Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: Johny Boy on November 10, 2026, 01:08:35 PM
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Hi all.
I have an issue with the Oil filter housing O Ring, which keeps blowing out.
I have fully rebuilt the engine and everytime I start her up, after 2 or 3 seconds the O ring blows and deposits oil all over the floor.
I have bought a replacement cover and new o rings.
Today I have removed the oil pump pressure relief valve, the relief valve part did appear to be stiff in the bore, but having removed, cleaned it and refitted it seemed much better, but still with the same result.
I have also tried it once without the filter fitted, just to check, same result.
I am now at a total loss on how to proceed.
Any thoughts / advice would be most welcome.
Thanks
John
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Simple suggestion,
check if the oil filter housing is perhaps warped due to overtightening,
You could check this by sitting it on a glass shelf from your fridge (when the wife's not at home).
Good luck
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If you still have the old cover, (undamaged!), try it with that and see if it still occurs. Another point being, and I know this sounds daft, but, when you mount the cover, is it the right way up?
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It sounds like the pressure relief valve is in the wrong way. We had this on a brand new OEM NOS oil pump, never been fitted or used before on a CB550F. The pressure cracked the oil filter housing. Trigger investigated and found the relief valve was in the wrong way round.
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Thanks for all the answers, I checked the valve orientation this morning and it is the same as the picture from CMSNL i.e. Long end in first
I assume this right, as the spring locates nicely around the short end.
I have refitted the old housing and it blew it in half.....although it did have some cracks radiating out from the centre boss before I refitted it.
The crack propogated all the way ythrough the O ring groove.
I suspect it had previously been over torqued and the previous owner may have had the same problem.
Trouble is I can't check with them as it had been off road for a couple of decades before I bought it.
I have ordered a new housing and O Ring, but still think it is generating too much pressure.
But surely if the pressure relief valve is working then it should bypass pressure at the pump?
Does any one know how loose the valve should be in the pump casting, i.e. should it fall out if turned upside down or should it take a few bangs, mine does.
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If you still have the old cover, (undamaged!), try it with that and see if it still occurs. Another point being, and I know this sounds daft, but, when you mount the cover, is it the right way up?
I think the Cover was right way up, so the thick lug engages with the slot on the crank case[attachimg=1]