So it is and only lost a little more than 2 liters and nothing showing on the dip stick which scared the .... out of me. Checked engine and traced the oil leakage back to the top of the engine. Removed plastic coil cover on top engine and noticed oil pooling 1/2 way along the length of the upper cylinder head looking at it from the passenger/exhaust side. This oil made its way leaking down backside of engine,trans.,and exhaust making it appear like a major loss of fluid. Cleaned the oil and ckecked the spark plug wells of number 5 & 6 which were empty and clean. Topped up oil and restarted engine and observed oil ozzing from an upper cylinder head center bolt,the one beside the 5th coil. What are the possibilities? Hairline crack, gasket,warpped uppercylinder head. Has anyone seen anything like this. Is it a cause of what you all call pourous blocks.
Thanks for your time Dieter.

This stuff is excellant. The picture shown in tjts1's post is exactly as if I took it. Where the oil is sitting on this is called the cylinder head upper half in the Volvo engine diagram. I guess it could also be called the valve cover. I was amazed to hear this is so common. I noticed a little blurb about this kind of oil leakage in the 900 FAQ and over looked it on account of the
terminology. Pictures do tell a thousand words and the input from your experiances will help me greatly. I'll try sealing it until I get the one that works on my engine. From what I read there is a torq spec of 13lbs. for these bolts.
Thanks again.

Those bolts are not cylinder head bolts but valve cover bolts. The cylinder head bolts are under that valve cover. There are pressurized passageways in grooves between the cover and head for feeding the cam bearing surfaces. Normally the space between the grooves and the bolt hole would be sealed with a thin layer of special glue.

Apparently your glue has failed allowing some leakage to the bolt hole. I would remove the bolt, clean it and load with RTV sealant and put it back in. That should hold until the time, hopefully never, when the cover has to come off. You are only holding a relatively thin aluminum casting in place so don't over-torque the bolt and strip the threads. The bolts are only going into relatively soft aluminum! Rely on the sealer and let it cure for awhile before starting the engine and putting pressure on it.

--
'96 965, 16' wheels, rear 18mm bar & Koni + 204HP cams at 123K. Had '85 745 Turbo Diesel for 200K.

I pulled the spark plug access cover last night and I've got the same problem. I cleaned it up and ran the engine for about 5 minutes looking for the source of the leak. I couldn't find it due to time constraints. I'm going to check again today. Where should I be looking, the hole that the torx bolt goes in, or the 4 bolts that surround each spark plug well?

Thanks

I had the same problem with my 960. Its pretty common I think. This is how my head looked when I removed the plastic cover.
My oil leak

The oil was coming up through the bold holes holding down the plastic cover. The solution was to wrap the threads with teflon sealing take. It worked like a charm and never leaked again. Its a manufacturing mistake by Volvo (there's a first haha). Its just a matter of using new tape every time I remove the cover now. Im going to replace the torx studs with regular hex studs to make removal easier. The torx can't really take the torque of installing a stud with the tape. If I were you I would replace the studs now.
Good luck.

I've got the same problem, and used the teflon tape as you have previously recommended. I'm still getting the oil leak, but I was afraid to tighten up the torx all the way because I already have 1 partially stripped torx. Upon heading to the hardware store, I couldn't find a perfectly matching thread. Do you know the specs for the bolt I would need to buy?

THanks
phil

If I were you I think I would find a washer that is a snug fit around the
bolt and maybe put a little gasket sealer on the side facing
the head before you torque it down. Be sure you follow the torque
recommendation for your engine.
--
George Downs Bartlesville, Heart of the USA!

Interesting problem and good sluthing on finding the problem. I have noticed that oil will find it's way on to the top of my cylinder head through the bolts from time to time, but it's so miniscule that I haven't really tried to address it.

I think the real curprit is the gasket material that Volvo used here (which is spread down, like a glue)has started to fail.

A solution to the problem ,I would carefully take the bolt out, clean the threads, then wrapp with teflon tape and snugg her back down carefully, then check her out for more leaks. If this has happen on one bolt like that it will probally spread to others, or then again it may well be isolated to that one bolt.
Good Luck
Poolman