I’ve had excellent luck using Permatex Super 300. It’s not silicon…I don’t think it is, anyway. Pretty sure it was HRL’s recommendation that put me onto it.
He didn't test Navistar 6040792C1 RTV SILICONE SEALANT (also available as Motorcraft TA-31). It's used to seal the oil pan on a 7.3L Powerstroke. I've removed the pan on one and I'll tell you it was a PITA to get off. Had to drive a putty knife along the seam with a hammer to get it loose. It has to be applied to CLEAN surfaces. If you want something to STICK, give that a try.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Silicone or RTV is the most over used (sorry) crap sealer there is. I have never liked it, I'm with JW and HL on the sealer type to use. At some point miles and years down the road the RTV will leak. Even the now built newer gasketless stuff that the factorys goo together with RTV, have chosen the wrong sealer in many cases, they would have been way better off using an anaerobic sealer, because it will not chance having parts of it fall off into the oil or fluid (automatic trans) and plug up a gallery or orifice, it seals better and last longer as well.
Kicking self for selling off my Taskforce trucks. Still looking for an LCF or conventional big bolt in decent shape.
As of 10-26-2022, A 55.2 Taskforce long bed now the work begins
Count me in on the disinterest in RTV for engine use. I've found Permatex 300 (or what they call Type 3 Aviation Sealer--seems to be the same thing as 300 and may be found more commonly) is available at almost any auto parts store. I've even seen it at big box retail stores. It lasts and lasts and allows you to remove a part if needed. Plus...and this is a big thing...it won't set up after you've opened it, so you can use that plastic bottle you bought for years. Not to say RTV doesn't have plenty of uses. It does, but in my opinion they're different uses.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Is the aviation sealer that’s more available….a bit “thinner” in viscosity than the super 300? I was under the impression that is was, but not sure where I got that idea.
I don't know...it might be, but the bottle I have is reasonably thick stuff. You probably can't appreciate it from the image below, but it isn't thin at all. The old bottle said use denatured alcohol if you needed to thin it. The bottle I bought around 10 years ago doesn't say that, however I suppose you could do so if you needed.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
I think I clarification should be made here. Silicone is almost never good when in contact with oil. It has worked very well for me when using it only for water sealing.
Is the aviation sealer that’s more available….a bit “thinner” in viscosity than the super 300? I was under the impression that is was, but not sure where I got that idea.
The poop-brown brush-on sealer Permatex sells is nowhere near as effective as the Super 300, which is almost black. I've heard rumors S-300 was developed during the early 1950's to be resistant to high octane aviation gasoline, which would eat most other sealers like candy. Not sure how true that is, but I've heard it from several sources I consider to be reliable. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I have used RTV sealers since Ford used it on valve cover in the late 70's. It was crap. If RTV is needed , both surfaces need to be SQUEAKY clean, and most people seem to think that more is better, not. Doesn't hold up on intake gaskets around coolant ports. Anaerobic sealers work best on machined parts as transfer case halves. Stay away from blue and clear. Garbage.
just retired and finally making headway on my project truck. 1940 GMC AC152.
For something interesting just do a search on the, New (2022, 2023) Toyota GR86 Engine failures, the cause is RTV, that was done at the factory. Also Ford has a rash of oil pans leaking on F150's because of RTV, and likely not installing parts clean enough, as well as the plastic oil pan.
Kicking self for selling off my Taskforce trucks. Still looking for an LCF or conventional big bolt in decent shape.
As of 10-26-2022, A 55.2 Taskforce long bed now the work begins
JW51, I don't believe Permatex's "The Right Stuff" is silicone but rather some type of rubber. It seals very well without seepage. I have used it on transmissions, oil pans, push rod covers and valve covers. It is very adhesive so, for example, on the valve cover I use it between the head and gasket so oil doesn't seep under the gasket where is puddles at the rear of the engine. Makes removing the valve cover easy. You wouldn't want to use it on an assembly that you expect to remove soon.
I don't like the name, very corny, but I like the product. Kent
Anyone have experience with “The Right Stuff” RTV? I tend not to use RTV products but suppose they have their place.
Some folks I trust speak pretty highly of that product.
From the Permatex data I got when doing the Rochester project it is a mix...a blend of plain RTV (room temperature vulcanizing) silicone and a proprietary elastomeric product (not further identified). Which honestly leaves open all limbs of that tree ranging from natural rubber to siliconized rubber (which I believe it probably resembles as much as anything else). It is resistant to oil, power steering fluid, transmission fluid but not resistant to gas nor ethanol nor a list of other solvents.
Jon H (CarbKing) and I were at one point considering some sort of gasket compound that would accommodate the warping, flexing and distortion those carburetors suffer but we weren't able to come up with an affordable alternative that would tolerate today's gas.
RTV is great for some things...kitchen and bath sealers (particularly at tile edges where movement will occur), window sealing/weatherstripping, other building sealing applications and for molds. Plaster, fiberglass...lots of pourable items can be used with it and a friend tells me some forms of it are used in casting pot metal and pewter. This conversation came up back when I was looking for a way to remake the AD fuel sender unit (which was made of inexpensive pot metal and could have been improved greatly by just adding another bearing point for the swing axis).
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
We used Honda Bond at HPD but those are 3600 mile max engines. Dad used Gaskasinch and gaskets.
Interesting point on the Honda Bond. I know those motorcycle products are very popular in the chainsaw world where folks port and/or increase compression by “deleting” the crankcase-to-cylinder gasket. Hondabond, Yamabond, Motoseal….everyone has their favorite.
I’m not super familiar with how these products differ from your various flavors of common parts-store RTV. But I do think they’re different.
D'Ecosse I learned from the old lead body man to use 3M weather strip adhesive on 352 ferd intake gaskets after washing surfaces dry with laquer thinner. Where those intelligent engineers made the intake a third of the engine a gorilla could hardly handle it !! After glueing it go home eat supper go back and just throw the intake in there,hit the 4 corners with red RTV first buckle it up!! Worked for us !! Company trucks were all GM except a ferd winch truck I never liked !!!
gms is me Those ferd valve cover cork gaskets...what a mess I guess the oil pump screens were big enough to hold all that fur and still let oil thru, cause you couldn't catch it all. On 216/235 I wash the head dry and clean set the valve cover gasket in silicon like a dam to hold the oil then next day install the valve cover so you can still take it off to watch your push rods rotate.
JW51 Ever used red hi-temp silicon ?? It is tuff .hard to get off of rough castings,best to razor blade it if you can where it's smooth cast iron like valve cover rail of 216/235. Very durable if you can get it in the right place.
