My mechanic is taking off the cam cover now to get to cambelt then water pump. He said by his experience he knows it is not just a sensor type problem it is definitely overheating. he doesn’t think its water pump as you can normally hear that. No leaks anywhere. No sign of steam on any plugs. He thinks likely to be head gasket. No oil in water or water in oil but he says sometimes doesnt as burns it off. Says also there is a fault with that model engine in that the head sometimes cracks when you remove it. Would be interested in thoughts on that.

 

BULL****!!!!!!

 

Get a second opinion from a REAL Porsche Doctor.

 

If so, where's the coolant going?

 

Heinrich,
The point is that if the impeller comes loose the coolant isn't circulating and therefore isn't going anywhere.
Ritchee,
I smell a payment hungry mechanic. Sounds like he thinks he has a live one ready to throw a fat wallet at him.
928 heads don't crack unless the engine has overheated to the point that the bearings melt, and you're a long way from that, OR if the heads are improperly removed or reinstalled. From the sound of it you PROBABLY don't have a head gasket problem. If your compression has tested good and if you have no products of combustion in your coolant (an easy and inexpensive test) you have a coolant flow or an air flow problem.
You need to find a mechanic who's willing to LISTEN. An intelligent mechanic who's willing to have an open mind is better than an experienced one who won't listen.

 

I thought I had read coolant was beng lost, but I see not. OK.

 

Pay attention, H!

 

If you don't have water in the oil, or oil in the water, and you passed a leak down test, start walking in a hurry.

You've eighter got a liar for a mechenic, or a not very smart one.

Your problem sounds like a t-stat, or water pump problem.

 

good information here. probably not a headgasket. if it is, pour in a bottle of Barr's Stop Leak. I raced on this stuff for 2 seasons, with a leaking headgasket. stuff is amazing. doesnt hurt anything either. next, if it is still over heating, (or probably before this) verify the water pump is flowing. KEY question. was the radiator hot in all areas (amazing how many mechanics forget this simple test) your over heat sensors and temp sensor are on the block , however, the fan cooling switch is on the bottom of the radiator. so, if the radiator is hot, fans coming on, and still overheating, then you probably have a head gasket issue. thermostat is easy to check by the temp of the radiator as long as the pump is working. if the pump is bad, it will over heat very quickly.

mk

 

I had the broken water pump impeller on the Holbert build up . it lasted for 1.5 race seasons and had intermittant over heating issues. little did i know, until it failed (BY THE WAY< never a peep out of it , no noise!!), that the shaft attached to the impeller was slipping. it would catch intermittantly, usually spin free on start up. I thought it was a sticking thermostat. anyway, finally, it failed and certainly made no noise at that point, as the impeller was stationary and the little shaft was spinning freely.

sounds like you need a new mechanic. or have someone else diagnos and he can do the repair if he is a good wrench.

Mk

 

Also, he probably saw bubbles due to air in the system when he WRONGFULLY removed the thermostat. It cant be removed anyway, its needed for proper flow. if your mechanic knew anything, he would have wedged i open and then re installed it. (heck,they are only $15-20 bucks). If that didnt work, its no big deal to replace it when the real culpret is found. (water pump)

mk

 

Update 14/1/05. Mechanic has reported that they have found an impeller problem in the waterpump. They have fitted a new thermostat, will be fitting a new cam belt and water pump and putting car back together early next week. He said with luck that maybe it, that there is a possibility the heating has affected or shortened life of headgasket.

So that outcome is what you experts predicted. I will confirm, but thank you for your help as im sure it kept the mechanic wary and ensured a pragmatic solution.

 

And by the way the mechanic said this is the first time he has ever seen an impeller failure

 

Make sure he checks the belt tensioner for a good boot and full of oil while he's at it. When he's done with it, make sure the belt rides centered on the cams and is tensioned correctly.

 

My wrench swears he never fits pumps with plastic impellers, because they are the ones that come loose. Make sure your guy does the same....
jp 83 Euro S AT 48k