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420A 420a Valve cover gasket

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609DSM

Proven Member
368
154
Aug 13, 2019
Langhorne, Pennsylvania
Started off with rough idle, turned into intermittent misfiring. Thinking vacuum leak, thinking spark plugs, coil pack, wires. What could it be!?! Noticed today my oil leak wasn't coming from my drain plug... pulled my new spark plugs out (NGK bkr6e or whatever the name is gapped to the recommended. 045) noticed some oil on the threads "huh" I thought. Further inspection lead to me using a flashlight all around my motor, found fresh oil on the back of my head coming from my valve cover. I've been getting a weird sound, like a sucking/blowing sound, the pulling of air when I rev higher and the release of it when I let off. The oil leak is more pronounced and so is the sound of the air pulling/releasing (only happens at specific rpm during specific loads).

After my research and inspection I found this valve cover gasket leak, the symptoms are there, rough idle with misfire and also oil on my threads. I believe this to be the issue, I hope I went into detail enough. If anyone has anything to add or if I might be wrong on something feel free to shoot your two pennies my way, hopefully this helps someone who is having these issues.

This was a sneaky ninja leak as it only just recently got to the point where it was noticeably bad. Neglegance on my part and lack of inspection (I've been extremely busy, school+work).
 
If the valve cover is leaking oil then you should go ahead and replace it. However, I think you have something else going on. I don't expect that this will fix your misfire problem. Put a new set of plugs in it while your in there and we can go from there
 
Have you ever checked any of your vacuum system? There are quite a few places it could leak. Also you can find any leaks by spraying starting fluid in what you believe to be the affected area.

And this "sucking/blowing" thing sounds very similar to when my intake manifold gaskets were bad. Check those too.

As far as the oil leak goes you should definitely do as @silvreclips said and replace the vc gasket first. I put black rtv in the groove in the vc and popped the seal into place before trying to place the vc back on the engine, this way you don't lose all the seal pieces down in your engine. Once you've done that properly then degrease the entire engine and run it some more to be sure you've found the issue. Also be sure not to over tighten your vc, YOU WILL CRACK IT. Hand tight, finger tight, 2 ft. lbs, or whatever you call it. Just stay mild.
 
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