Volvo valve cover gasket replacement as easy as it seems?

November 13, 2005 12:56 AM

Anyone have experience replacing the valve cover gasket on a Volvo, or general experience with engine seals in cars?

I own a 1994 940 GLE Wagon with 175,000 miles on the odometer. I don't drive the car much during the school year, so I just recently discovered an oil leak that substantially drained the reservoir since I last changed the oil two months ago. I think I lost about 3 quarts of oil, and there is quite a mess running down one side of the engine. After much consternation, cursing, oil cleanup, and test laps around the dorms, I've determined the source of the leak to be in the joint between the valve cover gasket and the cylinder head. The car is running perfectly, the engine oil is untainted, no oil in the coolant, no white exhaust smoke, nothing is running hot, so no signs of anything Very Bad like a blown head gasket. I’m just slowly re-enacting the Exxon Valdez spill all over town. Phew. Simple repair, $20 shipped for a new valve cover gasket, I just need a socket set to pop off 10 bolts, and everything is right on top of the engine where I can easily reach. I can throw some sealant on the new gasket when I install it for maximum longevity. At least, things seem that simple. I've replaced belts, hoses, and electrical components before, but have never needed to work on the engine directly. Advice and anecdotes from anyone who has experience with this kind of work would be welcome. Maybe the repair is actually as simple as it seems!

Bonus Question: I refilled the oil with the special high mileage variety, just for the hell of it. Does this stuff actually help preserve seals and does it have any additional benefit? Is buying this stuff at over twice the price of regular oil more cost effective than replacing seals (which seem to be very cheap)?

Here’s a picture of the offending seal and my engine; http://img356.imageshack.us/img356/8062/img11185ei.jpg
Sorry, couldn't get the direct link to work for some reason.
I think I might need to replace the oil cap seal as well; it looks like oil has also been coming out of the top.

posted by Derive the Hamiltonian of... to Travel & Transportation (17 answers total)

Looks like a sheet-steel valve cover, so the critical point is to not overtighten the nuts. If you tighten them too much, you'll distort the cover so it isn't flat on the head. There's should be a torque specification for those nuts. Make sure you get all traces of old adhesive or sealant off of the sealing surfaces.

As to the special oil, if it actually does extend seal life, it's a good thing. Some of those seals are cheap to buy but very expensive to install.
posted by Kirth Gerson at 3:43 AM on November 13, 2005

Best answer: Oh, the joys of leaking VCG's.

Well, the first thing is, this is a really easy operation. Really easy. But here are some tips that may help you:

1. Find out the torque values for those valve cover bolts. Seriously, ask on a message board or whatever. Valve cover bolts are easily the lowest-torqued bolts on the entire car. We're talking inch-pounds of pressure. If you can borrow an inch-pound torque wrench, awesome. Otherwise, the rule of thumb is "hand-tight, then a third more." If you overtorque your valve cover bolts, they'll snap off. VERY EASILY. And then things get very annoying very quickly.
2. Once you have the valve cover off, scrape off any RTV gasket sealent that might be either on the cover or the head. You want the mating surfaces to be smooth as butter. Scrape it off with a razor blade (but be careful not to score the metal), then wipe it clean with a rag and some alcohol/kerosene.
3. You most likely will not need any RTV (gasket sealant) unless you have any vertical angles (unless VW advises otherwise, but I'd be sure to see that in writing). The gasket does the sealing, the properly torqued cover holds it down. Sealent is only used if and when the valve cover isn't completely flat by design. That is, if you lay it down on a flat surface, and there are sections that are designed to mate over cylinder head areas that curve up, for example, you'll have to apply a blob of RTV to the angled part. Let me give you an example so you can understand better. This is the valve cover off a Mazda Miata. See how there are a couple of rounded parts on the cover? On the head, that's where the cam bearing caps go, so the gasket isn't totally flat. Here's a shot of the actual gasket for the Miata. See? Not completely flat. Anyway, the point is, wherever the cover goes from flat to not-flat, you put a dob of RTV. If your gasket is compeltely flat (and it looks like it might be), you can simply ignore this section entirely.
4. Make sure you clean out the grooves where the gasket goes. Brake cleaner works wonders.
5. When putting the cover back on, the generally-accepted order of bolting goes like this: pick a spot in the middle of a long side, put on a bolt hand-tight, then continue in a clockwise rotation (or anticlockwise, if you prefer). The point is, don't go corner-to-opposite corner like you might think. Just go around in a circle. If there were bolts in the middle of the cam cover (like on the Miata), you start in the middle, then spiral outwards. Once you've gone all around, then give each bolt another third-turn for final tightening.

As for the question of "oil for older engines" -- I think it's marketing bunk. It might have cleaners in it that help, but you could just throw in a quart of ATF and idle your engine for an hour and accomplish the same thing. (Be sure not to drive around if you do this, and be sure to change your oil+filter afterwards).
posted by Civil_Disobedient at 5:01 AM on November 13, 2005

Gah... sealant. Not -ent.

And counter, not anti-clockwise.

Finally:
When you take off your valve cover, look at the cover and the head to see if there's any areas where there's RTV sealant. That should give you a pretty good indication where it's applied, if anywhere. If you don't find any plasticy blobs, it's safe to assume none is used. If you do find some, the standard sealant is the "black" kind (there's a "grey" kind that works as well, but the black kind stands up to higher temperatures).
posted by Civil_Disobedient at 5:05 AM on November 13, 2005

I've had best results, with RTV-only and RTV+gasket, when I've let the applied RTV skin (dry/set-up) for about 15-20 minutes before assembling. I'll also second the caution not to overtorque.
posted by klarck at 5:50 AM on November 13, 2005

Best answer: I'm a little worried about the amount of oil you're going through. A valve cover gasket usually won't leak out craptons of oil, but be more of a seeping thing. You ddin't say how many miles or what type of driving, but unless it's a lot of high-RPM stuff I'm thinking you got more than a valve cover gasket blow-out.

(And btw, I'd check that the bolts/nuts holding the valve cover on are more-or-less tight, I've had them get loose on higher-mileage engines and just a quarter-turn and you're good to go.)

But the way your picture looks makes me wonder if something isn't putting pressure into the valve train area and oil is being pushed past the seal. A new seal wouldn't fix that problem.

The overall pressure should be fairly low, so with the engine running take the oil cap off and see how much pressure's coming out of the hole. If it's more than "negligible" you've got bigger problems than the gasket. If you're not sure have someone rev the engine while you're observing what's up.

Also, while I agree with the advice above regarding changing the thing, know that it's a kind of nasty job and you have to - as pointed out above - keep it clean while going back together, add the tools and blah needed to clean the area, you might well be ahead having a garage do the job, since they have all the stuff on hand and it's a small job to them and a orgy of parts cleaner acquisition to you.

But mostly I'm a little worried about the oil coming out being more than a seal failure, especially if it started doing this all at once.

Google "Bobistheoilguy" for useful info about oil types and additives.
posted by Elvis at 6:15 AM on November 13, 2005

If you're not sure have someone rev the engine while you're observing what's up.

With the oil cap off, that could be a very messy proposition. I've seen the results of driving a couple of miles after forgetting to put the oil cap back on the cover, and let me tell you, it looked like someone took a shotgun to a bag of oil. It was just EVERYWHERE. So, uh, be careful. :)

You mention that you've lost 3 quarts, but don't mention over what period of time. If it's a short period of time (say, less than a thousand miles) I'd agree with Elvis that you might have bigger problems than a leaking valve cover gasket. Are you sure the sole source of the leak is the top of the engine?
posted by Civil_Disobedient at 7:02 AM on November 13, 2005

Check to make sure that the bolts haven't already been overtightened. After you clean up the valve cover, check to see if the area around the bolt holes is puckered inward. If it is you will have to lay the edge of the valve cover on something anvil like (an anvil is best, but the edge of a concrete block will work) and tap it back flat with a hammer. You can check the flatness with a straight edge.
When you get the valve cover off, check to see if the motor is really gunked up. If the everything is covered with a layer of congealed oil 1/8" thick, you may have a clogged return passage. Oil gets pumped up to the valve train for lubrication, but is supposed to just run back down through passages. If clogged, the valve cover will fill up with oil and leak out much like you have described. You may be able to poke out the passages with a piece of wire. However, try not to break loose any more stuff than you have to, it can clog up your oil screen, filter and lifters.
posted by 445supermag at 7:45 AM on November 13, 2005

Response by poster: Elvis and Civil_Disobedient: 3 quarts of oil over two months. Actually, now that I've taken time to think about it; I do drive the car a lot on a weekly basis, and I tend to range far on the weekends. For instance, a 600 mile round trip to Stillwater, OK for a rugby game hauling four large guys and attendant gear, two 100 mile round trips to the nearby KC airport, other small highway excursions, and weekly short jaunts around town for business and pleasure. I haven't been keeping track, but I think the total for the past two months has been 1500 - 2000 miles added. The car usually does between 2500 - 3000 rpm for city driving and between 3500 - 4000 rpm driving about 80 - 85 mph on the highway. I have no idea if the valve cover gasket is the only problem - there is quite a lot of oil caked on one side of the engine, all of which looks like it could have come from a leak from the valve cover. Once the cover gasket is fixed and the oil cleaned off, I'll be watching for new leaks. It isn't anything underneath the engine - the oil drain cap and the underside of the engine in general are completely dry. New oil is appearing on the outside of the seal when the car is off, although it is not leaking quickly, so even if the seal was blown out by a pressure problem, it needs to be replaced, I think.
posted by Derive the Hamiltonian of... at 9:58 AM on November 13, 2005

There is typcially a hose going from the valve cover to somewhere on the intake (throttle body, behind air cleaner, etc.) to recycle engine vapors by burning. This has a one way pressure control valve (PCV) so vapors (ie higher pressure) can get out but nothing comes back from the intake. If the PCV is blocked or broken it can cause high pressure to build up inside the engine which eventually will force oil out somewhere. In my brother's Jeep it was out the rear main seal. From Autozone's website it looks like you don't have a PCV but there still should be a hose somewhere going to the intake. Check to see if it is blocked at all.
posted by 6550 at 10:32 AM on November 13, 2005

Response by poster: Elvis (or anyone else): I tried your suggestion of checking the pressure by removing the oil cap. With the engine idling and the cap off, there is definite airflow out of the cap. However, I don't think the pressure is even as high as 1 PSI; the air current is weaker than a room fan and when I covered the cap hole with my hand, I could barely discern force against my palm. I'm sure this increases at high RPM, but surely it couldn't be forcing oil through my seals? Is your definition of negligible pressure similar to what I just described?
posted by Derive the Hamiltonian of... at 10:34 AM on November 13, 2005

These suggestions are all really helpful, but don't forget about Brickboard - "The Volvo Owner's Resource Since 1997."
posted by Liosliath at 10:38 AM on November 13, 2005

That sounds pretty negligible to me. First things first, replace that valve cover gasket. Oh, and clean your engine bay, for chrissake! I know it always takes me at least twice as long to work on a dirty car. :) Gunk engine degreaser works great (and smells nice after it burns off your block) but the way your bay looks, even a healthy squirting of Simple Green would be a significant improvement. Just be careful with the electical connections.
posted by Civil_Disobedient at 10:43 AM on November 13, 2005

Is this car turbocharged? If so, I'd look at the turbo as a likely candidate for the oil loss. That's if it continues after you replace the valve cover gasket.
posted by knave at 11:05 AM on November 13, 2005

Response by poster: Well, Advanced Auto Parts actually had a valve cover gasket for a Volvo 940 (holy shit!!!), I have my own tools, and I picked up the other necessary supplies for under $30, so here goes...
Thanks all!

Hell, I might even post a picture of my shiny, clean engine bay after I'm done because Civil_Disobedient made me feel so guilty about it :)
posted by Derive the Hamiltonian of... at 11:57 AM on November 13, 2005

Response by poster: Success.
posted by Derive the Hamiltonian of... at 3:19 PM on November 13, 2005

Good job--that was nice and quick! Don't forget to check the oil level every couple hundred miles till 1000 to keep an eye on it.
posted by Civil_Disobedient at 7:17 PM on November 13, 2005

Response by poster: Oh, and for the benefit of anyone reading this in the future, perhaps because you have a similar problem;

1.) The old valve cover gasket was completely degraded. It came off in brittle chunks, and I don't think it was functional anywhere along the joint. It's too soon to tell whether I have more leakage or additional problems, but after seeing the condition of the old gasket, it doesn't surprise me that oil was leaking out all around the cylinder head. I don't think pressure was necessary for oil to leak, it just dripped out around the fossilized gasket.

2.) On the Volvo 940, you can slide the valve cover out without having to disconnect the wires to the spark plugs. Facing the engine block from the front, just lift the cover up and slide it to the left and down, it will clear the wires no problem.

3.) If you're slopping large amounts of engine degreaser around, really do be careful of the electrical connections like Civil_Disobedient mentioned. I completed the valve cover repair, ran the car for a few minutes to make sure things were peachy (they were), and then started sloshing degreaser everywhere. I though I was being careful, but some splashed on one of the distributor cap connections and I lost a cylinder until I dried the cap off and ran the car for a few more minutes. Scared the crap out of me; until the connection dried out and the cylinder came back I thought I'd be spending another three hours working on it.

4.) Liosliath's mention of Brickboard is a good pointer, although I found nothing helpful in the Volvo forums this time around (and therefore asked metafilter). I've personally learned a lot from Swedish Bricks, which is more a FAQ than a forum, but oh what a FAQ!

5.) The gasket bends around two semicurcular joint elevations, so if you're going to follow Civil_D's advice about only using sealant on seal elevations, have some on hand and use it appropriatley.
posted by Derive the Hamiltonian of... at 9:47 PM on November 13, 2005