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Snapper 1855 18Hp Onan O/h Questions


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#1 Kmac1 ONLINE  

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Posted November 20, 2014 - 05:19 PM

Since I have started the restore on my 1855 I have been going back and forth on whether or not to go ahead and tear it down and go thru it. Plan on replacing all the gaskets to stop the oil leaks. It didn't smoke or use any oil, had plenty of power. Since this is the one I want to make factory original should I overhaul it or just the gaskets. Thanks Willie
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#2 olcowhand ONLINE  

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Posted November 20, 2014 - 05:33 PM

I think if she runs well, no knocks or strange noises, with it not smoking and plenty of power, I'd just replace the gaskets.  But do check your oil pressure before taking her apart.  If the pressure is low, you want to find out why.  Could be a worn oil pump, worn bearings, or weak regulator spring.  You should have a minimum of 12psi at idle hot, and at least 25psi at full rpm's.  Factory high rpm pressure is set around 35psi.  I always install an oil pressure gauge so I always know what the pressure is.


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#3 KennyP ONLINE  

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Posted November 20, 2014 - 05:42 PM

I've put oil pressure gauges on my Onans as well! With a pressureized system, why not?


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#4 Kmac1 ONLINE  

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Posted November 20, 2014 - 05:58 PM

Checking the oil pressure may be a problem, it is sitting on the work bench with the carb off and one cylinder head off because the spark plug was seized in it. Willie

#5 olcowhand ONLINE  

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Posted November 20, 2014 - 06:02 PM

Checking the oil pressure may be a problem, it is sitting on the work bench with the carb off and one cylinder head off because the spark plug was seized in it. Willie

 

Well, likely it is fine being it had no knocks.  The pressure regulator can be tweaked to raise the pressure some anyway.  2 of my Onan's had lower pressure, but adjusting the regulator brought both back to like new readings.


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#6 KennyP ONLINE  

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Posted November 20, 2014 - 06:02 PM

Take the other plug out and spin it over real fast!


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#7 Snap1855 OFFLINE  

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Posted November 20, 2014 - 11:55 PM

This is an interesting read..
I would like to know where the best place is to
Put in a gauge...is there a port?
My onan runs good, doesn't smoke, but I do seem to hear more
Noises than I would like....I'm also new to onans and I'm
unfamiliar with them...
the noises I do hear aren't always present,, and aren't real
Loud....dont believe it to be serious. Or hope not.
a oil pressure gauge would be good reassurance.
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#8 KennyP ONLINE  

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Posted November 21, 2014 - 05:20 AM

This is an interesting read..
I would like to know where the best place is to
Put in a gauge...is there a port?
My onan runs good, doesn't smoke, but I do seem to hear more
Noises than I would like....I'm also new to onans and I'm
unfamiliar with them...
the noises I do hear aren't always present,, and aren't real
Loud....dont believe it to be serious. Or hope not.
a oil pressure gauge would be good reassurance.

Right above the oil filter should be a port with a plug in it.


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#9 olcowhand ONLINE  

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Posted November 21, 2014 - 08:36 AM

At the arrow.  

 

onan1220814.jpg


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#10 Kmac1 ONLINE  

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Posted November 21, 2014 - 03:35 PM

THAT WAS GOING TO BE MY QUESTON AS WELL.  ARE THEY STANARD THREADS



#11 olcowhand ONLINE  

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Posted November 21, 2014 - 04:22 PM

THAT WAS GOING TO BE MY QUESTON AS WELL.  ARE THEY STANARD THREADS

 

1/8-27tpi npt


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#12 old149 OFFLINE  

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Posted December 18, 2014 - 07:29 PM

I think if she runs well, no knocks or strange noises, with it not smoking and plenty of power, I'd just replace the gaskets.  But do check your oil pressure before taking her apart.  If the pressure is low, you want to find out why.  Could be a worn oil pump, worn bearings, or weak regulator spring.  You should have a minimum of 12psi at idle hot, and at least 25psi at full rpm's.  Factory high rpm pressure is set around 35psi.  I always install an oil pressure gauge so I always know what the pressure is.

I think if she runs well, no knocks or strange noises, with it not smoking and plenty of power, I'd just replace the gaskets.  But do check your oil pressure before taking her apart.  If the pressure is low, you want to find out why.  Could be a worn oil pump, worn bearings, or weak regulator spring.  You should have a minimum of 12psi at idle hot, and at least 25psi at full rpm's.  Factory high rpm pressure is set around 35psi.  I always install an oil pressure gauge so I always know what the pressure is.


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#13 old149 OFFLINE  

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Posted December 18, 2014 - 07:33 PM

Where would you put in your oil pressure fitting and gauge. Thank you old149
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#14 Kmac1 ONLINE  

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Posted December 20, 2014 - 11:40 AM

Worked on the onan some.  pulled the plugs out and one of them was seized in the head. Will go get a heli coil insert and put it in.  Helicoil is a good solid repair, I've done them many times on aluminum auto engines, never had one fail yet.


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#15 KennyP ONLINE  

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Posted December 20, 2014 - 03:59 PM

Where would you put in your oil pressure fitting and gauge. Thank you old149

Look at post # 9 above. The fitting is part of the oil filter adapter!


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