924Board.org

JvGinPDX · Guest

I found out the hard way that a 924 thermostat that runs cool most of the time can still cause overheating and a warped head. I just replaced the hoses, water pump and timing belt. The thermostat was replaced a couple of years ago, so I left it in there.
I took a spring break trip with my son from Portland to Southern California. The car never made it. It overheated in a steep mountain pass at the border. It was running cool, then suddenly hot. I pulled over to let it cool, then added some water. The car ran ok, but I started hearing exausht noise, but I was not too concerned, since I thought it was just loose bolts I could tighten the next morning. I drove the car another 400 miles or so to Sacramento. The car would not start in the morning, and I noticed hissing out of the expansion tank. I realised it was a blown head gasket. I had it towed to a shop that works on out cars, and then rented a car to continue the trip with. I need a cam, lifters, valves, and will cost about 2 grand. Since the car is pretty much restored, and was running great, it will be worth the expense. What are the warning signs of a failing thermostat? I want to avoid having someone else loose their car.I have not lost an engine in 30 years of driving. I

gohim · Guest

Are you sure that your radiator fans are working? If the fan switch or fan relay, or ac relay fail, it is possible that the cooling fans will not turn on when the coolant temperature rises.

Roger Hall · Guest

the only thing i know of is to keep an eye on the temp gauge the alumium head on these cars can warp but i am surprised that it caused the valves to go

wdb · Guest

your thermestat may not have caused the overheating, steep moutain passes are know to cause a water cooled car to over heat. Vw use to use this known problem to advertise thier air cooled engines.

JvGinPDX · Guest

I made the mistake of coninuing to drive the car for an additional 300 miles or so. The coolant did not leak, the car did not overheat after I had the thermostat replaced. What I thought I heard as an exaust leak could have been a stuck exaust valve. I will know more when I pick up the car in Sacramento next week. I will report on the damage. So far I know I need a new cam and lifters $$$$.

Richard · Guest

Sure is a bummer....I don't want to draw this out, but are you sure it was the thermostat? Did someone take it out and put it in hot water and watch it not open? Did the cam bend because the head warped (they can be straightened) or was the damage due to scoring because of lack of oil. How will the head be straightened? To much milling can make for timing problems. It really should be pressure tested and oven straightened on a jig. Aluminum head specialists know how to do this. These are just some of the questions I have, of course I am going by what you said. Wish I could see for myself.

Joes924 · Guest

When things get hot dont the valves stand a chance of getting tight or stuck..

_________________
JoeD. 1979 924NA
MSD6 rev control/big bore TB/P&P.head
Bursche header/Schneider cam/dialcam

[ This Message was edited by: joes924 on 2002-08-28 14:34 ]

JvGinPDX · Guest

To Richard:

The shop sent the head to a place in Sacramento that bakes the head some how. It had to be baked twice, then a valve job done. I took the car to a radiator shop shortly after it overheated, they tested the thermostat. They said that this was a two part thermostat. The car would usually run cool, and I could not get much heat from the heater. after I replaced the water pump and hoses right before the trip I took it on a drive in southern Washington, no problems. But once at a stop light, it overheated, returnuing to normal after I got the car moving. I noticed that the fan would come on at high temperatures, I believe that the stat would open at too high a temperature, then let coolant to the radiator. As soon as the water got there, the fan sensor would activate the fan. I am reportring all this so that other owners will not have the same problem I did.

Richard · Guest

That sounds real good about the head. Basiclly they heat the head slowly in a large oven and this relaxes the metal. Weird that the t-stat behaved so irradicly. Good luck!

dwak · Guest

JP,
You need to put in a manual over ride switch in for the fan and just turn it on whenever you get into traffic or mountain passes. Maybe even one of those high speed fans. On one of my cars, I had a manual control for the ex-aircon fan. I've had engines just 'hammering' in Mexican mountain passes but if you stopped you'd be killed by a lunatic in a bus.
dwak

JvGinPDX · Guest

Well, the car is fixed and back in Portland. But the repair bill is about what the car is worth. It is only because this car drives great, and fits my tall body better than anything else, or it would have been more economical to walk away from it.

The mechanic in Sacramento said that most 924 cars just go to the crusher. He was unable to find a head that fits an early 1977. He claimed that the later heads do not fit the early engines. is that true?