Correct Permatex sealer for these applications

[The Critic]

Permatex has a myriad of sealers and "form-a-gasket" products in their line-up. Their application guide isn't terribly clear on their correct uses, either. It seems as though many of the products could be used for the same applications.

Is there one sealer that I can stock that will work for the following automotive applications:

Oil Pan Gasket (Cork or Rubber)
Transmission Pan Gasket (Cork or Rubber)
Differential Oil Cover
Valve Cover Gasket
Thermostat Gasket
Water Pump Gasket

Would RTV work for all of these applications? They have many different types of RTV available, which one should I use?

Thanks.

 

[Quest]

Hey Critic,

Form-a-gasket has 2 popular types: 1 is dark brown colour and is hardening and the other one (permatex #2) is brown and non-hardening. Then there's Permatex RTV silicone.

For valve cover gasket (rubber to metal surface), if you have some sharp corners, bends or where certain metal pieces joining to the head portion, you will need to dab a small dab of RTV silicone (make sure it's O2 sensor safe) at those locations before you put things back together and apply pressure to it. Similarly, if you have rubber oil pan gasket that doesn't seem to seal properly when dry (most manufacturers with rubber oil pan gasket would recommend installing it dry), RTV would do justice.

For water pump or thermostat paper gasket, I typically use Permatex # 1or #2 with #2 being my choice. Differential oil cover, if it's paper then permatex #1 or 2 (with #2 being my choice). If transmission pan gasket is cork, I would use #1. If it's rubber, again, sometimes dry install while other times I use RTV to aid sealing.

Water pump gasket: if it's like most Honda all alu blocks with a custom formed O-ring gasket shape, I would use nothing(dry). If I have a hard time cleaning the grooves enough to seal, I would resort to using either Permatex #2 or RTV.

For automotive use RTV, I am indifferent so long as they can cure properly, )2 sensor safe and can handle decent amount of heat. Permatex blue or copper (or is it grey for imports) works wonders in many of my rebuilds over the years...

Q.

p.s. when restoring pressure lanterns such as Petromax, Aida or Coleman, I use Permatex #2 as valve thread sealer for it resists gasoline exceptionally well.

 

[The Critic]

Quest,

Can Permatex RTV be substituted for applications that would normally call for Permatex #1 or #2 sealer?

Thanks.

 

[Quest]

I would say "yes". There are times when I would choose to use RTV silicone over Permatex #1 or 2 would be as follows:

- there are some unusual pitting, scratches or uneven-ness on the mating surface of the 2 parts that would call for something thicker for proper sealing

- the original assembly (water pump, like Nissan been doing so to it's thermostat housing for the past 16 yrs, etc.) calls for RTV silicone

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If things like thermostat housing calls for paper gasket and the original assembly used some kind of hardened black, gooey paste to keep the paper thermostat gasket together, I would resort to cleaning it out with solvent, wipe dry and then apply Permatex 1 or 2.

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Given the superiority of RTV silicone over Permatex 1 or 2, it is not difficult to see that eventually, all gasket mating surfaces may eventually be sealed by rubber (neoprene or silicone) seals with RTV, or RTV alone. The use of paper gasket is gradually going out of fashion (and paper gasket works well with Permatex 1 or 2 mainly) as time goes by....so eventually, you may see Permatex 1 or 2 and paper gaskets going away.....

 

[doitmyself]

This is an excellent subject and I hope lots of people with real facts chime in. I, too, am confused by all the products available for automotive sealing.

In the current Permatex thread, already 3 or 4 different colors of RTV are touted as being the best. So, which one is it? When I called the company for advice on using RTV for a heater vent, the guy said Ultra Black has the best "properties" - better adhesion, etc..

I also have read on the "expert" forums that RTV should only be used alone and NEVER on a gasket - don't remember why.

Hope to hear from many others on this subject.

 

[The Critic]

Permatex states in their product data sheets for the RTV products that it may be used as a gasket maker or as a gasket dressing.

When I replaced the water pump this past weekend, no matter what I used (brake cleaner, Permatex gasket remover, etc), I could not get the mating surface on the engine side to be shiny clean. Also, when installing a water pump, I noticed that the coolant will drip no matter how long you allow it drain...would this interfere with the curing on the sealer?

 

[Quest]

Yes, if the mating surface for RTV sealant is dirty/wet with other foreign liquids (e.g. coolant, oil, grease, etc.), your RTV may not seal properly and as a result: a leak may occur again.

Typically, I would give RTV sealant some time to cure (sometimes up to 4+hrs before putting oil/coolant back). Once it's sufficiently cured, it will seal nicely.

Yes, I am aware of RTV sealant can be used as gasket maker but I'm also aware that there are some designs such as water pumps, etc. in certain applications that would require a paper gasket that also acts as a shim somewhat (to provide clearances) and you may get yourself into clearance trouble if you attempt substitute it completely with RTV silicone

Q.

 

[Quest]

doitmyself-

I don't know the story behind not applying RTV sealant to paper gaskets nor am I aware of any side effects (these are resin-impregnated paper fibre gaskets typical to your thermostat housing use or many automotive-related applications).

Sorry!

Q.

 

[ex_MGB]

For waterpumps & thermostats, use the Permatex specifically for that application. It comes in a small tube, you don't need much.

I stood at the gasket display at AutoZone for 15 minutes looking at all the gasket stuff. Finally, decided on Permatex Red. Asked at the counter if this would work on a waterpump. Guy said, "I guess so" but a lady said to use the stuff labeled for waterpumps. I thought, "ain;t no such thing cause I just looked", but said "Where is it".

Lady went over and lo and behold there it was on the left side of the display. Amazing I overlooked it, but, then again, I'll look for mayonaise in the refrig for two minutes and not find it but my wife reaches right in and grabs it.

 

[RyanHeo]

I bought RTV slilcon for the spark plug tube seal inside valve cover. My car is 96' Infiniti I30. Can I use RTV with new seal?
Thanks.

 

[Quest]

RyanHeo-

If the valve cover spark plug tube bore is clean and free from nicks, you shall consider installing those doughnuts dry. No need to add RTV or Permatex.

If you find the dry bore is a bit difficult to get those doughnuts in, lightly lube it with clean motor oil and that's it.

 

[mechtech2]

Ultra black or grey should serve all of your needs listed.
A perfectly clean substrate, and allowing time to cure before subjecting the parts to service is the key.

 

[doitmyself]

I spent a few minutes at the allpar (Chrysler) site regarding my van tranny pan gasket, etc. and have come up with some observations/questions.

1. Are gasket sealants/dressings always necessary? Most references seem to say no. Should sealants be saved just for problem applications or used always for insurance?

2. I've seen numerous references to difficulty with RTV (used alone) on trannies. It's hard not to have fluid inside the case drip on the uncured goo. Too much RTV, and it can get into the tranny workings. Hard to clean off, etc.. Letting it cure over night?...I'm already Mr. slow poke. Remember, at the factory, the engine is clean and dry when they use it.

3. The Permatex site has two categories: gasket sealants and gasket makers (Right, Critic, the "maker" can be used as a dressing). The number of products they make is staggering.

Yet, to repeat, it seems most manufacturers recommend a plain, non-dressed gasket.

Just some thoughts.....no thanks to Critic for opening up yet another can of worms.

 

[The Critic]

Quote:

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1. Are gasket sealants/dressings always necessary? Most references seem to say no. Should sealants be saved just for problem applications or used always for insurance?

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I've been told to always use a dressing to improve gasket durability. I'll admit, when I did my transmission valve body cover gasket repair, I didn't know any better, and didn't use it. I didn't even do a good job of cleaning off the factory sealer. But it hasn't leaked, either.

Quote:

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2. I've seen numerous references to difficulty with RTV (used alone) on trannies. It's hard not to have fluid inside the case drip on the uncured goo. Too much RTV, and it can get into the tranny workings. Hard to clean off, etc.. Letting it cure over night?...I'm already Mr. slow poke. Remember, at the factory, the engine is clean and dry when they use it.

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From Permatex regarding the Ultra Black RTV:

"Chemical / Solvent Resistance
The product retains effective properties in contact with
automotive fluids, such as motor oil, transmission fluids,
alcohol and antifreeze solutions. Note: Not recommended for
parts in contact with gasoline."

Nevertheless, they want the product to cure for at least two hours and the bolts to be retorqued 1/4-1/2 turn before fluid installation.

Quote:

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Yet, to repeat, it seems most manufacturers recommend a plain, non-dressed gasket.

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I'm not sure what the service manual recommends, but every factory gasket that I've removed has had some type of sealer or dressing on it.

Quote:

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Just some thoughts.....no thanks to Critic for opening up yet another can of worms.

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This is going to turn into another brake grease discussion.

 

[doitmyself]

Yes, another "brake lubricant" like discussion......I hope!

First, for some good reading, go to the Fel Pro site and go through the technical training on-line course. There it states:

" You should NEVER use a non-hardening sealer with valve cover gaskets of any type. Sealers can act as lubricants, causing the gasket to slide out from under the valve cover."

Granted, the Ultra type RTV is not a non-hardening sealer, I think. Permatex actually has a non hardening RTV sealant.

Studying that site, I get the impression that gaskets are to be used without sealant and that sealant is for difficult situations (damaged surfaces).

But, we all know that people use it all the time.

Are you sure your OEM installations had sealant or were they just stuck on from various engine goo (varnish, etc.).

Is the Permatex Ultra black resistant to oils in the uncured state? If so, why do they recommend "best results when allowed to cure overnight".

I recognize that the Fel Pro site is self serving. They recommend NOT to use RTV gasket makers under shop conditions , citing better conditions in factory use, possibility of contaminating internal passages, unskilled mechanics,etc.. Yet, I know Chrysler recommends RTV only tranny pan installs.

Maybe this topic depends on which "sealing" religion/opinion one follows.

 

[glenncof]

I thought this was going to be simple but no....

Transmission pan...on my Tahoe it is rubber...do not use anything. The rubber is supposed to swell.

Water pumps .... I use the Permatex version for water pumps and would use on thermostats. I would not install pump without a sealant, my experience it will almost certainly leak despite immaculate surface prep.

RTV.. I learned long ago that basic RTV does not like gasoline. I have some black Peratex that resists gasoline/oil and use it on bumper molding with great success. I would not likely use where constant fluids are involved.

Intake manifold on Tahoe uses RTV along back edge. I don't know about mating surfaces. I'd use a permatex for fear of coolant leaks.

Valve covers for Porsche...nothing...use silicon beaded gaskets, must be properly torqued like 6"-lbs.

Good question. Each case seems different.

One thing I do find is More is NOT Better. I use a putty knife to get consistent application. I think of sealers as filling in small imperfections not as the front line of defense. And I apply to only one side of a gasket.