I'm considering installing my spare 6.9 from 1984 into my van while I work on the 7.3 in the garage. I'm hoping it is a temporary situation for a few months, unless the 7.3 inspection turns up cavitation or cracked block or whatever. There are small differences between the systems (GP relay, etc)

Is there anything that would be a problem for the swap that I should anticipate? Will the engine harnesses work together? Can I use the 1988 GP relay on the 1984 engine? Also, both engines have the same tranny (C6). Should I swap the tranny too (meaning, keep the original transmissions with their respective engines)?

Any other advice would be great.

 

The engine harness should be fairly similar. I don't think that it would be that much different. If you change the glow plugs to ZD-9s you can use the new style glow plug system. I wouldn't think that you would have to keep the transmissions with their respective engines, but I am used to manuals so I am not sure.

 

When I swapped my 7.3 to 6.9 I noticed the 7.3 flywheel had a different part number than the 6.9 one. I used the 6.9 one. I think they are balanced different but I'm not sure and didn't really want to find out.

I did use the 7.3 C6 because the 6.9 C6 was 4x4 and the truck is 4x2.

The 6.9 I swapped in was a 87 so it had most of the 7.3 stuff already on it so I can't help you much there.

 

You can swap it right over, and I would swap everything, even the GP setup. I would also invest in a set of ARP 6.9 studs from Summit while you got it out, and just swap them one by one, I would hate to have HG problems with the turbo and 90 on a bolted 6.9 after you went through the trouble of swapping the engine out, $260 is cheap insurance. Just use the flex plate from the 6.9.

 

Is there a way to tell if the engine already has head studs? The Banks Turbo on it was installed professionally, so I'd expect them to put in the right studs. But maybe not, since this is a van. It's a pain to do that with the block mounted to the frame.

 

Just look at the fasteners and see what they are... original 12 point bolt heads or a threaded stud with a nut. Most kit turbo install jobs ~don't include studs, as they were not supplied nor recommended by Banks. But check it out, a good mechanic may have installed a set along with the turbo.

Swapping engines around in vans is no fun... I feel for you. I pulled my core 7.3 out of a E350 and it was a good thing I didn't care what happened to the van itself, and a really good thing I didn't have to put it back... Can you absolutely not afford the downtime to at least check out your 7.3 before you do the temporary 6.9!install? Seems like an awful lot of work if it's only temporary