1994-2002 [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
Did this for 9000 V6 3.0L, but could also apply to 900s?
I had leaking valve covers (1995 9000 CSE V6 3.0L) after an engine top rebuild. I read the topics on this and the NG 900 BBs and decided to try another approach. So far no leaks at all and no oil in plug wells (4 months).
Reading the BBs, the problem seems to be that older covers can warp. Also plastic cover on alloy head means differential expansion.
I therefore decided to bond a nitrile rubber gasket to the top of the heads. This way not only does the cover “O” ring contact rubber gasket, but also the cover channels (in which the “O” rings sit) themselves bite down into rubber and effect a seal.
Here’s what I did:
Got hold of 1mm nitrile rubber sheet. Traced out the shape of the valve cover base onto card and then transferred this to the rubber sheet and cut out gaskets. Then fitted these to the head and trimmed up (better would be to bet an impression straight off the head, but as mine was installed with cams etc this was impossible).
The head mating surface was degreased with spray brake cleaner. It is important to degrease well. For example oil trapped in the head can “wick” back up onto the surface. Soak it out with a bit of rag first then degrease again. The gaskets themselves were thoroughly cleaned in hot soapy water and then greasy finger kept off them.
I installed the flat part of the gasket using a thin spread out layer of Loctite 5926 gasket silicone blue flange sealant on the head mating face, taking care to not block the oil channel in the camshaft shells (I also experimented with Hylomar blue and a red not curing seal on test strips – the blue sealant seemed to give the best and most flexible seal). I let cure for at least 24 hours.
Now I know what you are saying – what about those difficult half-moon areas and the arch over the pulley end camshaft shell? With the flat part installed, just strips of gasket are required. I cut strips carefully to size, prepared as above and installed as above, with a little extra flange sealant where the ends met the already installed gasket. I was concerned that the rubber half moons of the valve cover “o” rings would not fit, due to the reduced diameter – but no problem at all – nice cosy fit.
The last bits are the square tops of the cam shells. Just as above, little squares of nitrile rubber sheet were cut out and holes drilled in them (maybe a paper punch would be better in hindsight). Again as above bonded to the tops of the shells.
Valve covers were meticulously cleaned (plenty of soapy water and careful scraping and the “O” rings installed using a thin bead of silicone blue. The 8 small “O” rings where the bolts fit also prepared in this way.
Installed valve covers and tightened bolts to about 6 ft lbs.
So far, not a hint of an oil leak. Previously, the plug wells were full after a weeks or so and when stopping at lights, other motorists thought I was on fire due to smoke from oil the exhaust..
I was fortunate in that I had time and didn’t rush.
Justin (UK)
posted by 80.126.1...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
