04 5.3 Vortec low idle oil pressure

[Jeffery Porter]

Is rod bearing replacement a cure for low oil pressure at 500 rpm idle..? New HV oil pump, new sender, new pick up tube. 100 or 200 rpm increase pressure jumps to 20psi. Driving I have 40 at 1500 rpm. Idle it is only about 4/8 psi. Gage is reading correctly.

[davester]

No.

[Jsdirt]

Just my opinion, but I wouldn't "bearing-slap", or do any sort of fix like that on any LS engine. When they get up there in miles and start having problems (or start having problems at 50k miles like my '07 ...), I'd either sell it for parts, or scrap it, and buy a crate engine from a reputable engine builder.

 

These are great engines - they make alot of power for their size, and are much more efficient than the old 350's. That said, the 350 was SIMPLE, CHEAP, and as reliable as a stone ax - none of which can be said of any LS. They are complex (there are TOO MANY little parts inside that can turn $6,000 into scrap in just a few miles), they are labor intensive (20+ hours just to remove heads), and they're expensive. For all those reasons, I'd go crate. If a customer asked me to do that, I'd pass on the job ... because it will be back with problems far too soon.

 

Just my .02..

[newdude]

2 hours ago, Jeffery Porter said:

Is rod bearing replacement a cure for low oil pressure at 500 rpm idle..? New HV oil pump, new sender, new pick up tube. 100 or 200 rpm increase pressure jumps to 20psi. Driving I have 40 at 1500 rpm. Idle it is only about 4/8 psi. Gage is reading correctly.

 

Was your idle pressure going of the gauge in the cluster or off of a mechanical pressure gauge attached to the engine?  

[Jeffery Porter]

I put a mechanical gage where the sender unit is to verify and both read the same. No engine noise, 195k, runs great, 5w30 Mobile 1 HM oil.

[CamGTP]

A tune would let you idle at 750-800rpm and cure all the problems lol.

[garagerog]

3 hours ago, Jeffery Porter said:

Is rod bearing replacement a cure for low oil pressure at 500 rpm idle..? New HV oil pump, new sender, new pick up tube. 100 or 200 rpm increase pressure jumps to 20psi. Driving I have 40 at 1500 rpm. Idle it is only about 4/8 psi. Gage is reading correctly.

What was the oil pressure before installing the high volume oil pump? You can go with a high volume or high pressure oil pump, unfortunately you can't have your cake and eat it too.

[Jsdirt]

2 hours ago, Jeffery Porter said:

I put a mechanical gage where the sender unit is to verify and both read the same. No engine noise, 195k, runs great, 5w30 Mobile 1 HM oil.

Runs great, and no noise = leave it be, and run it until it breaks.

Edited January 29, 2020 by Jsdirt

[Jeffery Porter]

I had the Meling 295 first and pressure was about 4 at idle. Changed to Meling 296 and now 6 or 7 idle, 40 driving. Had 20/30 with the 295. Stock pump was about what the 295 did, tad better. 

[Jeffery Porter]

I have the same motor in 02 tahoe with 150k idles at 40psi. 60 psi cold. My 04 silverado 5.3 is baffling me with the idle pressure, so That's why my thinking was rod bearings might help. Don't know if anyone has tried this with any success on a 5.3 with high mileage.

[88m53453]

Rod bearings ?  I was always taught oil pressure problems were either main bearings or the pump and since we know it’s not the pump...

[Jsdirt]

It's everything combined, but I'd say the mains have more an effect on pressure readings.

[Jeffery Porter]

I thought maybe I could do some good with new bearings, but most advice is to run it till it quits, replace with long block.

Jegs or Jasper have them for around $2500, so thats the path forward. I will change my oil back to 15/40 Rotalla in the spring, that will net about 5psi more at idle. Thanks for all the input here..

[Jsdirt]

That's exactly what I would do. 

 

I've been running 10w-30 in mine for the past 30k miles, when my oil analysis was showing signs of the notorious #2 cam bearing failure, plus high levels of piston ring and piston material in a prior analysis. I'm going to run this one until the block ventilates itself, or the camshaft snaps in 2.

 

Just turned 100k miles last week. Won't be long now ...

 

Edited January 30, 2020 by Jsdirt

[Doug_Scott]

2 hours ago, Jsdirt said:

That's exactly what I would do. 

 

I've been running 10w-30 in mine for the past 30k miles, when my oil analysis was showing signs of the notorious #2 cam bearing failure, plus high levels of piston ring and piston material in a prior analysis. I'm going to run this one until the block ventilates itself, or the camshaft snaps in 2.

 

Just turned 100k miles last week. Won't be long now ...

 

The oil analysis can narrow it down to a specific cam bearing?  Does each bearing have a unique composition?  I doubt the small block chev engine was always as dependable as it finished out its life.  Add in that the first 20 years were in vehicles that were not driven like they are now.  It was common practice to never drive a cold engine, not any more. You cannot take one item from an era and compare it head to head to something from a different era.  Much like you can't say that dead basketball player(sorry, don't follow the sport) was the best ever.  He did not have to take a bus from game to game, he had the best of everything, etc...

 

On vehicles with an oil light, they would come on at approx 7psi.  Problem with those systems was the light would also come on at 1psi.  If the truck is producing sufficient oil pressure to silence any noises, let it be until it no longer idles quietly.  

[txab]

4 hours ago, Jsdirt said:

That's exactly what I would do. 

 

I've been running 10w-30 in mine for the past 30k miles, when my oil analysis was showing signs of the notorious #2 cam bearing failure, plus high levels of piston ring and piston material in a prior analysis. I'm going to run this one until the block ventilates itself, or the camshaft snaps in 2.

 

Just turned 100k miles last week. Won't be long now ...

 

 

 

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