3406c model trouble

Pistons retaining too much heat from poor injector performance. It didn't just happen over night, it's progressive destruction.

 

When you say busted do you mean falling apart busted or just cracks in the tops of the pistons? Are the liners scarred in those 5 holes? Advanced timing will cause cracked pistons, and as Bender stated holding heat could be the cause of piston damage also, as to much raw fuel dumped into the cylinder can flush the liner of required oil and let the piston gauld to the liner and jerk a piece out of the piston. Pictures?

 

The cracks you describe are common with advanced timing on a Cat and not unusual. The one piston #6 evidently is cracked all the way through or the liner is scored, the bad nozzles might cause the miss and maybe the smoke, but I don't think it would cause the blowby.

 

When you say advanced you mean more than 17.5° BTDC for a C model right?

Re+arded timing will do it too. Some of the Cs were 11, 9, or 8 degrees from the factory for less soot but they all should be set to 17.5. - disregard the timing hole in the pump cam.




On a side note, I wonder if a bore hole cam would be able to see cracks on the piston top if inserted through the nozzle hole. I think mine's living on borrowed time considering the fires that burned inside when fuel was $1/gallon and I had those big squirters. Black smoke everywhere.

 

Yes a borescope should show the cracks, but make sure to get one with a small enough head, some of the cheaper ones won't go thru the nozzle holes.

 

I did mine by measuring the damper circumference and divide by 360 to get the length of 1 degree. Then I just add what I needed to the factory time and I know how far to turn the crank past the factory setting.

You need a diagram of the front gears and all to know what you are doing and which way to turn things.