6.9 Overhaul Kits

[TractorFactor]

I am considering overhauling a 6.9 IDI that I have. I also have a spare engine in case I run into issues with any major components such as blocks and heads. I think that Navastar/International no longer supports the 6.9. Does anyone here know of any place an overhaul kit can be found and bought? I have found rings, exhaust valves and one place that offers gasket kits. I am hoping that my block is okay. The engine that I have seen run before of the two I have was using oil. It ran good, and had power, but used a lot of oil. It is an 87 and possibly has the soft rings in it, which makes sense for oil consumption. It sounded good when running before it was shut down. Any ideas or help at all would be most appreciated. Thank you in advance|

 

[FrozenMerc]

Northern Auto Parts - Sioux City, IA.

I bought a 6.9 rebuild kit from them about 5 years ago (ended up having to replace it with a 7.3 once I found out the block was toast). They still list a 6.9 Master Rebuild Kit on their website.

Northern is my go to spot for any hard to find rebuild kit.

https://northernautoparts.com/engin...gory/Engine-Kits>Ford-Engine-Rebuild-Kits>6.9

 

[IDIBRONCO]

I agree with Northern Auto Parts. I haven't used them for about 25 years, but I haven't built many engines for myself either. The problem I see here is that I didn't see any pistons listed. 6.9 pistons aren't being made anymore. They're getting hard to find. The solution is to have your block bored out to a 4.11" bore and use standard 7.3 pistons.

 

[TractorFactor]

Thank you all for the replies and info. I did find out that HD Kits no longer supports the 6.9 I may look into the bore out for 7.3 pistons. I know that the engine manufacturers were being backed into corners early on when the diesels were first being offered in smaller trucks. Maybe if they had gone ahead and bit the bullet and made the 6.9 block, with a bit more bore, and larger head bolts with a turbo from the factory parts for the engine might still be available. Who knows?

 

[Old-Red]

Boring it out means one is introducing cavitation issues known to 7.3L so there is that

 

[david85]

Well, this sure is depressing. My engine is still doing fine on a 15 year old rebuild but not having pistons available is not something I wanted to hear.

 

[FrozenMerc]

Don't despair too much David. Custom pistons have come down in price significantly over the past couple of decades. Wiseco, JE, Diamond, Ross, RaceTec, etc all make high quality custom slugs. Most of those guys would probably even be able to take a 7.3 piston and turn it down to 6.9 dimensions for even less than a full billet piece.

 

[david85]

That could be an opportunity to have some fun with the design.

I always wanted to try dropping compression by making a deeper prechamber in the piston crown (would have to be careful to maintain minimum crown thickness). The pistons I'm running right now are dropped compression, but that was accomplished by shaving off the flat top. This probably wasn't ideal from a performance standpoint, but I also needed to make sure the reman heads I installed at the time didn't have valve interference issues.

For that matter, I also wanted to open up the prechamber in the head, slightly. Turbocharging would in theory require a little more room to move the extra air in and out of the prechamber.

Years ago, I compared the prechamber of the 6.9 to a similar Mitsubishi IDI turbo doesel (Diesel ranger). Although many dimensions were similar, I could tell the Mitsubishi had added a slightly larger prechamber in the piston crown, which doubled as valve reliefs. In theory, that also allows for more valve lift. And I think the inconel prechambers, and their openings were also slightly larger (the mitsu engine was built for 14PSI of boost from factory). Piston dimentions were all smaller than the 6.9, except for the wrist pin, which was slightly bigger.