I've ordered an HD oil-temp gauge to replace the worthless air-temp gauge in the fairing of my '07 FLHX. Rather than spend an extra $50 for the adapter required for the 96-in. engine, I plan on installing the sender in the second drain hole in the oil pan. Does anyone know the thread size and pitch of this plug? Knowing this will prevent me from draining my newly changed oil to take the plug to Auto Zone (or wherever) to find an adapter.

Has anyone done this and have any suggestions or caveats?

 

The temp sensor is 1/8” and the hole in the sump is 3/8”. I got the brass adaptor at Home Depot. I also did not sun the wires all the way back to the fuse box and battery area. I was much easier to install spade terminals on the power, ground wires, and just connect them to the original gauge plug-in.

 

Exactly what Red said including not running the power/ground wires to the battery. Just splice into the air temp gauge hot/ground wire and run the signal wire down the rh frame rail to the sender in the pan.

 

Ditto, use the electrical plug from the oil air temp guage to power the oil temp guage. The sending unit wire is the only one that needs to run all the way back to the sending unit.

 

Great info. Thanks to all. When you mention running the sender wire up the "RH frame rail," I assume you mean the front frame down tube where the engine guard is attached, right?

A few more questions:

First, did any of you have any trouble removing the oil pan plug the first time? I heard it was installed with red Loctite and that heat was required to remove it.

Second, did you first install the sender into the adapter as tight as possible by hand, then insert it into the oil pan and tighten it further? It seems that if the sender is removed the adapter will be impossible to get out, not that I would ever need to. If I install the gauge on another bike I could install a 1/8" plug.

Last, did you us Teflon tape and/or anti-sieze compound? I would think Teflon tape would be enough, but someone on another thread reported that he used both.

 

Yes, run the signal wire down the RH frame down tube and hide behind/with clutch cable.

My oil pan plug came out with a allen socket on a 3/8" drive ratchet with no problem.

I installed the reducer in the pan and then the sender in the reducer. I used just a little liquid teflon tape.
I did not use antiseize.

 

There should only be thread sealer on the plug from the factory.

Liquid thread sealer is a better option than tape.Do not use antiseize.

 

Picked up my adapter today from Napa after a try at Home Depot and Auto Zone, neither of which had it. I find that Napa has the really obscure stuff, so maybe I should've tried them first. My gauge should be in tomorrow or Friday and will report back the results. Thanks to all for the help.

 

I don't like that idea of a nipple spacer, let alone one of brass. I bought the gauges from Livorsi Marine, Inc. they have the exact same size sender for the hole in the pan. I sealed with pipe dope, its sets hard and does away with any leaks or the need for tefflon tape. Still conducts fine.

On my psi sender I used 0-3000 psi hydralic fitting out of cad plated steel. Won't wiggle with engine vibrations and crack like brass.



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I'd be leary of anything on the threads. That is your ground in the circuit. Thread in the sending unit, and it will not leak at all. Do not over tighten the brass fitting. Just snug it up and you'll be fine.