I have a very slight gas smell that seems to be coming from around the 2 cork gaskets on the top of the fuel tank. The 2 gaskets are made of cork. Should I put any gasket sealer on the new cork gaskets and if so what is recommended? I always think that cork gaskets should be assembled dry like wine bottle corks because they don’t leak!
Thanks
Andy
69 S2 FHC
Andy,
I think I used Hylomar, but the important thing there is to seal the threads on the screws. they (maybe only most of them) go through to the tank.
Jerry
Some times these leaks are the result of the plates being slightly warped fro POs tightening them too much, so that even fully tightened, the screws don’t bring the two plates together close enough. Use a hammer and dolly to get them straight. Also one of the plates (I forget whether it’s the pickup or the sensor) has screws in blind holes that bottom out if they are too long and again prevent the plates from making good contact. Another issue is the copper washers that seal the threads. Renew these every time. Replace them with stat-o-seals if the copper washers don’t work.
If you want to know for sure if those seals are leaking and causing your fuel smell, fill up the gas tank all the way. Those seals are below the fill line and they will clearly leak if there’s a problem.
I would recommend Hylomar A/F on these gasket seals.
I’m a test case on what not to do to end fuel odors. I can assure you all that you do NOT want to use Permatex Hylomar to seal the tank flange. After a fill up, I found my boot with about 2 inches of high test sloshing around the floor. Peeling paint and the obvious danger of turning the E into a Molotov cocktail. Hylomar doesn’t stand up to modern unleaded, gas turns it to a blue chalky substance. My new “goo of choice” is “Seal All” available at local parts stores. A fuel proof, pliable contact adhesive. I’m also using NAPA extra thick fuel proof gasket material on the tank flanges.
Andy - Fuel is so volatile, that any drip or seepage no matter how slight, will stink up the boot. There are a numerous places vapors can emanate from (no particular order): 1.The cork gaskets can permeate fuel odor over time. Gaskets can also be too thin to compensate for flange warp as was mentioned 2.The fuel sender can have wrong pitch or screws that are too long as they can bottom. A problem can occur if you change gasket material 3. Fuel sump gasket can be damaged and seep soaking 4. Fuel pump in the wing has two cork gaskets. I found one seeping. It wasn’t wet but I saw leak stains on the body. There are various MG forum posts that can help. I put hylomar on it so I’ll be back in there. 5. Any of the banjo fitting sealing washers.
Good luck with your project. /Dave
I’ve been chasing fuel leaks for the past several months. In the process, I changed the gaskets under both the fuel sending unit and the tank outlet plate. I used cork gaskets from the usual parts suppliers and assembled the units with Permatex “Permashield Fuel Resistant Gasket Sealer and Dressing.” The tube is orange and I believe I purchased it at O’Reilley Auto Parts. The sealer does not dry hard – it remains somewhat pliable. Follow the instructions on the tube and you shouldn’t have any problems.
Andy,
I had this problem on Is two S1 etypes. Here’s what I think the problem is:
If you remove the plates totally, and use a piece of wire to probe the tapped hole, you should find (unless it has been "modified’, a blind hole.)
If you measure the small screws length of thread, you will find it to be only slightly less than the tapped hole depth. It depends on the washers (shortening the thread engagement in the blind hole) in order to compress the gasket also.
Trying to understand the problem, I measured the thickness of the gaskets I received in my gasket kit, and those gaskets were so much thinner than the OEM gaskets that the screws bottomed out before the gasket compressed.The bottom of the tapped hole then breaks through by either (1.) tightening the screws after they are prematurely bottomed because of the thinner gaskets (2.) replacement of the screws without using the OEM washers, or (3) using newer longer hardware. I helped some along at first with a tap!
If you realize the holes are blind holes by design, and just tighten up the gaskets until they seem tight, the odds are that the gasket will leak because it is too thin. I bought some thicker gasket material and cut all new gaskets. I used Wellseal on one and nothing on the other and they did not leak.Finally! I probably broke through some of the blind holes before I realized they were supposed to be blind. It requires a thick gasket in order to compress it UNLESS you break through all the tapped holes so you can compress the gasket, and I don’t think thetas very good unless you dope everything up with gasket sealer.
Mike Moore 63 S1
Thanks guys for your wealth of information and help and as always presented in a very clear and concise manner. I also own 4 MGs and participate in an MG forum but the responses here are from owners who have been there and done that and know what they’re talking about. Thanks again.
Andy
1969 S2 FHC
Hi Andy, The only sealant that i know ( apart from epoxy ! ) that is significantly resistant to gasolene is “Seal All” . It smells like balsa cement, but sets to a slightly pliable solid.Made by Eclectic Products, Pineville LA. I was told about this by a marine engine mechanic, and seems to be the best I know!!
Permatex Aviation-Form-A-Gasket has always worked for me when all else fails:
Pretty much my go-to sealant when Hylomar isn’t enough.
But that said, some of the mechanical issues noted (bowed fitting, too thin gasket, too long screws, etc.) are worth exploring and possibly the more typical failures.
if the gaskets are thinner causing the screws to bottom out/punch through, would it help to double up on the washers((ie place two washers per screw)?
Yes, I did this on my first car, and it did work-I think it was the second car I used the thicker gasket material because the I thought the extra washers were a bodge.
Mike Moore
I just looked up a picture of this and believe it or not, I used this product to seal a pinhole in the gas tank of my 1964 Comet, my first car. It lasted until I got rid of the car. I don’t remember it being flexible though. Seamed a lot like plastic model airplane glue. ha.
Is gasoline supposed to be able to get into
the “inside” of the fuel tank sending unit?
Seems strange
Yes. There is no gasket sealing the inside of the sending unit.
The float is sealed but I think the rest of the works are exposed - indeed the whole thing will be submerged when the tank is full (hence the importance of getting an excellent seal between the plate and the tank).