Oil pressure gauge

[gbooth]

Months after getting the truck running and telling my self that the low oil pressure was just the gauge I decided to investigate further. The truck would build 30 lbs of pressure and that was all no more no less. After driving 50 miles this last weekend pulling my trailer with the jeep on it I noticed that oil pressure had dropped down a bit. Went Tuesday and got a cheep mechanical gauge and installed it. Started the truck and moment of truth, oil pressure built up to 90 psi at idle as we warmed up it dropped down to no less then 65 psi and warm at 1500 rpm still held 95 psi. The gauge only goes to 100 psi and being a cheep one will it blow if I max it out? I am looking to replace it with a 0-200 psi and steel braded line but have done it as of yet and may take a while. I still want to drive but not blow a oil line.

 

[devilman96]

I doubt the gauge will blow if it hits 100 psi but the way china builds things today there is always that factor... The original gauges and sending units do malfunction and there was a originally a 0-60 psi gauge installed in M35's.. Later they came out with a 0-120 gauge which is talked about in a TM or service bulletin somewhere (cant remember where I read it)... The stock gauges and sending units do fail over time but they are pretty cheap to replace ($60??) and a lot less work and money than pulling a SS line and getting a 200 lb gauge.

Install a new stock sending unit NSN 6220-00-814-4770 and go with a stock 120lb gauge like this... http://saturnsurplus.com/electrical/oilpressguage.htm

 

[Recovry4x4]

Check the top of your sending unit. You might have a 120psi sender and a 60 psi gauge. Also make certain that the gauge housing is grounded in the dash.

 

[houdel]

Greg - Kind of sounds like the problem I had with my OP gauge when I got my Deuce from the DRMO. The gauge would read high, read low, not show any reading at all, stick, swing back and forth wildly, still be reading 60 psi hours after I had shut the truck off, etc. There is a trouble shooting and diagnostic procedure in TM 9-2320-361-20 (download from the TM section on this site if you don't have it). The trouble shooting procedure is on page 2-31, the gauge diagnostic procedure is on page 2-126.

I followed the diagnostic, still got screwy readings. Installed a mechanical gauge, it read 60 PSI at idle, 90 PSI at road speed. Finally I pulled the gauge panel, wirebushed the OP gauge mounting bracket and panel where the bracket contacts it and put a light coating of gease where I wire brushed to prevent further corrosion of the contacts. I put it all back together and now the OP gauge reads fine, same readings as the mechanical gauge.

NOTE: To remove the gauge panel, first undo the 4 quarter turn fasteners holding the gauge panel to the dash, pull the panel out as far as it will go (not very far at his point) and disconnect the speedo & tach cables. Then you can pull the gauge panel out further and disconnect a fistful of wires and air pressure gauge line to get the panel out. I wrapped everthing I had disconnected with yellow electrical tape and marked the tape with a marker so I'd know where it went when I put it back together. When I was done and had it all back together, the bright light indicator came on when I turned on the dash lights, one dash light flashed off and on with the dimmer switch. D***, had to pull it all back out again and reverse the headlamp and dash light connectors to thier original locations!

 

[G744]

The easiest thing to do is just buy another GI air gage like is in your truck anyway. Put it in the oil hole, run a line to the spot on the engine normally taken by the sender unit.

Looks right, works all the time, reads to 120 PSI. Textile braid hose (i.e. Aeroquip) will handle the pressure easily.

dg

 

[Recovry4x4]

Novel Idea Dennis! I just happen to have one of those waiting for a place to go. Thanks!

 

[gbooth]

Thanks Guys for all the information. All the connections on the electrical are good, I had checked that when I had the engine out. The gauge and sender are probably still good most likely just miss matched. I have found a 0-150 manual gauge with a black face and white numbers. I have operated all types of heavy equipment and always have had a manual gauge, so now the truck will have one also. This list is the best source of info on these trucks. Thanks to all.