6.0L Problems.

[Wet..Paint]

So I have a 2003 GMC 2500HD with the 6.0L. This thing has been a damn lemon from the time I got it. Started out with an intermittent no crank, which I had to fix cause I needed the truck, it was the ignition switch / wiring. The not so major issues I am having off and on currently are intermittent service brake light, and intermittent service 4wd light. Of course neither of those will stay on or come back when I have time to try and scan it or stop at a shop...

Now the serious stuff... Had a check engine light come on about 2 months ago, scanned it and I need knock sensors, well work was busy so couldn't do it, couple weeks later it starts running HORRIBLE! Sounds like a lumpy cam on idle, stalls out in the cold etc. Scanned again, has like 8 codes... Knock sensors, couple misfires, lean condition both sides, Maf or Map? Sensor, O2 sensors.. Whatever, it was eating fuel had no power and ran ****ty, but being my tow machine I had to drive an hour on the highway so I rocked it anyways, got back to the City stop and throw gas in it, start it back up, no oil pressure! Of course me being me I said **** you truck and drove it home anyways (20 min drive) it made it so I left it on the driveway for 2-3 weeks... Had to pick something up so i fired er up again, has good oil pressure, so I drove it for that week, parked it again for a week. Start it up today has good oil pressure drive around, stop for gas again, no oil pressure again! Me being me again I drove the ***** home haha (20 min)

Where should I start? I think my plan is compression test it, if thats good, mech oil pressure test. (where can I hook up?) good or bad I will go from there.. I don't want to throw money at this thing if the motor is ****ed I'd rather swap a Cummins or D-max in it. (Before we all say no, I'm an ex Diesel Performance Tech) Just not sure about this damn 6.0L if its worth fixing or what....

*Drinks a beer or 3*

[Special-Ed]

oil guage does not mean you dont have oil pressure... those dash clusters are soo finicky and they always give odd readings.

if you had no oil pressure your drive train would be screeming lifters clacking rockers clanking

reset the codes after you write down all the codes...

take it for a spin until codes set... 1st code set is first problem you address.... solve that others may go away or then you can eliminate one of many problems.. its just logical troubleshooting

[DjS71]

Its probably intake gaskets and the knock sensors in the valley are corroded ( if its the same kind in the wells between the heads), combination of these two very common problems with these motors can do all sorts of wacky things. If you're going to toss it, toss it on a truck to California for me :P

[Wet..Paint]

Originally Posted by Special-Ed

oil guage does not mean you dont have oil pressure... those dash clusters are soo finicky and they always give odd readings.

if you had no oil pressure your drive train would be screeming lifters clacking rockers clanking

reset the codes after you write down all the codes...

take it for a spin until codes set... 1st code set is first problem you address.... solve that others may go away or then you can eliminate one of many problems.. its just logical troubleshooting

Normally that is what I do, but I can't get a single code to clear out. I erase them all, fire it up, and they are all back again. I did have a dead speedo when I first got this truck and had to change the stepper motor, so with the driving 20+ min with "no oil pressure" and no issues I am thinking a bad gauge / sender. Which is why I want to throw the Mechanical gauge on it. I like the old mechanical junk it's pretty much fail safe instead of this electrical crap! Buddy also said if I had no oil pressure the info center would tell me and it would ding constantly? Supposed to be cold all this week so wont be testing anything soon, she's parked for the summer anyways so whatever!

My old S-10 lost oil pressure on the highway when I had it and I said ff it and drove it home still, never made a sound until it seized up dead a block from my house haha! Was expecting the same with the 6.0L but shes still goin!

I have never had this much trouble with a GM engine before, which is why I think it might be something major.... Hopefully not, if Compression is good and Oil Pressure is good, knock sensors will be changed to start. If oil pressure is no good I'll change the pump, if it's still bad then obviously the bearings are toast and the motor is out! Still need to know where can I hook a mech oil gauge? I know the Cummins, D-max and Powerstrokes like the back of my hand but gassers aren't my thing, the price was right on this one but apparently there was a reason for that......