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Dommi 88 cylinder head oil return

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Dommi 88 cylinder head oil return

Posted by roger_wilson at June 08. 2017

Looking again at my '57 88 suffering from excessive smoking and severe c/head oil leaks I have found that if I fill the pushrod tunnel with oil it takes forever to drain. I surmise that the exhaust rocker feeds drain down this and the fact the tunnel is not draining would seem to confirm the cause of my problem. Has anyone else come across this? The inlet drain thru the head and barrel is clear. I have read through all previous correspondance re head leaks and I had already carried out all the usual work ie: gasket surfaces, new guides, rebore,stud checks, engine breather operating etc.

When removing the head this week there was oil pooling on the piston heads!

Re: Dommi 88 cylinder head oil return

Posted by howard_robinson at June 08. 2017

Hello Roger - The cam-follower bores should not be tight on the followers but they are prone to rusting if the barrel has been removed from the bike for a period.  Even then,  there should still be a path for the oil down the follower bores into the crankcase.  The follower locating plate can rust and that might form an oil-tight seal but I've never come across that myself.  Are you warming the oil before filling up the tubes ?   A possible reason for the over-oiling may be a crankcase breather sticking.  They can seize.  Do you have the internal one ( round Norton logo in timing cover centre ).  I have seen several problems after a lengthy lay-up.  They can only be examined with the cover removed.  The external type are easier to check and I find them more reliable.  Good Luck, Howard

Re: Dommi 88 cylinder head oil return

Posted by robert_tuck at June 08. 2017

After suffering head gasket oil leak for years , I re-tightened the head using a torque wrench and the leak stopped.

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