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Onan Master, new and used parts.
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Attached is a picture of the rear bearing plate from a p220G from a J.D. 420 garden tractor that I'm currently working on.

This is why you should never use RTV as a gasket sealer.

The owner is lucky he did not break the #2 rod and destroy the engine.

Thank you
Boomer
The used ONAN Engine Parts Guy
 

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iam moe, new here. i started working on cars in 1965. i have ALL ways used permatex #2. its NEVER failed me. i never liked rtv. my friend worked for felpro they would not warranty valve cover gaskets if used RTV on it.
 

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OK Moe... Welcome to the forum. I am Hilda and I am famous for putting new members to the test. :sidelaugh:

Please tell me how you would keep Permatex from clogging the oil passage that Boomer is pointing to in his post? :trink:
 

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Boomer's point was.... use the proper gasket so you don't risk having sealant blocking up critical oil passages. The cost of rebuilding an Onan fully has risen to nearly two grand. Is it worth risking oil starvation over an inexpensive gasket?

People put too much sealer on because they don't know what the correct amount is. The gasket eliminates having to guess. So ...........my answer is no... you did not pass but your opinion is always welcome, just the same.

As for hopping up an Onan, this would be the man to ask.

http://gardentractorpullingtips.com/index.htm
 

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Boomer.....

The item shown in your first post does not appear to have a gasket on it. Correct me if I am wrong but wasn't JUST RTV used to seal this item to the block?

If too much Permatex is used, isn't that just as bad as using the RTV? How about a little more explanation here than just your usual two sentences that leave many of us guessing. :thumbsup:
 

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This thread is timely as I was just looking over the B48 on my "new" 448 and noticed some blue permatex-like gasket material around the valve covers and also around the gear case gasket on the front of the motor. It does appear that there are gaskets installed in all areas in addition to the blue permatex-like material. Any thoughts? Cause for alarm? :headscratcher:
Thanks
 

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Onan Master, new and used parts.
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Discussion Starter · #11 ·
tom
you must know that i love to keep you guessing.
the BLACK thing in the pic. is the gasket.
i have seen LOTS of RTV in the oil pump screens,
i have never seen the permatex # 2. ( poss. because only a few of us use it ) SMILE
thank you boomer
 

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Here's the thing, Boomer. I don't want to guess.

And I'm thinking that most of the members here don't want to guess, either..because this is a critical decision that can affect the lifespan of a very expensive engine.

So, if the gasket was in place on the plate shown in the photo and RTV partially plugged the oil passage............what would prevent Permatex #2 from doing the exact same thing?

If a thin coating of Permatex is OK, then why isn't a thin coating of RTV OK?

And when these engines were put together at the ONAN plant originally, was any sort of sealant used other than the gaskets?

Back in the day when I used to work on small block Chev engines, we never used these sealants.... mostly because they weren't even available. All I ever did was to lightly coat both sides of felt gaskets with some trusty Lubri-plate and put the timing cover, oil pan, fuel pump, thermostat housing and intake manifold onto the engine. And if we used cork valve cover gaskets, then those got coated too. Funny thing......that stuff worked great. I never had a leak and if I had to take something off later, the gasket rarely stuck to the metal. You can't block an oil passage with Lubri-Plate either because the engine oil would just dissolve any excess and assimilate it.

You might have to write a whole two paragraphs to reply to this, Boomer. Can your fingers stand the strain? :sidelaugh: :sidelaugh:
 

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Early on I used Permatex on almost everything. My first experiance with Silicone was when Case started recomending it (mostly big tractors) in the late 70s. We took on Deutz in the early 80s and they used silicone on almost everything. I think that it is the best improvement in sealing in my time as a mechanic if used properly. I have never had a leak when using it. One other nice thing is if you ever have to go back into it, a gasket applied with silicone doesn't take long to scrape. If you are not paying attention to oil passages like the one Boomer found silicone, Permatex or not clocking a gasket right can cause problems. One of my mechanics destroyed a Detriot Diesel rebuild by not orienting the gasket right and blocking the oil return from the head. On valve cover gaskets I used a little silicone on the top side and a coat of grease on the bottom. On head gaskets I use Copper Coat and most everything else silicone. If there is a gasket and mating two machined surfaces like Boomers example, I use a very small amount and circle every hole. Auto manufacturers sold a lot of new cars and trucks with only silicone on valve covers and other places. I guess my point is don't blame the silicone. The problem is that that engine was assembled by an amateur.
 

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Here's what I posted in the Onan forum on this subject:
Hylomar is the best I've found for a sealer; If needing to use something instead of a gasket the permatex black when used correctly is good.

I use latex gloves and spread it thinly with my finger. do not assemble wet, let it skin over slightly, loosely assemble, let it cure, then tighten.

I don't think the product is bad, but a lot of techniques certainly are!

But I wasn't clear on the Hylomar use, I use it when repairing an intake, works great.
 

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Onan Master, new and used parts.
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Discussion Starter · #15 ·
tom
if you do not like my post, you can always fire me from this HIGH paying job.
SMILE
thank you. boomer
p/s i,m 65 and i remember my dad using it on the farm when i was a child.
the permatex tends to permeate the gasket, for a great seal.
 
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