Author Topic: 5100s air leak  (Read 489 times)

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Offline dolmar

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5100s air leak
« on: September 13, 2014, 10:26:42 pm »
what is the best way to find a air leak on my 5100s, saw run great last year but now I got a air leak somewhere any help would be great thanks.

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Offline 660magnum

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Re: 5100s air leak
« Reply #1 on: September 13, 2014, 10:42:29 pm »
You can do a close examination but likely the only way you will find it is with a pressure vacuum test.
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Offline 660magnum

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Re: 5100s air leak
« Reply #2 on: September 13, 2014, 10:55:48 pm »
Sources of air leaks . . .

Seals around the crankshaft bearings on either the chain or flywheel side or both sides.

Carburetor intake rubber boot

Compression relief valve but I don't think the 5100s has one?

Impulse line if it has one.

- - - - - - -

The test involves blocking off the carburetor and muffler exits. Pump up the engine with 7 lbs of air pressure and check for leaks with soapy water? If you find the seals leaking at the crankshaft on either side, you have found the problem and no need to do the vacuum test.

And then draw 15" vacuum on the crankcase and see if it still has 10" vacuum after 30 seconds. The vacuum test is to check for bad seals on the crankshaft ends. The vacuum test will show the seals bad where the pressure test did not.

If it fails, you try some heavy oil on the seals and see if it changes the leak rate any.
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Offline Nathaniel Vansickle

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Re: 5100s air leak
« Reply #3 on: September 14, 2014, 06:34:14 pm »
+1 and no decomp on a 5100
5105H and 6400H in stock

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Offline 660magnum

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Re: 5100s air leak
« Reply #4 on: September 14, 2014, 06:39:11 pm »
I have a 5105 with no decompression but didn't know about the 5100.
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Offline dolmar

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Re: 5100s air leak
« Reply #5 on: September 20, 2014, 08:20:55 pm »
still cant find the air leak checked everything I could think of any of you guys had this problem with your dolmar

Offline 660magnum

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Re: 5100s air leak
« Reply #6 on: September 20, 2014, 08:27:21 pm »
I have a 2009 5105 but never any trouble with it.

I've seen a couple 5100's with the clutch side bearing spinning.
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Offline farmboy

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Re: 5100s air leak
« Reply #7 on: September 20, 2014, 10:05:57 pm »
+1 and no decomp on a 5100
I put a  decomp on one of my 5100's won't do that again  pops it out every pull.  It is pulling 205 psi w/base gasket tho.  Checked it w/2 guages.
Shep

Offline jmester

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Re: 5100s air leak
« Reply #8 on: September 21, 2014, 07:01:21 am »
Not real familiar with the Dolmar saws. But may be worth a try to check the cylinder base screws for tightness. Have seen them come loose on some 50cc husky saws. Has the saw sat since this time last year? If so you may need to look for a fuel issue more so than a air leak.
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Offline aclarke

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Re: 5100s air leak
« Reply #9 on: September 21, 2014, 11:29:19 pm »
As Jmester mentioned, i'd look into fuel flow issue. Perhaps pull the carb apart and clean/inspect

 

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