2010 Problem (cam cover leak)


102 replies to this topic
  • aedwards07

Posted August 18, 2010 - 02:49 PM

#61

At this point ill try anything...

Rchurch22,
Your not supposed to cut that leash portion off?

  • grayracer513

Posted August 18, 2010 - 04:29 PM

#62

Just for starters, unless the gasket comes with a cam chain, I'd like to see how it's assembled with the bridge link from the plug hole over to the half moons intact. I'm sure I must be missing something....

Anyway, my own personal theory on this is that the gasket is being compressed excessively and squeezed out of place. To see if there is any merit to this idea, you need to take a couple of measurements.

First let's understand how this is set up. The three cover bolts are shouldered, so they can only screw in so far. The cover itself is sandwiched between the conical grommets on the bolts, and the gasket. The pressure on the gasket is determined by the length of the bolt shoulder in combination with the three grommets.

So, to begin with, what I would be curious about is:
  • With the cover bolted down on the gasket like it is now, what is the gap between the head and cover?
  • With the gasket removed, and the cover bolted down (bolts snugged up to say 50 inch/pounds) with the bolts, washers, and grommets, what is the gap between the head and the cover?
  • With the gasket in place, and the bolts run down just until they contact the cover, how many turns tighter do the bolts rotate before the shoulders bottom?

May it never leak again, but if it does, or if you check the valves, try to find that out, and maybe it will lead us to something.

  • rickallen124

Posted August 18, 2010 - 05:33 PM

#63

My friend had his leak a few rides after he checked the valves at 28hrs, not sure if it was an error on his part or faulty gasket. He put a new gasket in and hasn't had any problems since.

  • aedwards07

Posted August 20, 2010 - 11:37 AM

#64

Gray

1. 2.68 mm
2. 1.27 mm
3. 2 1/4 turns

I tried the super glue this time as well.

  • grayracer513

Posted August 20, 2010 - 12:58 PM

#65

  • With the cover bolted down on the gasket like it is now, what is the gap between the head and cover?
  • With the gasket removed, and the cover bolted down (bolts snugged up to say 50 inch/pounds) with the bolts, washers, and grommets, what is the gap between the head and the cover?
  • With the gasket in place, and the bolts run down just until they contact the cover, how many turns tighter do the bolts rotate before the shoulders bottom?


1. 2.68 mm
2. 1.27 mm
3. 2 1/4 turns

How thick is the uncompressed new gasket? That was a question I forgot to ask.

From your answers to 1&2, we can see that the three rubber seals themselves are compressing 1.41mm (.055"). Depending on how hard or soft they are, that could be reasonable or not so.

The answer to 3 tells me that since the bolts have a 1.0mm thread pitch, the bolt heads move down 2.25mm (.089") from contact to tightened. Subtracting the 1.41 grommet compression from that suggests that the gasket compresses only 0.84mm (.033"), which really doesn't sound like a lot unless it takes a lot of pressure to compress it that far.

Another thing to look at is this: If the gasket always slides the same direction at the same place, carefully check the machined surface of the cam cover and the head for any inconsistency in flatness that would lead to this.

  • 801pe

Posted August 20, 2010 - 05:41 PM

#66

My guess is the tank when full is pressing down on the spark plug boot. When you go into corners aggressively the tank is putting pressure on the boot, which is compressing the gasket. I thought about loosening the engine mounts to see how much lower I can get the engine. My other idea was to shim the tank @ 5mm higher. I told my friend to only fill the tank 1/2 full to see if it would help.

E.

  • aedwards07

Posted August 21, 2010 - 04:51 AM

#67

It seems they are all ripping in the same place and sliding out the same.The head not being machined flat seems valid.

  • Icon

Posted August 21, 2010 - 04:14 PM

#68

I went through three in the first 13 hrs. Each had a slice in the identical location around the spark plug hole. I quit tighening the cover bolts all the way to spec on my last one and so far have gone 12 hrs on it. My sliced gaskets were warrantied by Yamaha Canada and they advised they would do so until there was a permanent solution for the issue

  • Davey762

Posted August 22, 2010 - 06:44 PM

#69

I went through three in the first 13 hrs. Each had a slice in the identical location around the spark plug hole. I quit tighening the cover bolts all the way to spec on my last one and so far have gone 12 hrs on it. My sliced gaskets were warrantied by Yamaha Canada and they advised they would do so until there was a permanent solution for the issue


Did they allow you to change the gasket yourself?

  • Icon

Posted August 23, 2010 - 05:49 AM

#70

Yes they did.

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  • Davey762

Posted August 23, 2010 - 07:19 AM

#71

Yes they did.


That's good to hear, but BS for myself. Yamaha Canada said the dealer had to install the gasket because they are trained! What bs, if you do your own air filter maintenance, its three more bolts to change the gasket. :bonk:

  • Wallacedog

Posted August 31, 2010 - 01:38 AM

#72

We had one fail at about 30 hours, i called an engine builder who said that he increrases the size of the hole in the head when he takes heads off if he does not remove the head he takes a 1/2'' cutter and makes a half moon shape in the valve cover, I went a step further and blended the breather tube to increase air flow inside the head and valve cover area.

We have not had another failure since doing that and I know one other guy that used this fix successfully.

  • Chazmagnum

Posted March 06, 2011 - 10:08 AM

#73

Just curious, could we have;
1. State or country, of purchase of the problem bikes?
2. Air temps?
3. Type of use e.g. hard, intermediate, trail, desert ect?
4. Engine map?
5. Fuel type?
6. New oil type?
7. Hours of engine running time?
Just curious


Washington State
50 degrees
motocross only
jay marmot
same oil ive been using Amsoil full syn
55hrs

Mine just went I will tear into it today.:thumbsup:

  • brentn

Posted March 06, 2011 - 11:11 AM

#74

I'm at almost 30 hours and no leaks yet. I have even removed it to check the valve 8 hours ago and re-used the same gasket and no leaking.

  • Wallacedog

Posted March 08, 2011 - 11:22 AM

#75

Washington State
50 degrees
motocross only
jay marmot
same oil ive been using Amsoil full syn
55hrs

Mine just went I will tear into it today.:thumbsup:


California
Hot
Motocross only
GYTR agressive throttle response map
Castrol Black cap
20 hrs
Expert level rider

  • gfreeman902

Posted March 09, 2011 - 06:48 PM

#76

I had the same problem with mine. I put some high temp silicone around the spark plug and did nothing I tried it again and put a little more and it did nothing. I'm going to try a new gasket and hopefully that works. I've got about 50 hours on mine.

  • brentn

Posted March 09, 2011 - 08:22 PM

#77

I had the same problem with mine. I put some high temp silicone around the spark plug and did nothing I tried it again and put a little more and it did nothing. I'm going to try a new gasket and hopefully that works. I've got about 50 hours on mine.


Is it possible that the cam cover is warping under heat? For this issue to happen so many times for certain people is crazy.
Did you check your breather tube for an obstruction?

  • Wallacedog

Posted March 10, 2011 - 12:38 AM

#78

Here are the pictures, this is an easy fix.
Posted Image
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  • HRC

Posted March 10, 2011 - 01:04 AM

#79

Sorry if this question has been up before....but does this problem exist also on the 2011 YZ450F ?

  • grayracer513

Posted March 10, 2011 - 08:28 AM

#80

Here are the pictures, this is an easy fix.

I'm not sure why you would think that would be a fix for your problem at all. The gasket around the plug hole is torn down the center as a result of too little clearance between the cover and head when bolted down, causing the gasket to compress to an excess and split.





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