thick to see through, yet it wasn't nearly as bad in front of me or to the sides! I then glanced down at my temperature gauge and found that it was pegged at maximum. I backed off and limped into the pits, where I had to pour a gallon of water into the cooling system to get it back up to normal. Needless to say, that was the end of the day for me! It was lucky that the car would work OK below 3000 rpm, so I was able to drive it home to Boston. I was also lucky that it didn't do any serious damage to the head.

-= Rick =-

[breakaway500]

Troy,this coolant modification has been discussed on a few Miata forums and it works to help keep track cars run cooler...link..http://www.949racing.com/index.asp?Page ... D=106&HS=1

I will be installing one on my car.

[mr2sc]

Don't rule out the head gasket because the fluids look good. I had a similar, though more serious, problem with my MR2. As long as I kept the rpms below 3000, everything was fine; above 3000, the coolant would boil. No oil in the coolant, no coolant in the oil, no nasty smoke from the exhaust - just great clouds of steam from the overflow tank. Problem was a blown head gasket.

-= Rick =-

Rick, is your MR2 supercharged or Turbo charged? The reason I ask is sometimes depending on the engine design, gasket failure location and/or cylinder pressures you can actually loose a gasket near a water jacket and excess cylinder pressure can force coolant out of the motor (instead of it getting into the combustion chamber). The Subaru boxer engine is known for this type of head gasket failure (even on NA motors); more common on boosted Subarus.

You can actually continue to drive them so long as you keep the RPMS low and wait for parts to show up. Very strange.

Paul G.

I'll be very happy to ditto that...several times over the 21yrs I've been flogging blown MR2s (no pun intended).
Each time, coolant was being forced out by combustion pressure into the overflow bottle.
I could drive it forever normally, without getting into the boost and it'd be fine....

As a matter of fact, this very thing occured to me at LCMT with COM in 04 during the first session of the 1st day. I kept refilling and burping the system (a bit tricky on a MR2), going through various stages of denial all day. Finally, I skipped the morning of the T/T, and did manage to complete the timed runs.

I also learned not to re-use Torque To Yield head bolts and use ARP head studs when re-assembling, torqued to the fastener's highest rating.

BTW Rick, I think its your old MR2's roll bar that I bought...maybe 12yrs ago...

[rnoonan]

Yeah, Tommy, that's the roll bar from my old MR2. It's nice to know that some part of it, even if it's an aftermarket part, still lives on. I hope to see you again at a COM event some day, but I don't get to as many as I used to. I'm still indulging my passion for mid-engine sports cars, though I've moved up a level or two in speed, engineering and $$$.

-= Rick =-

[mr2sc]

wow...somehow I find that very cool. What are you driving nowadays?

[rnoonan]

A 2006 Porsche Cayman S. What a car! It makes even a duffer like me look good. But it does require $$$.

-= Rick =-

[mr2sc]

very nice ride! hope to see you out there with it!