thermobob temp port leaking

Thread sealant will be your best bet. Its 1/8 BSPP thread which is straight unlike 1/8 NPT. Its kind of a stupid design, I'm not sure how its supposed to seal with no crush washer or o-ring.

coryf89 said:

Hey guys, I have a thermobob and a TrailTech inline temp sensor. the port in the thermobob where the temp sensor threads into leaks when the bikes running. whats the cause and fix for this? did I damage the threads in the thermobob somehow? can an o ring or teflon tape be applied to the threads of the TT temp sensor?

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BSPP threads (British Standard Parallel Pipe) are meant to seal with an o-ring. When you pulled out the plug from the thermo-bob it should have had an o-ring on there. Swap that o-ring over to the trailtech sensor and tighten it snug, then 1/8-1/4 turn more; don't kill it.


If you can't find the o-ring that came with the thermobob plug you can find something that would work at the hardware store.


Check out some details on BSPP threads here and here.