Okay, I admit it...I'm no expert on these engines! Far from it, in fact...I'm an IDI but by the time I have my current project behind me I'll have learned possibly more than I ever needed (or maybe even wanted!) to know about the venerable 6.9.

So here's what I've got going and a few questions:

My boss recently procurred an '86 F350 crewcab dually with a very tired 6.9. It won't start cold in any weather without starting fluid in spite of new glow plugs and once started, emits a nice cloud of blue smoke. We know it needs a rebuild and with this in mind I decided to rebuild the Banks turbo'd '85 6.9 that I was saving for my '68 F250 so that I would have it ready to go and simply swap it in to minimize downtime on the boss's truck.

The first thing I learned is that 6.9 parts ain't cheap! But $2K+ later we have a rebuild kit consisting of new .030 over pistons and rings, std. bearings, cam and lifters, timing gears, oil pump, full gasket set including the valley gasket. The parts are all Clevite, Perfect Circle rings, Victor gaskets.

The block has been hot tanked and magnafluxed and checked out good, then bored to fit the new pistons and freeze plugs installed. The crank mic'd okay and was polished. The heads turned out to be cracked (each in three places, all through the valve seats) so I'll have to build the shortblock and then pull the heads off the boss's truck and go through them, installing them on the new shortblock before stuffing it back into the truck.

Now, here are a few questions:

1. Is there a good source out there somewhere for the piston cooling nozzles? This has the press-in type which don't exactly look new anymore after getting them out of the block. NAPA doesn't even show them, I can't find them online and the only source I have found for them is the Ford dealer who wants 44 bucks each for them! Owww!

2. Has anybody here ever successfully reused them? I could clean them up and straighten them, and reinstall with Loctite sleeve retainer...but I don't think I'd ever really feel comfortable with them, fearing that one might drop out...

3. The fuel pump eccentric shows some gouging and I'd like to replace it (just discovered it today when I pulled it off the old cam) but again, NAPA doesn't show it. Any other source (other than the Stealership)? Alternatively, has anyone used an electric fuel pump with these engines? How much pressure does the fuel pump need to put out?

4. And now...the pistons. I was doing some research a few weeks back and kept coming across references to the pistons as being a cast piston. The new ones certainly appear to be cast, Clevite TC 2190 is the part number. I would have thought that the turbo version would need forged pistons to withstand the high cylinder pressure (20.7:1 + 10-12 PSI boost = WOW!) but as far as I've been able to discover the original Banks kit was a straight bolt-on with no internal modifications needed. Of course the crown of the piston is probably something like 3/4 inch thick but still...

So today I'm giving the old pistons a good look-over as I remove the rods and see...they look forged (much smoother finish inside the piston) and are made by Mahle. I though forged pistons were all they made anyway. So back to NAPA where I had them look up the pistons again...sure enough, no other option, nothing that specifies turbo or non-turbo. Only the one listing. So I guess my question here is...am I right to be concerned about using these pistons in a turbo application? Or will they be fine?

And of course there's the neat little fact that the exhaust valves and seats are ground to 37.5º and I can't find 37.5º stones for my Souix valve seat grinder so I'll have to re-dress some 30º stones to 37.5º...but that's not a really big deal.

Anyhoo, I'd welcome any answers or advice y'all may have for me on this, my latest ordeal, and here's your chance to show up the ignorant moderator...

Most of my diesel experience is in rebuilding the engine in our Case backhoe, and the Mecedes 190 diesel I tore down and reassembled in high school shop class...but I'm not totally ignorant in the rebuilding of the internal combustion engine

So thanks in advance.

 

Have you tried an IH dealer..... they are usually cheaper than Ford. Plus they built the engine, however some parts they do not stock due to Ford installing them on their block.

 

Contact icanfixall over at OB. He's going thru his motor again. He's VERY knowlageable about these engines, and has many posts of interest for anyone doing a rebuild. He's got the hook up for the correct pistons. And he's a Socal'er

You need the Mahle Forged pistons.
Be aware, to much piston protrusion, and they'll kiss the valves.


"Well my 30 year experienced engine parts man, that I grew up with, said Mahle is oem in those engines. That is what I have found in all the ones I have done. He says DO NOT use anything else.. "

 

I had a nice part by part answer for you.
The site lost my post.



https://www.ford-trucks.com/forums/5...ur-engine.html

Read post #10, that is most of what is done in the engine pictured above.

 

This morning I called the nearest Cornbinder dealer which is almost 2 hours away and found a very knowledgeble and helpful you lady in the parts department who found the nozzles for me Portland @ 29 bucks a pop and the fuel pump cam in Chicago for 31 bucks. All items are on the way, being drop shipped to me.

But now I think I have a new problem:
When we got the block back from the machine shop it was crankcase up on the pallet and we kept it that way when we installed it on the engine stand. Today I rotated it right side up and found that the machist hadn't cleaned ther old gasket grunge, etc. off the decks so I set out to do it and found signs of galling from the head gaskets that I fear may interfere with proper gasket sealing. I'm thinking about sending the block back to be decked about .010 but I decided to mock up the crank and piston and check the deck height first, and found the pistons protrude about .030 above the deck. I can't find any specks on deck height so I'm not sure if this is normal or excessive. If I have .010-.015 taken off the deck I fear I may have to take an equal amount off the pistons. Yet more money... The boss is ticked off at me already as we're now $2700 bucks into this thing and we don't even know if the other heads are going to be any good or not.

Don't know if I can even get the Mahle pistons around here, and I'm sure the boss won't go for it...this gets more fun by the day!

 

I have seen a couple different pin to crown heights in pistons, you just need to seach the specs closely.

I used Sealed Power cast pistons.
They are cheaper, the casting is made out of hypereutectic aluminum, which has a higher melting temp than cast does.
I have over 14,000 miles on my engine running well over 20 PSI boost with lots of fuel turned to it. I also ran a tank of propane through it as a test a while back with no adverse effects.
Use the cast pistons, a better place to spend extra money that makes a difference is get head studs instead of using head bolts.
Makes a much more reliable motor running a turbo on a 6.9 with higher boost numbers.

My pistons were above the deck before I milled them down to lower the compression ratio, but I am out of town so I have no idea how far above they were.

If I remember right they were almost flush after I took .040 off the piston crown.

 

Thanks Dave, that makes me feel a bit better.

Interestingly enough, I did a search for Clevite pistons which took me to a the Clevite/Mahle website. I was wondering if the Clevite pistons were maybe hypereutectic but I haven't uncovered that info yet. I wasn't aware that Clevite and Mahle had a partnership.

 

Read this: http://www.oilburners.net/forums/sho...ht=piston+talk


Dave is right on, with the Head Stud comment.

 

Thanks, interesting read...though I don't really like to go anywhere but FTE for my Ford truck info...

Got some more things to think about and phone calls to make today, it looks like...

Thanks everyone for all your input thus far!

 

Then your missing out on tons of usefull info, that could save you lots of time, money,headaches.

The guys over there are a wealth of knowlage. They don't frequuent here because of heavy moderation, ads, ect.

I do have to admit, the moderators here, in the IDI section, are pretty darned good.
But being on dialup, it's hard to surf here at any type of speed. There's just to many fancy ads.