04 Denali losing oil pressure - looking for rebuilts

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pnwdan

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Runs great actually. Still like new. Never misses a beat

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This is cruising at 65 on the freeway. Maybe I will look into the O ring or pump. I really need throw a mechanical gauge on it. Just a pain to get my big hands back there.
 

#1taho

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This is cruising at 65 on the freeway. Maybe I will look into the O ring or pump. I really need throw a mechanical gauge on it. Just a pain to get my big hands back there.
Try the o ring. Maybe while you are in there you can wiggle the rod ends and check for movement and look up the cyilinders. Just to see if you can see anything noticeable. Oil pump is a little harder to do than the o-ring. The oil pumps are now on the front of the crank shaft and the front of the motor has to come apart. Try a flush. See how that goes. Do the o-ring. And drive it. In the mean time do research on the engine you would like. Crate from gm. Rebuilt or what ever. It seem to run ok so it's buying you some time.
 
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Just an update. I haven't driven the Denali much because I have a short commute and I've been super busy so I haven't had time to dig into it. I did swap the sender and had been seeing the same results. Today I had to go somewhere. About 20 miles freeway driving so on a back road before I got on I put the pedal down from a stop and watched the oil pressure peak at about 60 before it shifted then the rest of the trip it held steady on the freeway at 40. It leveled off just above 20 at a stop. Strange

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Definitely stick a mechanical gauge in to check the pressure

Have you considered the oil pump pressure bypass valve as the possible problem?

I would also change you oil much more frequently. Oil is the life blood of your engine. That pic of the plug has quite a lot of shavings on that. You need to get that out of your engine before it plugs a passageway somewhere. I might even would stick a big ass magnet on the outside bottom of you pan before you know you going to pull the pan. That way you can clean out all the shaving that stick to it when u drop it down.


I would suggest replacing the entire pick up tube instead of just the oring. The new pick up tube should have a new pickup tube oring with it. It is not anymore work since you have to remove the pick up tube to install and new oring anyway. Reason being, you have quite a bit of shaving, and possible slug which might cause some clogging in the screen and tube along with the oring pinch. The pickup tube and oring aren't really expensive, i think ours was 30-40. It just an easy way to eliminate that possible problem.

I just pulled the pan out on my brothers 2002 Tahoe 4wd and we didn't have to remove the front axle, we just unbolted the two bolts on the left and one hanger bolt on the right. I used a pry bar to pull the axle down more to provide more room for my brother wiggle the oil pain out so we didn't have to completey drop the front axle assembly.
 
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So this weekends update. The higher pressures were short lived. It returned back to the lower pressures I originally was seeing. I haven't had time to do anything but drive it nice on my short commute. Today I'm going to order a new pump, o ring, and cam retainer plate along with all the stuff to put it back together. I have a feeling it is the cam retainer because of the steel in the pan but since I'm there I'm going to replace it all.

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Update
I replaced the pump, o ring, and cam retainer with little change. I do have a bit more pressure because of the high volume pump. I guess we'll see how it goes


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#1taho

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I have read on performance trucks that the fourth cam bearing in will spin. I did a bunch of reading this weekend and stumbled across it. But sounds like it's time to replace the motor. I wouldn't trust it anymore.
 
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Update
Over the last couple weeks since the part change out I've slowly watched the oil pressure drop. Cold start it now peaks at 20 and short trips it levels at 10 after its warm. After a 25 minute trip on the freeway yesterday it hit the first red mark on the cluster while at idle and the display promptly and annoyingly notified me that I had low oil pressure. She's on her last leg. Time to weigh out my options for a replacement.

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