I have been having a hard time finding a thread sealer to use on the NPT fittings on the fuel tank that will withstand ethanol in gasoline. I have investigated a number of products advertised as being gasoline resistant, but none of them claimed to be ethanol resistant and based on postings on other forums, this is a key requirement to withstand blended gasolines.
I came across a product called Gasoila ("Gasoila Soft Set Thread Sealant with PTFE"). According to their website here: Gasoila® Soft-Set Thread Sealant with PTFE - Pipe Thread Sealants - Products
it is supposed to have "excellent resistance to gasoline (up to 20% alcohol).
Redoing all the fuel connections after the car is built will be awkward, so to be cautious, a test was in order. I coated one with Gasoila and set it on the bench. A second bolt was coated and placed into a jar of premium automotive gasoline, as sold at a local station here in Texas (advertised to contain up to 10% ethanol). After about 15 hours, the bolt was removed from the gasoline and set beside the one on the bench. You can see the result in the attached picture; nearly all of the thread sealer on the bolt submerged in gasoline melted off. The bolt which had been curing on the bench was then placed into the gasoline. It immediately started to "snow", looking like a little Christmas ornament. Within a matter of a few minutes there was almost no sealant left on the threads. The bolt was then removed and the attached picture was taken of the bottom of the jar, where the sealant fell off around the bolt.
I then tried a product called Hylomar Universal Blue non-hardening Gasket Sealer Hylomar – Non-Setting Compounds. I had good experience with the Universal Blue Racing Formula, which used to be advertised as ethanol resistant, but the Racing Formula doesn't seem to be available anymore, so I thought I should test the "regular" stuff to see how it compares.
Attached is a picture of the Hylomar two-bolt test. After immersion for 48 hours, the bolt in gasoline looks the same as the bolt on the bench; the sealant remains stuck to the threads and does not show any sign of dripping, melting or flaking off.
The can of Gasoila has gone into the garbage bin and the NPT parts of the fuel system have now been final assembled with Hylomar Universal Blue.
I came across a product called Gasoila ("Gasoila Soft Set Thread Sealant with PTFE"). According to their website here: Gasoila® Soft-Set Thread Sealant with PTFE - Pipe Thread Sealants - Products
it is supposed to have "excellent resistance to gasoline (up to 20% alcohol).
Redoing all the fuel connections after the car is built will be awkward, so to be cautious, a test was in order. I coated one with Gasoila and set it on the bench. A second bolt was coated and placed into a jar of premium automotive gasoline, as sold at a local station here in Texas (advertised to contain up to 10% ethanol). After about 15 hours, the bolt was removed from the gasoline and set beside the one on the bench. You can see the result in the attached picture; nearly all of the thread sealer on the bolt submerged in gasoline melted off. The bolt which had been curing on the bench was then placed into the gasoline. It immediately started to "snow", looking like a little Christmas ornament. Within a matter of a few minutes there was almost no sealant left on the threads. The bolt was then removed and the attached picture was taken of the bottom of the jar, where the sealant fell off around the bolt.
I then tried a product called Hylomar Universal Blue non-hardening Gasket Sealer Hylomar – Non-Setting Compounds. I had good experience with the Universal Blue Racing Formula, which used to be advertised as ethanol resistant, but the Racing Formula doesn't seem to be available anymore, so I thought I should test the "regular" stuff to see how it compares.
Attached is a picture of the Hylomar two-bolt test. After immersion for 48 hours, the bolt in gasoline looks the same as the bolt on the bench; the sealant remains stuck to the threads and does not show any sign of dripping, melting or flaking off.
The can of Gasoila has gone into the garbage bin and the NPT parts of the fuel system have now been final assembled with Hylomar Universal Blue.
