RTV (possible Guzzi content)

[Chuck in Indiana]

Just a heads up in case you think using RTV on an engine is a good idea.. There have been some failures because of it's use.

Special airworthiness information bulletin just released from Continental Motors:
bla bla bla bla of interest to powerplant mechanics snipped

Applying any unapproved sealant

(RTV, gasket maker, etc.) to the crankcase cylinder deck, cylinder deck chamfer, cylinder

mounting flange, cylinder base O-ring, cylinder fastener threads, or crankcase main bearing

bosses is not an approved procedure.

[John A]

Well that's just crazy talk, I hope we can still use it all over Lycomings 

[bigbikerrick]

Hi Chuck, It seems back in the 70'sand 80's I used to apply RTV or "silicone gasket maker" on everything almost including rye bread! Maybe it was I was more of a "shadetree mechanic" , or worked on more junky junk due to limited funds, or a combo of both factors, but it seems these days , I rarely use RTV much. I do use permatex 300 for a few things, but rarely ever . Back in the bad ol days, all sorts of things got a smear of the nasty orange colored silicone gasket goo!
Rick.

[lucky phil]

Just a heads up in case you think using RTV on an engine is a good idea.. There have been some failures because of it's use.

Special airworthiness information bulletin just released from Continental Motors:
bla bla bla bla of interest to powerplant mechanics snipped

I wouldn't use RTV Chuck but modern motorcycle engines are put together largely with adhesive sealants. All Ducati's for years have assembled their vertical split crankcases, cylinder bases, engine side covers etc with a Threebond like material only. IE Ducatibond, Yamabond etc.
I personally use Threebond1104 ( synthetic rubber). Its grey and fuel resistant and when dry is quite tough and rubbery so it doesn't"break off and clog oil passages.
When the Daytona engine goes back together I'll be making up alloy shims and using the Threebond on the cylinder bases, the rear main bearing and any other place I can within reason. Paper/composite gaskets are old school and suffer from compressing over time, distort torquing of fasteners, generally require replacement after disassembly etc. Modern engines such as Ducatis now machine everything to use sealant only, Much better.
As for old a/c piston engines, well lets face it Chuck they are so antiquated and so bound up by regulation and compliance which is understandable that they are largely irrelevant when comparing modern piston engine engineering matters. I mean do Continental/Lycoming still seal crankcase flanges with cotton thread!!!!
Ciao 

[lucky phil]

Always used thread on cases, RTV is too messy!!
:-)

Well I guess that answers my question, but I beg to differ on the "messy" point.
The correct application of say Threebond 1104 will be perfectly neat and tidy. The problem arises when people use about 20 times more than is actually needed. So when bolting together crankcases for example you only need a .020"smear on one face to get the job done.
Ciao 

[Wayne Orwig]

Well I guess that answers my question, but I beg to differ on the "messy" point.
The correct application of say Threebond 1104 will be perfectly neat and tidy. The problem arises when people use about 20 times more than is actually needed. So when bolting together crankcases for example you only need a .020"smear on one face to get the job done.

The last time a mechanic touched one of my motorcycles without me watching, he applied so much RTV that it was dripping off.
And the reply was of course to blame Moto Guzzi. He said the Moto Guzzi required that. 
Why do some mechanics feel the need to point the finger elsewhere, when they are incompetent?
And yes I quickly pulled off the oil pan and find strings of it inside.

[kirby1923]

Well I guess that answers my question, but I beg to differ on the "messy" point.
The correct application of say Threebond 1104 will be perfectly neat and tidy. The problem arises when people use about 20 times more than is actually needed. So when bolting together crankcases for example you only need a .020"smear on one face to get the job done.
Ciao

Guilty!!
Neat and tidy?

I always ended up getting it on everything, even on my elbows, in my pockets on my ear lobes....

I guess I never read the directions!!!

:-)

[Tom]

Ask Curtis about some of the engines that they receive at Harpers.

[HardAspie]

RTV the approved item on the 14 bolt diff cover of my R 20H. But, the key is just a little thin film so that a big old blob doesn't extrude itself into somewhere important.

[CalVin2007]

  The proper amount of sealer to apply is just enough to reach the edges of the joined surfaces after tightening. This is a complete mystery to most people working on machines.

  Terry

[HardAspie]

  The proper amount of sealer to apply is just enough to reach the edges of the joined surfaces after tightening. This is a complete mystery to most people working on machines.

  Terry

Wait a minute! There is still plenty left in the tube!

[twhitaker]

And yes I quickly pulled off the oil pan and find strings of it inside.

They make good lures.

[Rough Edge racing]

Well I guess that answers my question, but I beg to differ on the "messy" point.
The correct application of say Threebond 1104 will be perfectly neat and tidy. The problem arises when people use about 20 times more than is actually needed. So when bolting together crankcases for example you only need a .020"smear on one face to get the job done.
Ciao

 I believe the correct application of products like 3 Bond is a thin coat on both surfaces ... If assembly takes a bit longer than expected the stuff may skim over and not stick to a metal surface but will stick to itself........... If you're gonna get sloppy, use an anaerobic sealer because the excess  won't find it's way onto the sump screen... I say this from experience....

[Triple Jim]

Silicone RTV isn't even oil resistant.  I can't imagine using it to try to seal an engine.

Chuck:  You probably know about EZ Turn fuel resistant lubricant.  I found out about it a couple years ago, and now when I rebuild a petcock, the sliding parts get a tiny and careful smear of it.  I also use it on things like float bowl gaskets if they're trying to weep, and even cylinder base gaskets.  It really is fuel and oil resistant.  The trouble is if you get a blob in a fuel line, it's going to clog a jet, since it won't dissolve.  Hence the tiny and careful smear thing.

[Rough Edge racing]

Silicone RTV isn't even oil resistant.  I can't imagine using it to try to seal an engine.

 My experience on both old Triumphs and Chevys says it works very well when used properly....

[oldbike54]

 Yamabond .

 Dusty

[Two Checks]

Silicone RTV isn't even oil resistant.  I can't imagine using it to try to seal an engine.

Chuck:  You probably know about EZ Turn fuel resistant lubricant.  I found out about it a couple years ago, and now when I rebuild a petcock, the sliding parts get a tiny and careful smear of it.  I also use it on things like float bowl gaskets if they're trying to weep, and even cylinder base gaskets.  It really is fuel and oil resistant.  The trouble is if you get a blob in a fuel line, it's going to clog a jet, since it won't dissolve.  Hence the tiny and careful smear thing.

Blue silicone RTV IS oil resistant.

[lucky phil]

I believe the correct application of products like 3 Bond is a thin coat on both surfaces ... If assembly takes a bit longer than expected the stuff may skim over and not stick to a metal surface but will stick to itself........... If you're gonna get sloppy, use an anaerobic sealer because the excess  won't find it's way onto the sump screen... I say this from experience....

Point taken but if I experience a delay in assembly long enough to have the sealer skin over then I'll clean it off and start again.
Ciao