Topic: Can’t get oil temp sensor into block
in Forum: C3 Engines
Thanks guys!
Good Luck and keep us posted.
Scott
Lifetime MemberModerator
The hole is indeed a 1/4" thread, but it is a PIPE thread, different from a normal SAE type thread.
If your car is equiped with an oil temp gauge, then you should have an adaptor to install the sensor into. It would be a "T" type fitting, where the pressure sender unit would go into one side, and the temp sensor in the other.
Joel Adams
C3VR Lifetime Member #56 
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Joel, you're confirming my belief that it is the 1/4" NPT (pipe) threads, which is good. That is also the threads on the sensor. A'm also pretty sure it's the right sensor. I do have an oil temp guage. However, on the '81, the pressure sensor screws into the top of the block, just behind the back lip of the intake manifold. The Oil temp sensor supposedly goes in this location just above the oil filter.
Lifetime MemberModerator
Then you may very well have some screwed up(no pun intended) threads in the block. Get a tap & carefully screw it into the hole. it should go with a little resistance, but not a lot. Pipe threads are tapered, and the threads on the sensor are a little larger diameter at the rear than the front, which gives a good, snug seal. Try a tap first, but make sure your sensor threads are correct, too.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
[QUOTE=chesh]
Joel, you're confirming my belief that it is the 1/4" NPT (pipe) threads, which is good. That is also the threads on the sensor. A'm also pretty sure it's the right sensor. I do have an oil temp guage. However, on the '81, the pressure sensor screws into the top of the block, just behind the back lip of the intake manifold. The Oil temp sensor supposedly goes in this location just above the oil filter.
[/QUOTE] Just what I was thinking from my 84 engine, pressure sender (bell shaped )to the driver side of distributor Well, I was scared to death to try it, but I was running out of options, so I used a tap to clean-up the threads. I was very relived to discover that worked like a charm and the sensor is now installed nice an snug.
By the way, I went to a strictly "Tool Store" to get the tap. I asked him if he had both thread chasers and taps. He said he'd never heard of a thread chaser and they didn't have them. Can someone tell me the difference?
A tap is for cutting new threads in a hole you have drilled. Most taps will tell you by way of engraving on them, what size drill bit to use for the hole. Taps are designed to cut threads in a blank hole and are very aggressive in doing it. A thread chaser on the other hand, is for a previously tapped hole that has some deformed thread, and are not so aggressive, and don't enlarge the existing hole. 
Dave