Motor Swap: 1986 6.9 4spd to 1987 6.9 auto w/ATS

[FlySAR]

My 87' F350 Crew 4x4 6.9 w/ATS finally gave up, blew a head gasket! Prior to that it was burning a ton of oil, I presume blow-by as I could see blue exhaust smoke constantly.

I bought a 86' 6.9 4spd donor truck and according to the owner the motor was rebuilt & has about 85,000. The motor is very clean and runs real well; slight valve cover leak, that's it.

Before I go to the trouble of pulling the 86' and dropping it in my truck I need some input.

1. Besides a compression check what other checks should I or a diesel shop do to get the best idea that I'm putting in a strong motor?

2. I know I need to swap the flywheel & counterbalance (4spd to auto) anything else?

3. Would you recommend sending the turbo into ATS so they can go through it?

Any other helpful hints?

Thanks,
Del

 

[Agnem]

Welcome to the site. Why not just replace the blown head gasket? Your 87' 6.9 has the better glow plug system than what the 86 would have, and some other minor 7.3 add-on's that make it unique.

 

[FlySAR]

I thought about that but;

I was burning a ton of oil before I blew the head gasket, I could see oil dripping/running into my turbo inlet from the hose attached to the left valve cover, so I did a lot of research on this and other sites and everything led to excessive ring blow-by creating the increased pressure, suppose it could be the valve seals, so it seemed that replacing the one head gasket would only fix half the problem and it would be just easier to find a donor motor & do a swap. I also noticed that when I removed the exhaust manifolds, oil was dripping from around the bolts as soon as I loosened them up.

I've read a lot of your posts and value yours and others opinions so if you think the best thing to do is replace the head gasket... I've already pulled the motor out of my 87' but that just makes it easier to work on.

Besides swapping the flexplate/flywheel & counterbalance I did notice the following differences on the 86';

Glow plug connectors are different - electrical harness swap? are the glow plug specs (length/thread size, etc) the same otherwise?

Intake manifold has different IH numbers but appear identical - do I need to swap that?

IP on the 87 seems to have other additions (kick down for auto trans, my 87 had cruise) - do I need to swap?

I'm planning to put the CDR from the 86' somewhere between the crankcase vent hose & turbo inlet (wasn't one before) & I'm thinking I should buy the banks adapter at oil filler instead of the valve cover as originally designed - make sense?

I'm just looking for a reliable running truck again w/ the least amount of dollars & time... I'm willing to spend both, w/in reason, on what's right.

Any & all recommendations gladly accepted & very much appreciated.

Del

 

[Double-S-Diesel]

as for the flywheel just swap em , dont forget to put the spacer that the auto uses on.
as for the wiring/ gps, swap everything from your oriniginal motor.
you will also need to swap the parts on the ip for the trans etc.
as for the intake dont think there is a difference.

 

[towcat]

as for the flywheel just swap em , dont forget to put the spacer that the auto uses on.
as for the wiring/ gps, swap everything from your oriniginal motor.
you will also need to swap the parts on the ip for the trans etc.
as for the intake dont think there is a difference.

+1 to what he said in the above and affirming that there is no engineering difference in the intake.
btw...welcome to the site

 

[FlySAR]

Thanks for the welcome!

I was looking at the two motors for the last 2 hours and...

1. The wiring harness on the donor is in 10x better shape than my rig. Is the only difference the spade-type glow plug attachment, the glow plug controller (which I removed & now operate manually) & the alternator wiring attachment, if so, due to condition it makes sense to me to keep the harness on the donor; am I missing something else?

2. The filler neck/tach assy (cover, not sure of name) is different but it looks like I'd have to pull the IP in order to remove/swap. Never been down that road before so will have to research it. Any suggestions for a good manual, the Haynes I have doesn't cover much diesel.

3. From what I can tell the intake manifold is the same but here are the numbers in case someone here knows different.
1987 6.9 ATS Turbo - 1804357C4 IH RC1A
1986 6.9 (Donor) - 1804357C4 IH RC5

4. There is a vaccum type contraption attached to the throttle assy above the IP on my 1987 but nothing on the 1986, what is it?

As soon as I use up the diesel (probably next weekend) in the 86 the motor's coming out so I'm trying to get everything together.

Any other words of wisdom.

Del

 

[Agnem]

The accessory on the IP is dependent on what transmission you use. E40D's have an electrical one, while the C6 is a vacuum modulator. Manuals have none. I had to ask that question, but your point about oil consumption is valid. I would use whichever motor seems to have the least amount of blow-by, as this seems to be an indicator of general wear levels. Judging from what your saying, the donor motor IS probably your better bet. What will you do with your original engine?

 

[FlySAR]

I'm not exactly sure what I'm going to do with the motor.

I've been pulling items off today & I'm at a point where it probably wouldn't take much to tear it down & look at doing the minimum to get this thing back on the road with good compression/reliability.

On one hand I wouldn't have to pull two motors and it may not cost much to re-ring it & have the heads checked on the other hand I can pull the other motor & have it sitting in my rig in one day, two tops.

I paid $1,300 for the donor truck with plans to use the motor, power steering pump, radiator, & keeping several parts from my motor as spares. Part out whatever else & then haul it to our local salvage yard.

does that sound like the right idea or would you rebuild, buy a radiator & power steering pump & then sell the donor? I can go either way.

Del

 

[Camarogenius]

6.9 in an 87? My 87 came with a 7.3.
Were both available?

 

[Petri317]

Someone may have replaced the 6.9L with a 7.3, otherwise, they came from the factory with a 6.9L and could be had with the 4 speed T19, ZF5-42, or C6.

 

[92F350CC]

That was a crossover year, both were available, just like the 7.3 IDI and 7.3 PSD were available in 94, and the 7.3 and 6.0 were both available in 03.

 

[Diesel JD]

Hang onto the T19 also you can sell it or hang onto it in case you ever want to do a tranny swap. If your glow plug system on the 87 works swap it over, as that solid state system is much better than the 6.9 system. The glow plugs are the same physically except for the connectors, but internally they are very different. The 87 and later with bullet connectors are positive temperature coefficient plugs. The ones from the 86 are probably better if you want a manual system, but if I were using a manual system I would use the AC Delco 12G 12 volt glow plugs with the spade connector from a 5.7 GM which will also fit like a glove and probably never burn out since they are actually designed to take 12v. The ones for the 6.9 and the 7.3 both are 6v glow plugs so that they will hewat up quickly. Also if the donor was rebuilt 85K miles ago it might be a good idea to replace the head gaskets and oil cooler orings since you will have the motor on stand out of the truck. You might throw it in there and have no problems but it would be something I'd be worrying about if it was mine. Good luck. You'll get your 1300 worth easily out of the donor rig.

 

[Agnem]

A running motor is worth about $800, so you might want to at a minimum, fix the headgasket and try to pass it on.