Oil pressure problems :(

**ugotsmoked** · 11-11-2016, 05:53 PM

Hey everyone. I need some help trying to figure this out. When I start the car up is close to 60psi then drops to 40 at 160 degrees. Idles at around 20psi when full hot in traffic.

Now when throttle is applied driving around town it goes up to about 40psi but anything over half throttle or even at WOT it drops to about 10psi. At that time I left off completely and it goes back to 40psi. Hit it again and it drops to 10psi.

My friend said to change the opsu so I will do that first. But I'm fearing it may be the pump or a bearing. Any suggestions?

I'm thinking of changing the opsu first and take the intake off to see how much oil is passing through the intake and heads. Then I'll drain the oil and cut the filter. I didn't see any glitter from the dipstick but I'll be checking when I cut the filter.

Hoping it's nothing serious but I wanted to see if anyone encountered this.

Thanks!

**pajeff02** · 11-12-2016, 03:03 AM

First step is to confirm that your pressure readings are actually correct. Has the motor ever been apart before? It kind of sounds like a faulty sensor the way it is acting. OPSU is a bit of a bitch to get at, unfortunately.

**ugotsmoked** · 11-12-2016, 06:25 AM

No the motor has never been opened up.

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**ugotsmoked** · 11-12-2016, 05:09 PM

Changed the sensor. Now it's not dropping to zero at wot but it's acting sporadic.

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***SMWS6TA*** · 11-14-2016, 07:02 AM

How many miles on the oem oil pump?

In case you don't know this 97-98 oil pumps are a known issue. The older they get the weaker they become. It's what killed my LS1. Normal driving it will last a while but it's at high rev's that it can starve the engine.

If you do decide to get a new oil pump you have 3 options.

LS6 oil pump - This is the OEM replacement, good pump for DD and lightly modded engines.

Melling 10295 - almost the same thing as a the LS6 but can handle heavy track use.
Melling 10296 - High volume/high pressure pump. This is for builds that are cam' and purpose built for heavy track use. I have it on my 403, and my oil pressure never drops below 45psi. Usually hovers around 60psi at idle and on hard pulls around 70 psi. You have to be smart with this pump. I add an extra quart of oil because you can drain the oil pan moving that much volume at high rev's. I added it because of the spacer for my oil temp gauge and also use a truck oil filter. This gives me a little extra room for the oil. One day I may upgrade to a 7qrt aftermarket oil pan.

You can swap the oil pump without pulling the engine. However it is a MAJOR PITA to do so. You'll need to lift the engine off the mounts about an in on the drivers side to access the oil pan bolts. You will want to lover the pan but not remove it. It will hang about an inch to allow you to access the pickup tube bolt. STUFF (and keep count) rags between the block and the pan so you do not drop the bolt in the pan. Doing so will not only piss you off but you'll need to pull the engine to drop the pan to recover it.

**ugotsmoked** · 11-14-2016, 07:08 AM

Originally Posted by SMWS6TA

How many miles on the oem oil pump?

In case you don't know this 97-98 oil pumps are a known issue. The older they get the weaker they become. It's what killed my LS1. Normal driving it will last a while but it's at high rev's that it can starve the engine.

If you do decide to get a new oil pump you have 3 options.

LS6 oil pump - This is the OEM replacement, good pump for DD and lightly modded engines.

Melling 10295 - almost the same thing as a the LS6 but can handle heavy track use.
Melling 10296 - High volume/high pressure pump. This is for builds that are cam' and purpose built for heavy track use. I have it on my 403, and my oil pressure never drops below 45psi. Usually hovers around 60psi at idle and on hard pulls around 70 psi. You have to be smart with this pump. I add an extra quart of oil because you can drain the oil pan moving that much volume at high rev's. I added it because of the spacer for my oil temp gauge and also use a truck oil filter. This gives me a little extra room for the oil. One day I may upgrade to a 7qrt aftermarket oil pan.

You can swap the oil pump without pulling the engine. However it is a MAJOR PITA to do so. You'll need to lift the engine off the mounts about an in on the drivers side to access the oil pan bolts. You will want to lover the pan but not remove it. It will hang about an inch to allow you to access the pickup tube bolt. STUFF (and keep count) rags between the block and the pan so you do not drop the bolt in the pan. Doing so will not only piss you off but you'll need to pull the engine to drop the pan to recover it.

Thanks for the detailed answer as always. The pump was my next step. I'll see if I can attach the video if you guys can see it. This is what happened after I changed the sensor and did a couple things while I was in there. Cleaned up the intake, changed the intake gaskets, cut the egr pipe so it's not sitting halfway in my intake anymore. Ported the throttle body. Etc...

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**ugotsmoked** · 11-14-2016, 07:16 AM

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***SMWS6TA*** · 11-14-2016, 07:36 AM

It looks like it is acting normal. I've seen oil drop to 35 psi at idle and still be correct.

When you let off it will drop, next time take it up in rpm's and hold it to see if it stays or if it drops. Like when you accelerate getting on the interstate.

Also forgot to add this in the above post, the danger zone for the 97-98 oil pumps are around 6300 rpm's.

**ugotsmoked** · 11-14-2016, 07:42 AM

For some reason the video didn't ad sound. It's actually dropping from 60 to just under 40ish psi at wot. Then back up when I let off.

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**ugotsmoked** · 11-14-2016, 07:47 AM

And before changing the sending unit it was dropping to 10psi at wot from 40psi cruising.

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***SMWS6TA*** · 11-14-2016, 08:01 AM

How many miles?

**ugotsmoked** · 11-14-2016, 08:04 AM

Motor has 135k don't know about the pump. Could be original for all I know. Motor was bone stock when I got it. Only things New are the opsu and free mods.

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***SMWS6TA*** · 11-14-2016, 08:13 AM

It looks like the pump is going based on what you say. But before you do the pump check the filter and use a clean drip pan. Look for flakes.

**ugotsmoked** · 11-14-2016, 08:22 AM

I am planning on changing the oil. This all started when I switched oil types. Only have about 500 miles on this oil change and it's dark as coal. I'll check for glitter and cut the filter while I'm at it and see.

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