RTV on small engine?

[Lockasiam]

Need to replace an oil seal on a 300 series flathead engine. have to remove sump, but forgot to order a sump gasket. Can I just use a thin bead of black RTV? internet either says "yeah worst case is a leak" or "NEVER EVER EVER USE RTV ON SMALL ENGINES YOU KNUCKLEHEAD!!!!!!!!!" but want some opinions from this site

 

[ctechbob]

I'm in the 'worst it could do is leak' camp.

 

[ls1mike]

One of the box store John Deeres I recently worked on used RTV as the valve cover gasket.

 

[ctechbob]

One of the box store John Deeres I recently worked on used RTV as the valve cover gasket.

My Kholer Vtwin on the lawnmower is the same way.

 

[Lubener]

Need to replace an oil seal on a 300 series flathead engine. have to remove sump, but forgot to order a sump gasket. Can I just use a thin bead of black RTV? internet either says "yeah worst case is a leak" or "NEVER EVER EVER USE RTV ON SMALL ENGINES YOU KNUCKLEHEAD!!!!!!!!!" but want some opinions from this site

You might have some success if you make sure to have a clean surface and use an RTV product that is resistant to the oil and the heat to be encountered. I last used red RTV on a small engine and is still leak free today.

 

[CarbonToast]

Sound be just fine. Your application is exactly the intended use.

 

[cptbarkey]

Used RTV Ultra Grey on the intake for my X354. Mr Deere might not approve but it made sense at the time and I am assertive enough to not worry about it.

Why do you think it is a bad idea?

 

[BrendanC]

I use Permatex “Right Stuff” exclusively now. yet to have a leak from using it. i like the one minute stuff.

 

[fantastic]

How will you feel about the work when it's done? I'd order the gasket personally. If the gasket was NLA I could see using some high temp silicone.

 

[thastinger]

Need to replace an oil seal on a 300 series flathead engine. have to remove sump, but forgot to order a sump gasket. Can I just use a thin bead of black RTV? internet either says "yeah worst case is a leak" or "NEVER EVER EVER USE RTV ON SMALL ENGINES YOU KNUCKLEHEAD!!!!!!!!!" but want some opinions from this site

Yamabond would be the best RTV to use between case halves, or 3M 1211. If you don't have access to either of those you could use permatex gray.

 

[dvblanch]

Does the gasket provide endplay for the crankshaft?

 

[Trav]

Does the gasket provide endplay for the crankshaft?

Good point, sometimes gaskets are not just about sealing but about creating clearance also. If not RTV will work but not too much you don't want any excess getting into the oil galley. Hylomar M would be a better solution or if the parts are rigid with smooth mating surfaces an anaerobic sealer.

 

[KYMISTWALKER]

I have used it several times, RTV silicone gasket in case nobody knows, though I always try to use the seals and gasket’s, this is always a good option,I would use it

 

[jeepman3071]

In the words of Youtuber Taryl Fixes All "It's a lawnmower not the space shuttle".

I use Right Stuff RTV all the time. As far as crankshaft end play, I agree that it's important, but I've also had three visibly different sump gaskets in front of me for the same engine with the same OEM part numbers... The aftermarket stuff is even worse.

 

[ls1mike]

I use Permatex “Right Stuff” exclusively now. yet to have a leak from using it. i like the one minute stuff.

The "Right Stuff" is the best sealant I have ever used.

 

[Fordiesel69]

Leave the old gasket in place for its thickness and use the sealer the folks mention above.

 

[Lockasiam]

In the words of Youtuber Taryl Fixes All "It's a lawnmower not the space shuttle".

this was exactly what I was thinking of, but wanted some internet insight

 

[tnt_motorsports]

Need to replace an oil seal on a 300 series flathead engine. have to remove sump, but forgot to order a sump gasket. Can I just use a thin bead of black RTV? internet either says "yeah worst case is a leak" or "NEVER EVER EVER USE RTV ON SMALL ENGINES YOU KNUCKLEHEAD!!!!!!!!!" but want some opinions from this site

When I split my 15hp Kohler to fix a leak it required RTV going back together. I'd use the black oil resistant stuff with confidence.

Just my $0.02

 

[Exhaustgases]

The case gasket sets the end play dimension, sorta should have a gasket.

 

[slomo]

Don't know what a 300 series is but most Briggs use a specific thickness sump gasket. Creates proper end clearance for the crank.

Globbing RTV is total amateur hour. Use the OEM gasket when at all possible.