87 v15 Temp gauge & Oil Pressure Gauge

[sandorjoben]

Dear Everyone;

The truck: 1987 v15 350tbi th400
The problem(s): water temp gauge shows nothing, neither does the oil pressure gauge

The oil pressure gauge shows nothing because there is nothing connected to the pressure sending unit by the oil filter (hasn't worked since I got the truck), the wiring in my truck is a mess from POs. I'm probably going to put a new sending unit anyway but I can't find the wire I'm supposed connect to it, what color should it be(Haynes manual says a tan wire but I can't find one) with what type of connector?

The water temp gauge indicated temperature briefly when I first got the truck and put it on the road but then stopped. I put in a new sending unit yesterday and it worked fine for one run but as of this morning I have no engine temp showing again. When the engine starts there is very little needle movement on the gauge(it shakes briefly), I checked the gauge by grounding the green wire connected to the sender and it seems to work(the needle spikes to max temp), I also tried switching gauges with a spare that also passed the ground test and still the same result. The circuit paper for the instrument cluster is also in tip top shape so I don't think that's an issue. Could a sending unit crap out that fast (1 use) or is there another issue?

Thanks tonnes in advance for any assistance.

Dave

[sandorjoben]

Before I go and change the temp sender with another replacement, is there a chance that the teflon tape on the sending unit's threads(it came that way from Parts Source) is causing the problem? In trying to find a solution I've seen several write-ups troubleshooting temp gauge issues that say NOT to put teflon tape on the sending unit's threads, if that's the case I don't know why the company that makes the sender would package them with it applied.

[sandorjoben]

I've tested the ground on the sending unit and it's grounded properly, also checked the sender's terminal for a short so the new sender should be good, gonna check the wire itself next. I also think I may have found the wire and connector for the oil pressure sender, gotta check that also.

[68 TT]

My temp gauge was working sporadically. I figured out that it was one of the spring clips on the back of the gauge cluster not making complete contact with the printed circuit. I was able to snap it back into place so it was seated all the way. Now it works the way it should.