TheSamba.com Forums
 
  View original topic: Type 4 intake gaskets Metal or Paper??
cl55953 Wed Oct 01, 2014 11:20 am

I have a 1973 vw bus w/ 1700cc with dual 44 IDF.

I have run this carb/motors for years with no problems, until now

Last night I noticed a whistle sound coming from the right hand side of the engine where the intake bolts to the head. After removing the intake the paper gasket just fell apart. I think I found my problem.

The questions is, all I have on hand are the original metal type gasket. Will these work?? Or will I be better off to make some from gasket material to match what I had??

I’m in a bind and need them today, I can’t order the “empi racing” gaskets like were used previously.

I have seen this debated before on this site, but yet to see a good defiant answer about the metal gaskets.

Wildthings Wed Oct 01, 2014 11:26 am

The metal gaskets are what is called for. I have decided to just use just high temperature silicone as a test myself.

cl55953 Wed Oct 01, 2014 11:29 am

Wildthings wrote: The metal gaskets are what is called for. I have decided to just use just high temperature silicone as a test myself.

What type/brand?

How has it worked out?

Wildthings Wed Oct 01, 2014 11:35 am

cl55953 wrote: Wildthings wrote: The metal gaskets are what is called for. I have decided to just use just high temperature silicone as a test myself.

What type/brand?

How has it worked out?

I just used the copper high temperature silicone, but do not have enough time on it yet to say how well it will work in the long run.. You can also get gasoline resistant silicone which may or may not work better, don't know what kind of heat it can take.

Silicone will certainly get you running for today. Make sure you don't pinch the sheet metal under the intake flange when installing and give the silicone time to dry before driving. Also use very little as any that squishes out towards the inside with mess with the intake air flow.

SGKent Wed Oct 01, 2014 12:11 pm

generally gasoline will eat / soften RTV over time and it will fail. (It probably works on FI because the injector is downstream.) Been there done that. Used to be Permatex #2 or the heavy duty equally good stuff made by them for gas and steam flanges to 600 F degrees would work but with all the alcohol that may fail now too.

raygreenwood Wed Oct 01, 2014 2:05 pm

SGKent wrote: generally gasoline will eat / soften RTV over time and it will fail. (It probably works on FI because the injector is downstream.) Been there done that. Used to be Permatex #2 or the heavy duty equally good stuff made by them for gas and steam flanges to 600 F degrees would work but with all the alcohol that may fail now too.

If the copper RTV that Wildthings is speaking of is Permatex Ultrcopper....then gasoline will not touch that product in this usage. I use that on the intake gaskets consistently and have easily 500k miles on that product on intake gaskets. It works very well.

Its designed for use in oily locations. Gasoline wont touch it unless its constantly immersed. Ray

jtauxe Wed Oct 01, 2014 2:14 pm

cl55953 wrote: I have seen this debated before on this site, but yet to see a good defiant answer about the metal gaskets.
I would expect plenty of "defiant" answers from this crowd! :P

SGKent Wed Oct 01, 2014 2:55 pm

raygreenwood wrote: SGKent wrote: generally gasoline will eat / soften RTV over time and it will fail. (It probably works on FI because the injector is downstream.) Been there done that. Used to be Permatex #2 or the heavy duty equally good stuff made by them for gas and steam flanges to 600 F degrees would work but with all the alcohol that may fail now too.

If the copper RTV that Wildthings is speaking of is Permatex Ultrcopper....then gasoline will not touch that product in this usage. I use that on the intake gaskets consistently and have easily 500k miles on that product on intake gaskets. It works very well.

Its designed for use in oily locations. Gasoline wont touch it unless its constantly immersed. Ray

Ray - if you have FI that is downstream of the gasket then it sees mostly air. Here is what Permatex says about their RTV products "silicones are not recommended for use in a gasoline environment. The gasoline will attack the product." This is from the Permatex sheet on Ultra Copper:
Quote:
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.

I would not suggest using any RTV product for carb or manifold base seals based on my experience with it in that application as they are exposed to gasoline.

williamM Wed Oct 01, 2014 3:12 pm

Have had 100% sucess with a quality paint -assemble wet and let cure over night- like "crinkle paint" as it has a lot of metal in it. And X2 on the tin getting under the manifold.

Thought the FI took the thick bakelite insulators???

SGKent Wed Oct 01, 2014 3:50 pm

williamM wrote: Have had 100% sucess with a quality paint -assemble wet and let cure over night- like "crinkle paint" as it has a lot of metal in it. And X2 on the tin getting under the manifold.

Thought the FI took the thick bakelite insulators???

they do, along with paper on the bakelite, but many folks won't buy new ones every time they are off.

raygreenwood Wed Oct 01, 2014 6:05 pm

SGKent wrote: raygreenwood wrote: SGKent wrote: generally gasoline will eat / soften RTV over time and it will fail. (It probably works on FI because the injector is downstream.) Been there done that. Used to be Permatex #2 or the heavy duty equally good stuff made by them for gas and steam flanges to 600 F degrees would work but with all the alcohol that may fail now too.

If the copper RTV that Wildthings is speaking of is Permatex Ultrcopper....then gasoline will not touch that product in this usage. I use that on the intake gaskets consistently and have easily 500k miles on that product on intake gaskets. It works very well.

Its designed for use in oily locations. Gasoline wont touch it unless its constantly immersed. Ray

Ray - if you have FI that is downstream of the gasket then it sees mostly air. Here is what Permatex says about their RTV products "silicones are not recommended for use in a gasoline environment. The gasoline will attack the product." This is from the Permatex sheet on Ultra Copper:
Quote:
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.

I would not suggest using any RTV product for carb or manifold base seals based on my experience with it in that application as they are exposed to gasoline.


Actually.....no....it will not. Again...with full emersion where it has no way to dry off for extended periods...it may very well have problems.

However fuel first has to break down what silicone it comes in contact with (not a quick process) and then absorb into it....which it cannot. The level of breakdown of thin silicone used in this area....like .001-.005" maximum thickness....which is how it should be used.....is virtually nil over 50-70k miles.

Again.....as I noted....im not quoting from some BS tech data sheet or crap someone wrote on the web. I have plenty of documented miles on this product and others like it being used on intake manifolds with "0" failures....many other people here do as well.

I have spoken at length with people from Permatex and dozens of other silicone manufacturers. Much of this is put into tech data sheets to discourage those who insist that RTV can be used to build virtually anything or fill any sized gap.


I know exactly what im talking about because I work with this crap virtually every week if not every day.....and ...in fact im casting silicone boots tonight.....and one last shot at that part for that EGR diapgram (keep your fingers crossed).

I have a direct suggestion for you with all due respect:......quit qouting manufacturers specs and uses for chemicals and tools when someone has a non recomended use for them.....unless you have used them by the exact method and in the exact application. Because again....I have used them with complete success on a range of engines for upwards to 500,000 miles over 3 decades. No failures.

Manufacturers only list uses in their technical data that they themselves have proven in their LABS.....or major clients have proven for them. Even then....if it has any risks of misaaplication....they put plausible deniability into the tech data sheet.

One of the industry's I have spent the last 3 years in is a prime example.....medical device manufacturing....you know...defibrillator pads, ekc electrodes etc. Virtually half of the materials used are like adhesives, conductor s etc......are specifically not certified for use in medical devices or life saving devices in the tech data sheets......think about that next time you are in the emergency room.

We are able to qualify these types of materials through performance testing, age testing and destructive testing. The manufacturers are fine with that. ...but will still not put It into the tech data sheets befause they dont want the liability of other manufacturer's not testing to the level we did. Ray

Here is the kicker...and from more than a handful of silicone RTV formulators.....the primary reason they dont want you using it around fuel systems is that even know it is listed as "SENSOR SAFE".....it still has enough silicone in it that if a moron uses it in the "goop it" method. ...it could still fry an oxygen sensor.

And if you use the goop it method when sealing intake manifolds it will most, assuredly leak because it will shear apart....not from fuel attack.

SGKent Wed Oct 01, 2014 6:11 pm

so Ray - after that long dissertation explain why the RTV I used on the base of other carb gasket always got swollen and fell apart. What was that - gremlimimic RTV? BTW - I am still waiting for MY original good EGR diaphragm back. Did you send it to Hoody?

Wildthings Wed Oct 01, 2014 6:38 pm

When silicone is used to seal the intake manifold the thickness is going to be extremely thin so there is not much area for the gasoline to attack, plus once the heads are hot there is never going to be any liquid gasoline hanging around in that area for long.

I would not want to try and seal a gas tank with it, but an not adverse to at least trying it for a while on an intake manifold.

I do have a tube of gasoline resistant silicone that I bought to seal the fuel level sending unit on my T-181 which should work fine here, though for now I will stick with the ultra-copper just to see how it works.

FWIW, when my wife and I first got together, her ex borrowed my truck for the day. For reasons unknown he decided to rebuild the carb while he had it and used some form of RTV silicone on the gaskets. This of course didn't play well and the silicone clogged just about everything in the carb that could be clogged. I soaked the carb and blew it out numerous times and tiny bits of silicone would still show up. I am sure it was over 15 years after the "rebuild" that the last piece of silicone found its way into a jet. Yes it was swollen and soft but it hadn't dissolved and disappeared.

udidwht Wed Oct 01, 2014 9:10 pm

You don't want to use the metal gaskets with aftermarket intake manifolds...given you have IDF carbs. They'll leak like crap.

Use the thick fiber ones or the Bakelite ones that come with the VR gasket kit. Rub a little chap stick on both sides prior to install.

cl55953 Thu Oct 02, 2014 5:19 am

Update, well I used the metal gaskets with great success.

Put them on with new wavy washers – started up with no air leaks.

I sprayed some starting fluid around the intakes to help make sure.

I did also make some paper gaskets just in case.

I drove the bus 15/20 miles last night up and down hills, etc. got the motor good and hot. No missing or backfiring. It started back after letting sit about eight minutes by barley bumping the starter, no gas boiling.

I getting ready to take 120+ trip to Circle Your Wagons, I’ll let you know how it does.

SGKent Thu Oct 02, 2014 7:18 am

cl55953 wrote: Update, well I used the metal gaskets with great success.

Put them on with new wavy washers – started up with no air leaks.

I sprayed some starting fluid around the intakes to help make sure.

I did also make some paper gaskets just in case.

I drove the bus 15/20 miles last night up and down hills, etc. got the motor good and hot. No missing or backfiring. It started back after letting sit about eight minutes by barley bumping the starter, no gas boiling.

I getting ready to take 120+ trip to Circle Your Wagons, I’ll let you know how it does.

awesome!!! Enjoy your trip.

raygreenwood Thu Oct 02, 2014 8:06 am

SGKent wrote: so Ray - after that long dissertation explain why the RTV I used on the base of other carb gasket always got swollen and fell apart. What was that - gremlimimic RTV? BTW - I am still waiting for MY original good EGR diaphragm back. Did you send it to Hoody?

Read what Wildthings just posted. He has an operative grip on why RTVs....and not every RTV.....can work well around fuel.

Not all RTVs are even remotely the same. For instance...P-tex super blue, and most normal RTV will fail very quickly around fuels. Those that will work well actually have more silicone in them and are homogenized differently and are typically filled with other solid fillers that reduce porosity and form better linkage over time.

The operative factor is THIN application and proper surface prep. Both surfaces must be squeaky clean and must have a little bit of tooth.
The biggest problem with the use of high temp, oily location RTV in locations like the intake gasket is that most people make them too thick. The biggest wrong ever done by RTV makers....is calling these products "gasket makers". You cannot make a gasket with these materials. About the thinnest gasket you can buy...gasket paper wise.....is about 1/64th". Thats about .015" thick. Even at thicknesses of .010" in an intake situation....one of two things is going to happen.....causing it to fail:

1. If the surface of the manifold and head surfaces are both excellent.....because the face of the silicone between both surfaces is thick......the gasoline has a wide area to attack (that .010-.015" thick face open to air and fuel). It softens the RTV in that area....and because its well adhered and sealed to both surfaces because of good surface prep.....this fissure started by the fuel.....causes the thickness of the RTV to split up the middle leaving a layer attached to both the manifold and head.

In short....because of the lower durometer (hardness) of the RTV it has great adhesion and seal to the surfaces and poor cohesion to itself. The fissure or split starts because its to thick. Its not just the fuel causing the fissure at the edge...its, vibration and metal, expansion that pry the surfaces apart.

2. The other failure method from the RTV being applied to thick is from poor surface prep of one or both surfaces...but usually just one. The fuel again...attacks the face/edge where there is too much surface area. It migrates to the surface where either cleaning was poor (oily) or not enough tooth (too smooth).....and travels along that, surface due to vibration and metal expansion. You see this when you separate the manifold later and all of the RTV appears to have only stuck to one surface.

You need to use these products in these locations in very thin, cross sections. They are actually...adhesives primarily....and sealants secondarily. Use them with the same rules yiu use for adhesives. Thin is stronger because it does not allow the adhesive the, chance to shear into multiple layers.

Ray

Edit: in one way....gasket papers and RTV when used around fuel are similar.
Gasket paper is nothing special (materials wise). It is bleached vegetable fiber with a basic binder added to hold it together. Its porous. It absorbs fuel. Just soak a piece of it in a jar of fuel and watch what happens

The reason why it does not continue to keep absorbing fuel horizontally from the 1/64th inch open face of say a carb bowl gasket...is that once the fuel soaks into the first open pores of this narrow face...surface tension within the cells does not allow further penetration. Now....if the fuel were pressurized....the fuel will soak all the way through and weep out the edges of the gasket.
The same is similar with RTV. The fuel that soaks into the thin face cannot go very far. But...for instance if you try to use RTV in a pressurized fuel situation...like on an o-ring on the rail of a bayonet style injector or between the mating surfaces of a roller cell style fuel pump.....it will fail rapidly because thee pressurized fuel keeps pushing through the pores and dissolving RTV.

williamM Thu Oct 02, 2014 9:16 am

SO- not all sillycone is the same- :cry: :cry: with so much other quality gas / alcohol proof sealers round as explained by Ray/Kent/ everybody else- why not just use the bullet proof red spray- (one of my favorites) :?: :?:

I re-repaired a DIY guys twin carb volvo boat that he had used clear silicone on and when we took it apart- the shit had migrated up the fuel line to ahead of the screen. Needless to say it went everywhere. I blew little wiggly worms of the stuff from everywhere.

So thats all I know about that stuff and NEVER use it round fuel.

raygreenwood Thu Oct 02, 2014 9:30 am

williamM wrote: SO- not all sillycone is the same- :cry: :cry: with so much other quality gas / alcohol proof sealers round as explained by Ray/Kent/ everybody else- why not just use the bullet proof red spray- (one of my favorites) :?: :?:

I re-repaired a DIY guys twin carb volvo boat that he had used clear silicone on and when we took it apart- the shit had migrated up the fuel line to ahead of the screen. Needless to say it went everywhere. I blew little wiggly worms of the stuff from everywhere.

So thats all I know about that stuff and NEVER use it round fuel.

So....and I'm just asking....what would make someone think that a basic clear, tub and tile style, acetic acid cured RTV would work at all on not only a high temp situation...but a marine situation? See...thats part of my point. People think "silicone"...and go out and get a tube of whatever says its silicone RTV...like they are all the same except the color :roll:

Which "red spray" are you referring to. There are actually numerous. Some of them work very well and as you note .....are bulletproof. A little too bulletproof in many cases.

Most are adhesives actually that have some amount of silicone, urethane or polyester (im betting the one you are speaking of is a polyester if fuel wont touch it at all in any situation). The problem with polyester sealer/adhesives is that most will be awesome as far as solvent/fuel resistance....and water resistance....but...actually have very little resistance at all to a COMBINATION of heat and water.
And....since they are bulletproof to solvents...nothing short of aircraft stripper and abrasives will remove them.

I use bulletproof polyester adhesives in my industry all the time. Awesome! MEK, Xylene, acetone...gasoline....you name it...wont touch it. But they are easily removed with hot water with a little sodium bicarbonate added (baking soda). Ray

cl55953 Mon Oct 06, 2014 12:39 pm

Made the 120 + mile trip with no problems, run like a top

Metal gaskets sealed/worked great. Plan to leave them inplace untill the next time.

Thanks for the people that responded.



Powered by phpBB © 2001, 2005 phpBB Group