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2004 Chevy K3500 Crew cab DRW 6.6 Duramax
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Discussion Starter · #1 ·
Hello All,

When I bought this 2004 DRW CC pick up, it had dyno oil in it along with a Fleetguard filter. Had the injectors replaced and they changed the oil but not the filter. I hosed off the engine from the diesel they got all over the place and had water in the oil. So I replaced the oil with Rotella full synthetic oil and a GM factory filter. I have been seeing oil pressure at cold start around 35psi idle, and around 50psi at 55mph. Once warn it's been running about 10-12psi at idle and 24-26psi at 55mph. The other day with outside temps in the 90's, it would get up to 24psi at 55mph but at idle it drops down to 5-8psi and the warning goes off at 7psi. I still have the leak of either oil or fuel, it's hard to tell, I think it fuel due to the oil never moves on the dipstick and I can't get my broken body around to find and fix at the moment. Also it normally runs at 185* full warm but was running 195*. I figured that was due to the outside temps and running the AC full blow.

I have been told by a long time mechanic that the GM filter is designed for the dyno oil and isn't restrictive enough and not filtering the thinner synthetic oil and that is the cause of the low pressures. What is the thoughts on this? Can it be that simple as this pick up has the high volume, low pressure oil pump and the filter is the culprit?

Thanks,
John
 

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If you think fuel is getting into the oil then do a paper towel test to check.
Take a paper towel and place a few drops of oil from the dipstick onto the towel.
If fuel is in the oil it will wick away from the oil and create a halo around the drops on the towel.

Here is a thread with some info on the low oil pressure issue
 

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2004 Chevy K3500 Crew cab DRW 6.6 Duramax
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Discussion Starter · #3 ·
It's not making oil. I have just under 2000 miles on a complete rebuild and seal of the fuel system from the fitting under the cab to injectors. There is a leak out side somewhere and the shop that did the work refused to fix this. Same with the oil leak. It happened after they worked on the truck and refused to look at it. The oil pressure drop has happened after I changed the oil when I got it back and switched to full synthetic.

I have done the paper towel test so much, I know it never does the halo. But I still keep doing it.

I'm just at a loss. I read that low oil pressure is ok, that some LB7's have the low pressure high volume pumps. These will read at 9-12psi at operating temp. And then I hear that is way too low and should be between 25-30psi. And that low pressure is at idle. At 55mph, it's at 24-26psi warm.

Makes me miss that ol 6.5l that I knew top to bottom.

John
 

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2004 Chevy K3500 Crew cab DRW 6.6 Duramax
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Discussion Starter · #4 ·
Here is a thread with some info on the low oil pressure issue
The cluster is new. And the readings are from the CTS3. I can't read that dang factory gauge. I will see if I can find the sensor and check and clean it.
 

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The cluster is new. And the readings are from the CTS3. I can't read that dang factory gauge. I will see if I can find the sensor and check and clean it.
I would put a mechanical gauge on it for accurate pressure readings
 
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2004 Chevy K3500 Crew cab DRW 6.6 Duramax
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Discussion Starter · #6 ·
I will see if I can find the sensor and "T" it with one.
 

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A faulty dash gauge will NOT trip the oil pressure warning.
 

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2004 Chevy K3500 Crew cab DRW 6.6 Duramax
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Discussion Starter · #8 ·
A faulty dash gauge will NOT trip the oil pressure warning.
But if the sensor is bad or not working correctly, will it not cause the dash and warning to work with it's bad readings? And with the CTS3 reading the computer thus the sensor, also be a false reading?

John
 

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The factory manual for your engine specifies [email protected] normal operating temperature.
The oil pressure sensors are fairly reliable but the stepper motors in the gauges sometimes leave a lot to be desired.
If in doubt, hook up a mechanical gauge, then you know what you have. Running a 5w-40 synthetic vs dino oil will sometimes give a lower reading. My LBZ runs 5-8psi lower with Rotella 5w-40 than it does with dino. .
 

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Discussion Starter · #10 ·
I'm not taking the readings from the cluster. It seams to be close to what the CTS3 says but is off by a few psi.

Being limited on movement in my ol age, it's been hard. Both mentally and physically. But I did put a oil filter designed for full synthetic and the readings are a little higher. But at full operating temp it's going to still be pretty low. At 130* and at 1500rpm it's at 19psi. The thing that gets me is this all came about after the injectors were replaced. And the shop owner is being a douche over everything. All he wants me to do is leave the pick up with him for another few weeks. Not to mention it's 70 miles one way to get to him. And I don't trust him anymore.

I read there is three places for the sensor. Drivers side back of block, drivers side front of block behind a bunch of stuff and on top of the engine under the turbo. My body won't let me tear into this like I could even 10 years ago. So I'm at a loss and about to sell it for another problem.
 
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