Mike Frye

Isn't a pegged 5 bar reading an indication of reversed polarity on the wiring? I thought I read that somewhere. I would try reversing them first to see what you get.

marton

on mine it was an indication of a broken wire from the sender

Marton

Mike Frye

So it's at least a reason to check the wiring before thinking the sender is wrong. Right?

marton

Yes, I was supporting you....

Marton

Mike Frye

Yeah, I know. I was trying to confirm my own idea of the reversed polarity thing. We're on the same page, I just haven't had this particular problem, so I'm suggesting it second-hand.

michael j wright

Mine was so tight that I finally removed the whole thing and put the sender in a vise, squezzed the hell out of it and then used a wrench on the adapter- still had to use a cheater bar.

Jerome Craig

When I replaced mine I didn't worry about the polarity that much as there are a number of people that say it doesn't matter. On my '87 it matters a lot! With a fully functioning sensor and the wireing reversed, I gt a constant oil pressure warning. Once I changed the polarity it worked fine. BTW my sending unit came off on its own, without the pressure transducer part. I was all prepared to catch the flying springs and everything, but it just came off with very little effort.

On a cold engine, the oil is at its highest viscosity and is going to give a 5 bar reading. As the engine... and the oil warm up, the pressure will drop accordingly. Once the engine is fully warmed up blipping the throttle makes the oil pressure rise and fall.

Jerome

toofer

Thanks for the input guys, Tom if you go back to my first thread for this nightmare you`ll see I pulled the oil filter first. I have now dropped the Alt. as well. Cut the old unit off with my dremal tool, leaving the hex nut to the sender but the rest of it is gone. I just came in from putting an impact socket on it because I have now cracked 2 standard craftsman sockets prying on the beast. A impact socket that fits tight, a 18" breaker bar and 2` steel pipe and I still cant get either of them to move. My neighbor came over because he hasn`t ever heard me using the kinda words he was hearing from my garage. He sat down a put his 230 lbs against it and then I jumped in and we still haven`t been able to budge this thing. Once again, all that is left up there are the two hex head nuts, they are not lined up together and the sending unit hex is larger than the relif valve assbly hex head. I`m going to see if I can rent a impact wrench from the tool rental, hopfully they will have a 1/2" drive with lots of power, if not I`ll be having to purchase one. Can anyone shed any light on which impact wrench provides the most grunt, electric or air???? HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! toofer

toofer

Oh, I wanted to add that engine temp made no diff to the location of the meter. It stayed pegged cold, hot and everything in between and yes I checked all other possible cures before taking this approach. I don`t love working from the under the car, closed in spaces and I have never got along, but a man does what he has too. toofer "I`m trying to think but nothing happens" as Curly put it!!!!!!

928autobahndreamer

Have you been soaking it regularly with penetrating agents?
Soak, get medieval on it, curse, repeat.

Alan

When you swap the wires - you are not changing the sender polarity!

The oil sender/switch unit is combined it has 2 functions & 3 terminals - 2 obvious terminals and grounding via the threads.

The switch is between one terminal and ground and the sender is between the other terminal and ground. The sender controls the oil pressure gauge (variable resistance) the switch controls the low oil pressure light (on or off).

Terminal G is the sender (Blue/Yellow wire), terminal W is the switch (Black/Green wire).

Try just swapping these if they are incorrectly attached...

Alan

Big Dave

Alan...as Jerome stated, if the wires are swapped (i.e., incorrect), the pressure warning will trigger and the flashing light in the dash will illuminate. BTDT.

Alan

Oh - Ok I mistated the behaviour but still - you can't just swap these - you aren't just swapping polarity of the sensor.

Alan

toofer

OK, I`ll go soak it down again with penetrating oil, WD-40 is what I`ve been using and then I`ll get medieval on it. Found an impact wrench, will pick up and try again tommorrow. I afraid to try heat. I`m thinking the PO must have used loctite on the threads. I`ve worked on cars, trucks, motorcycles, boats and ford tractors, good hydo training, and have only encountered this when someone used loctite in a location they shouldn`t have. I believe that heat is the only way to deal with that situation. I read somewhere heat turn loctite to a gas substance. PO was not big on keeping the machanicals clean nor the interior for that matter. I have just finished a total restore of the interior. grase baked on for 28 yrs isn`t easy to get off. Does anyone know if loctite will disapate if heat is applied to the area it is on?? Again, I have no idea if that is the case but what else could be holding it. The threads on my new sending unit are standard, could the relief valve have reverse threads???? I trying to think but nothing happens

marton

I hope you have it on something really stable; I always have nightmares about putting a lot of force on a nut & pulling the car down on me.

For the really tough nuts I use a 4 foot scaffold pole as an extension on the breaker bar.
This also means I am no longer under the car....

Marton