Chevy Cummins Oil Pressure Issue

[jsavage977]

I have a 96 Cummins 12 valve 215 p7100 6bt sourced from a dodge 2500. Swapping into a 1988 gmc v3500. Im rounding up all the small things now but I cant seem to get my oil pressure gauge to work. I'm using a new chevy OP6640SB oil pressure sender in the stock cummins location where I took out the dodge two wire oil pressure sender. If you need pics you can check out my build thread.
http://www.rme4x4.com/showthread.php...-warrior/page2

The problem is that the oil pressure gauge is always buried at 3 o'clock weather the key is on or off, the engine is running or not. Always at 3:00. I tried to test the gauge itself by pulling off the wire that goes to the sender and grounding it. This puts the needle dead on at 0psi with the key on. I am baffled about why this is not working. I also have a extra gauge I tried but it does the exact same thing. Exactly 3:00.
Is it possible for a brand new oil pressure sender to be 100% broken?
Any help on this is very very much appreciated!!!!

[v30crewcab]

either a bad sender, or you have the wrong one. you did get the one for a gauge and not a light correct?

[jsavage977]

Thanks for the reply.
I'm pretty sure it is the right one, unless the desk jockey at napa had the wrong Idea of a 1/8" one wire gm oil pressure sender haha.
Here are pics, one of the box the new sender came in, and one of the new sender next to the old dodge one.





Do you know if there are any cosmetic differences between the two senders?

[v30crewcab]

the one on the right looks like the one I am running on my cummins. maybe you just got a bad one. the one for a light is alot smaller than that.

[jsavage977]

Ok, I think I will go swap it out for a new one. Thanks for your help v30crewcab!

[mrolds88]

Didn't use any thread tape, did you?

[jsavage977]

nope, no thread tape

[86c20]

always use some sort of tape or dope.
when you got the sender you did tell the kid for a 8? chevy right? thats all i know of doing for the cummins swap. use chevy senders and you are good.

[jsavage977]

Yes It should be for a 454 chevy, I guess. And I was thinking that the tape would be bad since it would insulate from the sender getting ground. Im pretty sure the sender needs to be grounded? If not that could be my problem I guess.

[v30crewcab]

yes It needs to be grounded thru the threads. if I use anything, its grey peratex, but I tighten it real good so it squeezes it out enough to ground. tape will cause problems.

[jsavage977]

yea thats what I thought, I will trade it for a new one later this week and Ill let you all know whats turns up.

[esbstuff]

I would be 99% sure the sender is bad or boxed wrong. I have a 94 Chevy with a 97 12v and used a GM sending unit in OE Cummins location with no problems.

The link in the first post won't work for me... But as an added 2 cents, make sure you add 3 more gauges to your truck. You need and exhaust temp gauge, a boost pressure gauge and a fuel pressure gauge. Make sure you completely inderstand 'Normal' readings for the gauges even before you start the truck. This will save you countless hours and thousands of dollars worth of repairs.

[mrolds88]

Since there is no tape involved, I would put my meter to work to see if the sender is registering. That should give you the bottom line. Also ground your wire that goes to it. See if that moves the needle on the gauge.

[jsavage977]

Hey everyone. I got it working!! Thanks for all your help and advice. It turned out to be a bad sender. I took it to Napa and they swapped me for a different one free of charge. I threaded it back in there and it works perfectly. I suppose that if all this didnt happen I would have missed out on a education on oil pressure senders ha ha.
https://www.youtube.com/watch?v=Hl-5iR8rwDQ

Thanks again everyone, you rock