compression

[Detroit Dan]

My cousins got a chance to buy a 97 6.5, it came into the shop on a towtruck, smoking badly. Compression check showed zero in number 8, and almost zero in number 7. Smokes like a chimney, but runs and drives great. You'd think if it was down a couple cylinders it wouldn't run so good. Anyway, they don't know what happened but I'd guess a head gasket leak or overheat back there started it all. But maybe a head probelm, valvesprings or something? Because there's definitely no compression, so it's pretty serious.

Anyway, if the customer doesn't want to fix the truck, and we think they won't, he has a chance to get a pretty nice truck that just needs a motor. Maybe a head, but we'll probably do a motor anyway.
So what do you think happened, and what's gone?

 

[BigBlueChevy]

If he has the money to do the motor and your cousin likes the truck then go for it. :thumbsup: Worst comes to worst you make it a project truck!

 

[jrsavoie]

It might be a good start for a Cummins or something.

 

[Matt Bachand]

I wonder if a valve came apart on the rear cylinder's causing no compression, and lots of smoke. Thats what mine did on cyl 7 (Drivers side rear). It was still driveable, in fact I plowed with it like that. Eyes bled from diesel smoke.

It even started unplugged overnight sit at 8df ambients. On 7 cylinders.

I had a valve come apart.

 

[SmithvilleD]

It's sometimes shocking the condition some diesels will still start in.

Years back, we were moving a Gleaner combine down the highway to another field. Along the way, the high-hour engine decided it wanted ventilated & poked several holes in the side of the block via broken rod.

Running terribly & puking oil, we got it off to the side of the road ASAP & shut if down. Then called a dealer mechanic to find out where to open hydraulic valves on the hydrostat trans so we could tow it home.

The mechanic asked if it was running 'til we shut it down (yes), & how far it was from home (~ a mile). He said in his experience, the engine/rotating assembly was already wrecked & he'd bet it would restart & run that far. And it did! with no remaining coolant, 3x big holes in the side of the block, running on 4 of 6 cylinders & two half-rod chunks still battering the block insides like a hammer-mill.

Not suggesting anybody run their 6.5 that''s knocking. It's just sometimes surprising what will run short-term in horrible mechanical condition.

 

[chevyCowboy]

It's sometimes shocking the condition some diesels will still start in.

Years back, we were moving a Gleaner combine down the highway to another field. Along the way, the high-hour engine decided it wanted ventilated & poked several holes in the side of the block via broken rod.

Running terribly & puking oil, we got it off to the side of the road ASAP & shut if down. Then called a dealer mechanic to find out where to open hydraulic valves on the hydrostat trans so we could tow it home.

The mechanic asked if it was running 'til we shut it down (yes), & how far it was from home (~ a mile). He said in his experience, the engine/rotating assembly was already wrecked & he'd bet it would restart & run that far. And it did! with no remaining coolant, 3x big holes in the side of the block, running on 4 of 6 cylinders & two half-rod chunks still battering the block insides like a hammer-mill.

Not suggesting anybody run their 6.5 that''s knocking. It's just sometimes surprising what will run short-term in horrible mechanical condition.

similar thing happend to me with my truck had it towed to brothers house and me and dad could not get it pushed into the garge (about 2* that night) kinda up hill so i said to hell with it and fired it up and ran it inside. i figured with the way it sounded the worst was over!

 

[saturntech95]

Sounds like mine. Cracked piston 7 in half and it still had great power but it smoked like a chimminey and sounded like it had a blown rod bearing. Still started fine in the cold and everything. It had so much blowby that it would blow the dipstick out.