Hitchcocks Forum

Hi on doing some lockdown work on my 250 continental gt ,I have the following question,on start up all is fine ,good oil flow but on running my hand over the top of the engine primary case joint I detected an air leak ,in investigating this it is coming from the primary case joint top face over a length of about 1 inch.The front crankcase breather is fine and so is the large top crankcase breather pipe both clear and some air movement can be felt.But when I remove the primary case inspection bung and with the engine running a very strong pulsing air movement exists,to the point that it can be felt approx 6 inches from the engine,please advise me is this correct,I understand people have modified the rocker cover to provide extra breathing is this a worthwhile mod,my worry is that the pressure within the primary case will eventually fail the gasket resulting in a major oil leak

Regards. Colin

The primary case on unit 250 RE machines communicates via the main bearing with the crankcase and they both share breathing and oil. With that inspection / filling plug removed, I would expect just what you describe. For this reason, you always have to use the same oil type and grade for both, as well. I think you must have a gasket problem somewhere, also make sure the two pillar bolts holding the cambox cover on are the right way up, or they might prevent the primary cover seating properly.

Hi thanks for this reply,not sure what you mean about the 2 cam box cover bolts ,it is a new primary case gasket but I only applied Wellseal to the bottom two thirds of the gasket the logic being that was the area prone to leaks and it is completely oil tight, on further investigation I am becoming more reasured as with the primary inspection bung out and engine running if you move the bung towards the casing it tends to pull it in more than push it away,I made sure on reassembly that the small interconnecting hole to the oil filler was clear,so as you say it seems the front breather valve is doing its job.Do you have any info the the rocker cover case breather mod
Colin