How to improve seal of crappy paper gaskets?

[B.C.]

So, I think I hate paper gaskets. Sometimes they just seem impossible to seal.

Workin on an old Homelite XL-901. Walbro SDC carburetor. Put a new kit in the carb, tightened the crap out of the bottom plate, still leaked air. Slow, but it leaked. Used come of the permatex copper spray slowed it down, still just a little leak...

Carburetor gasket. Leaked after replacing crank seals. So bad I couldn't even build any pressure. Took it out of the equation, made a quick cork one to go between the carb & intake plastic thing. Leaks BEHIND the plastic adapter that goes between the carb & reed valve assembly thing. Paper gasket again. I don't have new ones laying around. I don't like to use the permatex on the carburetor ones because if I need to ever take them off, its a horrible experience and you tear the crap out of them and have a fun clean up job.

I have tried taking paper gaskets and coating them thinly in motoseal or 1184, it's always difficult because of two things, one the impulse holes are small and two after about 20/30 seconds it starts to tack and if you don't have it perfect already it wants to goo up too much and shift around, de-laminate and other fun stuff.

Is there a good spray that would work that isn't permanently sticky like the permatex copper is, something more like motoseal, 1184 or dirko in can one could apply a thin coat of to both sides and let dry for a better seal? (But still be able to disassemble without a big headache and ruining a gasket every time.) Looking for ideas, I'm so sick of chasing air leaks on saws and finding a paper gasket to be the culprit, but you can tighten till you break something and they still won't seal...

 

[AUSSIE1]

Dont do things up so tight. This could be your problem.

 

[Bobby Kirbos]

Have you tried Hi Tack?
https://www.autozone.com/sealants-g...MIsojP7eWN6gIV1MDICh0l9wMoEAQYASABEgKIiPD_BwE

 

[Okie]

Thing I've noticed about leaking seeping gaskets especially where gas is involved.
Lots of the gasket sealers are not rated for long term sealing against gasoline, especially the silicone types.

Most generally when a paper gasket will not seal, something is warped and/or the surfaces need to be lapped.

I also have paper gasket material that are different thickness, but using a thicker gasket will result in warping surfaces if too much torque is applied when using a thick gasket.

 

[trains]

permatex no3

Thank me later.

 

[OM617YOTA]

Sometimes a thin coat of grease on both sides of the gasket helps.

 

[lone wolf]

Sometimes a thin coat of grease on both sides of the gasket helps.

Thats what I use or oil and it certainly helps.

 

[B.C.]

Thanks guys. I'm going to try the thin coat of grease for one.

I don't tighten things a ton unless they are already leaking. Sometimes tightening more works, sometimes it doesn't. Sometimes I think the gaskets are just too old and stiff, or they just plain suck I don't know, age isn't always a factor. Sometimes new ones stink too. Take the SDC carburetor for example. It's got 4 screws on the corners, I put a brand new kit & gasket in, everything clean, started out just snug, not too tight. Leaked like crazy. Tighten all screws equally a little more. Leaks less but still leaks. Rinse & repeat, got it down to just a little but still leaks. I've watched Leon on his youtube channel fight with old carburetors a lot to get them to seal as well. And that's one thing, the carburetor gasket to intake are another, can't just super tighten those.

I bought a can of that permatex no3 as well. I like that it says slow work time, that's one of the things that kinda pisses me off about the motoseal and 1184. One, they are like the hottest of mozzarela and stringy, and two, the short work time such that you haven't even gotten the part fully coated and it's so tacky already you are messing it up before you get it perfect.

 

[Huskybill]

My 396/400 hp drag race engine was blowing head gaskets, I installed a 4 row 409 rad and cut the heads .010” to clean, sprayed the head gaskets with permatex hi tac and never had that problem again.

My point is make sure your gasket area is flat with a straight edge, either file or sand the area flat, don’t over tighten. Put sealer on both sides evenly. If the problem persists try two gaskets.

 

[pioneerguy600]

Bill got it, clean flat surfaces will seal.

 

[OM617YOTA]

Try a sharpening stone for evening up and cleaning surfaces before assembly.

 

[Okie]

Take the SDC carburetor for example. It's got 4 screws on the corners, I put a brand new kit & gasket in, everything clean, started out just snug, not too tight. Leaked like crazy. Tighten all screws equally a little more. Leaks less but still leaks.

I've seen the SDC's type carb do just that. The little 4 screw plate is usually warped.
I've also seen the opposite side that has the single slot screwdriver type screw. Replace the screw with a 5/16 head screw that a socket will fit and get just little more torque and it will usually seal. Easiest is to remove the cover from a old carb and it will usually be ok at proper torque if it's not warped also. Over tightening stuff is usually what starts the warping leaks.

I also sometimes apply grease to a gasket instead of a silcon or gasket sealer so as to soften it it I think maybe I might need go back and need to re-use that same gasket later, especially carb base gaskets. (Usually prevents the gasket from sticking and ripping when carb is being removed)

 

[sean donato]

Loctite 515, would be an ideal sealant for this application. Its relatively thin and anaerobic, so you dont have to worry about it setting up before you can get thing together. This is one of the glues I have in my arsenal and use quite frequently, specifically for coating paper gaskets, and rubber to alloy/steel connections. It's also rated for direct flange seal as well. It comes apart relitivly easy, but will require a new gasket.

 

[B.C.]

Loctite 515, would be an ideal sealant for this application. Its relatively thin and anaerobic, so you dont have to worry about it setting up before you can get thing together. This is one of the glues I have in my arsenal and use quite frequently, specifically for coating paper gaskets, and rubber to alloy/steel connections. It's also rated for direct flange seal as well. It comes apart relitivly easy, but will require a new gasket.

That's kind of ideally what I wanted to avoid. I like to be able to take them apart without ruining the gasket.

I've seen the SDC's type carb do just that. The little 4 screw plate is usually warped.
I've also seen the opposite side that has the single slot screwdriver type screw. Replace the screw with a 5/16 head screw that a socket will fit and get just little more torque and it will usually seal. Easiest is to remove the cover from a old carb and it will usually be ok at proper torque if it's not warped also. Over tightening stuff is usually what starts the warping leaks.

I also sometimes apply grease to a gasket instead of a silcon or gasket sealer so as to soften it it I think maybe I might need go back and need to re-use that same gasket later, especially carb base gaskets. (Usually prevents the gasket from sticking and ripping when carb is being removed)

I didn't really think of using grease on the carburetor one too but that's a good idea I might have to try next time.

 

[sean donato]

Ok so take this coming from a life long diesel mechanic. Paper gaskets were designed as a one time use. I know you may be able to get away with a reuse or two. But if you want it sealed and want to coat it you've breached the realm of being able to reuse it. (Not trying to be a jerk, just dont want your leaks to continue to save a few $ in gaskets)
Another thought, have you thought about making your own gasket out of a better material? Paper styles are sometimes used because of cost savings as opposed to a butyl. Just a thought.

 

[Huskybill]

If you use sealant on one side the gasket stays on one half and is reusable.
I do that with valve cover gaskets.

 

[Okie]

Ok so take this coming from a life long diesel mechanic. Paper gaskets were designed as a one time use. I know you may be able to get away with a reuse or two. But if you want it sealed and want to coat it you've breached the realm of being able to reuse it. (Not trying to be a jerk, just dont want your leaks to continue to save a few $ in gaskets)
Another thought, have you thought about making your own gasket out of a better material? Paper styles are sometimes used because of cost savings as opposed to a butyl. Just a thought.

Right: I have a big box of gasket making materials, all kinds.
One of my favorites for paper gaskets when I want a thicker gasket than standard thing paper is a large sheet of gasket material I got from Napa back when you could buy large sheets at a reasonable price and its about 1/16 of an inch thick, easy to cut or stamp and is gray colored, looks like asbestos but it's not and appears to be oil impregnated and can usually be re-used. I sometimes just coat one side of a paper gasket with vaseline so as it can be removed, but don't use a grease on paper when doing aluminum case halves, such as the sumps on briggs engines, chainsaw or 2 cycle case halves, etc. Doing so can result in a thin paper gasket eventually slipping or not sealing especially the type paper gasket that is only .008 thick that thickness of the paper gaskets is selected to get the crank end play within specs. Quite common for Briggs engines to have case halves oil seeping leaks due to paper gaskets not sealing after the engine has aged.

 

[Cantdog]

When trying to use old thin (0.007/8”) paper gaskets that have dried out and distorted so they don’t even fit where they are supposed to, no amount of sealer will do the trick because the shape has been altered. What you need to do is take some flat paper towels and lay a couple out on top of one another, place the gasket/gaskets as flat as they will lay on these. Take two more towels and place over the top and saturate the towels with water and let sit for a while. The gaskets will return to their original shape and fit fine without gobs of sealer. Have had to do this time and again with old Harley paper oil pump gaskets as the thickness set up the end play of the pump gears so the gaskets had to be exact thickness and this always took care of the problem without sealer or leaks

 

[rupedoggy]

So the OP wants a paper gasket that will seal, can be used many times and not have to check for warpage. I don't think so mister!

 

[rupedoggy]

I have put some thought into this and have asked myself a question. Why does this man have problems with a leaking carburetor gasket and I have assembled hundreds and never had one leak?
I do something that has become so automatic that I don't even have to think about it. When I tighten down a cover I always do it evenly. Make sure the screws are all started down a little at a time and never stress one side or corner. It is a little like putting on a head gasket and tightening in a sequence and series of small increments.
If you think this does not matter try a small experiment. Install the cover with only one corner screw and tighten it down. Now look at the opposite corner. It will be up slightly and, if you put in the other screws, it may WARP the cover.
Just an idea, but if you get into this habit, it will serve you for a lifetime. If this does not apply to you then ignore it.