Sending Unit or Gauge??
Thread Starter
Instructor
Joined: Jan 2007
Posts: 133
Likes: 0
From: High River Alberta
Sending Unit or Gauge??
Just put in new 350/330 crate into my 80.Now my gauge reads 40 before I start er up then ofcourse goes to 80 while im driving.Would this be my old sending unit or my gauge?
Thanks for any help
Doug
Thanks for any help
Doug
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Try this, remove the sender from the block, clean the threads of both the bung and the sender, and reinstall it.
The senders rely on the block as the ground and that may be blocked by grime, corrosion, or even Teflon tape.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Same test for most things like this, fire it up, remove the wire from the sender, reading should go to zero, ground the wire and it should peg high. If it doesn't do both of these its a circuit problem, if it does then use an ohm meter and ring out the sender
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Drifting
Joined: Sep 2006
Posts: 1,986
Likes: 21
From: Columbus MN
What Db said. I have a GM 350/330 HO in my '80 too. I had the same problem at first. Cleaning the threads in the engine and on the sender to bare metal fixed the problem.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
When you put on a single layer of tape and then install the sender it will ground fine, trust me. The threads will cut thru the tape like it is supposed to and fill in the voids between the threads on the sender and the block. If you have a VOM, tape and install the sender, 1 layer of tape only. Use the OHMs function and check for continuity between the sender case and the block, I'll bet a paycheck its zero or near it.
So, if you ground the wire and it goes full right and open it goes full left, the gauge, sender wire and all that is ok. Only leaves the sender, ohm it with the engine off and then on, see what ya get.
Lots of guys get all freaky about sealing senders, but think about it, the general seals them.
So, if you ground the wire and it goes full right and open it goes full left, the gauge, sender wire and all that is ok. Only leaves the sender, ohm it with the engine off and then on, see what ya get.
Lots of guys get all freaky about sealing senders, but think about it, the general seals them.
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Just installed a GM Performance 350/300 in my 75. My gauge was reading the same pressure (45 @ idle and 60-70 @ cruise). Had the GM dealer put a mechanical test at the opening and it was reading 50@ idle and 65@ 3000rpms. Also the service mgr stated that the engine is new and has new seals so the pressure will be slightly higher.....
Thread Starter
Instructor
Joined: Jan 2007
Posts: 133
Likes: 0
From: High River Alberta
Well I cleaned the snot outta it.Grounded the wire it went to 0,reconnected it to the sender and it went bk to 40.Need to find my tester for my sender,but im guessing its shot?
Instructor
Joined: Apr 2007
Posts: 148
Likes: 0
I have a 1 yr old 355 cu in 350 and once this summer I noticed the oil pressure gauge go from 40 to 80 and back to 40. Yesterday it did the same thing but went to "0". I pulled over thinking I had a drastic oil leak but didn't. the oil was full and the engine wasn't making any noise.I drove it home and there it sits. anyone have any ideas? Thanks.
Drifting
Joined: Aug 2007
Posts: 1,924
Likes: 6
Well, here's a similar dilemma I have
This is my oil pressure gauge in 1995
looks the same today
When I turn off the key, it goes back to zero-ish
disconnected the wire from the sender.. same thing
It's on my to do list to trace the wire down, but what should I be measuring with my VOM? Volts? Ohms? and what readings?
This is my oil pressure gauge in 1995
looks the same today
When I turn off the key, it goes back to zero-ish
disconnected the wire from the sender.. same thing
It's on my to do list to trace the wire down, but what should I be measuring with my VOM? Volts? Ohms? and what readings?
Last edited by pbcanney; Oct 5, 2007 at 10:36 AM. Reason: i cant spell good somety mes