My 960 has had a slow oil leak for the past few months. My mechanic discovered that the bolts that hold the valve cover in place had been stripped at some time. The gasket is fine, but oil is leaking from these bolts, collecting somewhere on the back of the engine, and that is why I occasionally see oil in my driveway.

The mechanic tried using thread sealer with the existing bolts, but the leak is actually worse now. He thought he could remove the valve cover and drill new holes, but he was concerned that there would not be enough room to tap the new hole (est. cost for labor $800).

I plan to drive the car for a few more years so I'm interested in a permanent fix instead of a get-by fix. I don't do much work on cars, but would like to get some advice that I could give to the mechanic and get this fixed.

i would keep an eye of any oil accumulation around the coils.it could cause some shorting or other electrical problems that you dont want or need.
--
83 242 DL -129k, 92-965-195k, 94-965-203k, 84-242 GLT-Gone, but not forgotten,83-245GLT-1'st one (the 1'st 3 currently on the road)

This is not a job for the average mechanic. This job requires a person who is part mechanic, part machinist, and very careful and fastidious.

The top section of the head has to come off & the cams have to come out. Once you get those out you will see that about 70% of the area of the top surface of the bottom head section are oil communication holes or openings for things to fall into. These will all have to be masked so that no chips of aluminum get into them. That's after you identify all of the problem holes in the bottom head section. In your case, where someboby has apparently been messing with those bolts, all bets are off, and you would reasonably need to qualify each of these blind threaded holes (there are about 46 of them). This would require measuring the minor diameter & qualifying the pitch diameter of each hole. It's a bit tedious, but its not rocket science. It requires a few pin gauges and a pitch diameter plug gauge (~$30 of these tools).

Once you identify the bad holes, these must be heli-coiled after the careful masking of the top of the bottom head section as cited before. The heli-coiling must be done very carefully as there really can't be any mistakes. This is a lot harder leaning over that engine compartment than doing it in a machine shop.

All this is in addition to the usual Volvo issues associated with working with the chemical gasket which requires the utmost in fastidiousness and care to do the job right.

While you're in there, you might want to replace the hydraulic lifter set at another $135 if the engine has 100k miles or more. You don't want to be going back in there later.

The good news is that the job can be done and should yield excellent results in the right hands. The bad news is that you should try not to wait too long before fixing it as the incomplete and assymetric contact force should be expected to allow warpage in the casting over time. If this became too much you would be looking at buying both the top & bottom head sections (the only way they are sold). This would get VERY expensive.

One last note. Since all of the threaded holes in the bottom head section are blind, the fact that you are seeing oil seeping out of those bolt holes means that the oil is seeping over the chemical gasket interface, i.e. the head top section is lifting to some extent. There is no way this is going to get fixed without taking that top head section off.

For the hardcore driveway mechanic/machinst, its a solid weekend job. I'd think that at ~$800 labor you could get about 10 hrs for an experienced dealer mechanic. That might do it. You also need some special tools to do the job that the dealer mechanic WILL have. They may want to charge you a bit more for the lifter set, but they might let you get it. The price I gave is a super-deal price on the Volvo part.

here's a thought. IF the studs are only stripped down low then you can use a few washers or anything to take up the space of the stripped threads and then the Acorn nuts will grab the threads higher up wear hopefully they are in better shape.

Even if the gasket is in good shape, add Gasket sealent on the corners where the rounded section from the Cam bearing meets the flat surface. Thats where it's going to leak for sure if you only rely on the gasket.
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me

Sounds like the sealer is not doing it's job. There is no gasket in that joint as the cams are running in holes where half of the hole is in the head and half is in the "cover". A gasket would be too variable in thickness so a sealer which is very thin is used to make the seal.

If the cover is to be reworked, there is a lot of labor and some amount of skill/patience needed to get the surfaces prepared, (real clean without any gauges), for new sealer. If it isn't done right, you will have leaks worse than when you started.

Lookes like someone already has tried the brute force method resulting in your stripped bolts. I would try putting heli-coils in the head, without disassembling the cover to fix all the stripped bolts. With all the bolts once again holding I would evaluate whether I wanted to go through the expense of replacing the sealer. I would find someone who is experienced with the sealer for that job like a dealer, or good independent Volvo mechanic. (Not the corner service station.)

Good luck and let us know what happens.
--
'96 965 with 16' wheels at 114K. Had '85 745 Turbo Diesel for 200K.

Fun! The remedy is to pull the valve cover, timesert or helicoil all the stripped threads, clean the hell out of all of the surfaces, use the special chemical gasket, use the Volvo special tool, or one you fabricate, to hold it the valve cover tightly in place and down, and resecure the many many valve cover bolts.

You can helicoil the those bolts while the cover is still in place. I just did it to about 5 bolts this past fall, the real problem will be the sealer. Just tightening those loose bolts most likely will not seal the leak fully.

DanR 94 964 250,000 miles (16,000 on the new engine)
--
DanR

We've done that before as well, but only when we had one or two that "looked" fine when we were in there, but apparently weren't up to snuff...rather than pull it again, and clean it again, repair it again, and seal it again, to probably have the same thing happen again...yep...drilled right through it.