Piston failure analysis

[97singlecab]

This truck came into my shop the other day with a motor that wouldn't turn over. Upon further inspection I found the #6 piston damaged. I removed the head and found this.

The timing was recently set else where. I haven't measured it yet as I got it apart right at the end of the day. But it appears to be pretty high. Here is what the other pistons look like.

Is it pretty likely that timing is the sole problem here or should I look into other things.

 

[kino_fab]

I've got a VE mtor sitting in the floor with the #6 lokking just like that. Bad injector was the culprit, but it looks like yours maybe a combination of both high timing and a bad injector.

 

[97singlecab]

I was wondering about the injector as well. Anyway to test the injector to see? The tip is a little messed up from the piston.

 

[roachie]

I had one doe the same thing. I assume it was a bad stick.

 

[DISTURBED]

I was wondering about the injector as well. Anyway to test the injector to see? The tip is a little messed up from the piston.

Pop test it, if it doesnt pop and the pintal sticks open it will just roll fuel out of it and never chatter. Looks like a stuck injector

 

[97singlecab]

Thanks for the insights. I'm off to arizona in the morning for the weekend. But I will get that injector tested hopefully on monday and let you know what I find.

 

[golfersmith]

Isn't #6 the one that is most likely to have a failure? Just thinking of posts I've read. I know it is the hottest one temp wise.

 

[madmikeismad]

Isn't #6 the one that is most likely to have a failure? Just thinking of posts I've read. I know it is the hottest one temp wise.

If its a bad injector, it can happen to any cyl.

 

[G1625S]

Advancing the timing adds heat to the coolant, so if the injector tests out good, it would make sense that the cylinder with the poorest cooling would melt down first.

 

[97singlecab]

Well I measured the timing in this motor today and i'm wondering if some one can help check my math. I used a snap-on timing kit with the dial indicator in the number one barrell. This is a 215hp truck with a 913 pump. I measured it at 10mm of travel which is the highest i've ever seen a truck set to. My chart only goes to 8.1 so by my math I get 49.5 degrees of timing this motor is set at. Can someone please check my math make sure thats right.

 

[Smokem]

38°

 

[97singlecab]

Ok I thought that was pretty high. Not that 38 is low. Do you think that is enough to have caused this problem smokem? Also what is the correct math to figure that timing number out?

 

[straight 6 roar]

I doubt the truck would start without ether at 38*, I suppose it could have slipped while driving it last time but I always thought slipping would retard timing not advance it. Did the truck have poor low end power the last time it was running? I'm saying a dribbling injector killed it.

 

[DISTURBED]

No it would start. 38 is a ton if they are driving it at all like more then a mile it will burn up. 24 is as high as i set the timing if the truck is going to get drove any.

 

[97singlecab]

From what I was told it was started and ran very rough. They thought it was loaded up and drove it. From what I can gather it only made it a few miles down the road and the motor locked up.

 

[DISTURBED]

sounds like some body used the wrong cpl to change the timing or didnt know what they were doing in the first place

 

[97singlecab]

sounds like some body used the wrong cpl to change the timing or didnt know what they were doing in the first place

I'm guessing thats exactly what happened.