Ian928

A fellow Norwegian 928 owner sent me these pictures from his 1982 928 Euro S heads. The damage is on the two rearmost cylinders on both sides. Both heads had headgasket failure also. He mentioned he has had problems with the waterpump.

I am guessing his cooling problems caused both the pitting and the blown headgaskets. The two rearmost cylinders probably will get the least cooling when there is problems. Any opinions?

AO

Detonation? But it is strange that it's primarily around the exhaust valve. Maybe a factory defect?

UKKid35

Don't exhaust values burn when piston rings fail?

Imo000

No, I don't think so. Exhaust valves burn if there is carbon build up on the valve seat and the valve can not close all the way.

123quattro

That looks like detonation. Detonation at different engine speeds can affect different parts of the cylinder. Ring lands, cylinder heads, bores, and head gaskets can all be failed by it separately.

Ian928

Maybe detonation caused by overheating? The reason I am asking this is because he is reusing many parts from the old engine, fuel system for instance, and I worry that just putting a sound engine into the same system would make the same thing happen again... If the problem was lack of cooling from either a blocked water passage (seems the pitting is worse betwen the valves, maybe the passage is bloked) or the water pump that he reported to have had problems with, the problem was in the old engine itself and will not repeat itself on the new engine.

nr1rolf

Hello!
It`s me that was the unlukky one this happend to.....
A update in whats happening: I`vee got a "new" engine the same engine just been a manual gearbox on it, so i hope thats not gone be a problem for me.
Someone know if there can be a problem about that??
But of course it came a problem for me.... My engine mounts are fuc.. so i need new ones, some one know about a place to get them fast and cheap?

RyanPerrella

seems to be a regular occurance with age and mileage honestly. Most seats seem to have some degree of pitting.

This is why you recut seats and grind valves to get rid of it. It honestly wouldnt concern me. Just get the valve job done and run it hard for another 25 years

Ian928

But look at the pictures again, the pitting is not on the seats, but on the aluminium around the seats! This can not be removed by a valve job.

Rolf, welcome to Rennlist, you will find a lot of help here! Keep us updated on how it's going

944 guy

There seems to be some significant carbon buildup too. Together with the rear-most cylinders getting the least cooling (marginally) it may detonate: the cylinder temps are marginally higher, and with the carbon buildup compression is higher too. Both increase the tendency to detonate.

Landseer

For motor mounts you have the Porsche equipment choice, which is very expensive, hydraulic liquid-filled.

Very inexpensively you can substitute solid rubber mounts.

I have just put one set of solids on an 86. Another set on an 84. Both are now excellent. I think the price was somewhere around 75 USD for both, plus shipping.

Mine came from ROG100, who is a sponsor here, from 928SRUS.

Am not sure if the other sponsors here also provide the solid mounts, but they are all excellent and can be trusted if they sponsor this list. All can provide the more expensive Porsche originals.

JP Rodkey

The answer is in the OP: "....he has had problems with the waterpump...... caused both the pitting and the blown headgaskets....."

The pitting is caused by water (coolant) in the combustion chamber. Mixed with fuel, water turns to steam under pressure and pitting is the result.

It is common for a blown head gasket, often the result of overheating due to malfunctioning waterpump, to allow coolant into the cylinder and pitting at the exhaust valve.

RyanPerrella

HA HA YOUR RIGHT IAN

I wasn't looking very closely, nor reading very closely. Not sure what you could do with those heads and what caused that.

Ian928

I believe he has the early mounts (like I do - I need them also). To be able to use the Ford mounts he has to change the crossbrace to the later type, doesen't he?