Pics of the carnage: What was the cause?

[WarWagon]

Finally got the engine out and the heads off. #1 is scuffed badly with aluminum welded to the top of the bore. The other 8 are fine.

Both heads have a crack between the valves on #7 and #8 holes.

How does the fire pattern look on the other cylinders? Wondering if this was an engine oil failure, too hot, bad injector, or too much fuel and boost?

Injection shop says the injectors are fine.

 

[bison]

hard to say without knowing how it was run,i guess prolonged high EGT's played a role.
is a piece broke of the precup responsable for that hole?

 

[THEFERMANATOR]

High EGT's or overheated. The injectors would have caused different damage if it was them. The aluminum stuck to the cylinder walls is from the heat that was in the cylinder.

 

[Burning oil]

I/P fuel screw turned up, 14 psi of boost, heat ???

My machine shop says the crack like you have on the heads can be addressed. If you notice on the outside surface of the head are little freeze plugs. In the casting or machining process there is a tunnel that extends from the valve seats out to the outside surface. He said they can bore that out to a precise dia and press fit a rod into the bore. Its not in a water or oil jacket. According to them it works well. Sounded logical to me.

 

[3500GMC]

It's a little hard to tell, but the head looks like it's cracked between the valves.

Also. :smile5:

I've been personally getting to see all kinds of 6.5 carnage lately too.

 

[WarWagon]

hard to say without knowing how it was run,i guess prolonged high EGT's played a role.
is a piece broke of the precup responsable for that hole?

Nothing "broke" to cause the hole. I assume that is a flame cut through the piston.

Rear precups are cracked too. Heads are cracked between the valves. Not looked for other cracks yet.

Best theory to date is engine and oil got hot and scuffed this piston. Maybe synthetic oil would have saved my engine if that is what went on. It would have been 7000 miles since it started using oil quart/500 miles. So it took that long to come apart. Driven hard towing.

I guess the scuff would have caused extra heat in the cylinder esp from oil being present. Maybe it even cracked.

The good news is I found the source of the oil consumption and blowby.

 

[turbovanman]

Nothing "broke" to cause the hole. I assume that is a flame cut through the piston.

Rear precups are cracked too. Heads are cracked between the valves. Not looked for other cracks yet.

Best theory to date is engine and oil got hot and scuffed this piston. Maybe synthetic oil would have saved my engine if that is what went on. It would have been 7000 miles since it started using oil quart/500 miles. So it took that long to come apart. Driven hard towing.

I guess the scuff would have caused extra heat in the cylinder esp from oil being present. Maybe it even cracked.

The good news is I found the source of the oil consumption and blowby.

I would agree, the oil brought the temp up and caused it to melt.

 

[WarWagon]

I would agree, the oil brought the temp up and caused it to melt.

Hot oil at a specific high temperature fails to lubricate. Metal on metal does the rest to cause the "scuff".

 

[Matt Bachand]

Makes ya think a little bit.

Would have synthetic made the difference? At the rate you were adding it, it would have been expensive either way.

Would a squirter block have kept the heat down and protected the piston like more modern diesels have?

Either way, I think this IS a EGT/Temp gauge lesson to all. Unfortunately expensive to one.

 

[WarWagon]

Makes ya think a little bit.

Would have synthetic made the difference? At the rate you were adding it, it would have been expensive either way.

Would a squirter block have kept the heat down and protected the piston like more modern diesels have?

Either way, I think this IS a EGT/Temp gauge lesson to all. Unfortunately expensive to one.

At the rate I was adding oil - too late by then - damage was already done. Would have had to be synthetic before the scuffing happened. That is if the piston simply did not expand too much and run out of clearance.

Further lesson is to change an old fan clutch and get a better than a 6 blade fan before any hard work. Worried that a fan is running too much? Well this can be the result if the fan isn't running. Better for the fan to be running excessively.

 

[bison]

IMO,Not hot oil is the cause,, but the lack of it making it to the top of the piston. A lot of blowby pushes the oil down from between the sleeve and the pistons

 

[NVW]

In another thread you mentioned the hills (mountains) and having your foot in it to climb them without an EGT gauge. I think high EGT's caused that and oil would def. get hot then as well.

 

[bobbiemartin]

Finally got the engine out and the heads off. #1 is scuffed badly with aluminum welded to the top of the bore. The other 8 are fine.

The problem could be you have 9 cylinders. Most 6.5's only have 8! ):h

 

[WarWagon]

The problem could be you have 9 cylinders. Most 6.5's only have 8! ):h

My bad: rounding error… 0.5 busted/burned in half piston rounded up to 1. There are actually 2 pistons in hole #1 after rounding up… :rolleyes5:

9 piston 6.5: Sounds a little funny when running and very hard to start

 

[WarWagon]

Update

Finally put the events together and have the will to post it.

I scuffed and cracked a 6.5 piston over using an old fan clutch. Yup, got hot and then a defective radiator cap, new one, let go suddenly and shock cooled the block. The hoses were collapsed after cool down that evening. So the cap would not release at the proper pressure or let coolant back in.

Per Bill Heath cooling research: water flow is to the #1 cyl first and greater flow to that side. This sudden radiator cap release combined with high temps from a OEM worn out fan clutch and ineffective 6 blade fan caused the #1 cyl to shrink the most with a hot piston and hot thin oil. This chain of events scuffed the piston/rings severely and cracked it. The next oil sample said overheated oil and fix the egr due to soot. Fix egr due to soot the next samples - no EGR on that engine... and TM turned up the boost so there was no exaust smoke. So soot was from cracked and scuffed piston/rings.

The new fan clutch was on the way and replaced the next day. :nonod: I already had a HO water pump, new radiator, 180 T-stat, and new condenser installed.

I got another 7000 hard towing miles out of the engine before the crack burned through and required the engine to be replaced. It was burning 1 quart every 500 miles of oil as well. The engine was a zero blowby engine when I got it and had idle blowby after that day and high oil consumption till it failed.

1st thing you need to do when you buy a 6.5 is get rid of the 6 blade fan and test or replace the fan clutch. If the clutch has crud on the spring or is over 5 years old - $94.00 for a new clutch is cheaper than $1200 (used military 6.2 w/ 30 day warranty.) on up for a used/new 6.2/6.5 engine.