Gas Leak - The Culprit

[scannon]

I've been getting some gas fumes from the rear of the Caterham for awhile now but could not find the source. When I put in the new differential support struts a few weeks ago I checked the screws holding the fuel level sensor and all were just a little loose. No more than one turn snugged them all up. I also tightened the three hoses connected to the fuel filler.

 

Seemed all was well until I filled the tank yesterday. When I got home not only were the fumes much worse I found gas dripping off the bottom of the tank and the frame tube in front of it. I wiped up the gas and put a pan under it but when I checked later the drip pan and floor were dry and the fumes gone from the shop (the swamp cooler was running).

 

Today I pulled up the carpet and honeycomb floor of the boot and had a look at the tank. As the pictures show, the rubber fuel sensor gasket is toast. I called Jon at Caterham USA and he said the only way he can get the gasket is with a new fuel sensor. He said to make another one out of rubber sheet. He said to use rubber rather than some synthetic material.

 

Is there a better material to make the gasket from? The original rubber gasket lasted 5 years. Is there another source that might have a gasket in stock this side of the big pond?

[coffee break]

McMaster-Carr is a good industrial supplier. Look them up online and look for "raw materials" You should be able to find a thickness that works in a 12 in x 12 in sheet. They also have descriprions of the material applications. "Resists petroleum" or similar descriptions of gasoline should work.

[bsimon]

Cut a paper type gasket, 1/32". Coat both sides and the screw threads with Hylomar and stick it back together. The threads will weep if they are not coated. Don't use RTV as it will perish in fuel.

 

FWIU...the gasket is a standard pattern that is used in the Mini (real Mini, not BMW) and a number of other British cars. The bolt circle is 2-3/8". You might be able to score a pre-cut one at O'Reillys.

[scannon]

Cut a paper type gasket, 1/32". Coat both sides and the screw threads with Hylomar and stick it back together. The threads will weep if they are not coated. Don't use RTV as it will perish in fuel.

 

FWIU...the gasket is a standard pattern that is used in the Mini (real Mini, not BMW) and a number of other British cars. The bolt circle is 2-3/8". You might be able to score a pre-cut one at O'Reillys.

 

Bob,

 

Thanks for the info, I'll try O'Reillys and the import parts place in Boulder and if none is available I will go with the paper version. I assume you are talking about standard paper gasket stock?

[slomove]

I used a sheet of thin rubberized cork gasket (cut to size) that I found at the auto store and installed with non-hardening fuel-safe gasket maker for good measure (forgot the brand, but also from the auto store). That held up for a few years now.

Edited July 24, 2012 by slomove

[bsimon]

A paper gasket will work if the mounting surface is still flat. A rubberized cork gasket may work better if the surface is warped a bit. The warping comes from over-tightening the screws.

[blubarisax]

I had the same issue and ordered two from Caterham UK. I have since switched to a fuel cell and have no use for the extra gasket I ordered. Send me a PM with your address and I will toss it in the mail to you.

 

Karl

[bball7754]

"....Caterham USA and he said the only way he can get the gasket is with a new fuel sensor...."

 

"I had the same issue and ordered two from Caterham UK."

 

http://www.caterhamparts.co.uk/product.php?id_product=96

 

I find myself often going directly to Caterham UK for parts these days, because of the above.

 

Steve

[pi7ot]

I'd go to the local tyre outfitter. They have inner tubes. You can then make as many as you'd wish.

 

m

[scannon]

I got an email from Jon this AM. He was able to order just the gasket and already had a FedEx shipment coming so the new gasket is already on its way and will be here tomorrow or Thursday.

[Taber10]

Skip,

 

I don't know much about working on Caterhams, but I am qualified to offer this input:

 

Your stock gasket may have been (probably was!) a synthetic "plastic" material, and a rubber fuel safe gasket material will be better. Recommend you cut/punch the bolt holes to just match the size of the bolts/screws. I used either .380 or 9mm empty cases....

There is a sealant "Marine 5200" that works great also.

 

Just my input!

 

Taber