Where the heck is the oil pressure sending unit?

[jordan]

My dad blew his most recent MG engine because of what that might be, the pressure sending unit had some sludge or grit in it, or something that would never allow it to be an open or closed circuit (how ever it was designed) so it read 30psi at idle and would creep up at higher rpms so it wasn't completely jammed which made it quite deceiving, though it was never noticed that it would shoot to 30psi from just turning the key; even after the conrod tried getting out of the block. You might best try another sending unit, just test it.

[that wasn't the last engine, the most recent spun a rod bearing in september]

[69opelgtfvr]

That's a good idea. I'm also having trouble with my temp. gauge, I can't tell for sure if the reading is correct. I'm thinking of getting an aftermarket gauge cluster to install as a temporary fix, just so I can monitor the vitals while I'm working.

[MarkRHayes]

i finally located where it's supposed to go. do i need to take the carburetor off to get to it?

[tekenaar]

Originally Posted by namba209 If you are measuring between the two connections on the oil pressure transmitter, that's not the way to check it out. It should be either terminal to ground. The oil light switch terminal should read 0 ohms with the engine off and the gauge terminal should read high ohms. With the engine running, the oil lite switch terminal should read an open and the gauge terminal should read a lot higher and decrease as the rpm goes up, indicating a higher pressure as the rpm increases. Here's the approximate readings of the gauge side of the transmitter taken at the Green instrument panel connector, pin 6 to ground: HTH. 1 bar = 45 ohms 2 bar = 77 ohms 3 bar = 113 ohms 4 bar = 145 ohms 5 bar = 175 ohms gauge pegged = 250 ohms.

. . . I was just rereading this thread and thought I'd correct the "not entirely correct" gauge readings/sender resistances info based on recent experiences discussed in my "OP Sender Conundrum" thread.

The VDO OP sender's ohms resistance range is specified as 10-180 ohms, i.e. 10 ohms minimum reads 0 BAR/PSI and 180 ohms maximum reads 5 BAR/80 PSI. ANYTHING outside of the 10-180 ohm reading on the "gauge" wire, i.e. short/zero ohms or open/<180 ohms will cause the OP gauge needle to peg! . . . ask me how I know! . . . this is also why the OP gauge needle "jumps" slightly when you first turn the ignition key "on" . . . current flow through the OP sender's minimum 10 ohm resistance.

[MarkRHayes]

tekenaar, do you know about having to take the carb off to get to it?

[First opel 1981]

Originally Posted by MarkRHayes tekenaar, do you know about having to take the carb off to get to it?

Not to step on toes....

You don't have to take the carb off to change the oil pressure sending unit. It would make it easier to change it if the intake/exhaust manifold were not there but it can be done with everything in place.

The easiest way is to go up under the car and snake your tools through the exhaust. Its a pain but doable. It might help if you bend your wrench as needed to make it work.

[tekenaar]

Originally Posted by MarkRHayes tekenaar, do you know about having to take the carb off to get to it?

. . . you can get to it with a 3/8" ratchet, short extension and a 19mm "crowfoot", if memory serves . . .

[First opel 1981]

Originally Posted by tekenaar . . . you can get to it with a 3/8" ratchet, short extension and a 17mm "crowfoot", if memory serves . . .

I KNEW I bought those crowfoot wrenches for something....

~LOL~

[MarkRHayes]

thanks fellas. back to the garage...

[MarkRHayes]

Originally Posted by tekenaar . . . you can get to it with a 3/8" ratchet, short extension and a 17mm "crowfoot", if memory serves . . .

well, i ended up taking the carb out which really helped. i just couldn't see going up through the bottom. i can get my hand on it easy enough but hard to get a tool in there. did you say it's 17mm? i've tried 18 mm and 3/4 to get the old one out but they didn't seem big enough.

[tekenaar]

Originally Posted by MarkRHayes well, i ended up taking the carb out which really helped. i just couldn't see going up through the bottom. i can get my hand on it easy enough but hard to get a tool in there. did you say it's 17mm? i've tried 18 mm and 3/4 to get the old one out but they didn't seem big enough.

. . . must be 19mm then . . . did say, "if memory serves"

[saxybiker]

Originally Posted by namba209 If you are measuring between the two connections on the oil pressure transmitter, that's not the way to check it out. It should be either terminal to ground. The oil light switch terminal should read 0 ohms with the engine off and the gauge terminal should read high ohms. With the engine running, the oil lite switch terminal should read an open and the gauge terminal should read a lot higher and decrease as the rpm goes up, indicating a higher pressure as the rpm increases. Here's the approximate readings of the gauge side of the transmitter taken at the Green instrument panel connector, pin 6 to ground: HTH. 1 bar = 45 ohms 2 bar = 77 ohms 3 bar = 113 ohms 4 bar = 145 ohms 5 bar = 175 ohms gauge pegged = 250 ohms.

OK - it's stupid question time!
1) What is the proceedure to bench test an oil sending unit? (Before I get chastised, yes I did spend an hour using the search function on this site).
2) Gene - what part number on the egauges.com site did you order?
I want to try to get Opie's 2.0 up and running, but I want to be sure that the oil pressure gauge is reading accurately.

Thanks for your help guys (and girls)!

Allen Gage

[tekenaar]

Originally Posted by saxybiker OK - it's stupid question time! 1) What is the proceedure to bench test an oil sending unit? (Before I get chastised, yes I did spend an hour using the search function on this site). 2) Gene - what part number on the egauges.com site did you order? I want to try to get Opie's 2.0 up and running, but I want to be sure that the oil pressure gauge is reading accurately. Thanks for your help guys (and girls)! Allen Gage

This is the correct "egauges" OP sender, 1/8NPT P/N 360-009 . . .

. . . and this is the correct "egauges" adapter to adapt the OP sender male 1/8NPT fitting to the block's female M14x1.5 threaded OP hole, P/N R7963

[hrcollinsjr]

Originally Posted by saxybiker OK - it's stupid question time! 1) What is the proceedure to bench test an oil sending unit? (Before I get chastised, yes I did spend an hour using the search function on this site). Thanks for your help guys (and girls)! Allen Gage

Allen, I would assume you will have to come up with a way to apply pressure to the sending unit with some sort of adapter and a source of pressure that can be adjusted and measured. From there it is pretty straight forward with Otto's chart x OHM = x PSI

Harold

[saxybiker]

Otto and Harold:

Thanks guys..... just the information I was looking for!

Allen

[SpringGT]

Originally Posted by saxybiker OK - it's stupid question time! 1) What is the proceedure to bench test an oil sending unit? (Before I get chastised, yes I did spend an hour using the search function on this site). 2) Gene - what part number on the egauges.com site did you order? I want to try to get Opie's 2.0 up and running, but I want to be sure that the oil pressure gauge is reading accurately. Thanks for your help guys (and girls)! Allen Gage

Can you adapt the sending unit to a standard quick-release, compressed air fitting? Then you could tie it to your air compressor outlet hose and use the tank regulator to supply controlled, measured pressure to the sender as you check it against the resistance chart.
Bob

[saxybiker]

That sounds like it would be a good way to go. I'm assuming I can find an adapter somewhere that would work. Thanks for the suggestion.

Allen Gage

[hrcollinsjr]

Originally Posted by saxybiker That sounds like it would be a good way to go. I'm assuming I can find an adapter somewhere that would work. Thanks for the suggestion. Allen Gage

You can be pretty and look for an adapter or git 'er her done and use an old air hose and clamp. You're probably only going to submit it to 50 or 60 PSI max.

Harold