965 replies to this topic

[KennyP]

Good to see the herd out grazing. Old Girl is looking real good.

[larrybl]

Question on gaskets.... Most of the gaskets came off intact except for the front bearing cover, it had to be scraped off. Should I apply any gasket sealant like permatex, or just go with dry gaskets? I have used permatex on the Briggs and not had any issues, except when I go back into the engine. I am thinking of sealer on the front bearing cover and oil pan, rest will go on dry. Your thoughts?

[MH81]

I hate permatex, but it does serve a purpose. Probably best to do it on the big leaks areas, like you say.

[larrybl]

Hard to make progress, I gave up looking for the missing feeler gauge, wonder how long now before it shows up? Installed the new rings, main seal, and crank..... Band clamp won't work as a ring compressor on this one.... so another stop at Pep Boy's tomorrow. 

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[larrybl]

Well, I re-orded the main gasket and seal after I read the info Onan posted. Any suggestions on removing fresh permatex?

 

 

Originally Posted by onanparts.com

New gaskets do not require any permatex etc. type of sealants. A new gasket "compresses" when installed and that's what makes the seal. Old gaskets have already been compressed and if reusing them a sealant is advised.

The biggest issue with sealants like permatex or any kind of RTV is "excessive" amounts used and it finds it's way to places you do not want it, oil passages etc.

I use a graphite spray on most gaskets, goes on wet but drys fast. Helps seal but down the road when the cover, pan etc. needs to be removed for any reason the gaskets let go easy with little to no scraping.

Where to use permatex etc.? Timing cover bolt threads and under the bolt head. Same for the oil base. Oil filter adapter bolts too. Valve cover bolts but only a small amount under the head, none on the threads.

Rear bearing plate bolt threads. Intake manifold bolt threads. Point box mounting bolt threads. Basically any bolt threads where oil might try to escape.

Head bolts. Hi-temp anti seize on the threads.

On the filter adapter bolts I actually use Permatex Aviation #3 gasket sealer. Coat the threads and both sides of the copper washers that should be used there. Do not use any sealer on the adapter gasket.

All of the above has worked fine over the last 30 years with no leaks on hundreds of rebuilds.

[KennyP]

Good info to know. I may make that into a PDF and put it with the Onan Manuals!

[MH81]

I personally would've used it, Regardless of the above info, but I'm a pessimist.
I may not have rebuilt hundreds of Onan engines, but I have put my fair share of gaskets in. The few leaks I've had, I've wished I'd used a sealant.
I think the main reason why companies are against it is that people tend to use the "a little is good, a lot has to be better " theory of application. All that extra goo gets itself in trouble banging around in there.
Skim coat is good enough, if it requires more... The surfaces need to meet better.

[KennyP]

If I am using gasket sealer, I also try to get just enough on to help stick it on the part. Most of my left over sealant dries up in the container before I use it all up.

[TAHOE]

Yea, I used to be one of those "globbers" until I learned the proper way to use it. I use enough to spread a thin film over the gaskets, helps fill any small pits or imperfections in castings.

There is only 1 time when you need a big glob of RTV, small block Chevy front and rear intake where they meet the block.

[KennyP]

Yea, I used to be one of those "globbers" until I learned the proper way to use it. I use enough to spread a thin film over the gaskets, helps fill any small pits or imperfections in castings.

There is only 1 time when you need a big glob of RTV, small block Chevy front and rear intake where they meet the block.

I did that on the the GM engines for a while until I learned to take a center punch and put small divots in both surfaces. That worked to hold those rubbers gaskets in place.

[larrybl]

Well I am taking Onan's advise. I pulled the main bearing and saw that the permatex had plugged the oil port somewhat. His advice seems sound and follows the OEM instruction manual. I cleaned the permatex off with "goof off" worked really well. I also picked up a ring compressor so when the gasket comes in I should be able to make quick work on assembly.

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[KennyP]

Glad you opened it back up.

[larrybl]

Thanks all, my experience has been mostly with "splash lube" engines where the use of sealants tend to be a good thing. This one is a little different. I have another question, actually looking for suggestions to fill the hole in the dash where the hour meter was. 

Volt meter..... Simple to install, wires are already there.

Amp meter .... Gives a little more info on the charging circuit, will require additional wiring. 

Oil Pressure.... was mentioned somewhere, there is a fitting on the oil filter for this. new ground as for me to install without leaks.

Or just get a new hour meter, not OEM,

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[KennyP]

An hour meter can be helpful with keeping track of fluid changes/such. Oil Pressure is a nice addition for pressurized systems. But it could be mounted under the hood if you want. I will have to go back to see what the dash looks like.

[MH81]

What's wrong with the hour meter? You may be able to get it running again.