The car is a '82 5 speed.

I've had a slight fluid leak for about a year. Every couple of months the coolant light would come on and it would take about 12 ounces to top it up. I wasn't sure if it was the cap not holding pressure or what. Lately I noticed fluid in the indentation on top of the coolant expansion tank, so the tank is toast & I've got one of Carl's aluminium tanks on order. The car has never overheated or even run hot - until now.

About two days ago, I hopped on the freeway to run an errand and as I took my exit after only about 5 miles, I saw that the temperature guage was almost pegged & then the warning light came on. Let it cool down, topped it up and limped home. Again, it was boiling over after only about five miles. A friend suggested that maybe the thermostat wasn't opening, so yesterday I stuck in a new thermostat & replaced the expansion tank cap. No help - the car was overheating again within 5 miles of freeway driving.

I know I need an expansion tank, but that has been leaking for some time without any overheating. Any thoughts on what would cause my car to suddenly start overheating almost immediately? The waterpump and thermostat had last been done about 36,000 miles ago. Thanks.

James

 

If you have no white smoke coming out the tailpipe during cold starts, then it's probably:

- Air pockets in the coolant system from the leaks causing poor flow
- Water pump is toast

Dan
'91 928GT S/C 475hp/460lb.ft

 

Is the fan working?

 

5 minutes? I sure would suspect the pump. Plastic or metal?

 

Thanks guys.

Aryan: Yes the fan is working, but at freeway speeds, the fan really doesn't do anything.

Dan: No smoke that I've noticed. In my experience with water pumps they usually get noisey, wobble or leak when they fail. None of those symptoms here. The only failure mode I can think of is that maybe the impeller came loose - but no way to check that without pulling it apart. I still have the old pump from my last timing belt change....

Bill: I don't remember if it is plastic or metal - I think metal. It was a "new" pump - whatever 928 Int'l was selling about 5 years ago.

James

 

Check compression!!!

 

Is it possible to do a water pump swap without doing a complete timing belt/water pump disassembly?

I know, I know, but I have my old water pump & time and finances don't really allow much more at the moment.

James

 

Hi - impellers have come off on rebuilt pumps (ask me how I know). Exact symptoms you have here. One way to tell for sure is run the engine until it's getting hot (but don't let it overheat) and feel the hoses inlet / outlet hoses. If they don't heat up...

 

Unhook your hose and see if it is flowing prepair for a mess.

 

Yes. Since the belt doesn't have to come off the pulleys and harmonic damper can stay on.

 

How do you get to the water pump bolts that are obscured by the damper? And what about the center timing belt cover?

Dan
'91 928GT S/C 475hp/460lb.ft

 

There are no water pump bolts that low on the block. I think you're right about the center cover so the damper needs to come off.

On my car the center cover comes off without the damper because I busted off the tab that goes underneath the tensioner. A handy thing to do, actually.

 

They don't? The water pump pulley almost touches the damper, so there are a couple of bolts under it that are obscured. The pump has to be that low so that the timing marker sits right on the damper:

https://rennlist.com/forums/1503211-post28.html

I really don't see how the pump can be removed without taking the damper out even if there was no cover. The above pic has the damper almost all the way removed and it still looks like a bitch.

Dan
'91 928GT S/C 475hp/460lb.ft

 

the damper HAS to be removed to remove the water pump and the also the center cover IF you have a AC pulley installed, otherwise the center cover will come off if no AC pulley is fitted

 

OK OK

Be prepared to take it all off.