valve cover bolts keep loosening?

[TheGeneral]

Hi everybody,

I am pretty sure I was not supposed to use threadlocker or torque down too hard on my valve cover bolts when I replaced it recently, but so far I have replaced gasket/bolts, driven, retightened, driven, retightened, driven 3x and they still seem to get loose enough after about a week that I start dieseling again.  What gives?  I don't want to warp my cover.   Could these be incorrect bolts or something, or should I use a very specific threadlocker?   She sure runs great when it's freshly tightened.

Cheers, Bell

[Gary Lewis]

I'm confused.  I can't imagine why the valve cover bolts would cause the engine to diesel.  Do you mean intake manifold bolts?

If it is the valve cover bolts, did you use cork gaskets?  They do tend to change thickness after you install them.  But in any case, I'd pull each bolt, clean it and clean the threads in the head, put blue Loctite on it, and put it back to the right torque spec.  Go through all the bolts one at a time and they shouldn't loosen again.

[mat in tn]

dieseling? what engine do you have?

[RenoHuskerDu]

In the old days, 70s, we stole this idea from GM to put on our Fords.  My 289 put out about 350hp after I rebuilt it, and propelled me to 136mph one time. I'm lucky to be alive.

Spreaders for valve cover bolts

[Gary Lewis]

Yep, I used those spreaders on a bowtie 350.  Worked good.

[TheGeneral]

I did use cork gasket+ Permatex aviation liquid gasket (not sure exactly what name)...I scrubbed all bolts with engine degreaser before install, so they were as clean as they could get.  

The 'dieseling' I am referring to does not seem to occur at all for about a week after I tighten everything up, then it slowly starts again....rumbling after I turn the ignition off.  Clearly a vacuum leak type of thing.

Now, I *did* have my exhaust manifold professionally replaced several months ago, and I thought they were going to do the intake at the same time but alas they did not:(   But for the most part I think that stuff is ok.  I managed to pass smog afterwards, anyway lol.

I will try the Blue stuff as suggested later today if the weather holds, I just wanted to make sure I did not use a product that could damage gasket or make it impossible to remove bolts later.

Thanks so much!!

[TheGeneral]

straight 6

[TheGeneral]

Ooh, great idea!   Gotta find me a set of those!  While it doesn't APPEAR to be warped in any way, I know that can be an issue as far as getting a good seal.  

[TheGeneral]

You know, now that I think about it, I have a feeling one of my motor mounts might be failing, causing a lot more turbulence and rattling so to speak.  Oof

[Gary Lewis]

It sounds like you are getting way too much air into the intake via the PCV system when the valve cover works its way loose.  But the PCV valve should limit that, so I think there is something amiss.

Anyway, if you get it sealed up tight then you shouldn't have the problem.

Good luck!

[mat in tn]

if you had the exhaust manifold replaced you should have new intake gasket also. they go on sandwiched together at the same time. also ther is another gasket where the intake and exhaust manifold bolt together

[ratdude747]

TheGeneral wrote

The 'dieseling' I am referring to does not seem to occur at all for about a week after I tighten everything up, then it slowly starts again....rumbling after I turn the ignition off.  Clearly a vacuum leak type of thing.

My 300 does that about half the time... slight dieseling, assumed it was a byproduct of being carbed. That was before and after a rebuild no less. My gaskets are slightly leaky but I kinda doubt that's related.

Personally I wouldn't look into it if there are no other issues.