twotone84vette

Good morning,

Replaced oil sender and oil pressure switch on my '84. On a cold start, oil pressure shows normal readings. When restarting a warm/hot engine, oil pressure reads "0" psi and the warning light comes on.

Any ideas why this is happening?

Thanks

onedef92

Have you checked the sender and switch for continuity with a multimeter? Sounds like one of them could be defective.

With the influx of ghetto, offshore parts these days on the market, it's certainly possible to buy replacement parts (even O.E.M.) that are D.O.A. or dying straight outta' the box.

bwiencek

Low oil pressure? Have you checked it with a good mechanical gauge?

383vett

Hook up a mechanical gauge quick.

IBVETN2

Don't mean to hi-jack your thread but my 86 started doing the same thing this weekend. When engine is warm,at idle oil pressure drops to 0 -3 psi. At 1500 rpm pressure goes up to 25 or so.


If the oil pressure switch is working, shouldn't it cut out the fuel pump relay and kill the car when pressure drops to an unsafe level? So if it keeps running might it be a bad sender and the car still has sufficient pressure to keep the pressure switch from stopping the motor?

I am in the process of installing a mechanical gage.

Is there anyplace else to tap into besides removing the factory sender and installing a T fitting?

What is the "trick" to get to the factory sender to remove it? It is in a very tight spot.

bwiencek

The simplest place to access is the port that is right above the oil filter and the 'trick' to get to the factory oil pressure sender that I've used in the past on other cars is to pull the distributor since it'll give a lot of room near the sender (but you have to know how to re-time it and have a timing light if you do that)

383vett

You should be able to remove it with a 9/16" open end wrench. The pressure switch will not shut the engine off if the pressure is zero. It is there to allow the fuel pump to engage if the normal fuel pump circut is inoperative. During cranking, if the pressure switch sees pressure, it will energize the fuel pump.

IBVETN2

My car is a Z51 and has the oil cooler above the filter. Is there still a port that is accessable there?

Are you referring to the oil temp sender port?

383vett

That must be the one he is referring to. If you want to hook up a mechanical gauge just to compare with your stock gauge, the temperature sending unit can be replaced with the pressure sending unit. This one might be easier to get to. On my car with long tubes, it's not very easy either.

bwiencek

It's above the cooler - and YES it is the temp sender - you can disconnect the oil temp sender until you verify the pressure (which is WAY more important than temps in this case)

With the stock 'headers' it's not bad to get to - with long-tubes - I'm guessing they'll be in the way....

IBVETN2

Well guess what! I have long tubes on my car and yes, they are in the way.

Going to fight the pressure sender till I get it off and a Tee fitting in there.