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SOHC.co.uk Forums => CB500/550 => Topic started by: Harold 400/4 on September 08, 2025, 02:04:46 PM

Title: CB550 oil leak from sump bolt/washer
Post by: Harold 400/4 on September 08, 2025, 02:04:46 PM

Looking for advice pls.
I’ve got an annoying oil leak from my sump bolt. It’s only a minor leak but I need to sort. The sump threads look fine and the bolt torques up OK. I have tried a new crush washer, but to no avail. There is no sign of any cracking to the sump.

What I have noticed is the surface on the sump where the washer sits is scored, and the old washer I took off is also scored. I am thinking this may have happened as a result of the sump not being properly cleaned of muck when previous oil changes were done??

Is this scoring enough to cause the slight leak I am experiencing? If so, what’s the best way to sort??
Cheers
Harold

Title: Re: CB550 oil leak from sump bolt/washer
Post by: Johnny4428 on September 08, 2025, 02:58:03 PM

This is maybe stating the obvious but make sure the washer or bolt is not riding up against the raised edge of the bolt flange. Also make sure there is not another old crush washer still on the drain bolt.

Title: Re: CB550 oil leak from sump bolt/washer
Post by: McCabe-Thiele (Ted) on September 08, 2025, 03:48:43 PM

I think the washer should be made of Aluminium, a use once type.

Title: Re: CB550 oil leak from sump bolt/washer
Post by: Bryanj on September 08, 2025, 04:21:07 PM

It is supposed to be a single use ally washer but copper should do, maybe trya dowty hydraulic sealing washer