Valve Cover Leaks

[Sulley]

One thing I hate is anything that leaks under a car. Once I got my Manta Mirage I resealed the trans-axle, oil pan, and valve covers as they were all leaking. This is pretty 101 stuff but I continued to have an issue with my valve cover gaskets on the Chevy 350. So here is what I did to stop the leaking valve covers on my Manta Mirage 350. It maybe helpful to other novice DIY'ers battling with this issue.

When I last replaced these I spent extra money to get 'high performance' valve cover gaskets thinking it would be worth the extra $. Unfortunately in short order after removing the valve cover the gaskets were already hardened. So the process I went through was as follows:

1) I purchased new cork gaskets but thicker ones hoping that if there were any irregular areas on the valve covers that this would help seal them better.
2) Remove and clean old gasket material and thoroughly dry.
3) I checked the valve covers flanges for any uneven or irregular areas from over torquing of the bolts.
4) I used the extra valve cover hold down flanges. These are very thick and my theory is that they would help to evenly distribute the pressure across the valve cover. I only used on the lower 2 bolts of each valve cover.
5) I needed to re-bend these as they had been over torqued in the past likely by me and the pressure was not evenly distributed as needed. With the adjustments that is corrected as you can see in the image.
6) I used a spray adhesive and sprayed ONLY the valve cover and one side of the gasket and positioned it exactly where it needed to be so I was ensured a correct fit when I installed the valve cover.
7) No silicone used!
8) I used new lock washers as mine were flattened out. My engine has a big cam and I needed a lock washer to prevent potentially the bolts backing out.
9) When installing the valve cover, one side of the gasket has 2 holes and the other has 4. Position the side with 4 up as to reduce potential leaks.
10) I slowly hand tightened with a socket and extension and just my hand each bolt until they started to get firm doing so in a rotating pattern around the valve cover.
11) Once they started to get firm I only 1/4 turned each one in the continuing random sequence until they stopped. The key is not to over tighten but get them tight enough.
12) I ran engine and after it was warm I again rechecked the bolts and re-secured.

I'll drive today but so far so good no leaks on the floor.

[Ken Walsh]

TIG welding the valve covers to the heads seems to work pretty well, too........

[Blueovalz]

Not applicable to your configuration, but this was addressed extremely well with the current generation of engines, particularly the GM motors in that they are metal/silicone pieces that maintain shape and seal, yet allow the user to torque the bolts down without squishing the gasket out. Virtually foolproof gaskets.

[Sulley]

Unfortunately I don't know how to Tig weld....

So far no leaks from what I can tell after a few short drives. I think my timing chain cover may have a small leak and that is a pain if I have to change that out. I don't like anything leaking under my cars. Kind of OCD about that.

[Blueovalz]

We may both be able to celebrate then. I've had a nagging leak somewhere on the dry sump pump area (it is part of the oil pan, so it was not easy to find). After weeks of trying to find it, I caught a glimpse of where perhaps an O-ring was squished out between the pump segments. So I dropped the pan, removed and re-assembled the pump (yes, 3/4's of the 12 O-rings were not seated correctly), and then today I tested it with no leaks thus far. Before this fix (at least I'm hoping it is fixed), I lost over a gallon of oil in about 45 minutes of total driving time. So it was a pretty significant leak that appears to be staying dry. The problem I believe was due to me using a 2mm O-ring instead of a .070" O-ring. That extra .008" of cord evidently was enough to make the O-ring not compress properly in the grooves. So I went back in with the slightly smaller cord, and it all went together nicely. Yes, bigger is not always better.

[Sulley]

Lol - glad to hear that about size!

12 O-rings that must have been a time consuming job! With that kind of leak it must have been making a real mess. Let's both keep our fingers crossed!

[Blueovalz]

After taking it apart and rebuilding it half a dozen times, it gets pretty easy now. Here's about half of the disassembled pump.

[Nidrahynnad]

OOOPs! Because it is all apart, does that mean it still leaks? Or is this just for reference since the "o" ring replacement?

Dan

[Blueovalz]

No leaks (going on two weeks) so far, so it looks like that was the problem. That was an old photo to help me put it back together again. Today, I think I could probably put it back together in my sleep.

[Manta22]

One big advantage that cast aluminum valve covers have over stock stamped sheet metal covers is that their gasket surface is much stronger and stays flat as the bolts are tightened. I like to seal the gaskets with Hylomar. It is easier to disassemble and reinstall than when silicone RTV is used.