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matchless 3gl -excessive oil on startup

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my 1941 g3l has been running ok,i have cleaned oil filter replaced oil with morris 50w and she has been on a couple of runs with no problems.

she has sat in the garage for a couple of weeks and last night started her and depleted some of the ozone layer with the plumes of white smoke out of exhaust and oil trickling from exhaust to cylinder head flange as well as very thin oil coming out of primary cover. after running the bike for a few minutes and pissing off the neihgbours as the smoke just stayed the same i put her back in the garage,this morning i checked the fuel tap as i thought it might be leaking into crankcase but looks ok,then i drained the sump and there was about quarter of a litre of oil that came out readily,didnt have a strong smell of petrol.cant get the bike to start now i think the plug is knackered as i have a decent spark out of cylinder,(get a new plug this afternoon ,i am running a champion l82c is this the best plug for the bike?.

 

has anyone got any ideas,im thinking scavenge pump or oil seeping from oil tank when she has sat for a few days,

 

whats the oil level in the oil tank,i filled it up to approx an inch lower than the filling neck union about 4inches below oil tank cap?

CHEERS

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Well, it's certainly wet sumping - if after ten minutes running there was still that much oil in the crankcase I shudder to think how much there was when you started up. I suppose that you could have wear between the pump body and crankcase but from experience it doesn't seem to be a common malady. A pump usually dies because the worm drive or the actuating groove has worn out, but very rarely the body itself. Wet sumping can depend alot on where the engine stops I suppose - if the feed port is open the only thing that limits oil from pouring into the crankcase (to an extent) is the clearance between the crankshaft and the bush - now that does wear. Another thing to check is if the scavnge side is doing it's job properly, apparently there are some duff oil filters around that create too much back pressure leading to the crankcases filling up, it's never happened to me but that's what I've heard. On another note, do check the oil level in the primary chaincase, because engine oil can finish in there as well, and our clutches don't take kindly to straight 50....

Keep us updated on how it works out,

Cheers,

Stef

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thanks for the info stef,

 

after draining the sump,i adjusted the oil feed screw to the inlet valve(1/2 turn from closed) as it was unscrew by 3-4 turns.put a new plug in and she started first kick with no smoke!! the oil return is dribbling nicely as well.

 

im going to have a look at the oil pump plunger in the next day or so.

 

you mentioned that they do not like 50 weight oil? what do you recommend

 

p.s i noticed you have a triumph 3hw,you dont have a spare set of girders for sale? worth a try eh,,

 

thanks

again

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you mentioned that they do not like 50 weight oil? what do you recommend

 

 

I know that AMC had a thing about using engine oil in the primary chaincase, principally to protect the engine shaft shock absorber I presume, but I use 30 grade with no ill effects because I think this helps protect the clutch plates from gumming up. Has anybody else got any thoughts on this?

Alas, no 3HW girders I'm afraid :(

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WD bikes can be funny old things..........my Ariel, fitted with the "Triumph type" double plunger pump is very good and never wet sumps............she does weep a little from the top of the pushrod tubes and the valve lifter, but is otherwise great.......

 

Never known a 3HW or Matchy to wet-sump.......seems that plunger and worm-drive pumps are pretty damn reliable.....

 

Yet my 16H and all the M20s I've owned all wet-sump if left for a time......the 16H has a totally new-old-stock pump, pipes, etc, fitted but still does it.............gears - v - plunger/worm drives.......I'd opt for the latter any day...:)

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Both my G3 and G3L will wet sump if left unattended for any time. In that event I don't even try to start them until I have drained the crankcase and pored it back in the tank. Ron

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With my Matchboxes its very opposite, the G3L does it after 2-3 weeks, my G3 NEVER does it, not even after one year of not running.

 

Some people say it matters at which piston position you assemble/enter the plunger, but has not made a difference for me, another theory is that if your oil lines are not airtight, the pump leaks quicker, I don't know, even after 35 years of riding the things, it's still a mystery to me, but I can live with it, and will never fit a tap in the lines, and also not a special valve, the risk of forgetting/malfunctioning is just too big!

 

My 2 p's,

 

Lex

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My experience is exactly as Ron's. My G3 and my brother's G3L both wet sump. We do just as Ron does, drain the crank case and pour the oil in the oil tank.;)

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thanks for all the info,ive used the bike a couple of times this week and i havent had anymore wetsumping problems,i also have checked the crankase breather is working correctly and im going to replace the oil pump plunger and guide pin.thanks again for everyones help

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im going to replace the oil pump plunger and guide pin.thanks again for everyones help

 

Just a quickie. If you remove the oil pump plunger check the condition of the teeth of the worm drive before you do, because if there is excessive burring on the tips you run the very real risk of scoring the crankcase as you push the plunger out.

This is most definitely Not a Good Thing.

If there is burring a quick run over the teeth with a file will save you a lot of problems further on down the line :)

Also, sometimes the guide pins need a certain amount of "fittting" to avoid any suspicion of binding. Obviously this is easier if the engine is in bits, but can still be done in situ. If going through a full rotation of the pump there is always a trace of axial play on the plunger then you're fine. If not, find out the reason why. Usually it can be just due to the guide pin bottoming in the groove and it's easy to put right.

 

All the Best,

Stef

Edited by Stefano

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