User 52121

Supposed to be literally hitting the road in 4 hours and suddenly the car is running much warmer than normal. Fresh (~4k mi) motor just recently installed.

Got extra Autometer gauge installed. Fixed/cleaned a few grounds, all on Saturday. Was hot Saturday (upper 80s). Test drove it for an hour - seemed to run "normal" - temp gauge just off the lower white line, temp gauge around 200.

Autocrossed it Sunday. Hot outside, low 90s. Car behaved fine.

Drove car home from AX Sunday. Everything seemed fine. Noticed sitting in driveway idling before I pulled it into garage temp climbed a bit. Figured it was just another air bubble, didn't think twice, parked it, burped the bleeder. Parked car until yesterday. Drove it (partway) to work. Cruising on expressway from the house, everything 100% normal. Hit traffic, lots of stop and go, temp climbed a bunch, and never returned. Got 3/4 of the way to work and the temp gauge hovered around the top line, maybe a little below. Autometer water temp gauge seemed to hover between 210-215 whole time - it was only in the 60s outside.

Took it home, burped it, little air came out, figured, "ok must have found another air bubble". Just took it out for lunch today, and for the first 10 minutes (mostly 55mph driving) temp gauge was normal - right until I stopped at a light. Temp climbed, got back up to 55, temp never really returned to normal. Hovers around the top white mark, Autometer gauge sits between 210-215.

Fans work. No leaks that I can tell. Burped it again, maybe a quick "fft" of steam, then coolant. Also have coolant pressure tester, have used that a few times with the car cold and never really pulled anything other than fluid out.

Radiator 2 years old. Thermostat unknown age.

Keep burping it? Drain it and put a thermostat in it? Something else amiss?

I recall burping these things is a bitch. My last motor had a steam vent kit and I never had to worry about this. It's been a few years though.

LexVan

Coolant ratio correct? Waterpump fins good?

odonnell

Skip burping, jack up the front of car about 6" and make sure heater valve is open. Crack the bleeder screw at the top of the water neck and fill the expansion tank until solid fluid comes out, best way to make sure there is no air in the system.

Then, run the car to temp (and assuming thermostat is good and has opened), repeat once it has cooled down.

Dougs951S

This is how ive always done it and ive never had an issue with air, after I usually take it for a short spin and then crack the bleeder once, thats usually all it takes to get all the air out. My car stays at a constant 180* pretty much all the time.

StoogeMoe

Since you keep finding air when you burp it, it sounds like you have a slow leak somewhere. Do a pressure test to confirm.

User 52121

Talked to a few folks more knowledgeable than me - they all think it's the t-stat.

Car up on stands now with fans blowing to cool it down. New t-stat in hand. This is gonna suck.

User 52121

Not the thermostat.

Anybody got a recommendation for a 944-shop somewhere on the NW side of LA? Just going to dump it with somebody when I get out there. Beyond pissed off and no time or tolerance to deal with it. Figure it's either a water pump or a HG. If it's a WP I'll have someone fix it. If it's a HG it's going to Lart.

Dougs951S

Test the coolant for a hydrocarbons. If none present, wp. The fact that you keep getting air on the system suggests hg.

V2Rocket

by fresh engine do you mean total overhaul?
i doubt you could blow a HG in 4k miles but if it wasn't all the way tight...how old is the WP?
when the car gets into the hot range, check if the oil cooler is hot or not.

LexVan

Sorry about your troubles. Have a safe trip out to Monterey. Enjoy your time with SP.

User 52121

Ok when I swapped the t-stat on Thursday night, I noticed that behind the t-stat, inside the pump itself, was another ring/gasket thing that the backside of the t-stat (the smaller ring) seemed to seal against. From what I can tell, it's a metal ring that's wrapped in rubber.

Well the rubber was totally deteriorated. It was all bubbled up and blistered. I took a look up inside my old motor (currently sitting on an engine stand) and noticed that this same gasket/ring thing was also present there, but was made of plastic (and fairly easy to remove). I could NOT get the old ring out of the pump that's in the car though - but I did clean up what was left of the rubber bits since half of it was gone anyways. All that's left now is apparently the underlying metal. I figured half rubber/half metal would probably seal less than just having straight metal, especially considering the seal in my old motor was very clearly plastic.

I didn't think all that much of it since I found plenty of posts and what not through Google where people talk about running NO t-stat. But while I was on the road, my dad did some digging and dug up what must've been from the old Rennlist e-mail list:

Looks to be P/N 951-106-155-00. Could this be the culprit? Perhaps the seal started to "let go" after the motor ran through a few heat cycles, and me pulling it apart finally did it in?

mytrplseven

I don't know how many miles you have since the rebuild but if the timing belt is not tight enough, the WP will not have enough tension to turn, especially at higher RPM's and can slip. Something to consider.

Tom M'Guinn

I ran without a t-stat in Miami and it did fine -- ran too cool on the freeway actually. With the t-stat in place, however, blocking the bigger opening, it might funnel more of the coolant through the small bypass port if the seal is bad, but I doubt it honestly.

You need to pressure test the system and look for external leaks. If you find no leaks, yet continue to vent air from the system after multiple attempts, then it's likely a bad head gasket or tank cap. If you find more air after harder driving, and less air after gentle driving, then that points to the HG. An easy way to know if air is in the system is to turn on the heater and listen for gurgling -- a vented system won't make gurgling sounds, but as soon as air is in the system it will gurgle. If you have no leaks, and the coolant stays air-free, then you have some other problem like a bad/slipping pulley, blocked radiator, gelled coolant, bad gauge reading, etc.

From your other thread, if you have a vacuum pump, but not a pressure tester, you can test for leaks with vacuum by pulling a deep vacuum and confirming the system holds vacuum for 5 or 10 minutes, without the reading creeping up. I'm not aware of any way to suck air our with vacuum without also sucking the coolant out (though maybe there's a system or technique out there...)

User 52121

Ok it's not really burping anymore. Not pressurizing the overflow tank like a blown HG would.

Warms up at the normal rate but then seems to keep climbing and settles in around or just above the top white line.

Here's a video with a laser temp gauge: http://youtu.be/-qRJWcaYFLQ

odurandina

prolly got the H2O pump going.

in the winter you'd see steam. but no puddle.

sniff around.