Possible Effects of Wet Sumping

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Possible Effects of Wet Sumping

Postby phenry » Sun Oct 07, 2018 4:37 pm

Started the 41 G3L after 2 weeks and this is what happened

1. Oil draining out of the chain case.
2. Oil leaking through the plug hole.
3. The beat of the engine is not rhythmic
4. Oil through cylinder (Exhaust Joint)

I to some extent understood that the reason is that I didn't drain the oil before I started
But what baffles me are 2 things

1. Oil leaking through one of the cylinder head bolts
2. Absolutely no oil from breather.

I always was worried about the breather not working right. Please help me with your valuable suggestions

Regards

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Re: Possible Effects of Wet Sumping

Postby SPRIDDLER » Sun Oct 07, 2018 5:24 pm

Before progressing with a detailed reply it would help to know if there was (black) smoke from the exhaust.
Is the spark plug oily and black (inside)? This could cause your non rhythmic beat (misfire).

phenry wrote:1. Oil leaking through one of the cylinder head bolts

Can you explain that more exactly? From where to where is it leaking? Is it coming from the cyl head to cylinder joint? From the rocker box to the cylinder head? Where do you see the leaking oil?
Has it been running o.k? Have you worked on the engine recently and before this problem occurred?
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Re: Possible Effects of Wet Sumping

Postby phenry » Sun Oct 07, 2018 5:39 pm

Dear Sir, thanks so much for offering to advice.
I will explain this in a bit more detail

Black Smoke from Exhaust: Yes there was black smoke
Spark Plug Oily: Yes but not much
Has it been running o.k?: Yes before 2 weeks (Started after Restoration for the 1st time)
Have you worked on the engine recently and before this problem occurred?: Yes worked on the engine recently and started only before 2 weeks
Can you explain that more exactly? From where to where is it leaking?: See attached pic
GB - Marking.jpg
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Re: Possible Effects of Wet Sumping

Postby SPRIDDLER » Sun Oct 07, 2018 5:53 pm

Well now, where to start? My initial thought is that if oil is coming out of all those places, plus black smoke, but nothing from the crankcase breather I would suspect excessive oil at the top end rather than wet sumping. Oil at the top end can only come 'down' from the rocker box via the valve guides. Is the inlet oiling screw in place and only opened (unscrewed) about 1/4 of a turn?

The oil can only be coming 'up' from the crankcase via a worn cylinder and/or piston rings.
Oil may not be coming out of the breather because it is stuck shut or obstructed which would pressurise the crankcase and force oil up past an otherwise serviceable piston/rings and cylinder. The oil leaking from the cyl head bolt will be due to a failed cyl head gasket but that is a result of and not the cause of the oiling problem.

Was the engine running o.k. or at all when you got the bike? What work have you done? Have you taken off the cyl head and cylinder or replaced piston rings or valve guides? Are the bottom pushrod tube 'O' rings old/squashed and blocking the pushrod drain holes that allow oil returning from the rocker box to pass from the bottom of the pushrod tubes into the cam chest? (This recently happened to the G80CS of our President ('ajscomboman')
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Re: Possible Effects of Wet Sumping

Postby Mick D » Sun Oct 07, 2018 6:52 pm

Hi

In my opinion you could have two issues:

Wet sumping coupled with a stuck breather would account for the chain case leak - first stop is to check the oil level in the chain case, has it risen?

Black smoke from the exhaust, a black / wet spark plug and poor running are indicative of a very rich air fuel mixture - is the carb correctly jetted? is the choke working correctly? (Burning oil normally results in blue / grey smoke from the exhaust).

Regards Mick

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Re: Possible Effects of Wet Sumping

Postby SPRIDDLER » Mon Oct 08, 2018 9:15 am

Having looked back at Henry's previous posts I see that he has just recently reassembled the engine. In July he asked:

phenry wrote:Greetings. I'm trying to fix the breather to my crankcase and I do see a small plate. I am now wondering how this operates or how do I even know if this is working right?
The cases are apart and is there anything that I need to check before I start with the restoration


Assuming that the breather is now working O.K. maybe it's simply the result of wet sumping (as Mick D suggested) plus an over-rich mixture and the black exhaust smoke is masking the grey oil smoke. :? Another test after verifying the carb settings and draining the crankcase may be the next step.
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Re: Possible Effects of Wet Sumping

Postby phenry » Tue Oct 09, 2018 4:29 pm

Thanks so much for the advice. During rebuilding the engine, the breather disc was missing so I used an alternate disc (0.25mm approx) and the the diameter was just about right for axial movement in the breather.
I am now wondering to think if the disc is too big (Diameter) so that it is stuck after the breather is tightly fixed to the crankcase

Breather.jpg


Regards
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Re: Possible Effects of Wet Sumping

Postby clive » Tue Oct 09, 2018 6:06 pm

So many problems are caused by using non original parts that I think you may have found your own solution. The original disc is very thin looks thinner than yours. This may be the problem as well as the diameter. It has to be able to flap backwards and forwards under crankcase pressure.
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Re: Possible Effects of Wet Sumping

Postby SPRIDDLER » Tue Oct 09, 2018 6:51 pm

0.25mm is about 10 thousandths of an inch which makes it quite thin and I don't have a spare one to measure, but the weight and diameter would effect its operation. I assume yours is made of steel.
Test it by refitting the breather assembly. It's a 'one way' valve so you should be able to easily suck air out of the crankcase but not blow air into the crankcase. You will probably need to fit a piece of pipe to the breather outlet in order to do this. If you don't fancy breathing in oily air from the crankcase you could easily rig up say a bicycle pump (or bribe a passing 10 yr old) to do the sucking and blowing.
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Re: Possible Effects of Wet Sumping

Postby phenry » Sun Oct 14, 2018 12:29 pm

Hello, thanks much for the advice. I was able to sort the issue. It was just a combination of breather disc not working + wet sumping. Fixed and now no oil leaks except between the cylinder head and the rocker box. I think I am using too thick a gasket.
Once again a sincere thanks for all the replies and advice

Regards

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