Yanmar SC40N Compressor

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jrvakil
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Yanmar SC40N Compressor

Postby jrvakil » Mon Jul 11, 2011 5:33 pm

Hi All,

Good Day.

We have Tested one Yanmar SC40N Air Compressor, during the test process it is building pressure inside the crankcase, any possible solutions please.

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The Dieselduck
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Re: Yanmar SC40N Compressor

Postby The Dieselduck » Tue Jul 12, 2011 8:25 am

rings are buggered? That's the simplest. Hows the oil pressure?
Martin Leduc
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jrvakil
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Re: Yanmar SC40N Compressor

Postby jrvakil » Sat Jul 16, 2011 4:15 am

New Piston Rings were installed!! Problem remains!!

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The Dieselduck
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Re: Yanmar SC40N Compressor

Postby The Dieselduck » Sat Jul 16, 2011 5:28 am

It's a pretty simple machine usually, if it ain't the rings, then perhaps you have a piston cracked, or the bore is out of round... The other thing, how much pressure do you have in the crankcase? It is pushing out the dipstick? Its not uncommon to have some pressure in the crankcase. One of my compressor here, a typical small quincy has a fair bit of back pressure, not sure how much exactly but id estimate 5 psi. I noticed on the newer machine they switched to a screw type dipstick.
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
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Big Pete
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Re: Yanmar SC40N Compressor

Postby Big Pete » Wed Jul 27, 2011 1:17 pm

If the the pressure is much more than normal check the wear and ovality of the cylinders and replace them if required.
It is best to hone or deglaze old liners when fitting new piston rings to compressors, just as it is with engines.
Check the wear and ovality of the piston and the clearances between the pistons and the rings, the piston may need replacing.
Check the piston rings are installed correctly, some piston rings must be installed one way up.
There should be a crankcase "breather" designed to allow air to flow in and out of the crankcase, without oil loss, as the piston reciprocates, check that this is not blocked.
That is all I can think of for now.

BP
It is always better to ask a stupid question than to do a stupid thing.


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