Oil Pressure Sensor Question Again

[ram1220]

Can someone please help? 90 GMC Sierra 5.7l TBI, I bought the socket that fits the new oil pressure sensor. But the socket does not fit the old sensor. The old one is much larger than the new one and the tool I bought. Diameter and length. Can someone please tell me what size socket I need to buy to remove the old sensor? Not sure why the old one and new one are different sizes. Thanks.

 

[burnhedge]

I think 88-89 had a different style sensor. Perhaps the old style was used on a 90. I've never used any special socket. I just find a way to get a wrench in there and break it loose then unscrew by hand. If all else fails pull the distributor.


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[ram1220]

Ok. I've never pulled the dist. Is it a tough job? Thanks for the reply. I already have the cap off and I'm going to change it as well as the rotor. Both aren't looking so well. Lol

 

[ram1220]

I finally got it changed. What an ordeal though. The old one definitely is bigger than the replacement. I was told by a Chevrolet mechanic that GM changed the design. I couldn't find a tool anywhere to fit the old sensor so I had to get creative. But I got it. New one went in fast and it works like a charm. I put on a new distributor cap and rotor since the old ones were in bad shape. Thanks to those of you who replied.

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[1500z71]

If you don't mind me asking, what symptoms caused you to change it?

 

[ram1220]

Erratic readings on the gauge. I would start the truck and the gauge would be pegged at the high mark. Then when I pressed the gas pedal the gauge would drop and bounce up and down. After engine was warm and I stopped at a traffic light if would bounce around from the 3/4 mark up to the stop peg at the highest point. You could hear the gauge making a tap tap tap tap sound as it bounced around.

 

[1500z71]

Gotcha. Reason is asked is I thought that was the problem with my dads '92 so I changed them out. His was always reading 0-10 but that didn't fix it so I guess it's the oil pump.

 

[ram1220]

That sucks. Hope you can get his truck fixed.

 

[SAATR]

Gotcha. Reason is asked is I thought that was the problem with my dads '92 so I changed them out. His was always reading 0-10 but that didn't fix it so I guess it's the oil pump.

Could be the pump, but bearing wear and loose clearances are just as likely. If you pull the pan to replace the pump, I would go ahead and pull at least one rod and main bearing and check their condition. Will likely be worthwhile to roll in a new set of bearings, if the crank isn't trashed. Cam bearings can and will also cause oil pressure issues, but are much more difficult to replace.

I would also verify that the gauge is reading correctly by hooking up a mechanical gauge before throwing any parts at it. Could just be that the factory gauge is off.

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[1500z71]

Could be the pump, but bearing wear and loose clearances are just as likely. If you pull the pan to replace the pump, I would go ahead and pull at least one rod and main bearing and check their condition. Will likely be worthwhile to roll in a new set of bearings, if the crank isn't trashed. Cam bearings can and will also cause oil pressure issues, but are much more difficult to replace.

I would also verify that the gauge is reading correctly by hooking up a mechanical gauge before throwing any parts at it. Could just be that the factory gauge is off.

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Yeah I guess that will be my next route. Figured it wouldn't hurt to try the $30 part first.