Why RTV sealant is bad!
 

I pulled this engine apart yesterday and found this. From the outside I noticed the blue goo oozing from every joint around the timing cover. Photos 1 and 2. Photo #2 has blue lines pointing to the over application of RTV. When I pulled the head photo 3 shows the RTV that was inside of the water passage. The 4th photo shows the total length of the RTV that was in the passage. It is obvious that there was little to no water flow to number one cylinder.

RTV sealant must be use with discretion. Too much can be damaging. The is a reason that manufacturers like CAT no longer use RTV sealants. They now use the more expensive Anaerobic type sealants to prevent to prevent this kind of problem.

Re: Why RTV sealant is bad!
 

I think the problem is 'misusing' RTV, not using. Too heavy an application I have known to be bad for many years. It's a good thing when used right. I never used it all that much, but it has it's good uses.

Re: Why RTV sealant is bad!
 

I guess I'm still old fashion as I still use gaskets with a very light film of RTV to fill any voids.
A few years back before the internet I went to a parts house for a couple of front/rear differential gaskets for my 46 CJ2A, I was told #1 "we don't have those" and #2 "everyone just uses silicone"....not me, I eventually got my gaskets.

Re: Why RTV sealant is bad!
 

I only use RTV where necessary. I prefer to use gaskets with a light coating of Permatex Aviation Form-A-Gasket on both surfaces.

Re: Why RTV sealant is bad!
 

there isn't a sbc on the planet that won't leak somewhere without rtv :lol:

Re: Why RTV sealant is bad!
 

Don't blame the gun - blame the gunner. RTV in the appropriate amount is ok

Re: Why RTV sealant is bad!
 

Hogwash! I love it so much I use Ultra Copper as toothpaste!

Re: Why RTV sealant is bad!
 

Many years ago I had a '75 Dodge Coronet that I got really cheap. It jumped time so I bought the gears and chain only. Cleaned the mating surfaces and used Permatex Aviation Form-A-Gasket and no gasket! My neighbor was going nuts, not believing that it would seal. :lol: I'd hate to be the person who had to pull it apart later, though. :waah:

Re: Why RTV sealant is bad!
 

Intake valley gaskets at the ends and oil pain gasket at the main seals. A little dab'll do ya... ey?

I get what HO455 is saying about excess RTV "internal ooze". Button the thing up and that's the part you don't see and it can cause some serious issues. This is why RTV "can be" bad

Re: Why RTV sealant is bad!
 

I remember an old story (I think in Hot Rod Magazine) about some team losing a drag race because the carb had a chunk of RTV in it. I don't let stuff like that get anywhere near the fuel system. I wonder how that happened?

Re: Why RTV sealant is bad!
 

NOTHING wrong with RTV.

Re: Why RTV sealant is bad!
 

I bought a used but looked brand new 600 Holley on craigslist for a $100 bucks, the guy said he ran it about 100 mi and decided to go with a different carb......found out the real reason why.

Got it up and running and had problems right away, pulled the front bowl off and it was full of RTV bits, of course plugging the jets and whatever else.
I thought how in the sam hell did that get in the fuel system. It appeared that the carb had not been separated and no sign of RTV on the bowl gaskets.

Got a gasket kit cleaned it all out still runs perfect today. One of those mystery's.

Re: Why RTV sealant is bad!
 

Everyone is missing the point of HO455s post! There is something BETTER than RTV.

HO455 please tell us about the newest Anaerobic sealants. Product names part numbers where we can get it...

Re: Why RTV sealant is bad!
 

.
Gaskets + Gasgacinch!

-klb

Re: Why RTV sealant is bad!
 

no - they are two different product categories used for different applications..

the proper use of each is the path to success ;)

THE TEN MOST COMMON GASKETING MISTAKES

6. Trying to fill a large gap with an anaerobic gasket maker.
Anaerobic gasket makers and flange sealants are designed for sealing assemblies where two close fitting machined metal surfaces come together. They’re generally recommended for gaps of up to 15 to 20 thousandths of an inch only. If you’ve got larger gaps – such as sealing a stamped steel oil pan, you should be using an RTV gasket maker.

what you may not understand is that anaerobic sealants will stand in open containers for years and never cure until applied where isolated from oxygen.. loctite thread lockers are a perfect example of this, they'll sit without caps for years and still be liquid..

rtv products work much differently, they react to the moisture in the air which initiates curing process.. they are also a type of anaerobic as they continue to cure internally where oxygen is not present.. that is why a slightly used tube of rtv will be cured to the seam with a year or two after opening..

there are hundreds of these types of products out there.. best practice is to become more familiar with the process you're working with and apply the proper sealing technique and sealants to the job..

happy sealing!

https://s2.studylib.net/store/data/0...c97d4bed78.png

Re: Why RTV sealant is bad!
 

Way back in the 80s the company mechanic ( and I use that term oh so generously ) kept the trucks running, in and out of the shop mostly. :lol: My truck had no heat. He yanked a heater hose off at the firewall and there was a blue strip of silicone. He pulled it out and it was almost 12" long. NO WONDER I had no heat!

Re: Why RTV sealant is bad!
 

If you use the right stuff in the right places there is nothing wrong with it. Just rebuilt a Toyota 22re and the pan gasket is still laying on the workbench. The gasket will leak long before the FIPG gasket maker will. Lots of auto manufacturers recommend gasket makers in a tube over regular gaskets nowadays.

Re: Why RTV sealant is bad!
 

Right stuff is the #### I put the hashtags in . Use a little and it pretty much will outlast the part

Re: Why RTV sealant is bad!
 

we're captured fleet here.. this is what uncooperative drivers get from my guys :lol:

not directed at you Boog but your story reminded me of it :)

https://dl.dropbox.com/s/v9ned5yncxa...oning.jpg?dl=0

Re: Why RTV sealant is bad!
 

When you say the right stuff are you talking about the sealant called the "right stuff"? I've used that many times and it does work great. I've also used Toyota FIPG many, many times and it works great as well.

Re: Why RTV sealant is bad!
 

This thread has some good examples of how the "the more the better" philosophy is bad. I do use sealant but as stated by others just enough to do the job IE: small 1/8" to 1/4" diameter beads. For the high temp I use spray on to make sure I get a seal and to make sure I don't over apply the sealant.

I was taught by my dad who permatexed everything. Old habits die hard..

Re: Why RTV sealant is bad!
 

I've read about people cracking intake manifolds they tried to remove after being sealed on with The Right Stuff.

Re: Why RTV sealant is bad!
 

I should have phrased that differently. I do know about the "Right Stuff" but I was referring to using the right type of sealant/gasket maker. There are different types for different applications.
Use the right amount of the correct sealant and you shouldn't have a problem. There are some applications though where using the correct gasket without sealant is best. Certain intake gaskets already have a bead of sealer where needed and should be applied dry. The same for head gaskets.

Re: Why RTV sealant is bad!
 

True that!!!