Cylinder Head Cover seal

Duporth

Duporth

Joined
Apr 24, 2017
Messages
415
Location
Australia
Bike
2022 BMW R1250RS
I have read some of the forum comments on the sealing of the cylinder head covers. I wanted to check with the forum there is no single piece gasket as such and the seal is applied as a liquid or paste. Would that be so thanks?

My mate's ST1300 (~2004) has a light but extensive oil stain below the width of the cover seal area, both L and R covers. Should I try to tighten the cover down as a first action or should I remove the covers and re-seal.

Thank you, D
 
The valve cover? There's a rubber seal and only the half-moon parts of it get some sealant applied in the corners.
 
Probably worth pulling the covers and making sure the gasket isn't installed incorrectly, but likely the corners of the half-moon areas are the culprit--a small amount of black RTV sealant there helps that.

Be careful with threading in the head cover bolts (items 13, 14 above). When inserting, make sure the bolt shank isn't misaligned as they're a long 'blind' reach and it is hard to know if you've got the threads engaged correctly. Once they're hand threaded in, only go to the torque in the service manual--more torque won't compress the gasket any further given their design. The bolts are known to fail with overtightening or misalignment.
 
Another thing that isn't obvious from the parts diagram is you need to periodically replace the washers, part number 18.

These are made of some kind of hard rubber and will compress over time and get thinner. If you look at bolts #13/14 notice they have a lower shoulder by the threads. When you tighten them the bolt will stop turning when that shoulder contacts the head. So the force holding down the valve cover is determined by the distance from that lower shoulder to the top of the bolt, minus the thickness of that rubber washer. So as the rubber washer gets thinner, the force applied to hold down the valve cover is reduced, and you may get some seepage. From your description it sounds like his washers may need replacing.
 
DO NOT try tightening the cover bolts. They have a hard stop and once seated will provide no addition clamping pressure. Trying to tighten the them further usually results in a broken bolt and a potentially expensive repair.


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A couple of things to check. If the seepage is bad enough, you should probably replace them.

When replacing them:

1. Small a mount of silicone is used ONLY at the corners of the half-moons. No other area needs to be "sealed" with anything other than the gasket.
2. make sure that the rubber heat shield is not caught in the valve cover gasket. (Very common problem.)
3. torque the valve cover bolts down to the proper torque (look that up to make sure). Otherwise you Will have a leak.
 
Terrific advice, thanks very much everyone. Two follow-up questions please:
1) Does the cover gasket compress over time and need replacing (Ths subject ST has travelled ~75,000 miles). If the bolts actually seat on their ends it may be that the gasket itself is leaking. Sorry if that was included in above advice, may have missed it.
2) Can the job be done without remove the surrounding large mid fairing? I proably know the answer but just thought I'd ask.
Thanks again, D
 
it could be either the gasket leaking, or the "grommets" (I think that's the official Honda term for the rubber washers I spoke about earlier) are too thin and restricting the amount of clamping force applied to the gasket. If it were me, I'd replace all of it to remove any doubt. If the grommets are too thin then a new gasket will probably continue to leak anyway, that's what happened to me (on an 1100, but the concepts are the same between the 1300 and 1100).
 
The above info is very useful. I've not had this problem, but thanks to all who posted.
 
Yes, thanks for great help.
I will adopt your approach dwalby, and thanks again.
D
 
Duporth said:
Yes, thanks for great help.
I will adopt your approach dwalby, and thanks again.
D
Click to expand...
yeah, at 75k miles both the gasket and grommet set are due for replacement anyway if they haven't been replaced before. You'll be surprised at how much the grommet will compress, I wanna guess they're maybe 3-4mm thick to start with, and if you check your valves every 15k and don't replace them they'll eventually shrink down by about 1mm from their original thickness, its an easily noticeable difference if you put the new and old ones side by side.
 
One final thanks: I expect it is best to remove the large mid-fairings to complete the work, or even impossible without removing the. Would that be so thanks?
………………...
SORRY: I tried unsuccessfully to remove this silly message. I wrote the message without even looking at my ST, very lazy of me.. I see the task can be done only with the fairings removed.
 
Thanks John h. I will keep that in mind as I go ahead with replacing the gaskets and rubber washers.
 
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