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960 Leaky cam shaft seal opinions


Part-time Tinkerer
Feb 25, 2015
Austin, TX
Hey all, I have my 960 in the shop for a power steering leak, and have an oil leak looked at.

It's looking a lot like it's the camshaft seals; you can see in these photos how the back of the cam gear is moist, and how it's running along the head seal and down the side of the timing belt cover slowly.

My question is - how urgent is it do you all think to fix this? How quickly do seals like this disintegrate? I know it's a ton of work to replace these. Right now it's dripping away from the timing belt, but I'm concerned that if the seal fails catastrophically it could get the belt wet and cause it to slip... we had the belt slip once years ago, and so I've always been a bit paranoid about it since then.




The side shot of the timing belt cover is from underneath the car.
I'd definitely agree that is from cam seals. The job really isn't too bad as long as you are careful and mark everything.
Being that this is still a white block like the 5 cylinders I typically deal with, I would take care of that as soon as you can. Those front cam seals can fail catastrophically and soak the timing belt and run your oil down REALLY quickly (some have reported the engine seizing due to oil deprivation, believe it or not). My cousins and I were stranded in the middle of nowhere on the way back from a trip for about 8 hours because of a failed front cam seal on my cousin's S70.
Some will tell you to wait until they are leaking to replace, I say it should be preventive maintenance even if they aren't showing signs of leaking yet.
Thanks for the input!

I was going to ask my mechanic to replace the seals, based on what you’re telling me, but he called and said he put some stop leak on them to soften them up, and we’ll see if that helps for now. I’ll keep a close eye on it, and start saving up for the replacement.

I’m halfway to my new timing belt being due, but I do have this done soon, is there anything else you recommend being done while the timing belt is off?
Thanks for the input!

I was going to ask my mechanic to replace the seals, based on what you?re telling me, but he called and said he put some stop leak on them to soften them up, and we?ll see if that helps for now. I?ll keep a close eye on it, and start saving up for the replacement.

I?m halfway to my new timing belt being due, but I do have this done soon, is there anything else you recommend being done while the timing belt is off?
I wouldn't recommend using a stop leak. Any kind of seal swelling agent, in my experience, has caused worse leaks.
If you are doing a timing belt job, I would replace the cam seals, obviously, and the idler and tensioner as well as the water pump, if it hasn't been changed in a while.
Be sure to service the pcv system. A poorly functioning pcv system will cause oil leaks.

That is definitely something to check out. A "glove test" may be a good idea.
Thanks guys - I’ll keep a close eye on it then.

I tried doing the glove test over the oil filler cap; the glove just fluttered, it didn’t really get sucked in or pushed out. I also disconnected the flame trap and (with the oil cap off) blew air back through the breather box - it had a satisfying hollow sound and there didn’t feel like any resistance. It’s also not smoking out of the dipstick... is there any other test I should do?
Not that I can think of off the top of my head, no. Your PCV is probably okay for now, but it will need servicing soon.
When mine was bad on my GLT, the glove inflated like a balloon.
Thank you all for the advice! I got the car back from the mechanic, and so far there are no leaks, but I will keep an eye on it for now. He did say if it leaks anymore, he will definitely pull everything apart and replace the seals.

From what I can tell, the PCV system should still be pretty clear; it’s not smoking from the dipstick and there doesn’t seem to be any excess pressure in the system. When I did the glove test it didn’t really pull the glove in to the oil filler cap or push it out it - just kind of sat there and fluttered. I also checked the flame trap - it was clear; I also pushed air back through the breather box out of the open oil filler cap, and air flowed very freely. I do know that the S90 is smoking out of its dipstick so it likely needs to have all that serviced very soon.

That being said another related issue has come up, but let me give some background information first. Around 2004 the serpentine belt snapped and somehow got bound up at the bottom of the crankshaft. In doing so, the timing belt jumped three teeth, and bent all the valves. We took it in and had everything repaired and replaced, but… we’re not sure if they used all the right parts (we assume they’re all new parts). My mechanic noticed that the cam gears don’t match, and said one is a VVT gear, and the other is a plain one. You can see the picture that I have attached both my 960 and my later 1997 S90. According to what I can find engines up to 131,000 should have two identical cam gears, where as engines above 131,000 should have two different gears. My engine, according to the number stamped on the block, is 13,818. Which means, as you can see, one of the gears is wrong. You can also see in the picture that the timing belt is sticking too far out on the intake gear, and is too far in on the exhaust; the two gears are not flush with each other. (See EDIT 2)



Now, I know that 1992 engines for retrofitted in someway to use the wider belts of the 1993 cars; originally my car had to have the timing belt changed every 25,000 miles whereas now it only needs to be changed every 30,000 miles. Does anyone know if it was the cams that were changed or what part exactly was used to retrofit the engines?

The other concern, is that I get an odd noises at certain RPMs under load going up hills; I wonder if this might stem from other things possibly being wrong, such as the cams themselves may be the wrong ones or mismatched; which I wouldn’t know unless until we tear apart the engine. We’re thinking about pulling a used head from another 960 – would a 1993 or 9094 head work just as well as a 92? Is this a feasible route to go for making sure everything is as it should be?

I would really like to get this whole front engine stuff sorted out before the next time we replace the belt and the seals, so I’m trying to do all of my homework now while I’m saving up to have it all done. I would probably also have the intake taken off and the breather box cleaned or replaced at the same time. That also being said – you mentioned that the hydraulic tensioner is NLA, is there an aftermarket one, or is something that I can use from say an S80 engine?

Thanks for all the advice everyone, I really appreciate it!

(Edit: sorry for being so long winded - I used dictation on my phone haha)

(EDIT 2: so apparently the thing behind the exhaust gear is a “oscillation dampener” for cars 93 and newer; is this what was added in the retro fit?)
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That's not a VVT cam gear, but likely the "oscillation dampener" you mentioned. I've never seen that, but I don't typically deal with S90/960s. I don't know what's up with the intake cam, but I feel I remember the S90 having two different cam gears. I'm not sure that the S90 ever came with VVT. I wouldn't sweat it too much.
You won't be able to get the tensioner from an S80, it uses a mechanical tensioner. However, if the 6 cylinder is similar in this way to the 5 cylinders, you should be able to retrofit the mechanical tensioner. That's something to look into.
FCP doesn't seem to carry any hydraulic tensioner for the S90, so it probably isn't going to be something easy to get.

Honestly I wouldn't bother changing out the head unless there is a REALLY good reason, such as the valve stem seals are leaking pretty badly and you want to do a full refresh or you have bent valves. If your compression is good and you aren't burning oil, I don't think it's worth spending the money right now. The sound could likely be something else. Of course if you want to do it anyway for peace of mind if you plan on keeping the car for a while, then go for it. Just my $0.02.
That green wheel behind the exhaust cam gear is normal. What it does I don't know. I had to do the front cam seals on my '96 and it wasn't too bad. I don't like using additives especially in the oil. Whatever your mechanic used is a bandaid, could reappear at any time. I also remove the white disc with all the holes in it from the flame trap housing. Have been doing so at least 15 years and haven't had any issues. But that is up to you. Not recommending it, but it is something that could clog up.