Author Topic: Oil filter housing O Ring keeps blowing out  (Read 644 times)

Offline McCabe-Thiele (Ted)

  • Grogu
  • *
  • Posts: 8713
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #15 on: November 10, 2026, 08:12:50 PM »
One possibility, is the outlet from pressure relief valve blocked? I ha rebuilt lots of pumps but never checked where the oil goes if relief opens!

Presumably when the pump is removed you can see the oil path hole on the engine casing face?
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline Johny Boy

  • Newbie
  • Posts: 49
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #16 on: November 10, 2026, 08:19:09 PM »
Funny, I've just been sitting here wondering about the same thing.

I'll strip it tomorrow and find out
CB550 (85% there)
New BSA Goldstar (my daily)
MV Agusta F4 750 Senna (Front room love affair)
BSA bantam (my constant pain in the arse)

Offline McCabe-Thiele (Ted)

  • Grogu
  • *
  • Posts: 8713
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #17 on: November 10, 2026, 09:08:47 PM »
Should be easy enough to squirt some oil through with an oil can to test the gallery.
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline Bryanj

  • Grogu
  • *
  • Posts: 12629
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #18 on: November 10, 2026, 09:22:20 PM »
Being honest its one of those things you dont look for till you have a problem and i have not seen that problem

Online badger_eng

  • SOHC Member
  • Posts: 103
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #19 on: November 10, 2026, 09:39:58 PM »
The picture that’s been posted shows a lovely finish to the cases. Have they been vapour blasted??

Only wondering as if they were not rinsed out thoroughly by the blasters afterwards, it’s possible that some of the glass beads have solidified in an oil way??

If they’ve not been vapour blasted.,,,,, just ignore me 😬
Current:-

Suzuki GSX-S1000GX+ - 2026

Suzuki GT500A Cafe style - 1976
https://www.kettleclinic.co.uk/kcforum/viewtopic.php?t=14273

Honda CB550K - 1977 (Winter 2026/27 project)

Offline Johny Boy

  • Newbie
  • Posts: 49
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #20 on: November 10, 2026, 09:51:51 PM »
Hi badger, yes they have been vapour blasted and they do look brand new, well worth the money if doing a full rebuild.

You raise a good point, I did give them an extra wash but now really wishing I had blasted some 6 bar air down every hole, which I can't guarantee I did.

If I can't find the issue with the relief valve, a full strip and clean might be necessary.
From what I read the relief valve should open about 60 psi, roughly 4 bar so I am going to investigate and then see if I can get it to move with some air pressure.
CB550 (85% there)
New BSA Goldstar (my daily)
MV Agusta F4 750 Senna (Front room love affair)
BSA bantam (my constant pain in the arse)

Offline Johny Boy

  • Newbie
  • Posts: 49
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #21 on: November 10, 2026, 09:55:14 PM »
You can see the overall look of the vapour blasting here [ Guests cannot view attachments ]
CB550 (85% there)
New BSA Goldstar (my daily)
MV Agusta F4 750 Senna (Front room love affair)
BSA bantam (my constant pain in the arse)

Online badger_eng

  • SOHC Member
  • Posts: 103
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #22 on: November 10, 2026, 10:09:41 PM »
Mmmmmnnn shiny! I love shiny 😬


I’ve had 3 engines VB’d previously and 2 were well washed down. One was not and it took a while for me to get it bead free.

My CB550 engine is getting done next week now it’s fully stripped. I’m ultra careful now with the oil ways and threaded holes after my one bad experience. I still get them blasted even if I’m painting / polishing as the finish is great to work with.

Hopefully you’ll find the issue quickly and cheaply.

Current:-

Suzuki GSX-S1000GX+ - 2026

Suzuki GT500A Cafe style - 1976
https://www.kettleclinic.co.uk/kcforum/viewtopic.php?t=14273

Honda CB550K - 1977 (Winter 2026/27 project)

Online Oddjob

  • SOHC Jedi
  • Posts: 4812
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #23 on: November 10, 2026, 11:51:12 PM »
Did you remove the oil gallery plugs? One under the points cover, simple 14mm nut affair, the other sits under the rotor cover and is a press in fit. You can pull it out but it does tend to ruin it a bit. Best way is to remove the points end plug, get a long piece of wooden dowel and knock the rotor end out from the back with the dowel. No damage that way. Once both are out you can look down the gallery and see if it’s clear. The oil filer empties into this gallery so check the gallery that joins the two isn’t blocked. That would blow the housing apart if it was.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline K2-K6

  • Grogu
  • *
  • Posts: 6098
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #24 on: November 11, 2026, 09:24:16 AM »
I'm of the same view as Bryan, in that the pressure relief valve should prevent the risk at oil filter. That's if there were blocking further along distribution. 

That doesn't mean there's no impairment within the system for flow, but primarily the relief would appear obstructed in some way.

Looks like there's enough questionmark over absolute cleanliness from blasting operation to need stripping anyway though.

Difficult to have confidence longer term if all passageways haven't been checked and accounted for to run competently. 

Offline McCabe-Thiele (Ted)

  • Grogu
  • *
  • Posts: 8713
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #25 on: November 11, 2026, 09:38:57 AM »
If you didn't fully check and clean the oil ways then I agree a strip down is needed.
I don't know the particle size they use, you don't want any of it reaching your crank bearings etc.

Many years ago I had a major issue with a Mini engine after having the block sand blasted, for that reason I have avoided  bike engines being blasted by anything.
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline Johny Boy

  • Newbie
  • Posts: 49
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #26 on: November 11, 2026, 11:45:18 AM »
Many thanks to everyone who has contributed to this thread.
The knowledge here is amazing and offered so freely.

I have decided it needs a full strip, clean and rebuild.

I guess you live and learn
CB550 (85% there)
New BSA Goldstar (my daily)
MV Agusta F4 750 Senna (Front room love affair)
BSA bantam (my constant pain in the arse)

Offline martin_uk

  • SOHC Pro
  • Posts: 504
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #27 on: November 11, 2026, 12:02:21 PM »
If you didn't fully check and clean the oil ways then I agree a strip down is needed.
I don't know the particle size they use, you don't want any of it reaching your crank bearings etc.

Many years ago I had a major issue with a Mini engine after having the block sand blasted, for that reason I have avoided  bike engines being blasted by anything.

Me too, heard so many horror stories
1977 CB750F1
1978 CB750F1
1975 CB500K1

Triumph Street Triple 675R
Ducati 800 Icon Scrambler
Triumph 3TA
AJS 350 mod16
BSA BantamD1
Honda C90zz

Online badger_eng

  • SOHC Member
  • Posts: 103
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #28 on: November 11, 2026, 12:06:35 PM »
No horror stories with Vapour Blasting in my experiences.

Like anything you do, do it right.

Clean / check any oil ways, run a tap thru the threads…. then do it again.

Costs nothing but time
Current:-

Suzuki GSX-S1000GX+ - 2026

Suzuki GT500A Cafe style - 1976
https://www.kettleclinic.co.uk/kcforum/viewtopic.php?t=14273

Honda CB550K - 1977 (Winter 2026/27 project)

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
  • Grogu
  • *
  • Posts: 8746
    • View Profile
Re: Oil filter housing O Ring keeps blowing out
« Reply #29 on: November 11, 2026, 01:37:15 PM »
Here's the correct way round of you want to check.

[ Guests cannot view attachments ]

[ Guests cannot view attachments ]
LINK TO MY EBAY PAGE. As many of you know already, I give discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new