09-02-2023, 03:51 PM
(This post was last modified: 09-02-2023, 04:02 PM by Reckless Rat.)
Hi Dave. I had exactly the same problem, but I discovered that it wasn't the silicone gasket that was leaking - it was oil mist coming out of the 4 vent holes and settling on the rear lower corner of the cover and being blown rearwards by the fan. This venting wasn't due to wear in the engine because it has recently been rebuilt, but may have been exacerbated by a good seal on the oil filler tube.
I have since modified the cover to allow it to vent below the chassis rail. It has cured the problem.
The secret of getting a good seal here is cleanliness. First of all give the inside of the valve chest cover a good clean with acetone and then stick the silicone gasket in place with superglue. Also clean the mating face on the block in the same way (with acetone), and assemble the joint dry. It doesn't need to be too tight.
Check that the cover is flat before assembly. Overtightening tends to distort the cover. I also made round gaskets for the fixing screws out of silicone sheet.
If you're going to solder on an elbow and block up the remaining vents, make sure you leave enough room so that it isn't contacting the underside of the exhaust manifold.
I have since modified the cover to allow it to vent below the chassis rail. It has cured the problem.
The secret of getting a good seal here is cleanliness. First of all give the inside of the valve chest cover a good clean with acetone and then stick the silicone gasket in place with superglue. Also clean the mating face on the block in the same way (with acetone), and assemble the joint dry. It doesn't need to be too tight.
Check that the cover is flat before assembly. Overtightening tends to distort the cover. I also made round gaskets for the fixing screws out of silicone sheet.
If you're going to solder on an elbow and block up the remaining vents, make sure you leave enough room so that it isn't contacting the underside of the exhaust manifold.