[Saab_c900] 8V turbo engine problem - might be head gasket

No compression (probably).

On second attempt there is a bit of oil in the cylinders and compression improves a bit.

Gasket or a valve that does not close or electrical or ...

Steam?

There isn't any evidence that I've seen so far of water in the

Do a compression test.

Is this an 8v or 16 valve head? The 8 (don't know about the 16) had a habit of cracking in line with ??? inlet valve No 3 ???. Not repairable if it has cracked. Gasket or crack can explain some of the problems.

The metallic sound it likely to be from valves or camshaft (sticky valve, worn camshaft bearings ...) ... uhmmm does this head have hydraulic tappets? (too new for me then) in which case until the oil starts flowing they are noisy because they are worn out.

If it helps at all.

Charles

sometimes

All your points are probably worth pursuing, but have you tried the following stuff first? I'm sticking to my old principle of cheapest/easiest first often saves time, money and knuckles... When I bought the 81 turbo it was running on 2.5 - 3 cyls for about half an hour. Highway run sorted out a lot of that. Check the resistance on your plug leads. They can look fine but be rubbish anyway.

The metallic thrashing in mine above 3600 - 4000 dpending on temp logically / finally seemed like it might be timing chain related. It's gone away since the injectors were changed. The fuel consumption has improved at least 30% too! Have you run a flow test lately? Mine was more like a drip test, poor old thing. Steve can still get the turbo injectors in, or he could 3 months ago anyway!

Mine smokes (white) wonderfully if it's left idling for a while or started/stopped several times and not run - especially when the nose is pointing downhill. I suspect it's oil buildup either in the chambers or the turbo because it goes away pretty soon (less than 5 minutes).

Mostly cheap and quick stuff to try anyway. See how you go and hopefully it'll save you a big bill. Cheers

They're all new! I replaced them because the old ones were a bit burnt from heat off the turbo and downpipe. I also replaced the distributor cap, rotor and also the spark plugs themselves with new NGK BP7ES's.

Well I can't get an accurate timing figure off the driveplate at the moment. When I tried yesterday the number on the driveplate wasn't readable with the revs as close to 2000 rpm as I could get them (going on the tacho reading on the timing gun). It might just be that the numbers on the driveplate are worn off though.

I don't know what sounds to listen for in terms of timing chain problems, but when the engine was running every so often there is a dull thud which seems like something's igniting at the wrong time. It's sort of like the sound that a gas BBQ makes when the gas is first ignited and there's a tiny 'pop' sound from the small air-vapour explosion as the gas starts to burn. I can't work out when that's coming from but it's definitely internal somewhere.

Thanks very much for the advice. I am hoping it's not a cracked cylinder head but I've still got the one on the engine in the donor car to use, though it's probably corroding a bit as that engine has not turned in more than 3 years and most external bits are missing. I actually have two new K-jet injectors here also but I'm not sure if the same Bosch part number was used in the non-turbo and the turbo engines. Probably was the same though I'll try to check using some references sites I've got linked on the tech library page of my site.

I will check the injectors for fuel flow since I don't think I have done that yet. Might be a good time to change the injector seals also.

It still has oil smoke flowing up from the exhaust side of the engine when running too. It's a small plume of burnt oil that comes up from around the centre of that side of the block. I think the turbo oil return pipe goes into a port there somewhere and it might be that connection that's leaking.

Regards,

Craig.