Oil Pressure Grounding Problem

Roscoe · #1 (**permalink**) 11-03-2003, 12:37 PM

I recently re-plumbed my Accusump pre-oiler to flow directly into the port on the block previously occupied by the pressure sender. I used all aluminum AN fittings and placed one of those pressure gauge adapters commonly used for fuel pressure gauges (union at both ends). I could not get the gauge to work and figured out it was all that aluminum. To solve the problem I used a stainless hose clamp around the sender with one of those connector tabs. I ran a ground from that to the chassis and it works perfectly.

Roscoe

Curt C. · #2 (**permalink**) 11-05-2003, 06:07 PM

Yup, I have had to do that before. I put a oil temp sender in my Canton pan. Could not get it to stop leaking without using RTV. Once the RTV went on, the grounding was not present. Hose clamp and 16 guage wire got it grounded.

snakeeyes · #3 (**permalink**) 11-05-2003, 08:22 PM

Roscoe, that's really interesting. What was your gauge doing--was it not working at all, or was it erratic, or what? I have some suspicions about the oil pressure gauge in the aluminum Chevy motor installed in my Lister. A friend who was helping get the motor installed used a bunch of teflon tape on the fittings where the sender screws into the intake manifold. The gauge has been giving me some pretty erratic readings, which I find hard to believe represent the actual engine oil pressure. Between the teflon tape and the aluminum block, intake, and heads I'm starting to wonder if those might be the culprit.

I was going to install a mechanical gauge for comparison but I may need to try grounding it better first...

Bob

need4speed · #4 (**permalink**) 11-05-2003, 11:39 PM

Hi Bob,

The teflon tape is definitely contributing to the problem since it insulates the sender, which needs to be grounded to function properly. You are likely getting erratic readings since teflon kind of falls apart when it gets threaded and you likely have somewhat of a ground that may vary due to temperature and any oil that seeps onto the threads. I assume that you are using the Classic Instruments gauges and senders that came with the Lister like I am, so I pulled their installation instructions off of the web to show you that they specifically recommend not to use teflon tape. I followed this advice and have no problems.

GM Installations - OHV Engines

The correct location for the pressure sensor on most GM-V8 engines is under the distributor housing at the rear of the block!

Use the Brass Bushing Kit from Classic to allow the Sender to be mounted at a 45-degree angle pointing towards the driver's knees.

This allows Sender to clear the back of the intake manifold, the underside of the distributor housing and firewall.

* CAUTION *

DO NOT use Teflon sealing tape or Gasket Cement on the threads of your Pressure Sender or the Brass Bushing Kit! The threads are tapered and self-sealing and should be tightened just enough to prevent an oil leak!

Do NOT overtighten!

The url for this and more on guages is: http://www.egauges.com/Cla_Inst.asp?...resssender.htm

Alan

Roscoe · #5 (**permalink**) 11-06-2003, 06:56 AM

My gauge was just not working at all. I suggest you remove your teflon tape and see what happens. You can always run a ground wire to the sender like I did.

Roscoe

snakeeyes · #6 (**permalink**) 11-06-2003, 08:09 AM

Thanks, guys. I did dig out the CI installation instructions late last night. I have a slightly different version of the instructions (probably older, since my gauges were purchased several years ago) that warns against using teflon on the water temp sender but is silent with regards to the oil pressure sender. I am going to start by pulling off the teflon and see what happens.

Thanks again!