6.9 IDI smoking questions

Numb Nutz

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Good afternoon, Noob here. I was looking at an 84 F350 4x4 8ft dump and plow with an 6.9 and c6 for $1500. The owner says his son was driving it and it started blowing white smoke, drove it home and parked it. They have removed the radiator, starter and alternator in preparation of a motor swap, lost interest, bought another truck. The motor does turn over with a socket and bar on the crank, so it is not seized. It has been sitting for a while, less than 2 years.It looks in good shape, tires, dump bed, plow and such. The cab corners, floors and rockers look to have been done in the last few years, just need finishing. Also home brew 2.5" dual exhaust is fairly recent.

My questions are as follows.

1) I checked the oil and it is dirty. However no sign of coolant, diesel or metal shavings in it. Could the engine be ok even though it was smoking? Another issue besides head gasket/cracked block cause this?
2) If it is ok, what do i need to get it running? These are fairly simple correct? Diesel, air and 2 good batteries and it should run... Its about 45 miles from me and id like to drive it home instead of having it towed

I can fix just about anything with a little bit of knowledge on the subject, on the IDI subject i have none :) Any info will be greatly appreciated and any thing i learn from it, i will be happy to share here

Thanks, Keith
 

FrozenMerc

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1. The engine could be just fine, or it could be roasted. Buy it under the assumption you will be doing a full rebuild and pay accordingly. White smoke can be caused by any number of reasons. Could be a problem with the injection pump or an injector, could be coolant ingestion (bad head gasket, cracked cylinder head, bad intake gasket), or could be oil ingestion (bad valve seal, bad CDR valve, large amounts of blow by, etc).

2. Simple for sure. Good batteries, fresh fuel, and new fuel and oil filters, and you should be able to get it started, assuming there isn't a major fault with the Injection Pump.

Do your research, lots of info on this forum, but nothing tricky about these motors, especially an early NA 6.9.
 

KansasIDI

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Good afternoon, Noob here. I was looking at an 84 F350 4x4 8ft dump and plow with an 6.9 and c6 for $1500. The owner says his son was driving it and it started blowing white smoke, drove it home and parked it. They have removed the radiator, starter and alternator in preparation of a motor swap, lost interest, bought another truck. The motor does turn over with a socket and bar on the crank, so it is not seized. It has been sitting for a while, less than 2 years.It looks in good shape, tires, dump bed, plow and such. The cab corners, floors and rockers look to have been done in the last few years, just need finishing. Also home brew 2.5" dual exhaust is fairly recent.

My questions are as follows.

1) I checked the oil and it is dirty. However no sign of coolant, diesel or metal shavings in it. Could the engine be ok even though it was smoking? Another issue besides head gasket/cracked block cause this?
2) If it is ok, what do i need to get it running? These are fairly simple correct? Diesel, air and 2 good batteries and it should run... Its about 45 miles from me and id like to drive it home instead of having it towed

I can fix just about anything with a little bit of knowledge on the subject, on the IDI subject i have none :) Any info will be greatly appreciated and any thing i learn from it, i will be happy to share here

Thanks, Keith
Diesels, especially old mechanical diesels, will darken their oil 5 minutes after an oil change. Just the way they are.

White smoke, on an IDI, could be injectors. However, head gasket failure is quite common on 6.9s, and block worm can be an issue with the 7.3s. But most 7.3s that were gonna cavitate, have by now. Block worm is possible with any engine, must keep on top of coolant SCAs. Or buy precharged coolant, which I do.

I would suspect head gasket on a 6.9, if there was TONS of white smoke, but old injectors, can also do it. They aren't hard to replace, I replaced the ones on my 7.3 when I went through the motor, my truck originally had a 6.9, which had a headgasket failure. But, I wanted to run boost without worry, so I went the path of the studded 7.3.


Yup, fuel, air, and plenty of cranking power. They aren't hard to work on.
 

Numb Nutz

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Thanks for the fast response! On my gas job when it lunched a head gasket, the oil looked like chocolate milk. Is this not the case with a 6.9? The oil looked fine, just in need of a change.

I have done a bunch of research over the last 2 days and most stuff points to bad return lines/ injectors/ injection pump/water separation filter. I figured id ask the experts on IDI's. I just want to be confident i can go down there with some tools, filters,and coolant and drive it. The more info i have, the more dangerous i become
 

IDIBRONCO

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First, let me say "welcome to the cool kid's club"!
Your best bet would be to do a compression test and then a leak down test if that didn't show anything. Of course it would have to be yours before you'd be able to do that. I agree with Frozen Merc and say to plan to do a rebuild or replacement on the engine. Budget accordingly, plan for the worst, hope for the best but don't be upset if the best doesn't happen since you budgeted and paid for the worst.
 

Reggie f250

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Definitely plan for the worst and hope for the best. I got my 92 f250 for $120. It was going to scrap because the engine was bad. Needed glow plugs fuel pump air and fuel filters batteries and a radiator and it ran good. Done a lot of work on it since then but it's been a reliable truck.
 

Nero

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Sadly most people I know live in either apartments or HOA's that disbar working on your own stuff. So these rigs fall to the wayside here.
It's always nice seeing stories like yours though. These old pigs need a rescuin'
 
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