An example of why RTV should be used sparingly

[The Critic]

Just wanted to show an example of why it is important to only use a small quantity of RTV (or the OEM specified amount) when sealing components together.

Here is a picture of the area being sealed:

This is a 2.0-2.5mm bead of Nissan RTV (TB 1217H):

Although I only applied a small amount of RTV, look at the amount of RTV that gets squeezed out inside the component:

I commonly see people apply beads of RTV that are double this size, if not more. This can result in RTV breaking off and causing component failure.

 

[Jimmy_Russells]

People generally use way too much. Even 1/16" bead is usually more than adequate

Case in point:

 

[The Critic]

People generally use way too much. Even 1/16" bead is usually more than adequate

Case in point:

View attachment 93170

Reminds me of the timing cover in this post:

https://www.tacomaworld.com/threads...-and-tear-down-pictures.617275/#post-20982851

 

[Silver]

Reminds me of the timing cover in this post:

https://www.tacomaworld.com/threads...-and-tear-down-pictures.617275/#post-20982851

Wow. I stared at that like ... I can't describe it.

 

[BMWTurboDzl]

Reminds me of the timing cover in this post:

https://www.tacomaworld.com/threads...-and-tear-down-pictures.617275/#post-20982851

Where are the candles for all that frosting!??!

 

[atikovi]

Some people can't visualize the difference between the dimensions of an applied bead of sealant vs. it's compressed dimensions. When two parts are bolted together and there isn't even .001" clearance between them, a bead 10 times as thick, or .01" is more than enough. That's less than 1/64".

 

[brianl703]

This can result in RTV breaking off and causing component failure.

It can but one reason they use RTV is that it is an excellent elastomer. It usually has to be stretched something like 600% before it breaks, and it takes a lot of force before that happens. And it has no plasticizers to migrate out so it will be as flexible, pliable, and stretchable years later as it was new.

 

[eljefino]

Wow. I stared at that like ... I can't describe it.

Put that much on and you're in danger of getting a bunch on the tip of a bolt, hydrolocking it, and breaking something.

 

[doitmyself]

Looking at the first picture, wouldn't it be better to run the bead more towards the outside edge of the flange and maybe put a circle of RTV around each bolt hole.

 

[The Critic]

Looking at the first picture, wouldn't it be better to run the bead more towards the outside edge of the flange and maybe put a circle of RTV around each bolt hole.

The bolt holes are enclosed within the cover so they do not need to be sealed. A perimeter of RTV around the opening itself should prevent any oil from seeping out, though, having it more towards the center wouldn't hurt either.

 

[bcossa2020]

I’m thinking RTV should work well on plumbing connections…..

 

[nthach]

When I go to to a junkyard, a very common thing I see is RTV that was gloped on from the tube without a nozzle. I haven’t done any high-precision work recently that uses RTV but I cut the nozzle to the first step and apply from there.

 

[brianl703]

I’m thinking RTV should work well on plumbing connections…..

And a trash pump should work well to help clean up the resulting mess.

 

[JimPghPA]

I have fixed a drain by saturating fiberglass cloth with RTV and plastering it on like a plaster cast on a broken limb. Waited a day for it to set up, and now the bathtub pipe connection upstairs no longer leaks. It would of been a bear to disassemble and replace that joint because of the lack of access. And the silicon saturated fiberglass cloth could be cut off it, if it was ever really required to do some future work on that joint.

I would not use RTV on anything with significant pressure, like a water pipe.

Natural gas lines have very low pressure. It is measured in inches of water equivalent.

I have fixed a very old (73 years old at the time I fixed it) multi junction water connection for a bathtub and shower, that had one connection dead ended and that dead end had a small leak. I saturated fiberglass with pipe epoxy, and plastered that on (after cleaning it up well) and stopped that leak. Maybe on the Mickey-Mouse side of a way to fix something, but it worked and is still working after more than 15 years.

 

[Rand]

in case anyone else didnt scroll down far enough this is the timing cover.

 

[JGmazda]

Good pictures and agree with OP. However... Getting that close the the edge, one can only predict the outcome... It's going to go where it has the least resistance when compressed. Maybe a tad not-so-close wold help?

 

[bdcardinal]

When I first started taking auto classes in junior college there was an example of this that sticks with me to this day. One of the students the previous semester rebuild the engine in his Aerostar that uses RTV for the oil pan gasket. He used way too much and the RTV got sucked into the oil pickup and wrecked the freshly rebuild engine.

 

[bcossa2020]

I would think RTV would work well in place of pipe dope on threaded connections but perhaps is not intended for connections under that magnitude of pressure.
I suppose if all else fails I could read the manufacturer’s instructions

 

[Snagglefoot]

At the end of this thread there is a “ Similar Thread” called “Product Review - Permatex Ultra Gray RTV”. I am the OP of that one. I’m happy to say that after three long years that water pump is still in service with no leaks.

 

[RooflessVW]

At the end of this thread there is a “ Similar Thread” called “Product Review - Permatex Ultra Gray RTV”. I am the OP of that one. I’m happy to say that after three long years that water pump is still in service with no leaks.

Keeping the installed component from leaking is not why you avoid using too much RTV.

It can but one reason they use RTV is that it is an excellent elastomer. It usually has to be stretched something like 600% before it breaks, and it takes a lot of force before that happens. And it has no plasticizers to migrate out so it will be as flexible, pliable, and stretchable years later as it was new.

When you have a big glob being held on by a 0.001" sliver, oil flow will tear it right off.