Oil pressure sender

[Bart Reid]

I bought a new gauge cluster from LMC truck for my 90 K5. Very happy with the looks and installation was tough but not too bad. Wouldn't recommend for anyone without some fab and wiring skills. Only issue is the oil sender they supplied. It is 1 wire and the stock one is 3 wire. Called tech support and they don't have a 3 wire. They say any sender set up with 240-33 output will work. Anyone know of a 3 wire sender with this output range?

 

[dyeager535]

I bought a new gauge cluster from LMC truck for my 90 K5. Very happy with the looks and installation was tough but not too bad. Wouldn't recommend for anyone without some fab and wiring skills. Only issue is the oil sender they supplied. It is 1 wire and the stock one is 3 wire. Called tech support and they don't have a 3 wire. They say any sender set up with 240-33 output will work. Anyone know of a 3 wire sender with this output range?

It's going backwards IMO (more complex wiring and plumbing), but for the oil pressure switch side, you can run an earlier two wire switch. I believe those were ~'87-89. I don't know how the earlier electric choke switches worked, they could theoretically be the same part, but I'd stick with TBI applications in my search, just to be safe.

 

[Bart Reid]

It's going backwards IMO (more complex wiring and plumbing), but for the oil pressure switch side, you can run an earlier two wire switch. I believe those were ~'87-89. I don't know how the earlier electric choke switches worked, they could theoretically be the same part, but I'd stick with TBI applications in my search, just to be safe.

Only problem I see is putting in a T and running a 2 wire switch and a 1 wire sender may not fit? Pretty tight under the distributor. I am going to replace the distributor this week so that would be a good time. Thanks for the reply

 

[dyeager535]

Only problem I see is putting in a T and running a 2 wire switch and a 1 wire sender may not fit? Pretty tight under the distributor. I am going to replace the distributor this week so that would be a good time. Thanks for the reply

You can run one of those two above the oil filter. However, be aware that it's a tight squeeze, will probably need a nipple to get it out far enough to thread a sender or switch in that position, and verify there is enough clearance to not burn it on the exhaust.

There is also a port on many engines that is plugged behind the water pump about 11 o'clock when facing the front of the truck. Often that one has a lot of stuff in the way though.

IIRC the carbed and earlier TBI setups that ran the large cap HEI were able to cram the separate switch and sender off that back port next to the distributor. FWIW I can't use that port with my TPI, and use the one above the oil filter for a three wire switch/sender combo.

 

[frankin5]

90 is a three wire as it part of the fuel pump turned on over 4 PSI. Tan wire off the three wire is oil sender wire to cluster. i would find it at the cluster plug and go to new gauge The grey and orange wires go to the fuel pump relay.

 

[dyeager535]

What I understand as his issue is that he went with aftermarket gauges, and they don't use the stock GM 0-90 Ohm sender(s). So he has to go from the three wire switch/sender combo, using the provided aftermarket sender, but keeping the oil pressure switch portion as GM had it.

For our vintage (at a minimum) there is no alternative to the 0-90 Ohm senders, it was GM standard for the gauges (oil, fuel, and temp). When I was thinking of going with a temp gauge for other components, I wanted to be able to use the commonly available GM senders, but it's not possible, as no aftermarket gauges work with the same resistance as OEM.

 

[frankin5]

That sender is on a 3" 1/8' pipe riser ,with a flat type elbow that the unit attaches to. There is a possibility to
put a tee instead of the elbow.

 

[Bart Reid]

You can run one of those two above the oil filter. However, be aware that it's a tight squeeze, will probably need a nipple to get it out far enough to thread a sender or switch in that position, and verify there is enough clearance to not burn it on the exhaust.

There is also a port on many engines that is plugged behind the water pump about 11 o'clock when facing the front of the truck. Often that one has a lot of stuff in the way though.

IIRC the carbed and earlier TBI setups that ran the large cap HEI were able to cram the separate switch and sender off that back port next to the distributor. FWIW I can't use that port with my TPI, and use the one above the oil filter for a three wire switch/sender combo.

I appreciate the help. Used the port above the oil filter and the new sender fit, was tight though. Just left the three wire stock switch/sender and abandoned the sender wire. Works great now. Thanks again!