Question about applying RTV

[The Critic]

I have a question about the application method of RTV. Most OEM service procedures ask for a ~1/8" bead to be applied to one side of the sealing surface and allow for the clamping force to spread out the bead.

Yet, I see a lot of people spreading RTV with their fingers instead of applying a bead. Why is that?

 

[RooflessVW]

I have a question about the application method of RTV. Most OEM service procedures ask for a ~1/8" bead to be applied to one side of the sealing surface and allow for the clamping force to spread out the bead.

Yet, I see a lot of people spreading RTV with their fingers instead of applying a bead. Why is that?

Because most people don't know what they're doing.

 

[2EHA]

get a piece of plexiglass and experiment with manually spreading vs letting it get crushed.

i use a thin bead. less is usually more when it comes to gaskets

 

[tasch72]

I have a question about the application method of RTV. Most OEM service procedures ask for a ~1/8" bead to be applied to one side of the sealing surface and allow for the clamping force to spread out the bead.

Yet, I see a lot of people spreading RTV with their fingers instead of applying a bead. Why is that?

I see both ways. I think the whole "1/8th inch bead on one side" thing is to give people a better idea of how much RTV to use, especially if you haven't used it before. Much more than that and you're going to have a mess in most cases, unless you're sealing an intake manifold to a China Wall on a V-shaped engine.

Either way, the RTV is going to get spread out. If you are a perfectionist and want the peace of mind that the RTV is definitely where it needs to go, then spread it out before assembly. Otherwise, you're not going to hurt anything by letting the surfaces smoosh it out.

 

[nthach]

Most see RTV like house caulk, put on a thick bead and smoosh it around. But in a sealing application that needs a controlled bead, failure.

I feel with RTV/FIPG, always apply in the smallest bead possible and don’t touch the bead with bare skin. Skin oils can lead to seal failure and not so much with gasketing but dead skin cells can seed mold with caulk(as if the clay/starch fillers in caulk isn’t enough).

and especially NEVER use RTV to dress a gasket. I’m not a professional wrench but DIYers love to coat cut gaskets in RTV. I use a little rubber-based adhesive like weatherstripping adhesive or high-tack to “tack” them on unless it’s not called for.

 

[t1snwrbrdr12]

I worked on Chrysler and Jeep where almost every pan and cover is sealed with RTV. I got good at making a simple bead around the covers or pans, usually just around the inside of the bolt holes, sometimes around in a circle around the bolt holes especially if they were constantly under fluid level (diffs, crooked trans pans) and let the bolts draw in the pan or cover. Never touched the RTV to smear it, and always hated getting my vehicles back to service again as the pans and covers were ON THERE. We’d constantly be re-doing the guys services that smeared the RTV on, as they’d soon leak afterwards.

 

[Tundragod]

I have a question about the application method of RTV. Most OEM service procedures ask for a ~1/8" bead to be applied to one side of the sealing surface and allow for the clamping force to spread out the bead.

Yet, I see a lot of people spreading RTV with their fingers instead of applying a bead. Why is that?

As you know, I recently re-seal my oil pump and pan for my 11 MDX. I used Honda bond II. I tried to use a 1/8" bead but the tube exploded in the opposite end making the 1/8" idea useless. I use my finger to apply instead. So far so good.

 

[The Critic]

As you know, I recently re-seal my oil pump and pan for my 11 MDX. I used Honda bond II. I tried to use a 1/8" bead but the tube exploded in the opposite end making the 1/8" idea useless. I use my finger to apply instead. So far so good.

I have experienced similar issues with the toothpaste tubes. Luckily I usually have a spare tube. But I have since switched to Nissan/Subaru RTV's (1217H) which can be applied using a caulking gun.

 

[DGXR]

It depends what you are sealing. If the mating surfaces are very narrow or fit extremely flush, a 1/8" bead may be too much sealant. So a finger spreading may be exactly what is needed for the right amount of sealant.

 

[Supersonic]

Used a long handle needle nose pliers to roll up the tube of Ultra Gray for easier application on my latest task, a coolant plate, then I found out the bead goes outside the grooved channel and luckily I still had the intake manifold off and corrected my first application, the video linked here explained the proper application using a water pump;

More Information for AISIN AB1207B1

 

[atikovi]

Get a proper RTV dispenser gun if you do this often.



It will make laying a clean bead much easier.