I have a 1993 960 with a leak from the valve cover. It is so bad the oil that leaks floods the #5 spark plug hole. It seems like who ever had the vehicle before me over tightened a couple of cover bolts and they are now stripped and oil is leaking from around them.

Does it really take 7 hours to remove and replace the valve cover?

Has anyone just retapped the stripped bolts without taking off the valve cover and how successful were you?

And if have to remove the valve cover, is there any instructions out there.

The vehilce has only 100,000 miles on it and besides this leak is running great.

Thanks

Hello, I have had the same problem on my 94, 960. The oil was leeking so bad it was dripping onto the exhaust. I found 5 stripped bolts that were leaking. I went and removed them (all 5). I spent some serious time cleaning the holes out with brake cleaner untill all the oil was out of the hole. I used thread repair by loctite. I cleaned the bolts and filled the bolt holes with the thread repair after mixing. Inserted the bolts and just run them down to the flange of the bolt and let it sit overnight. I removed the extra compound that oozed out and gave each bolt a snug. I have no more leak. It has been over a month and 4800 miles. I am crossing my fingers. To do the job the other way you need to remove the valve cover, then use a heli coil for each hole that your able to not tighten. IMHO there are plenty of bolts to hold the valve cover down and the few that I added the quick repair to should last a long time.

I have done this removal and replacement of the upper head section. It does or will take 7 hours or more with the evaluation of ALL the holes & helicoiling of the problem holes.

The fact that you are seeing oil seepage means that the chemical gasket is compromised (seperated). This is not going to be fixed by tightening bolts. I'm not a fan of funky fixes, so I would recommend the removal and proper fixing with helicoiling.

The oil you are seeing in #5 plug well is creeping across the interface between the upper & lower head sections that is supposed to be glued together with chemical gasket. It is creeping past the o-ring seal around #5 plug well indicating that the upper head section is lifting and also that the o-ring gasket is probably brittle & hard. I would estimate the longevity of any fix other than the correct fix with the helicoiling to be temporary at best.

It would seem prudent to evaluate the state of the motor in general against the cost of accomplishing the repair. If oil consumption is reasonably low, and the motor has good power, and idles evenly, and hasn't been overheated, then it would seem to have the potential for some longevity and thus be worthy of the repair.

The good news is that the parts are reasonably cheap. The bad news is that you need several special tools and you need some familiarity with threads & qualifying threads. Part mechanic, part machinist, part QA inspector.

Because you know that someone has messed around and damaged some of the threads, now you must suspect ALL the threaded holes at that interface. To qualify them, you would be best to get a GO/NO_GO thread gauge to check the threads and find out which ones are bad. I'm pretty sure the thread is an M6 thread, and I did some calculations and found that at the spec torque of 13 ft-lbs yields a bolt preload of about 90% of the proof strength of a 90,000 psi tensile strength bolt (a high quality grade 5 type bolt). This requires a length of engagement in aluminum internal threads of about 0.200 inches. All of this shows that the design needs to be assembled just right; over-torquing is not an option.

These threaded holes in the top of the lower head section are blind holes. One has to be careful about just sticking in a longer bolt lest you bottom the thing out in the blind hole and crack the casting as cast aluminum and especially aged cast aluminum is definitely somewhat brittle.

If you decide to do the job, I could send a basic procedure. It's not terrible complicated, but it is a tedious procedure and the helicoiling will be a little tricky leaned over the engine compartment.

This may or may not help but here goes. You will need a couple of 7mm bolts about a 1/2 inch longer than the bolts that are in the head now. They should be full threaded parts. You will need a few washers of good strength as well as a couple of hex nuts. You will also need a 7mm tap. I would go to a place called Fastenall Co. for the parts.
What you do is take the bolts out and retap the holes as best you can and as deep as possible. Take a dremel tool and cut the heads off the longer bolts you bought. Wrapp the side going down into the hole with teflon tape, put two of the hex nuts at the top of the other side of the bolts and jam them together tight and then run the bolt down till it bottems out. Do this on each bolt, then take the hex nuts off and use the bolt now as a stud with a washer under the hex nut and tighten down.
Along with whats above I would clean the spots up very carefull with brake clean before and after doing the job and mix up some JB weild and apply to the leaking area and let set up over night. I would also use the JB weild around the hex nuts and washers to make sure it doesn't leak through again.
You may be able to go to an over size bolt if there is room-like buying 8mm bolts insted of 7 and retaping with 8mm ( or posible 1/4-20)and then doing the same job discribed.
Studs will have a better holding power in a case like this than a bolt being tightened into it's own threads.
Hope that helps
Poolman

That sound like a good plan.

I have seen those bolts leak even when not stripped. There is oil under pressure very close to the 4 bolts around each of the plug holes. If the sealant used between the upper and lower head fails the oil will run up the unthreaded portion of the bolt and out under the it's head. Then some ham handed "mechanic" comes along and says "oh better tighten that" and he strips it. Before it is stripped though it is quite easy to withdraw the leaking bolt a bit, apply a sealant under the head and retighten to 13 ft/lbs.

If tapping is not an option but there is grap with the bolt wrapped in teflon tape I would be inclined to just reset the bolt with sealant under it's head and tighten with great judgement. There are so many other bolts in such close proximity that one bolt not fully torqued would not matter
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David Hunter

Some 960s leak from the torx bolts that hold down the plastic spark plug cover. The problem is Volvo tapped the these holes too deep which allows oil to leak out. The easy solution is to use some teflon threat sealing tape on these 6 bolts. This fixed the oil leak on my valve cover permanently.
Good luck
Justin

Some body set me straight here-I thought some time back one of members stated these bolts were 7mm-not 6mm-I set 6mm studs in the head where the plastic cover holds are so I could use the knobs I got to hold the cover down. I taped them heavy with teflon tape when they were put in-but I know some one here has said they are 7mm bolts-and I belive they are.
Poolman

Someone posted that the bolts holding down the top head section are M7x1.0 thread. This appears to be correct. It is an unusual metric size, but is fairly readily available. Helicoils are also available in this size.

I'm not sure exactly. I remember when you said you were going to switch to knobs and I was going to try to do the same. But I didn't find the right ones at the hardware store. Do you have some specs for the ones you bought?

The stock torx bolts always seemed very lose in their threads. I have no idea about size.
Justin

Tjts1-I found the knobs at this company www.monroeengineering.com/knobs/page071.htm
I paid for them on line and they were shipped too me in about a week.
I got 6mm thraed size thinking that was the right size -haven't had any leaks and I like how fast I can get under the engine cover with these on there.
Hope that helps
Poolman