VHM Cylinder Head Water Leak


2 replies to this topic
  • beamishnz

Posted March 24, 2007 - 10:44 AM

#1

I've just fitted a VHM cylinder head to my sons CR85. Got to say over all I'm pretty impressed with the VHM head. It does away with the expensive OEM gasket that should be exchanged everytime you remove the head and instead has an inner and outer rubber o rings which don't need to be changed after head removal. This suits me cos I like to regularly remove the head to check the condition of the piston crown and bore. Also with the VHM head the combustion chamber is a seperate piece and can be changed as required for higher and lower compression chambers to suit tuning requirements and courses etc.

The problem I have is that on testing the head I notice that small quantities on water are tracking up the cylinderhead studs and leaking out of the cylinder head nuts!

I've googled this issue and seen a number of articles about 'wet studs' that relate to some 4 stroke motors where the studs run through the water jacket and I guess with the studs sitting between the inner and outer o rings this is what is occuring here.

They recommend thread sealers but I'm thinking if I seal the thread at the nut then it will just track under the nut at the interface with the cylinder head.

Any thoughts on this??

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  • skipn8r

Posted March 24, 2007 - 12:18 PM

#2

I guess with the studs sitting between the inner and outer o rings this is what is occuring here.

They recommend thread sealers but I'm thinking if I seal the thread at the nut then it will just track under the nut at the interface with the cylinder head.

Any thoughts on this??

Have you tried to fill the space between the cylinder head and stud with an appropriate Permatex sealant? If you get the RTV on the threads or head nut seating surface, you'll need to reduce the torque you put on the head nut (hope that makes sense...).

  • beamishnz

Posted March 24, 2007 - 08:01 PM

#3

I think that might be the way. I've put an email out to VHM and I'll let u now their recommendation. I just tried some thick grease and of course that didn't work!





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