Oil pressure switch

[S30Jay]

I installed a new oil pressure switch on my l26 last week. Engine is still on the stand, it occurred to me I may have been better off using Teflon tape on the threads?

 

Thoughts or experience with this? What do you guys/gals do with them?

[thisismatt]

On newer motors (KA, VQ) nissan says to use liquid gasket (RTV).  I would say a high temp thread sealant would be good, which you should be able to get at a local auto parts store, eg: http://www.permatex.com/products-2/product-categories/thread-compounds/thread-sealants/permatex-high-temperature-thread-sealant-detail

[datzenmike]

Agree with Matt. I don't think tape will fit or work. The oil sender is not known for leaking (at the threads at least) but this sure won't hurt anything. The threads are 1/8 BSPT. British Standard Pipe Taper and not metric or NPT National Pipe Taper. These pipe threads are tapered along the length at 1 to 16 ratio so the sender gets tighter as you turn it in. This is what seals it as opposed to a nut and bolt that just keeps turning. The threads are rounded instead of a V shape too.

[flyerdan]

Another thing, since the sender completes the ground circuit, teflon tape may act as an insulator which would render it inoperable.

[S30Jay]

Ah, thanks for the replies everyone. Didn't even consider the grounding issue.

 

Also didn't realize that it's tapered. So in theory then the threads should seal. I may just leave it alone in that case and see if it does leak. I can add liquid sealant if needed later.

 

Good information everyone!

[thisismatt]

It may seal well enough for oil without sealant. I don't know about BSPT, but NPT doesn't necessarily make a perfect seal without tape or sealant

[datsunaholic]

Teflon tape isn't meant to be a sealant- the threads cut it up instantly.  The purpose is to make it easier to tighten further by reducing friction, which makes a tighter seal.

 

But you also don't want to use it on anything that flows petroleum- like gasoline or oil, because it breaks down in that.  For water, its fine. 

 

You shouldn't need thread sealant (Nissan didn't use any originally) but if you feel you need it there is liquid thread sealants made for use in oil systems.

[Stoffregen Motorsports]

There is a different sealer for every purpose, just about, but I have had the best luck with what is known as "2 stroke case sealer". The brand I use, Threebond, is found on many new cars today and they offer different sealers for different applications.

 

For thread sealing, I like to use the Threebond 1211. You can buy it online or at motorcycle shops.

 

As a testament to the durability of 1211, while running a Datsun L series on the engine dyno, we noticed that there mere no bolts holding the intake manifold on, only 1211. We had been doing some work on the engine and someone forgot to put the bolts back in. The engine ran through dyno pulls with no bolts holding the manifold on.

 

If you want cheap, regular old plumbers "pipe dope" can be used on tapered threads. It works fine too.