I'm looking at an '84 F350 with a 6.9 and was wondering what issues, if any, these engines have and what I should look for when I go look at it. The truck is 4x4 dually with a 4 speed tranny.

 

ive heard from some that the glow plugs will have issues heating up and mine is having that same issue right now

 

the block heater when used alot wil crack the block. the block casting is waek around it. didnt change untill 85 1/2.

 

I know this entry is kinda late but I'm a newbie, just say'in from experience that the cylinder walls have a habit of pitting in the 6.9, ended up doing a complete rebuild because of this however it's one of the tough ones.

 

cylinder walls only pit when you dont use SCA in the coolant, putting a good diesel additive in the coolant will keep the cylinders from pitting if they havent already started.

 

my dad had a 6.9 and he had trouble with the bellhousing going out

 

When I bought the truck the engine was already gone, my machinist told me about the pitting of the cylinders, I've not heard of SCA additive, is this the same as non electrostatic coolant? I'd like to hear more about this to protect my newly rebuilt 6'9.

 

explain please... bell housing really just connects the tranny to the engine, only moving part directly connected to it would be the clutch fork if it was a manual... unless you overloaded the snot out of it and sheared the bastard in half...

 

The 6.9L have a weak bell house and the clutch fork goes through it or they get a crack and fail, my dad went 2 of them

 

Sounds more like a transmission problem than an engine problem

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SCA is "supplimental coolant addative" put it into diesels to keep cylinder walls from pitting from the outside in due to very high cylinder pressures that diesels produce during ignition and power stroke of the piston. Lines the cylinder walls on the ouside to keep "bubble collapse" of the coolant from going through the cylinder walls. Fleetgaurd DCA60L is what i use.