oil pressure switch observations

[Rick in PA]

I got an after market oil pressure switch for my car as the original one was going bad. It's the type with a pipe thread connection into the block. The replacement came with white sealant (Teflon?) applied to the threads.

It went in OK but as I tightened it I did noticed something. The tightening torque just kind of got firmer and firmer, there was no sharp rise in the torque you usually get when the threads go metal-to-metal.

I went to install the electrical connector but had problems, so I had to remove the oil pressure switch. It came out way too easy. I know I tightened it reasonably, but the torque to remove it was like nothing. I noticed the thread sealant was gone from the threads.

I sorted out the electrical connector problem. There was an insert in the connector that didn't belong (remember this was an after market part). I removed the insert and the connector worked fine.

I put two wraps of Teflon tape on the threads, one thread back from the nose of the sensor. When I reinstalled the switch it tightened up just right, firm resistance at first with a sharp torque rise as the pipe threads went metal-to-metal.

I ran the engine a bit and re-checked the tightness of the switch, it was fine.

I think they put too much thread sealant on those parts, something to look out for.

 

[Lapham3]

Not sure I'm following exactly, but you want enough tape to seal, but not so much to prevent the switch finding a ground. I miss the first couple threads with the tape and with a couple wraps usually get a good seal without needing to go real tight.

 

[Lapham3]

Disregard previous

 

[Rick in PA]

"One thread back from the nose" is mainly to prevent getting a sliver of Teflon tape in the flow passage. It's standard "good practice" for applying sealing tape to threaded pipe fittings.

 

[Trav]

It sounds like this sending unit uses a tapered pipe thread, that would explain it being so easy to remove even though you tightened it well.
They didn't use too much thread sealant.

http://www.wellsve.com/showall_ds_oil.php

 

[tgrudzin]

Slightly off topic, but had a Dodge Neon. Maybe 3rd owner with 135K when I got it. Oil pressure switch leaked. Purchased after market, then another. Finally ended up with a Mopar.
I'd say that 40+ years ago, after market were as good as OEM. I don't believe that anymore. Not where it says 'made in China'.

 

[Rick in PA]

Originally Posted By: Trav
It sounds like this sending unit uses a tapered pipe thread, that would explain it being so easy to remove even though you tightened it well.
They didn't use too much thread sealant.
http://www.wellsve.com/showall_ds_oil.php


Nope, 50 years of experience with threaded fasteners & fittings here.
There was too much sealant.

Originally Posted By: tgrudzin
Slightly off topic, but had a Dodge Neon. Maybe 3rd owner with 135K when I got it. Oil pressure switch leaked. Purchased after market, then another. Finally ended up with a Mopar.
I'd say that 40+ years ago, after market were as good as OEM. I don't believe that anymore. Not where it says 'made in China'.


Yeah, I should have gone to the dealer and gotten an OEM switch, but I was in a hurry, it was convenient, yada, yada. At least the replacement was stamped "Made in Mexico" so there's a fair chance it came from the OEM vendor.

 

[Trav]

Originally Posted By: Rick in PA
Originally Posted By: Trav
It sounds like this sending unit uses a tapered pipe thread, that would explain it being so easy to remove even though you tightened it well.
They didn't use too much thread sealant.
http://www.wellsve.com/showall_ds_oil.php


Nope, 50 years of experience with threaded fasteners & fittings here.
There was too much sealant.


Originally Posted By: Rick in PA
I think they put too much thread sealant on those parts

Stuff like this are usually machine applied, i doubt that they are wasting product (money) unless the machine was way out of adjustment but i guess its possible.
Not being a ball buster or anything just saying.