Topic: Cam chain wore through valve cover--Is this a problem? PICS

[hevykevy420]

So I've been having some problems with a leaky valve cover if any of you have read my past posts.  I decided to try to redo the valve cover seal using Permatex red silicone gasket sealer, rather than the non-hardening gasket sealer originally used that was not working (and now is inside the valve cover). 

I noticed in the dissassembly that the cam chain wore completely though the valve cover in a small area.  I think this may have happened before the rebuild, but I did not think it would affect anything.  I'm also getting oil pooling up around the valves, could I have a blockage in one of the return openings???  I did notice chunks of gasket sealer in there which I'm trying to fish out with the engine in the frame, that cannot be good.  My question is, Is it normal to have oil pooling in the valve areas, and could my oil leak be caused by the lack of vaccuum from the cylinder head because of the cam chain wearing through the valve cover?  The vaccuum, as it is now, is not limited to the valve cover area because of the worn through cover.

[nickjtc]

Can't speak for your 750, but on the 650s Honda designed the top end so that there is always a pool of oil under the cam lobes, so that on start up they are lubricated straight away. Makes it a bit 'moist' when checking valve lash, but I'd rather have it that way than end up with excessively worn cam lobes, due to red lining it from start up. Just kidding about that.

Drop the sump to see what debris has found it's way down there.

[Fiend]

My 750 is the same way, my friends is too.
A word to the wise, I myself would stay away from Permatex or RTV.
At the dealer they have stuff called "Hondabond", its wonderful.

[Tim.]

I don't think the chain wore through your cover - that area open to the chain in your picture is there by design if I'm not mistaken.

There's no physical way of your chain reaching that surface of your cover and your bike still running.

[bryanj]

That hole is part of the "breathing" system

[Bodi]

Vacuum?

[hevykevy420]

I don't think the chain wore through your cover - that area open to the chain in your picture is there by design if I'm not mistaken.

There's no physical way of your chain reaching that surface of your cover and your bike still running.

The edges are sharp, like something wore through the cover at that point, not like the cover was manufactured that way.  Maybe the cam chain snapped on the PO or something, causing the wear???  It would appear to me that if the way it is now, I am venting the crankcase through the cylinder head breather tube.  Shouldn't the crankcase breather tube operate for this reason?

If anyone has a spare valve cover laying around, it would be great for someone to check for me whether or not there is an opening here...before I patch the hole.

[Bob Wessner]

I think you may have a problem. Here's a pic of an earlier 750 valve cover. Note the location of the holes in it and the lack of any such holes in the guide/shield directly over the cam chain... unless the later 750 covers were manufactured differently. 

This shot was taken from the underside.

[crazypj]

The first picture looks stock or modded for something?
 The machining/castin mark goes all the way to the top right next to the bolt boss.
You can see the step/ridge, there is no way the cam chain did that.
As its on the front run of chain, most of the oil will be flung off before it reaches the area shown
PJ

[Lumbee]

...hold u'r horses hevy...I went through the same thing with my 78K.  Is the motor from the K8 in u'r pic?  Not sure if its a later model thing or what, but my 78K and both F2 motors I've rebuilt are like this.  I know what u mean about the edges not looking manufactured, and I swore the chain must have done it, but no dice, they built'm that way, so no worries...

...the oil pooling in the head is a good thing...it means oil is getting there, if u didn't have it there then I'd be worried.  What is not so good is the chuncks of gasket sealer u said u found.  My personal preference is no sealer anywhere on any gaskets.  It makes the job of keeping the engine leak free a little tougher, but for me its worth the trade off of not getting any gasket bits in my oil system.  If u feel u must use gasket sealer use it VERY sparigly.  Pull u'r oil filter and oil pan and check for the chunks of sealant every few hundred miles, and keep doing so til its all gone.  Good luck...

Just noticed I hit a milestone... ONE THOUGHSAND POSTS!!!   

[hevykevy420]

Thanks for the advice everyone!

It seems I'm getting two different answers here!   Lumbee- My engine is the original K8 engine (but modified) from this bike.  It is not a transplant from another bike.

Bob- I definitely have a breach on the cam chain shield/cover area...I can see the chain right through the cover!

Crazypj- I did not machine the cover this way or mod the cover (unless PO did), this is simply what I found when trying to stop the valve cover leak.

Lumbee- Are you sure my cover should have this opening here?

I'd love to not have to use gasket sealer!!  I did not use any after the rebuild except for a spray sealant I used on the Cometic head gasket (no leaking from head gasket), but after all the oil leaking from the valve cover I tried some non-hardening sealant, but still oil is leaking out of the valve cover gasket.  (I've checked the tappet covers, and the tach seal which was replaced, and I'm getting no oil from these.)  Now I'm going to try stronger gasket sealer because I'm out of options!!!  (I've already added a crancase breather filter in the line between the oil tank and crankcase breather, which helped a bit.)

I guess what I'm really wondering is:  if I plug this hole through the valve cover, will this help stop the oil leaking from the valve cover, or maybe reduce pressure in the valve cover area that may be caused by crankcase pressure???  I'm running out of ideas and pants without oil stains!!!!!!!

[sparty]

Seems to me that everything is in working order.  My valve cover looks the same and the casting makes for some roughly finished edges.  The oil around your springs is normal.  Is this your first time taking apart the top end?  If so, you'll learn a lot, I did.

Sparty

[Lumbee]

Lumbee- Are you sure my cover should have this opening here?

...all I can say is all 3 engines I've rebuilt were this way...

I guess what I'm really wondering is:  if I plug this hole through the valve cover, will this help stop the oil leaking from the valve cover, or maybe reduce pressure in the valve cover area that may be caused by crankcase pressure?

I'd say no. 

#1  The pressure escapes from the vent in the valve cover, so there is no real pressue to speak of in there.

#2 Blocking the hole is a bad idea.  Honda made it that way for a reason.  It seems to me there is an open loop to the environment from the vent at the back of the crankcase, through the case up the cam chain corridor out through the cut out in the valve cover, then out the vent in the top of the valve cover cap.  If you close this area, it effectively closes the loop, which to me would not seem good.  Perhaps could effect oil flow/pressure?  Of course this begs the question, is the valve cover closed on earlier bikes?   

[wardmoto]

Silicone in your oil will clog returns and pick up screens and will cost you an engine

I would be concerned if there was no pooling of oil in the head

The oil runs down those gallerys via gravity...not vacum

The cover is vented to the atmosphere becuse it is a crank case vent that alllows pressure changes below the pistons (as they ascend and descend) to go somwhere so they dont produce parasitic, power robbing, pumping losses (say that three times) 

Any hole in the valve cover that Honda didn't put there is bad