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Onan B48 On Gt18 Slobbering Oil From Exhaust

sears gt18 onan b48

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#16 KennyP OFFLINE  

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Posted June 22, 2012 - 05:23 AM

A tube of caulking to seal the hole it slobbered from? LOL

#17 MH81 ONLINE  

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Posted June 22, 2012 - 06:55 AM

Kenny, I was thinking cork. :rofl2:

US, I don't know of anything that only cost $5 anymore... You have my attention.
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#18 olcowhand OFFLINE  

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Posted June 22, 2012 - 08:39 AM

Screen cloth missing from the breather tube?

#19 Utah Smitty OFFLINE  

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Posted June 22, 2012 - 09:25 AM

A tube of caulking to seal the hole it slobbered from? LOL


LOL!!!! Good guess... I had thought of giving it a bib, but it would have got caught in the belt!! ;o}

#20 Utah Smitty OFFLINE  

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Posted June 22, 2012 - 09:37 AM

Well, I won't keep you in suspense... it was a sparkplug gasket.

I started up the engine and put my hand near the mufflers. The exhaust from the front cylinder was warm, but not hot. The rear cylinder got hot real quick... that told me the cylinder was firing, but either had a weak spark, or wasn't getting good compression.

I pulled the plugs and did a compression test, and the "bad cylinder" had slightly better compression than the other. hmmmm...

I looked at both plugs--they had some carbon residue, but that is also when I noticed the one from the front cylinder didn't have a gasket--it wasn't sittin around the spark plug hole, either.

I had pulled the plugs out when I removed the shroud to grease the bearing on the starter. One of the gaskets must have fell off the sparkplug and I didn't notice. - mystery solved.

I put in two new plugs and she runs good now...
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#21 MH81 ONLINE  

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Posted June 23, 2012 - 02:01 AM

This was causing the oil leak? Wow, I'd have never guessed. Thanks for the info Smitty.

#22 KennyP OFFLINE  

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Posted June 23, 2012 - 05:42 AM

I never would have guessed that! Glad you pinned it down!

#23 JDBrian OFFLINE  

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Posted June 23, 2012 - 06:26 AM

Smitty, have you figured out why that cylinder wasn't firing. Without the gasket it would have been a bit further into the head but maybe it just wasn't sealing and you didn't have enough compression for it to run. Glad you got it sorted out and it's running good!
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#24 Utah Smitty OFFLINE  

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Posted June 24, 2012 - 08:24 AM

Smitty, have you figured out why that cylinder wasn't firing. Without the gasket it would have been a bit further into the head but maybe it just wasn't sealing and you didn't have enough compression for it to run. Glad you got it sorted out and it's running good!


Yeah, that's pretty much the same conclusion I came to. The cylinder wasn't sealing completely without the sparkplug gasket, so it didn't develop the power it needed... both cylinders are worn-- compression in the 90-95 psi range, so the oil wasn't burning off--it got pushed out the exhaust and collected on the muffler. When I got a good plug in there it fumigated the neighborhood for 10 minutes while it burned off all the oil in the exhaust port and muffler!!!

This is definitely a lessons-learned to keep in mind if this comes up again.

U.S.
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#25 MH81 ONLINE  

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Posted June 24, 2012 - 09:20 AM

It's funny how the littlest thing can cause so much problem. I know you have hours in tracking it down, like you said "Lesson Learned". Good of you to share your lesson with us.

#26 JDBrian OFFLINE  

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Posted June 24, 2012 - 11:54 AM

I've never seen one of those washers separate from the plug. That's a good way to spoil your day when it happens especially on a single cylinder engine. Thanks for letting us know it can happen!

#27 Utah Smitty OFFLINE  

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Posted June 24, 2012 - 09:52 PM

I've never seen one of those washers separate from the plug. That's a good way to spoil your day when it happens especially on a single cylinder engine. Thanks for letting us know it can happen!


I've seen it happen once or twice--generally when the plug has been removed and reinstalled a few times. There are 3 or 4 little tits projecting out from the ID of the gasket that keep it from sliding past the screw threads...

U.S.

#28 MH81 ONLINE  

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Posted June 25, 2012 - 07:06 AM

I remember taking those off for something we owned when I was a kid. I think it was an old NH baler. The plug area was tapered to accept the plug taper and the gasket he'd it out far enough it'd run funny under load. I'll have to ask Dad, see if he remembers.




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