Damn valve cover gasket..

[James C.]

Hello all,
l am looking for some input on the valve cover gasket. My front cover started to seep a bit in the fall just before the end of riding season. I stored my bike for the winter and early this year purchased an aftermarket gasket online and changed the gasket before riding season. After I replaced the gasket it was leaking quite a lot from one of the half moons. I pulled the cover back off and tried tightening it down again making sure it was tightened down even. Then it began to leak in a couple of other spots. So I pulled the cover again and put a thin layer of Loctite 518 gasket eliminator all around the bottom side of the gasket and reinstalled it. It was STILL leaking, this time leaving a small puddle on the floor where it was parked. I purchased a new gasket from Yamaha and had a local shop install it, just picked the bike up today. After riding it for a bit, it is still happening. I am at a loss here. Is there something else going on thats causing this? I do not see any damage on the cover. Could there be a plugged breather somewhere? I did switch the bike from yamalube 20w50 to Rotella 15w40 this year as it seemed to run warm with the old oil in 30°C.

 

[James C.]

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[KSRider12]

There is a crankcase breather hose that goes to the rear of the airbox that can get kinked if not attached properly. I feel ya. I did both of my valve cover gaskets earlier this year, replaced the coolant hoses too.
I used high temp RTV and installed the gaskets into the covers and let them cure overnight, just have to be careful not to snag the cam/chain when you finagle the covers on. The cover bolts are shouldered so you can't really crank down on them to compress the gasket any more than they allow. Could the cover be warped/bent? It's a long shot, but...

 

[James C.]

I will have to take a look this evening and make sure that breather hose isn't kinked, but it's only the front cover that is leaking the rear one is fine. I'm starting to wonder if there is something wrong with the cover. I did not see any physical damage when I had it apart, and I would think the shop would have seen something as well. At this point I don't think the gasket is what my problem is anymore.

 

[one2dmax]

Likely you need to replace the grommets on the bolts. We have had occasions where over-torquing of the bolts damaged the cam caps and caused the bolts to go too far down and damaged the gaskets.

 

[James C.]

The bike is back at the shop today, seems I paid them to "fix" it I figured I would try and get my moneys worth. If I am not successful with that then I will go to Yamaha and order another gasket and some more of those grommets. Thanks for the input guys. It seems the only tool I can get in there to tighten the bolts is an Allen key. Is there a way to actually torque the bolts without tearing everything apart? I've never put much force on them even with the Allen key, especially in fear of breaking those little bolts.

 

[sdt354]

The bike is back at the shop today, seems I paid them to "fix" it I figured I would try and get my moneys worth. If I am not successful with that then I will go to Yamaha and order another gasket and some more of those grommets. Thanks for the input guys. It seems the only tool I can get in there to tighten the bolts is an Allen key. Is there a way to actually torque the bolts without tearing everything apart? I've never put much force on them even with the Allen key, especially in fear of breaking those little bolts.

The bolts do bottom out, so not much torque needed.

 

[[email protected]]

Damn near impossible to get a torque wrench in there. Tighten bolts till they bottom out then a little more oomph into em to just snug them up a bit.

 

[Edward]

... I replaced the gasket it was leaking ... Is there something else going on thats causing this? I do not see any damage on the cover. ...

You are using an OEM gasket so you've done everything you can do regarding materials. OEM gaskets don't leak. The problem is with the installation. The installer MUST make sure ALL traces of oil are removed from BOTH mating surfaces AND the gasket itself, before installing the cover. Oil is designed to flow into the smallest of passageways. If there is any trace- AT ALL- on any of the mating surfaces, oil WILL find its way through.

Your mechanic should know this! He must disassemble the cover and clean every mating surface with MEC or other VOC like lacquer thinner and then guard against any oil contamination until the cover is torqued down. "Clean" here means wiping with a MEC dampened paper towel until there is absolutely NO TRACE, of oil on the towel after wiping!

Also check to make sure all bolts are of the correct length.

Make sure there is no porosity in the castings' mating surfaces. If found, clean as above, fill them with body filler, file flat and try again.

 

[James C.]

So I picked the bike back up yesterday evening. The mechanic said there was about a 1/4" section where the gasket had pushed out. It only took about 20 mins of riding before it started leaking. He removed the cover and cleaned everything up had a second person help him make sure everything was seated correctly all the way around when laying the cover back on. He said he would recommend changing the cover if it happens again. I rode it for about 3 hours after and it hasn't leaked so far.

Even when I had it apart, the surface on the top of the head where the gasket sits had no signs of wear or rough spots, I am wondering at this point if the gasket popped out or if it may have not quite been seated properly in that small section when the cover got installed.