| Propane for old engines [message #67051] |
Wed, 09 December 2009 19:39  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Senior Member |
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I read this on the Powered by Propane site and thought it was curious...
<http://www.poweredbypropane.net>
Talking about adding Propane to older engines:
"However, there is a small disadvantage in case of 12- 20 year old cars. Namely, the carbon deposit makes kind of a "sealing crust" from the inner side of the older engine and when it runs on propane this "crust" melts and may make a small oil leak bigger."
I know that propane will clean up a crusty engine, but I'd never thought that the crust might be serving some purpose.
Any thoughts?
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: Propane for old engines [message #67060 is a reply to message #67051] |
Thu, 10 December 2009 02:06  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I just got burned by cleaning out the carbon from a cylinder. I had low compression on one cylinder. I removed the cylinder and found a broken ring. I replaced all of the rings and honed it. I also cleaned it and the piston up and removed all of the carbon that I could get to without removing the valves.
This is similar to what you might get if you switch to something that cleaned out the engine. I had reasonable compression after reassembling the engine before I initially ran it to seat the rings. After two hours of operation the compression went to almost zero. If I grabbed on the exhaust valve and wiggled it I could get the compression to raise some. You could hear the exhaust valve leaking while doing a differential compression test.
I finally had to remove the cylinder a second time which is not an easy job and it is very cold out now. The exhaust valve had impacted carbon and lead between it and the seat. After removing all of the crap from the valve and seat the valve would not seat any more. So yesterday I had to have the seat ground smooth again. I finished reassembling the cylinder today and tomorrow I might reinstall it.
My point is if I had just replaced the rings and not cleaned it up real good, the engine would probably still have run OK. It will run OK now but I sure had to go to a lot of extra work to get it there.
When switching fuels or oil that cleans out things you run the the risk of causing the same problem that I ran into. Granted this is not a GMC engine but the basics are the same.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Propane for old engines [message #67126 is a reply to message #67051] |
Thu, 10 December 2009 17:02 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| ljdavick wrote on Wed, 09 December 2009 17:39 |
Talking about adding Propane to older engines:
"However, there is a small disadvantage in case of 12- 20 year old cars. Namely, the carbon deposit makes kind of a "sealing crust" from the inner side of the older engine and when it runs on propane this "crust" melts and may make a small oil leak bigger."
Any thoughts?
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I drive a '37 Ford with a '38 Flathead engine. At about 20K miles on a rebuilt engine, I switched it to propane. Best thing I have ever done. All the horror stories have failed to manifest them selves. I have about 35K on the engine. It burns no oil. The oil stays so much cleaner and flatheads are not known for their sanitary oil. I have to really remember to change it even though it looks great. Starts well. Runs well. I have noticed that I have to change the spark plugs about every 10K. I have electronic ignition and the plugs look perfect, but it starts to miss occasionally and becomes a little harder to start. (Too bad the propane doesn't help keep the engine's outside cleaner.)
http://www.pggp.com/37ford.htm
Since those pictures, I have added Hotrod Air heating an AC. I haven't driven it since yesterday.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Propane for old engines [message #67136 is a reply to message #67051] |
Thu, 10 December 2009 19:24 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| ljdavick wrote on Wed, 09 December 2009 20:39 |
I read this on the Powered by Propane site and thought it was curious...
<a href="http://www.poweredbypropane.net" target="_blank"></a>
<http://www.poweredbypropane.net>
Talking about adding Propane to older engines:
"However, there is a small disadvantage in case of 12- 20 year old cars. Namely, the carbon deposit makes kind of a "sealing crust" from the inner side of the older engine and when it runs on propane this "crust" melts and may make a small oil leak bigger."
I know that propane will clean up a crusty engine, but I'd never thought that the crust might be serving some purpose.
Any thoughts?
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Larry,
It isn't.
The changes in combustion with propane are considerable. Very different pressures and temperatures can be created. The only place that gets any direct grief is the combustion seal in the head gasket. I got more than a few claims that a gasket failed when the engine was switched to propane, but all of the examples that I saw had failed before the switch and had been running failed for some time (usually the result of a fastener issue). The only other factor is that the engine may produce higher cylinder pressures and this will cause the joints to work and thus leak more.
Aftermarket warranty is really interesting on occasion.
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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