tankertoad

I told a local P-car mech about my seeping lower valve covers and how I should probably do the gaskets soon. He said that won't fix anything and the seepage will return. He stated that there is a known design flaw in the 993 valve covers and that I should ensure that I replace the covers with new ones (he said they've since been redesigned). He said not to bother with the billet ones, OEM replacements will cure the problem.

Anyone heard of this "design flaw"?

TCallas

I have seen this but it's a really rare problem. I would have him/her clean the engine really well and diagnose exactly where the oil is leaking out first. He/she has to (or should) clean the engine when he/she repairs your oil leaks anyway. This will tell him/her if the Valve covers are leaking or not. Chances are they are not faulty, just the gaskets.

Monique

IIRC, the valve covers are hard plastic. The gasket will leak if during replacement, the torque values and the buttoning down process is not followed precisely.

The covers warp.

FYI, someone sells an aftermarket version in alu... do a search... good luck.

pcar964

Wow, I've never seen someone so careful to be PC about a car mechanic! I have NEVER seen a female Pcar mechanic. Never.

chris walrod

993 valve covers have integrated aluminum bobbins that set the height or gasket 'squish' when tightened. With this feature, it seems as though torque spec and/or tightening sequence wouldnt matter too much?? Out of habit, I always dig out the Snap-On in/lb torque wrench for fastening these guys up as a matter of thoroughness.

BS911

I have heard a lot about this and searching on the matter makes things more confusing. Many people say its hogwash and that they don't warp, you just need to replace the gaskets and torque properly. (Read: not overtighten) Some say they do warp and they will never reseal once warped. This is not what I would call a known design flaw any more than the engine tray is a design flaw. Those lower covers sit really close to a lot of hot parts. Heat and time can do weird things.

I know this though... they absolutely CAN warp. True it might be rare, but they do. Mine currently ARE warped. I have replaced my gaskets twice and tried removing/reseating several times to get the perfect torque and seating. Keep in mind that they only take 7 ft lbs (IIRC ?) of torque - VERY LIGHT. But they still leak. I can visibly see a slight curve to the cover.

Next question is about what to replace them with. imagineauto.com (Rennlist sponsor) has some aluminum covers for $400 which includes both covers, new gaskets, and new bolts and washers. The original lower valve covers are about $91 (from vertex) a piece with no extra hardware. So the aluminum ones suppopsedly will never leak again, but the original ones won't warp in short order either. It will take years and many thousands of miles to warp again. May not be worth the "upgrade."

Also, for what it is worth, changing the lower valve covers is an EASY DIY job. Add about 1 hour for both sides on top of the time it takes to remove both rear tires. Your uppers will / should NOT be warped because they aren't exposed to the heat as the lower ones are.

TheOtherEric

I would have been in the "hogwash" camp, but if Tony & Brian say they've seen warpage then apparently it can occur in rare instances. Since it's not common, I wouldn't call this a "known design flaw," he's just trying to sell you some parts. I'd stick to OEM parts if you do replace them, but if it were me I'd buy new lower gaskets and do it myself.

ceboyd

I heard it is a common problem for the lower covers to develop seepage leaks but have never before heard of the actual valve covers being a 'known defect' I suppose it is possible BUT I smell extra parts and work being sold IMHO.

f_scaife

I think the 'design flaw' he might be refering to is the use of a plastic valve cover (his opinion). I replaced mine with the Imagine billet covers due to slight leak on the right side. When I bought mine I thought they came with new hardware but they did not, might want to clarify this with them if you order them.

Bull

In our PCA Region, it is fairly common for 993s that are tracked regularly, and therefor subjected to higher temps than street driven cars, to develop lower cover leaks with stock covers. I have personally seen warped covers. I, and most of those I know who regularly track 993s, now use the billet aluminum covers. To date, none of us have experienced any leakage, some after several years.

Marc Shaw

I got the IA billet ones for my 964 and they did come with gaskets and lock nuts - what other h/w were you missing? (Oh yeah, and the new ones do not leak while the old stock ones were warped).

Marc

Bull

Same here, for the 993.

Pickled Piper

I was given the same information in the UK. I had leaks from lower covers. The mechanic replaced the complete covers and gaskets for the very reason you state.

pp

cesar

My indie here on the East Coast said the same thing about a design flaw that has been fixed now.

black ice

the gaskets are cheap enough and it's an easy DIY such that it makes sense to just swap the gaskets and see how it goes. The torque spec of 7 or 8 ft lbs is impressively small - you really need to torque wrench one or two to see just how small. It would be no surprise to me if the majority of leaks after repair are from overtightening.

Dave