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Milling 3120 XP leaks chain oil through muffler, any hints.

J D

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My 3120 xp doesn't get hot but shots out bar oil from the muffler. Thought of that too and replaced crankcase gasket for a new thicker one. I believe the crankshaft lube hole one way valve is broken and is suctioning air and bar oil into the engine.
My 390XP wasn't "getting hot" either. What I meant was the leak between the oil reservoir & crankcase would only show up when the saw was at operating temperature... making it hard to diagnose on the bench. In your case it may well be the crank valve, or possibly that it got some oil spilt into the muffler. Does it smoke? If extra oil is entering the crank case (especially enough to be running out the exhaust I'd expect it'd be smoking noticably). Does the crank valve leak the same under both pressure & vacuum? I don't have experience with these specifically but I'd imagine it should vent under pressure but seal under vacuum. I'd be looking at what the service manual has to say about pressure testing & the crank valve also. Keep us posted. Cheers
 
Anniwoodlator

Anniwoodlator

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My 390XP wasn't "getting hot" either. What I meant was the leak between the oil reservoir & crankcase would only show up when the saw was at operating temperature... making it hard to diagnose on the bench. In your case it may well be the crank valve, or possibly that it got some oil spilt into the muffler. Does it smoke? If extra oil is entering the crank case (especially enough to be running out the exhaust I'd expect it'd be smoking noticably). Does the crank valve leak the same under both pressure & vacuum? I don't have experience with these specifically but I'd imagine it should vent under pressure but seal under vacuum. I'd be looking at what the service manual has to say about pressure testing & the crank valve also. Keep us posted. Cheers
I don't know for certain if the crankshaft actually has a valve inside but if it does it may be broken because it's not holding any vacuum/pressure unless I plug it. Service manual doesn't mention anything about crankshaft valve . How can I find out?
 
Clyde85

Clyde85

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The hole in the crank should for grease. It should be open to the Saft center on the clutch end of the crank so you can grease the bearing without pulling the clutch.
 
sean donato

sean donato

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Also refer to post #8
It's supposed to be there.
 
sean donato

sean donato

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It should be just a grease passage. It shouldn't go any further than the clutch bearing from the clutch end of the crank.
It's not a grease passage, I've just given 2 threads on this issue thats been discussed multiple times over the years. Do your very best to get grease from the pto end of the crank to come out that hole. It ain't gonna happen.
 
Anniwoodlator

Anniwoodlator

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It's not a grease passage, I've just given 2 threads on this issue thats been discussed multiple times over the years. Do your very best to get grease from the pto end of the crank to come out that hole. It ain't gonna happen.
Now I know that it must be sealed for good. i think I'll use my tool and Die kit and get creative.
 

J D

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So assuming the oil is entering the crankcase via that hole there must be plenty of oil around the bearing... Possibly too much due to a leaky oiler? I would be tempted to clean it & put a dab of RTV in the hole before taking to it with a tap & die kit
 
sean donato

sean donato

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My mind is still trying to figure out why this insanity exists! Why in the hell would the drill a hole there! WTF!
It's the same crank as the 1320k cut off saw. No oil pump like the chainsaws to sling bar oil everywhere. Needed another way to keep the clutch bearing lubricated. It's an odd design for sure, and has been a reoccurring problem that few seem to remember. I was hoping hamish would still have the bulletin about this issue. Any way. Plug it up, there was the weld the counter weight method, and a jb weld method both seemed to work fine. The guy that JB welded it put the case under vacuum to pull the epoxy into the crank a bit.
 
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