97 Miata issues After Track Day
 

I'm not sure where this goes, so I put it here. My miata is N/A.

I went last weekend for a track day, and blew my radiator. It was on the start of the cooldown lap, I cruised in at like 2000RPM. Car definitely overheated, when I pulled into pit and came to a stop it died. I trailered it home.

New radiator was put on tonight. That let me fill up the cooling system again instead of pouring coolant in and having it dump all over the ground. When I cranked it up, it smoked white - I am hoping maybe it sucked in coolant, the radiator sprayed it everywhere. Could be a headgasket.

There's a possibly related possible unrelated issue now too though - the engine is making a pretty good knocking noise. I took a video of it http://www.youtube.com/watch?v=sFp7y...ature=youtu.be

Any ideas on what's going on?

It's done fuxored.

Jim, do a compression test. Report back.

Yeah, I'll be able to get a compression test done in a few days... It's looking like I should start shopping for a junkyard motor though.

From the description I assumed it's just the headgasket. Pull the head, deck it, put it back on with a new gasket.

Headgasket is a possible, although it has stopped smoking, and the oil didn't have any coolant in it when I did a change. Also, the little bit of coolant remaining in the engine block didn't have any oil in it. I think maybe it just sucked up some of the coolant that sprayed everywhere.

The issue is the noise its making when it runs though, if you heard the video...

terminal knock... she's done.

Blown head gasket. Coolant mixed with the oil and spun all the bearings. Start shopping for a motor.

Yeah... I think my radiator cap failed, and the pressure got to the radiator and the headgasket. Well, I'll do a compression test tonight, and then its most likely time to look for junkyard engines.

Huh? Radiator cap causes head gasket failure? :giggle:

Seriously though, knock = bad. You're on the right track, engine swap time.

If you're planning to track a lot (even N/A), do a coolant reroute when you put in the new engine.

Radiator cap being stuck closed at infinity PSI combined with tracking and heating up the engine builds up pressure and stresses an already-tired 16 year old radiator and head gasket.

Oh and thanks for being an arrogant dick. :fawk:

Uhhh . . . a stuck cap can certainly overstress a radiator. But a head gasket is designed to withstand combustion chamber pressures. Spiking coolant pressure (which stops spiking when the radiator cracks at WELL below infinity PSI) won't even come close to combustion chamber pressure.

The coolant reroute suggestion was made in earnest. Uneven cooling due to Mazda's coolant flow design becomes a serious issue when you start putting more heat into the engine block than is encountered during street driving.

Bit of hyperbole, I was mainly responding to being dismissed. :friday: You're right of course - I didn't mean to say if I had gotten a new rad cap, everything would be OK today. I meant I think I have some old components that were headed to the graveyard, and I wouldn't be surprised if extra stress on them hustled things along.

I've checked out the reroute kits, I'm definitely interested. It seems spendy for where I am right now though - I didn't have any issues with cooling prior to the radiator blowing open. Although then again, I've read it does a much better job cooling #4 - I'll have to see if that one was particularly bad compared to the other 3 if I tear the engine apart after it comes back.

I am going to go ahead and guess that before long I'll want forced induction, and in that case I'll also be looking at bigger radiators and the rest, and probably coolant reroute with that. I have only one track day under my belt though, so there's a lot of driver improvement to go before the car is the limitation for sure.

Careful who you call a dick, noobie. I don't think he was screwing with you.

Besides, you are the dumbass that wasn't watching the temp needle on the track and lunched your engine. Be mad at yourself. The headgasket can take several hundred PSI of cylinder pressure between the combustion chamber and the water jacket under normal conditions. But the head warps when it gets overheated causing HG failure at much lower pressures. The stock radiator tanks are known to be weakend with age and routinely fail anyway. You were probably losing some water initially before you realized it, overheated it, and roasted everything.
You wouldn't be the first or last.

Thanks for the input, guys, I imagine you're all correct and the engine is fuxored. I'll compression test it to make sure, but at least parts are cheap on these cars!

Well shit. I realize this has no bearing on whether it's actually a bearing (HA HA HA) but the compression test looks pretty fucking good for a 16 year old engine. Spec according to haynes is 128psi minimum, 182 standard, 28psi max variance. I didn't warm the engine up, because I don't want to run it any longer than I have to, so these are cold pressures.

Tested twice, got in order from #1 to #4: 170psi 155psi 180psi 152-ish PSI

Really debating whether to fix the exhaust leak just in case I don't need a new engine...

I watched the video, and it sounds like classic rod knock.... which has no affect effect on a compression test.

C

Yeah, you're right. I probably caused more than one issue with the overheat, including bearings. At least the head might still be in OK shape.

Pulling sparkplugs one by one doesn't cause the noise to stop, but I guess the crankshaft is always turning over the main bearings even if one cylinder has no spark?

That'll help isolate slight issues, but you're past that.

C

In some defense to not watching the gauge- I seemed to had ruptured the small coolant line going from the back of the head to the stock oil cooler one day/night. The next day I was on my way to work and kicked the heat on to rid my windows of some condensation. Heat was cold. Luckily my drive to work is shor. Got out of the car and grabbed the upper rad. hose and it was cool/soft. Yet the temp. gauge was read normal at just below half from left. The engine definitely "smelled hot"....