Low Oil Pressure, Engine Clatter

[dallasz71]

I recently purchased a second Tahoe last week, it's 2005 LT 4x4 with right around 180,000 miles. Appeared to be a well cared for 2 owner, in very nice condition. Always had synthetic oil ran through it. While test driving, it maintained 50 PSI no problem.

One week later, and about 750 miles I'm having major oil pressure problems. I had noticed a gradual decrease in pressure, but I thought it may be the sending unit. Now this morning, at idle, I'm lucky to get 5 psi, low oil pressure lights on, and engine clatter. Pressure builds back up if you throttle up, but it loses it soon after returning to idle. When first started, it will idle around 30 psi, then gradually drop down to about 5 psi.

This all occurred this morning, right before making a 500 mile trip. I changed the oil (10w30) and filter thinking the filter may have been plugged, but had no success. So, needless to say, the Tahoe is in the garage until next week when I get home.

Any ideas? From what I searched, I saw that the o-ring on the oil inlet tube can fail, any have have this issue? Figure that might be my first try. And maybe the oil pump. Thanks in advance....

 

[wesleyb420]

Get a mechanical pressure gauge and check...I don't trust the electric one when it comes to diagnosing a pressure issue. You can get one for less than 30$

 

[livingez_123]

Well if it's already making noise, the damage is done.

 

[wesleyb420]

Also check the cylinder pressure...that will tell you a more complete story about what's happening.

 

[dallasz71]

Well if it's already making noise, the damage is done.

I guess I should have been more clear.... the engine only sounded horrible just for a few seconds, I was able to get it shut down right away. Started it back up and kept the rpms up and it sounds perfectly fine assuming I keep the engine idled up.

It seems to me like it'd be the inlet tube, any changed one of these? Does the front differential have to be lowered?

 

[shofzr]

I had the same thing happen to my 06 escalade at exactly 180k (about 2weeks ago now) ended up being the pressure valve stuck open

Kind of a PITA to get the bolt out if the pickup tube, but I was able to replace the pump without lowering the oil pan or axle.

 

[shofzr]

I replaced the timing chain and gears while I was in there

 

[dallasz71]

Thanks for the pictures. How hard was the crankshaft pulley to deal with?

 

[shofzr]

The crank pulley was no problem I used a long break over bar, put the handle end on the floor and bumped the starter to break the crank bolt loose, then used a harmonic balancer puller, the most frustrating part was getting the oil pickup tube bolt out, I tied dental floss to it so I could pull it up out of the oil pan when it eventually came out.

 

[dallasz71]

Just an update on my situation, it ended up being the pick up tube o-ring. Replaced the oil pump while I was there. Engine now runs 40 psi at idle and 60 psi on the highway. Thanks shofzr for the pictures!