Author Topic: Sludge trap plug leak  (Read 268 times)

Offline Daveh67

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Sludge trap plug leak
« on: 08.10. 2021 22:14 »
Good evening everyone, Finally I am reasembeling my A10.
After building up my crankshaft I was air testing the oil galleries to ensure the sludge trap plug is not obstructing the oil gallery.
Well its all good but I noticed the plug is leaking a lot of air and will drop my oil pressure and supply to the main bearings.
Suggestions are appreciated on how to fix this issue. Has anyone else had this problem. Im going to order another plug and try again.

Sealants for the threads? or any other ideas
regards
Dave
1960 A10 the new toy
1930 AJS R6 outfit
1934 Triumph 2/1
1932 AJS TB6
BSA model K project

Online mikeb

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Re: Sludge trap plug leak
« Reply #1 on: 09.10. 2021 09:46 »
i've read about this being an issue - they are a short coarse thread. I think mentioned in an article by John Healy on 'vintage bikes' re Triumph cranks. at that suggestion I put some thread sealer (i had some loctite 567 nearby) around the inner section of the female thread. then some threadlocker near the outer of the plug thread (tho John says not to) and punched the face of the plug (not the crank) for good measure. however I did not air test it for leaks - reading your post I wish i had - i just stuck a piece of wire up from the bush side to ensure it was not blocked.

FYI John had written to use a "little bit of Hermatite Blue sealant, ThreeBond #4, or Loctite 515 or 518 anaerobic gasket sealant" on the thread.
Loctite 567 is a slow curing coarse thread sealant so sounded ideal to me.
New Zealand
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Offline Greybeard

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Re: Sludge trap plug leak
« Reply #2 on: 09.10. 2021 12:59 »
I don't suppose many people carry out that air test. I can't imagine that much oil would escape. Better to not loose any pressure of course.
Greybeard (Neil)
1955 Golden Flash, sprung frame
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Online orabanda

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Re: Sludge trap plug leak
« Reply #3 on: 09.10. 2021 13:30 »
I always airtest the sludge trap plugs; not uncommon to leak.
Loctite 569 Hydraulic sealant is suitable to seal the threads.

Use Loctite Primer T (green aerosol can) on the threads beforehand, and let the loctite set (say 3 hours) before testing.

When stripping an engine airtest the crank plugs before removing the plugs; If you find a leak, then the oil supply to the big ends would have been compromised.

Richard

Offline Greybeard

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Re: Sludge trap plug leak
« Reply #4 on: 09.10. 2021 13:44 »
But.... think of the thousands of  crank plugs that were put in over the years without a thought that they might not be sealed. I doubt if that leakage is a serious issue.

If I have to replace sludge trap plugs again I will be sealing the thread.

To harp on again about my 1929 Austin Seven: Hot oil pressure was expected to be 4lb. The big ends had oil delivered to them via small trough's machined in the crank web that caught a stream of oil squirted in their direction from two nozzles in the crankcase gallery. Most of the engine relied on oil mist. That design was raced and achieved over 100mph.
Greybeard (Neil)
1955 Golden Flash, sprung frame
Supporter of THE DISTINGUISHED GENTLEMAN'S RIDE https://www.gentlemansride.com

Warwickshire UK


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Online Triton Thrasher

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Re: Sludge trap plug leak
« Reply #5 on: 09.10. 2021 14:20 »
Leakage on the route from the oil pump to the big end was notorious for destroying late Unit BSA single engines.

Offline Daveh67

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Re: Sludge trap plug leak
« Reply #6 on: 10.10. 2021 00:05 »
Thankyou everyone, I can imagine there are a lot of untested cranks out there. This forum and its many many tips and tricks has taught me to check and check again on all aspects.

I will be ordering a new plug as the hex is a little distorted from fitting and try again with sugested sealing methods.

Once again thankyou to all. Looking forwrd to the day she is back on the road..
Dave
1960 A10 the new toy
1930 AJS R6 outfit
1934 Triumph 2/1
1932 AJS TB6
BSA model K project

Online RichardL

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Re: Sludge trap plug leak
« Reply #7 on: 10.10. 2021 00:22 »
I always airtest the sludge trap plugs;

Fair enough, Richard, but when it comes to being typical among us, you aren't "many people," but kind of in your own league.  *respect* *smile* Daveh67 is in good company.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.