dlpalumbo

I had purchased and had installed by indy aluminum valve covers during a rebuild. They leaked. A lot. I posted a thread voicing my dissatisfaction here. I received many responses varying from "they dont leak for me" to "use some sealant" or "have them milled".

I tried Hylomar sealant, twice. Once very thin, then more liberal application. Still leaked. Even had a preset torque wrench to not over tighten. The car is now back at indy where he is recommending having having them milled. We'll see.

The interesting thing is that he told me he's seeing a lot of leaking aftermarket valve covers. This made me think. My covers are powder coated. I have had experience with assembling powder coated components where they didn't fit together properly. The coating is too thick and I needed to scrape it off to get a proper fit.

I asked the indy if the other leaking aftermarket covers were powder coated. He said they were.

Now for the question(s). If you have aftermarket valve covers, are they power coated, and, do they leak?

Cheers ,

Dan

See update below...

tbennett017

Mine are not powder coated. They do not leak at all.

Though I'd question the installation procedure. Using new O-ring style gaskets, the amount of torque is minimal. (7 ft lbs) which is only wrist tight. There is a distinct risk of over tightening, which will allow leaks. I have had mine on and off about 5 times with no leaks.

dlpalumbo

Bought a torque wrench set to 84 in lb specifically for this job. Torqued nuts from inside out a bit at a time. Was very fussy and very pissed when they still leaked.

Maybe the powder coating reduces the diameter of the cover's D-channel enough so that the gasket doesn't seat right. Might have equivalent effect of over tightening.

cobalt

If anything the D channel being filled will push the seal out more and should prevent leaking. If you use a sealant What type and use it only in the channel.

I am assuming you are using new gaskets each time? Most of these leak de to dried out gaskets which shrink over time and cheap Chinese gaskets are undersized. I have just redone two engines with original mag covers and no leaks. Are you verifying all surfaces are clean prior to install? Sometimes running a flat file across the mating face will verify if their are any high spots which can interfere with the gasket doing its job.

PhatPhlatSix

My Rennline covers leak, but only if I've been giving it the beans - no leaks with 'sensible driving'. My theory from this is that the engine twists under hard acceleration and this causes the leaks. Probably not a lot that can be done apart from some valve covers from a flexible material...

ALEX P

It amazes me how these covers leak with the size of the gasket on 964's when earlier cars like 3.2's have a little paper gasket and don't leak.
I know the magnesium covers warp and this would account for them leaking a bit but earlier cars had aluminium covers and don't leak as bad and 993s have plastic covers and don't leak as bad so what is it with 964s???
For me, if you replace with aftermarket ally ones they really shouldn't leak and shouldn't need sealant.
I would also prefer an anodised finish instead of a powder coated finish. It can't chip off.

cobalt

61k miles on original aluminum valve covers. No leaks. I just reworked two 90 C2's using original mag valve covers and after replacing the gaskets no leaks. Seems odd that you have leaks especially since the gasket is the critical aspect of them sealing or not.

Have you checked the covers for flatness by using a quality straight edge? It is critical you clean the heads where the gasket sits. A lot of times there is rubber that is left behind that can cause the seal to not sit properly. I also found that the gaskets used on the timing chain covers can sometimes remove some of the magnesium leaving pits behind and can use some sealant to help them from weeping. When you mount the gaskets into the covers there should be at least .060 of gasket sitting above the adjacent surface of the cover. If that isn't the case that could be your problem.

Here is a picture of one of the 90 C2's many miles after I replaced the gaskets. Still no signs of weeping. The others from when I reworked my engine tins on my C2 and after years of track miles not a sign of oil weeping.

dlpalumbo

Hey, PhatPlatSix, are your cover 's powder coated? Do they leak more on cat converter side? Reason I ask is wondering if heat cycle is issue.

Thanks for all your inputs.

Super90

Appreciate your insight Anthony !

I bought a set of Porsche OE aluminum lower valve covers to install next oil change and get rid of my magnesium covers.

Next option from magnesium, after the OE aluminum models, would be the Rennline units that Singer is using? A local shop is using them to replace mag units too.

Seen here:




Would appreciate the thoughts of the other engine builders that frequent RL too, as they always have good insight/experience.

cobalt

I'm not a singer fan but their engines are IMO a thing of beauty. That is one engine I wouldn't say no to having in my car.

You should be fine with the factory aluminum covers. The rennline are nice but overkill unless you're racing. They sure look nice though. I have seen a number of people paint or powder coat their covers without taking into consideration the amount of extra material build up.

I did clean the mating surface before painting the covers for the 90 C2's. I found that the mag covers had high and low spots but nothing I would consider warped. If the cover touches the head and doesn't allow the gasket to do its job you will always have a leak. Removing 10 thousands or so of mating surface before applying any paint or powder coat might prove to prevent any leaks.

Rennline

The benefit of our billet aluminum ones is that they will not warp like the stock magnesium covers under high heat and stress. We offer them Anodized in clear, grey or black, and powder coated in red.

I would be interested to know what torque spec and gasket you are running. If your Cam towers are completely flat and you are using the recommended Victor Reinz gasket + torque spec, it would be physically impossible for oil to leak. It is also essential to make sure the mating surface on the cam towers has no residue from previous gaskets and buildup. One very common source of leaks is through the rocker shaft bore. From there, oil will often run down the back of the cam towers, and drip from the bottom front corner of the valve cover. This may be something for you to double check @ PhatPhlatSix.

dlpalumbo

I have the Rennline black powder coated vavlve covers and believe me it is not impossible for them to leak. Engine was rebuilt by experienced air cooled engine shop. Correct gaskets and torques applied.

Really not sure what is wrong here and, as claimed above, its hard to imagine how the covers could leak, but shop has seen several cars with aftermarket aluminum covers leaking. All powder coated.

Thus my inquiry with this thread.

HiWind

I have rennline w Vic Reinz gaskets... no leaks even after 3 valve adjustments and 1 top end refresh - lots of track time (no cats)

dlpalumbo

HiWind

Please tell us if your covers are powder coated.

Thanks

jimq

I just had to replace my pitted and corroded lower valve covers and ended up with the Porsche Aluminum Covers with a .2R part number. They were a lot cheaper than the magnesium ones .1 R part number
Lost a couple drops in 2 weeks out of one of them.