| Re: [GMCnet] Oil sputtering (4K) Onan [message #322378 is a reply to message #322377] |
Sat, 19 August 2017 21:14   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
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Senior Member |
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Peer Oliver Schmidt wrote on Sat, 19 August 2017 21:42Matt,
did you ever try fixing the probable cause, ie. the not working breather
hose?
--
Best regards
e
Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA
'76a Eleganza II, CA
'73 Sequoia, VA
Peer,
Funny you should mention that. I thought that this was an indicator of an engine problem.
So, I did a cylinder leak check first.
That was good (pretty good really).
Then I set up to actually measure the crackcase pressure. (I was an engine lab rat for decades.) This was exciting because it alternated between blowing the water out of the manometer and sucking it into the crankcase.
This was at the dipstick/lube oil fill. I gave up on that and put the manometer down stream of the crankcase reed valves.
That was almost disappointing - Nothing there.
With new orifice and a Magnahelic (expensive manometer) I finally got a reasonable blow-by measurement at power required for the A/C, the water heater and the microware (How's that for a load bank?) to be a quarter of a CFM.
Then, the LED in my brain lit (only recently upgraded from incandescent) and I realizsd that the with the engine being an opposed twin, it has to have immense crankcase volume and therefore pressure fluctuations and there is nothing to be done, but live with it.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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