Oil Pressure Issue, To High??

[OneBadasz71tahoe]

Oil Pressure Issue

I have just been through a big rough patch with my 1998 2DR WG Tahoe 4x4 5.7L Vortech that has a 153K on the truck. Just over the weekend I replaced the Felpro Lower Air-Intake Manifold Gasket that had gone bad and then two weeks before that I had to replace my transmission because the sun shell gear failed. Never the less, I am not ready to sell my beast. I need to solve this next issue that is annoying me. The issue is my oil pressure seems to be running really high. This issue developed at the exact same time my LAIM gasket went bad. It seems that my oil pressure runs at about 80PSI solid when the truck is first cranked and driven done the road. Once the vehicle gets hot after 6 minutes it runs between 45-70psi according to my gauge cluster. Before all went to crap with my truck, the engine would operate between 30PSI and 55PSI. It seems like the gauge responds to acceleration and idling just as it did before the problems began except for the fact that the psi range is much higher. I think the first step to solving this problem is to put a manual pressure gauge on the motor to see if it is something in the sensors or gauges. Seeing that I am mechanically challenged, can someone walk me through what I need to do to run such a test? Any ideas on what is causing this issue? Thanks for the help.

[j cAT]

Originally Posted by OneBadasz71tahoe

Oil Pressure Issue

I have just been through a big rough patch with my 1998 2DR WG Tahoe 4x4 5.7L Vortech that has a 153K on the engine. Just over the weekend I replaced the Felpro Lower Air-Intake Manifold Gasket that had gone bad and then two weeks before that I had to replace my transmission because the sun shell gear failed. Never the less, I am not ready to sell my beast. I need to solve this next issue that is annoying me. The issue is my oil pressure seems to be running really high. This issue developed at the exact same time my LAIM gasket went bad. It seems that my oil pressure runs at about 80PSI solid when the truck is first cranked and driven done the road. Once the vehicle gets hot after 6 minutes it runs between 45-70psi according to my gauge cluster. Before all went to crap with my truck, the engine would operate between 30PSI and 55PSI. It seems like the gauge responds to acceleration and idling just as it did before the problems began except for the fact that the psi range is much higher. I think the first step to solving this problem is to put a manual pressure gauge on the motor to see if it is something in the sensors or gauges. Seeing that I am mechanically challenged, can someone walk me through what I need to do to run such a test? Any ideas on what is causing this issue? Thanks for the help.

somethings restricting the oil from flowing 30-55psi with non synthetic is normal..gasket material etc...

[OneBadasz71tahoe]

It seems that the oil pressure issue has settled down some. This morning I went to crank my truck and it fired right up. The oil pressure was steady at 60psi. Once warm, the truck would idle at about 40psi and going thorugh the gears between 45psi and 65psi. However, this afternoon the oil gauge indicated 60psi both idling and accelerating. This tells me that something is wrong somewhere between the gauge and the oil. Any ideas on how to solve this mystery?

[RainRider]

Just went out and fired mine up. Cold at idle: 60 psi - rev a bit: up to 75.
With 180,000 on the motor, I use 10W40 synthetic. As soon as I started using it, the oil pressure increased. When the motor warms up, the pressure goes down to about 40 at idle, and stays in the 55 to 60 area hot on the highway.
Outside ambient right now is 91 in the shade, so under the hood/motor ambient "cold" start has to be over a hundred degrees (truck sitting in sun all morning).
I really don't think you have a problem.
It may be that you had a bit of water in the oil causing reduction in pressure?
Fixing the coolant contamination makes for just oil in the motor?
By the way, the oil in my truck has almost 5,000 on it, but I don't notice much pressure difference from a fresh oil change to now.
Edit: (All readings from in-dash gage)

[j cAT]

Originally Posted by RainRider

Just went out and fired mine up. Cold at idle: 60 psi - rev a bit: up to 75.
With 180,000 on the motor, I use 10W40 synthetic. As soon as I started using it, the oil pressure increased. When the motor warms up, the pressure goes down to about 40 at idle, and stays in the 55 to 60 area hot on the highway.
Outside ambient right now is 91 in the shade, so under the hood/motor ambient "cold" start has to be over a hundred degrees (truck sitting in sun all morning).
I really don't think you have a problem.
It may be that you had a bit of water in the oil causing reduction in pressure?
Fixing the coolant contamination makes for just oil in the motor?
By the way, the oil in my truck has almost 5,000 on it, but I don't notice much pressure difference from a fresh oil change to now.
Edit: (All readings from in-dash gage)

you say that your using 10-40wt synthetic oil and when on cold start dash guage goes to 75psi....
I use 10-30wt mobil 1 synthetic and the pressure goes to 65psi max with little if any difference in pressures from hot to cold operating...

what oil and filter do you use ? who makes it...

[maxwedge]

As you said get a seperate mechanical gage on it and see, the sender could be bad or have depositis on it.

[OneBadasz71tahoe]

Can anyone provide me with some instruction on how to hook up a manual gauge so I can compare the pressurer with what my dash gauge is saying? Should I go with a Delco sending unit or is this a part simple enough where I can use a Autozone part and be okay?

[j cAT]

Originally Posted by OneBadasz71tahoe

Can anyone provide me with some instruction on how to hook up a manual gauge so I can compare the pressurer with what my dash gauge is saying? Should I go with a Delco sending unit or is this a part simple enough where I can use a Autozone part and be okay?

remove and clean the sender unit as maxwedge suggests this is very possible with what you engine just had with the oil contamination...


placing a T pipe fitting into the sender threads with a pressure guage should give you your test fixture to compare readings..