Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Electric Motors General Discussion > Onan Generators
Forgot Password? Join Us!


Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

15.0JC Need Head Gaskets

this thread has 1 replies and has been viewed 2195 times

Thread Tools Display Modes
Old 06-10-2007, 01:43:28 PM
Posts: n/a
Default 15.0JC Need Head Gaskets


Does anyone know where I might obtain a set of head gaskets for a 15.0JC.

I am going to pull the heads and clean the combustion chambers and possibly have a valve job done.

I have the unit all tuned up, electronic ignition, new plugs, cap, rotor, wires, etc. and the timing set to 35 BTC on propane. It is a Spec S setup for gas -- 15.OJC-3CR/8505S. So I assume it does not have 9:1 compression, that should be Spec U & W sets for Natural Gas Only.

It runs real well, although It seems to run hot and will start to knock a little after running for about 45 minutes under about 1/2 - 3/4 load.

The head temps also seem a little high at around 375 F, and number 2 around 410 F. I am thinking that it had been running so badly at the time it was removed that it is most likely carboned up -- compression is good, but also a bit too high. 230 Psi Cold Cranking.

The service manual indicates that you put Permatex #3 on both sides of the gasket? Sounds archaic.

Is there any thing I should look for once the top is off?

Best regards;

Reply With Quote
Sponsored Links
Old 06-10-2007, 05:06:30 PM
Joe Stewart Joe Stewart is offline
Join Date: Oct 2005
Location: Lafayette, Louisiana USA
Posts: 119
Thanks: 2
Thanked 8 Times in 8 Posts
Default Re: 15.0JC Need Head Gaskets

I just bought a pair of head gaskets for my JC. I got them at the local Onan/Cummins dealer. Cost was $17.82 apiece plus $5.20 for the UPS charge to send them to my house (the dealer was about 20 miles away, so I had them shipped rather than driving there). J. Stewart
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Head Gaskets Byron Roberts Antique Gas Engine Discussion 6 03-11-2005 07:36:46 AM
Reusing Head Gaskets Larry Kastens Antique Engine Archives 11 08-02-2004 11:14:07 PM
head gaskets smootz Antique Engine Archives 16 11-13-2002 08:43:44 AM
Ignitor and Head Gaskets Dave U Antique Engine Archives 8 02-11-2002 09:32:40 PM
Head Gaskets Tom Jamboretz Antique Engine Archives 6 12-01-2001 10:21:43 PM

Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 03:23:35 PM.

Smokstak and Enginads site search!

All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277