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General Category => General Discussion => Topic started by: Tkelly on May 21, 2025, 01:21:05 PM

Title: Old Eldo blowing oil out thebreather tube
Post by: Tkelly on May 21, 2025, 01:21:05 PM
A friend started his old bike for the first time in a few years and it blew out about a quarter quart of oil thru the breather tube.Any suggestions ?I think it is a 73 Eldorado.
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: Dirk_S on May 21, 2025, 01:22:56 PM
Water accumulation via atmospheric fluctuation?
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: moto on May 21, 2025, 02:59:55 PM
A friend started his old bike for the first time in a few years and it blew out about a quarter quart of oil thru the breather tube.Any suggestions ?I think it is a 73 Eldorado.
Right away? Or over a ride of X miles? (X=?)
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: Tkelly on May 21, 2025, 03:07:40 PM
Didn’t say,what are the likely causes in each situation?
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: guzzisteve on May 21, 2025, 03:39:50 PM
Stuck flap or disc on pin w/spring in the box on block. New box used to be $25 that was awhile back. I don't trust old ones.
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: jhem68 on May 21, 2025, 04:27:04 PM
Always an outside chance of gas seeping past the float and migrating into the sump if the petcock leaks or was left in the on position, so hopefully he checked the oil level before starting it up.  But most likely the flapper is stuck shut as Steve suggested.

John H
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: Tkelly on May 21, 2025, 04:57:08 PM
He traveled to MG and they gave him advice on how to clean the flap in the box.Thanks for the tips.
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: michaell32 on May 21, 2025, 05:04:51 PM
If it was sitting for years there could be rust on the cylinder walls not allowing the rings to seal as well as they should.  Compression leaks past the rings and builds up excessive crankcase pressure.
Title: Re: Old Eldo blowing oil out thebreather tube
Post by: Antietam Classic Cycle on May 21, 2025, 06:27:57 PM
A friend started his old bike for the first time in a few years and it blew out about a quarter quart of oil thru the breather tube.Any suggestions ?I think it is a 73 Eldorado.

Deteriorating chrome bores?

If it was sitting for years there could be rust on the cylinder walls not allowing the rings to seal as well as they should.  Compression leaks past the rings and builds up excessive crankcase pressure.

Eldorados had chrome plated cylinder bores from the factory and the chances of that flaking off are good. If it was fitted with aftermarket iron liners, then rust could be an issue.