Oil Pressure Sending Unit

[CK-1]

I have a 1984 Chevy K10 P/U with a 305. It orginally had warning lights in it but I just swapped it out with gauges. After replacing the temp. sending unit all is working fine except for the oil pressure gauge. I have an oil pressure switch located just above the oil filter. According to manuals, the oil pressure sending unit should be located near the distribitor but there isn't one there. My question is, since no oil pressure sending unit was every mounted on this engine, where do I mount it?

[Gooseneck]

I'm not sure on a 84 but from what your saying it seems like you could replace the switch with a sending unit for the gauge. Was not the switch used for the light or is it used for something else?

[JWhite8055]

Replace the dummy light sending unit near the filter with the pressure gauge sending unit.

There are several GM manuals (Chiltons)that refer to a sending unit near the distributor, but I have yet to find one there, (on motors dating from the late to mid 70's) perhaps they once did exist in that position, but who knows.

[CK-1]

While doing some digging around the distributor I found a rubber boot with a wire attached. This boot attaches to the oil pressure sending unit, but a sending unit was never installed in this vechicle

Gooseneck - in doing some testing, I'm pretty sure the switch is just used for controlling the light when the oil pressure drops real low. I have heard that some oil pressure switch setups controll the fuel pump, so when it drops low the fuel pumps shuts off to save the engine.

JWhite - I went to a buddy of mines shop yesterday evening and he found the bolt that screws into block for the sending unit. The distributor/rotor and housing would need to be removed and a bushings installed to angle the sending unit. We didn't want to go thru the hassle to taking down the distributor so we decided to use the same location as the switch (above the filter). Using a brass parts like a pipe nipple, T fitting and a 1/4 to 1/8 coupler.. we connected the switch and the sender in the same located. Now, we seem to have a wiring problem. The oil pressure gauge doesn't move and we tried every configuration..

[JWhite8055]

Maybe i should have been a little more clear, I've also noted the bolt and wiring connector on many models, but never an actual "sending unit" mounted in that configuration, sorry.

I assumed a fitting of some sort might be necessary to put the sending unit above the oil filter, but not a "T" fitting. It may simply not be close enough to the oil to correctly measure pressure or it may even have an air bubble in the fitting assembly. The unit itself could also be bad.

(You did have oil in it right?

[Gooseneck]

If you have voltage at your gauge and you ground your sending unit wire, your gauge should move to max reading. If not check your wire for continuity. Tee-ing in with the other switch should work fine.

[CK-1]

Thanks Gooseneck and JWhite for the advice. As of this past weekend I now have a working oil pressure gauge. After sitting down with a shop manual and testing a few things I found out two problems. One, I had a bad oil sending unit and two a wire conflict. To resolve the wire conflict I have to run a wire thru the firewall (via speedmeter grommet). The brass nipple and T fitting worked like a charm...

CK

[bammax]

I just bought an '88 full size Blazer and am having problems with the sending unit. The guage is reading 0 at all times but the light isn't coming on. I have the 350 engine and it has a sending unit by the filter and another by the distibutor. The filter one is blowing oil everywhere and the one by the distibutor seams fine. Does this mean that the lower one is for the gauge and that is why the gauge isn't working? Or is that just the dummy light unit and it happens to be leaking?

[JWhite8055]

The one by the filter is the "dummy light" unit, (which should not be leaking BTW) It may be bad and there really is no oil pressure, and the gauge is working fine, or there may be oil pressure and the dummy light sending unit is working fine (save for the leak) and the gauge just isnt functioning.

If you've driven it this way and it hasn't overheated or siezed up yet, it's probably a bad gauge or wiring/connection

[Rbraczyk]

I love people who are too stupid to read their guages and they end up siezing their motors.