Valve cover bolts loosen up over time?

[mclasser]

I had the VC gasket & valves adjusted at the Honda dealer about 2 yrs back. For the past few months, I've noticed some dried oil along the front of the VC. Honda gaskets are good quality so I don't think it's leaking already. I've read the torque of the VC bolts should be re-checked some time after gasket replacement. Is it common for the bolts to loosen up over time? I don't have a torque wrench that measures 86 in-lbs so I'm just going to use my 1/4" ratchet to check the bolts.

 

[Kool1]

I don't believe the bolts loosen but the rubber gasket will set. It's a good idea to snug the bolts once in a while.

 

[BRZED]

Torquing the valve cover bolts properly, beginning in the center and working your way outwards, alternating sides a in criss-cross fashion is important to assure even torquing, which helps prevent leaks. I fidn this escially to be true with plastic valve covers. A dab of RTV in critical areas where the gasket makes sharp bends helps also. You can also put a little RTV on each bolt as a sort of threadlocker. Make sure all surfaces are absolutly oil-free.

 

[The Critic]

Check to see if there is Hondabond/RTV in the proper places. It's possible that they did not put enough on those spots and somehow, coupled with some other factors, may have caused a leak to start.

 

[Merkava_4]

The gasket shrinks over time, making you think the bolts loosened up.

 

[Hokiefyd]

The bolts for the cylinder head cover thread through a large rubber seal (image search for "honda valve cover bolt seal" and you'll see what I mean). These rubber seals can also take a bit of a set after you initially tighten the bolt, especially if they were replaced during the job.

Was the cylinder head cover gasket replaced during the job? I've never replaced one, myself -- I just re-use them. If it was replaced, then I'll bet the bolts could use a bit of a snugging.

 

[Garak]

Originally Posted By: Kool1
I don't believe the bolts loosen but the rubber gasket will set. It's a good idea to snug the bolts once in a while.

This, exactly. When my Audi's valve cover gasket started to leak, and I went to replace it, I was able to remove all the nuts (that's what Audi uses rather than bolts) by hand.

 

[Tegger]

Originally Posted By: mclasser
I don't have a torque wrench that measures 86 in-lbs so I'm just going to use my 1/4" ratchet to check the bolts.

Be VERY careful!!! 86 in/lbs is the same as 7 ft/lbs, which is nothing. Those valve-cover fasteners are easily snapped or stripped if overtorqued.

You would be very wise to go to AutoZone or other place and get a cheap beam-type torque wrench that measures in ft/lbs.

As for the leak... It does happen. And once it starts, the only way to fix it is to pull the cover off and clean off every trace of oil from the gasket and the mating surfaces before reassembling the unit. Do NOT apply RTV or you will never get that cover off again. RTV may be applied--sparingly--to the points of the humps around the camshafts.

A new OEM gasket would be advisable despite the cost. Re-using an old gasket isn't a great idea. I've found that once they start leaking, they will tend to leak again fairly soon even if you managed to stop the original leak.

 

[kschachn]

Are you sure the cover doesn't bottom out onto the head? My Toyota does (actually the bolts are shouldered), and I'm pretty sure my Accord does too. If the cover bottoms out then it has nothing to do with compression of the gasket after it makes contact.

 

[Tegger]

Originally Posted By: kschachn
If the cover bottoms out then it has nothing to do with compression of the gasket after it makes contact.

That doesn't make any sense. ALL gaskets need to compress a little (sometimes a lot) in order to function.

Your shouldered bolts probably apply a calibrated amount of compression to the gasket.

 

[kschachn]

Originally Posted By: Tegger
Originally Posted By: kschachn
If the cover bottoms out then it has nothing to do with compression of the gasket after it makes contact.

That doesn't make any sense. ALL gaskets need to compress a little (sometimes a lot) in order to function.

Your shouldered bolts probably apply a calibrated amount of compression to the gasket.


The rounded gasket sits in a groove in the cover, and protrudes above the edge. Both the shouldered bolts and the bottomed out cover work to impart a predetermined compression into the gasket. This prevents squeezing out the gasket by over-compression, but also prevents you from being able to re-tighten it down once it starts leaking.

All four of my cars are this way, I've not seen a old-style valve cover with a flat gasket for a long time.

Random photo:

 

[Tegger]

Originally Posted By: kschachn
Originally Posted By: Tegger
Your shouldered bolts probably apply a calibrated amount of compression to the gasket.

Both the shouldered bolts and the bottomed out cover work to impart a predetermined compression into the gasket.

Yes. Correct compression is everything.

If thoroughly cleaning the gasket and mating surfaces of oil does not cure the leak, then the only solution is a new gasket.

 

[mclasser]

Thanks for the input, everyone. Ended up getting an in-lbs torque wrench from Harbor Freight fr cheap. Will probably come in handy when I tackle plugs, coils and VCGs on my I35 eventually (yay for pulling the intake plenum!). Anyway, 2 bolts were slightly, I mean slightly under-torqued. Will verify everything once more with a cold engine.

 

[Tegger]

Originally Posted By: mclasser
2 bolts were slightly, I mean slightly under-torqued. Will verify everything once more with a cold engine.

Once an oil-leak begins, it cannot be stopped with a simple re-torquing. It's NOT like a water-leak.

You need to take it all apart and clean off every trace of oil from all mating surfaces, then reassemble. If the gasket is in decent shape, the leak may then stop.

 

[kschachn]

Originally Posted By: Tegger
You need to take it all apart and clean off every trace of oil from all mating surfaces, then reassemble. If the gasket is in decent shape, the leak may then stop.


If it's leaking, taking it apart and cleaning it up isn't likely to help. The problem usually a compression set in the gasket due to heat and age. Only a new gasket is going to help that.

 

[Tegger]

Originally Posted By: kschachn
Originally Posted By: Tegger
You need to take it all apart and clean off every trace of oil from all mating surfaces, then reassemble. If the gasket is in decent shape, the leak may then stop.

If it's leaking, taking it apart and cleaning it up isn't likely to help. The problem usually a compression set in the gasket due to heat and age. Only a new gasket is going to help that.

I agree. A new gasket is the proper answer.

 

[mclasser]

Originally Posted By: Tegger
Once an oil-leak begins, it cannot be stopped with a simple re-torquing. It's NOT like a water-leak.

You need to take it all apart and clean off every trace of oil from all mating surfaces, then reassemble. If the gasket is in decent shape, the leak may then stop.

I was afraid of that. I would try and complain to the dealer that installed the VCG but they'll be quick to turn me away saying the 1 yr warranty is up.

 

[GiveMeAVowel]

Originally Posted By: mclasser

I was afraid of that. I would try and complain to the dealer that installed the VCG but they'll be quick to turn me away saying the 1 yr warranty is up.


It is however I think it is reasonable to expect a valve cover gasket to seal for longer than just one year, most of the time they will last (unmolested after the initial install) for up to a decade. I'd go back and politely explain the situation, they might replace it or possibly if you are lucky a re-torque might work.