Hey guys I am new to the diesel world and I have a couple of questions about doing an engine swap from gas to diesel. I have a complete 86 f250 xlt diesel auto 4x4 donor truck that is beyond saving due to rot. My truck is an 86 f350 460 4spd 4x4 (see sig). I have a bell housing to keep my f350 a 4spd.

Will the 6.9 engine mount bolts line up with the 460s engine mount bolt holes in the crossmember of the frame? Or does it need some fabrication?

What should I do to the engine while its out of the truck?

I will change the rear main seal, glow plugs, valve cover and oil pan gaskets. Is there anything else I should look at or change?

Also I want to delete the air pump, can I do that too without it causing any problems?

Thanks for any ideas.

 

By air pump do you mean the vacuum pump thats mounted under the alternator?
You need that to run the vacuum booster for your brakes, and the vacuum heater controls. Diesels don't pull a vacuum off the manifold like gassers do, so they need an auxiliary vac pump.

 

The motor mount ~brackets (that are in between the motor mounts and the frame cross member) are different. They bolt on. Just use the set from the diesel truck and your engine will sit exactly where it should. Did I understand correctly that you found a diesel bellhousing? You will need one, as well as a 6.9 flywheel and clutch. Also, the radiator core support is different for diesels, you said the donor truck is pretty rotten, is the core support saveable? You might want to look for one if it isn't and you are junkyarding for other things. Not sure if you can use the gasser fuel tanks, you need the sending unit with the return line. The fuel selector valve is different, and if you want to keep your WTS/ WIF light system... well, it's generally a good idea to switch out the entire wire harness, instrument clusters etc., I'm sure there are more details... biggest thing is don't get rid of that donor truck until the swap is complete, running and everything working correctly. That way you don't junk something you need

 

if u might sk y are u swaping in a 6.9 into ur truck

 

Good advice so far. I'd also recommend you drill and tap the driver side manifold for a pyro. A regular pipe plug will work fine until you buy one down the line, but it is worth doing when it's not in the truck. Might also want to replace the o-rings in the oil cooler while it's out.

Also, what gear ratio are you running in your F350?

 

Thanks for all the good advise so far guys! I will be tearing it apart tomorrow to get the wiring harness out and get the engine ready to come out. I will be inspecting all the parts that come out that I will be changing over. I will not be putting the A/C in my 350, but I may hold on to it for future use. The donor truck instrument panel doesn't have the factory tach.

Tec, It is the air pump under the alt. I will be definately keeping that now that I know what it is for. I thought it was some kind of smog pump.

Ford, I will be keeping it until the project is complete for just that reason, I don't want to go hunting for some part that I had but got rid of. Yes I do have a diesel bell and 4spd from an old truck that my cousin got to scrap. I have to get a clutch and flywheel for the diesel. Too bad the gassers dual friction center force won't work, still 80% life left. I have some other parts that I saved from that truck as well including the fuel tank (almost brandy new) and fuel pick up. Thats good to hear that the mounts will change over without modding the crossmember. I will be changing the entire harness since the gas and diesel is just different all together.

joe, The 460 was on its way out. The main bearings were just about junk. When it was at normal temp, the oil pressure dropped to between 2-5 psi! Thats on a mechanical oil press gauge. I talked to a couple different guys that build ford BBs for drag racing and truck pulling and they both told me the same thing about the main bearings. I was going to have the 460 machined and built the right way but it would cost alot more money than I have to spend then I came across the complete diesel truck with an 8' Fisher plow for $300.

Ihateminiumwage, The pyrometer is a good idea. Where would I drill the manifold? Is there a special location? I will change the o-rings when I get it out. I am going to change the intake, valve cover, rear main seal and gasket, oil pan, timing cover, and water pump gasket. If they aren't too bad to get off the exhaust mani gaskets too. This I figure would be the best time to go through and change all the gaskets. There are 3.55s in it. The rear is a locked sterling 10.25 and the front is a straight dana 60. I got the diff info verified from the Ford dealer. I was considering eventually converting the drums to discs on the rear axle.

Heres a few pics of the donor truck. The body mount is not doing a thing on the drivers side. It should be interesting when I pull the fenders off. I just can't wait to be able to drive it again. 3yrs is a long time for it to be sitting as a dang garage ornament!! Hopefully before winter it'll be driving!!

 

Holy salted roads Batman, that's a lot of rust!

What's that gizmo strapped to the dryer and hooked up to the heater hose? Some kine of pre-heater for the coolant?

Joe, what kind of question is that? He's ditching the 460 and putting in a 6.9, that's a win/win!

 

That's a in line block heater tied to the heater box. It heats and circulates the coolant.

 

It has 2 separate heaters in there. There is a block heater and a coolant circulater heater, which is the red thing under the hood. That means I have a back up when 1 of the heaters decide to take a dump on me. Going back out to tear into it some more.

 

I thought I had a picture of my own install, but I guess not. Here's one from another member that I used as a reference.


If you're planning on running those 38s with 3.55s it'll be...interesting. I ran my 37s with my 3.55s, and first gear would lug down pretty bad. Currently with 4.10s and 37s, the ratio works out near 3.55.

 

ihate, Thanks for the picture. I have a better idea now. It looks like it is on the drivers side manifold. I think I will get a pyrometer for when I drill it out.

I ran the 38's with the 3.55s on the 460 and it had no problems leaving the line. I won a few light to light races with that set up, while getting confused looks because it was so quick off the line. I lost count of the u-joints i replaced! The only thing in the driveline I didn't replace is the driveshaft but I think the last time I dropped the shaft, it may have bent or warped.

 

Subscribing to this thread as I'm contemplating the same thing for my '85.
Keep us posted.

 

Wow that looks about like what my 1990 F250 looks like..... damn salt.



Still not bad for 300$!!!


Subscribing as well, love these kind of threads!

 

Ok so I haven't been here for a while due to working long hours so I'll give a quick update on the little work I've done with some pics.

I have removed the dash to get the wiring harness out. While inspecting the cab harness on the garage floor I found 2 wires that were melted. I traced both of them and the first one goes from the light switch to the fuse panel. It is a tan wire with a white tracer. I found a 30 amp fuse in the slot for the lights fuse. That doesn't sound right to me. Seems a little high. Also I found the directional socket in the fuse panel melted and an external directional fuse hanging beside the fuse panel.


The other wire goes from the ignition plug on the top of the steering that puts power to whole truck when key is turned on to start. This wire is red with a blue tracer. I traced it from the plug through the harness down to the trans. It is melted most of the length of the wire. I'm not sure what this wire powers but it is also melted on the current gas harness that will be removed from my truck. Is this a common problem on these trucks?


And that dang buzzer has some melted wires too. Can I get away with not putting the buzzer back in and still having my int lights work? Or do I need to keep it in?

I think I have intermittent wipers here too. My f350 doesn't have this set up on the wiper plug.

 

Sorry, not sure on the wiring issues. I'd just say cut and splice the burnt sections out, and make sure to run fuses in case that was caused by jumper wires.

I ran 37s when I had 3.55s (ended up around 3.08 ratio). It was great for fuel economy on the freeway, but absolutely terrible around town. My engine would lug down in 1st. Swapped a guy straight across for axles with 4.10s, and now I can start it in 2nd if I want (37s and 4.10s even out to about 3.55 ratio) and it gets up and goes WAY faster. Talking to a guy tomorrow about finally getting a 5 speed to make up for the fuel consumption on the freeway...