Would This Be A Good Engine For A Rebuild Project?

[Poorman]

I met a guy at the parts counter a few weeks back, when I was asking about parts for my "86" 6.9 IDI, he said he and a friend had just bought an "84" f250 with a 6.9. They were going to pull the 6.9 and put in a big gasser, he didn't think much of diesels. I gave him my number and he called last night, said it's coming out this weekend and do I want it for 250.00$, so on a whim I said sure. He talked like it was in decent shape, just been sitting awhile, would turn over but no start, he thinks it only has 160,000 on it but who knows could be 460,000. So it'll be a bit of a surprise package but I know none of the wrecking yards within 100 miles has one so if nothing else it'll have lots a parts, he said it has a brand new alternator on it. My question is, would this "84" be a good one to build back to like new? or were there issues with that year? I'll get a pic of the door tag to see when it was built. My thought was, I have a guy that rents from me that is always 2 months late with rent, he just happens to be an automotive machinist and has a nice shop with his dad, I know he would be up for some trade out. Did I score? or am I a fool?

 

[FrozenMerc]

Sounds like you have a good core to start a build from. I would not build that back to a stock configuration, but plan on a turbo, cam regrinding, and improved injection pump for starters. In other words, figure out how to get more air and fuel into and out of that engine.

We are all fools for messing around with this rusty old junk, that doesn't mean it isn't fun though!

 

[WrenchWhore]

BEWARE. You need to check the block numbers and make sure it isn't the casting that cracks by the block heater. No point IMO to build an engine that has this issue. I sold my 84 reluctantly back when I lived with 3 other roommates and couldn't keep 3 vehicles. After it sold the new owner found that it indeed had a crack behind the starter where the block heater goes. BEWARE.

 

[Poorman]

Thanks, hoping for info on how to tell a newer improved block from an older problem prone block. I know it's very close to the change over.

 

[IDIBRONCO]

Thanks, hoping for info on how to tell a newer improved block from an older problem prone block. I know it's very close to the change over.

Other than the engine serial number, you can tell by looking at the block where the oil dipstick tube passes close by it. The later blocks "wrap" around the dipstick tube more than the earlier ones. This is because the block was made thicker in this area to prevent the cracking. Assuming that the engine in your '86 is original, you can compare the two to see if they're the same or not. Honestly, if the engine is complete and was running the last time it was used, I feel that you will do good for $250. If all else fails, you can swap it in place of your current engine while you build that one up.

 

[TahoeTom]

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[TahoeTom]

If the 6.9 is an 1984 it will have pressed in piston cooling jets/nozzles. That is a deal breaker as a candidate for a rebuild. The bolt in nozzles were an upgrade that allowed the removal and replacement of the nozzles. Pressed in replacement nozzles are NLA and expensive if you can even find them. You may be able to reuse them but the jury is out on that. I have an '85 block with pressed ins and would be afraid to remove them. If it is a good runner it may serve you for years, or as a temporary engine while you rebuild your current one. Most all the internal parts will work with any other IDI 6.9 or 7/3. The heads are 6.9 only. The serial # is at the top of the block on drivers side of the IP gear cover.

 

[IDIBRONCO]

You may be able to reuse them but the jury is out on that.

They can be reused. They have to be pressed out before attempting any machining of the cylinders. The hone or boring bar will hit them and break them off. They are a PITA.

 

[Poorman]

Thanks guys, I'm learning a lot. When he has the engine out I'll go take a look at it. My main concern would be a cracked block. Will it be easy to see a crack around the heater area or is there maybe a trick to make it stand out and easier to see?. I'm waiting for a call back from my machinist friend, I know he has work on these so he will have an opinion about the nozzels. The good news is that I finally found the serial number on my truck "87"dually, 6.9du2u257,344!! That's a good number, right?

 

[IDIBRONCO]

Will it be easy to see a crack around the heater area or is there maybe a trick to make it stand out and easier to see?.

They are usually 2"-3" long so they're are easy to see although sometimes they look like grease on the block when it's old coolant buildup instead.

The good news is that I finally found the serial number on my truck "87"dually, 6.9du2u257,344!!

Since that number is after all of the ones listed above, you have all of the updates. You'll be fine with that block.