I am a new member to the site. I have a 95 6.5 turbo K2500. Factory exhaust pipe, Just with out the muffler and Soot Trap.:ro)

I bought the pickup in january and now I noticed a knock. I thought it was an Injector knock so I put in brand new injectors and the knock if anything got worse. Now When the truck is warm, after sitting for about 30 min when I start it it blows Blue Smoke and chugs, and runs rough for about 30 sec. Once warmed up it runs good but still has a kind of metalic knock to it. The truck only has 105,000 miles on it. I own a 83 6.2 and have always loved it. Until now I loved this one too, now I parked it and started driving my 6.2. Did I make a mistake here. Is this noise in the motor or should I try something else. Thanks

auto or manual transmission? Might want to check you flexplate to convertor bolts and the flexplate for cracks, if you have the auto. I had something like this happen to my 6.2 and didn't find the problem till I was installing the tranny back in. Flexplate holes were enlonged and cracked out. Just a thought.

Oh BTW Welcome

That could cause the knock, but not the smoke.

I had one a very similair complaint, OPS had failed, verify that yours works, while the truck is idling open the drain on the fuel filter. If thats not it, a scanner might shed some light.

I have a 4L80-E Auto Tranny. I have hooked a scan tool up to it and there are no codes.

It's nice to finally get some reply's to my problem. I tried at a different forum before I found this one. I never mentioned a stalling problem but first thing I was told that stalling is a common PMD problem, and I should buy a PDC from duramax.bizhosting.com. I don't have that much money to buy that if it's not my problem. If it has anything to do with my problem I appreciate the help.

Hey Matt Welcome to one of the two best 6.5 site out here! Glad you came over here you need to what the "Steak Sausce guy"!
Something else but you might check is the harmonic balancer they can cause rough rounging but the smoking issue......not sure of. Keep posting and you'll keep getting suggestions. There is a very broad and deep knowlege base here and plenty of good folks willing to share that knowlege.

16ga

what kind of knock is it? real fast like a lifter? or a different knock?

It seems to me that when idling it knocks like it is when one cylinder fires. It's not a fast constant knock. But the mechanic I had listen to it thinks it's in the valvetrain. Also when it knocks it slows the motor down then speeds back up a little bit, over and over.

New Member here. I recently purchased a 97 6.5,automatic. Mine will just shut down going down the road. Never know when it will do it.We checked the fuel pressure, and it is fine and it stays around 4-5 on the guage when it stalls.I've changed the fuel filter which had a lot of crud in it. It ran fine for a day and it started again.There is no code, and the man that sold me the truck conveniently told me later that a mech. told him the brain or something was saying that it had low oil pressure and would shut it down. But the oil pressure is fine.What the heck is wrong!

Sorry MattC I'm new at this meant to post it on the new thread.

New Member here. I recently purchased a 97 6.5,automatic. Mine will just shut down going down the road. Never know when it will do it.We checked the fuel pressure, and it is fine and it stays around 4-5 on the guage when it stalls.I've changed the fuel filter which had a lot of crud in it. It ran fine for a day and it started again.There is no code, and the man that sold me the truck conveniently told me later that a mech. told him the brain or something was saying that it had low oil pressure and would shut it down. But the oil pressure is fine.What the heck is wrong!
Classic PMD but it could be the wiring connections/ground too. I have two in the glovebox at this point waiting to go. I paid ~$20-30 used and they work.

I ran a compression test. All cylinders were over 300 except one. #6 was down to 250 p.s.i. I have been working at it after work and should be able to get the head off today. What should I be looking for in the head.

The head could leak without a crack through the CC's but you might see a reason for the compression loss once it's off.

OK - I am a newer member also , but have a thought .How often did the previous owner change the oil , and what oil did he use ? could he have run the oil too long , let it get low or just crudy ? Could a hydraulic lifter have gotten crud in it and partially collapsed and thats making the sound and the difference in idling up and down . One of my employees drove one of my company trucks ( 6.5 TD ) and this happened to him because he didn't check or have the oil changed on schedule . It had about 120,000 miles on it . I freaked out . I ran some motor flush through it , changed the oil and filter and it solved it . It has now been 45,000 miles and never happened again . I thought this might be worth a shot .

I got the head off and there are cracks inbetween the valves on the front and back cylinders. Also the front and back pistons look alot cleaner than the middle two. Is this because of the cracks between the valves. I one valve in the front and you can see it in where the valve seats into the head. Not sure if I should spend the money to fix the heads or get a different motor and be done with it. Thanks.

Find a machine shop and pressure test the heads . Thats what was causing my 94' to overheat . When i showed the heads to a speed shop machinist , He said that was common on 6.5's to have small cracks but he pressure tested them and said that they were leaking too badly ,so I bought new heads for 1800.00 (ouch) .That was the cost of the heads and new valves and labor to put together . I felt that was expensive , but no one else had time to do it for me . Hope your heads come back OK .

I got the heads back from the machine shop there was a cracked valve and two more valves that had to be replaced. I have the heads back on and should have it done this week. My mechanic told me to set the tdc back to around zero. Im not for sure but I hooked up to the computer before I took it apart and I thought it was set around 5? What is the best way to set it and where should I set it. Thanks.