Tahoe 6.2 swap

[1994ch]

I have started explaining some of this over in the 6.2 section when I started rebuilding my engine, but I figured I would put it together over here as a lot of this could apply to other swaps as well.
The what: I am starting out with a 1996 4 door tahoe 4X4 5.7 gas with a 4l60e transmission. Pulling the engine and transmission out and putting in a 6.2 diesel with a 4l80e transmission behind it and converting to a 2X4.

The why: There is no better way to learn about something than getting a project going and doing something. I got the tahoe super cheap, did not care for the poor gas mileage (4mpg worse than my truck) and I really like the idea of a diesel tahoe, but the price of one is more than I want to pay, and I prefer the 4 door, so that means I have to make it myself.
I decided to drop the 4X4 because of mpg gains, weight concerns on adding several hundred pounds with a larger engine and transmission, the 6.2 oil pan would interfere with the front axle, and the transmission I was able to get a hold of was 2X4.

Progress so far: I have the engine and transmission mounted (not much hooked up yet) and a long to do list including:
wiring mods, instrument cluster mods, transmission controller (USShift) installation, brake booster, fuel supply mods, fuel tank mods, drive shaft shortening etc................................

 

[1994ch]

Progress tonight was getting Leroy's filter and LP installed, and finishing up moving the modified trans cross member. Had modify the cross member to give the drive shaft clearance on the torsion bar cross member.
Once the drive shaft is trimmed down in length it should fit nicely (it is originally out of my excab long bed parts truck)
Important mod!
Just enough room to slide it out! so I should not have to remove anything to change the filter
moved the transmission support cross member back about 6-8 inches for the 4L80e transmission.

 

[n8in8or]

I would love a 4 door diesel Tahoe. Sounds like a cool project, I'll be following along.

 

[WarWagon]

That's an awful lot of filter weight to support with just a pipe on the Walbro. Diesel vibration IMO will make this a problem in the future. Either *SNAP!* *cough* *Stall* or leaks. Have you removed the screen from the Walbro bowel as the spin on is doing the job now?

 

[1994ch]

The Walbro is sitting on a plate bolted to the frame, and the filter base is also bolted to the frame. Should not be any weight hanging on the pipe. Leroy's filter setup has 3 mounting bolt holes in the filter base (I trimmed the top one off because of the tight fit) so the filter has two bolts through the frame.

 

[1994ch]

Progress tonight was taking the grill and bumper off and getting ready to hook up all the coolers (trans, oil and power steering.)

So far the trans cooler is going ok (have to bend the lines a little bit to fit around a 2" receiver the PO welded in the front)

My oil cooler off the parts truck has some buggered up threads so it looks like I'll need a new oil cooler

@Burning oil will the cooler and line kit you sell for 92-97 engines fit a 6.2 block? And will the cooler fit into the same brackets as the original cooler?

 

[1994ch]

Thinking about the electrical system. I am slowly trying to wrap my mind around which wires I need to keep and which ones I need to cut. My main question right now is a wire or two that runs from the ABS controller to the computer. I assume that the ABS needs a speed signal input, but since I will be using a Quick 4 for the trans, the computer will probably not be able to give the proper signal to the ABS. Are there any guys on here that know these systems and would know what kind of signal I will need to supply to get it to work?

 

[6.2 turbo]

I did a Tahoe swap ,and left the stock computer in the vehicle. It runs the speedometer. I deleted the abs,but probably it would have worked ? The oil pan clears the front diff just fine. I also converted to truck torsion bars and cross member.

 

[n8in8or]

Thinking about the electrical system. I am slowly trying to wrap my mind around which wires I need to keep and which ones I need to cut. My main question right now is a wire or two that runs from the ABS controller to the computer. I assume that the ABS needs a speed signal input, but since I will be using a Quick 4 for the trans, the computer will probably not be able to give the proper signal to the ABS. Are there any guys on here that know these systems and would know what kind of signal I will need to supply to get it to work?

I haven't done the exact swap that you did, but I did do an electronic diesel to mechanical diesel conversion in my 97 Tahoe and I'm using a US Shift transmission controller. My ABS, speedometer and cruise control work fine. I detailed my conversion in this thread including showing which wires I tied into http://www.thetruckstop.us/forum/threads/going-mechanical-with-a-moose-omega-marine-ip.45204/page-11. The only thing that might cause an issue with your conversion is the additional change from 4L60 to 4L80, though I suspect that won't be an insurmountable hurdle to overcome. Based on my conversion, I'm thinking you can remove all engine wires except for the ones that run your water and oil gauges. The tach, I'm not 100% sure how that will work out for you. You may want to find a diesel cluster and then find how the factory ran the wiring from that to the alternator?

 

[1994ch]

Thanks for the link.

The tach, I'm not 100% sure how that will work out for you. You may want to find a diesel cluster and then find how the factory ran the wiring from that to the alternator?

Yes I have a diesel parts truck, so I will be able to use the signal off the alternator, and the cluster.

 

[1994ch]

Got some more work done on this Saturday. I decided that it will be easier to swap the entire harness from the truck rather than patch the original gas harness. This will allow the computer to control the glow plugs, the low coolant light will work with no wire patching.... basically all of the instrument cluster will plug in and work with no cut and splice. Also the 4x4 wiring for the tahoe was making me unsure how well/easy it would be to splice in for the speedometer. And I get to move the computer out of the engine compartment (opening up some free space for something) to under the dash. I am not sure why it took me so long to decide to do it this way.....guess it was not wanting to pull all the wires out of the truck, but the job went much quicker this time (since I learned how to pull the dash on the tahoe) It will not all be easy cause now the cruise control will need more work, and anywhere the tahoe chassis wiring does not line up with the trucks I will have to modify, but I think it should not be to bad.

The dashes are different colors so I will have to transfer the wires over...............

 

[1994ch]

Here is a list of the gotchas that I have run into so far.

When converting a 6.2 v belt to a serpentine belt, requires a different water pump and front cover as the water pumps have a different bolt pattern

If you install the water pump before installing the HB make sure that you do not allow the water pump to sag on its bolts or it will/can hit the HB

A 6.2 flywheel will not bolt up to a 4L80E (mounting the transmission went much faster the second time...)

These I had the joy and privilege of learning first hand the hard way. Just goes to show that searching around and reading up on here is not a waist of time.

 

[1994ch]

Which oil port would you hook the turbo up to? There are the two oil cooler lines, then there is one hole that did not have anything in it when I got the engine (not sure what was hooked up there, if anything) then the plugged hole.

 

[1994ch]

I did a Tahoe swap ,and left the stock computer in the vehicle. It runs the speedometer. I deleted the abs,but probably it would have worked ? The oil pan clears the front diff just fine. I also converted to truck torsion bars and cross member.

What year 6.2 did you swap in? I just went off information, I did not try to fit the engine over the front diff. But my understanding was that the early 6.2's (which I have) had a different pan that would not fit.

Do you have a turbo on it? If so what did you use for the exhaust?

 

[1994ch]

Got one tranns cooler line hooked up and one fuel connection worked out, tonight. Moving like a sloth, but I'm movin........

I also tried to get the accessory brackets installed, but either I misplaced the bolts re-placed them with longer bolts or I am missing a spacer or another bracket cause the bolts that I had with the driverside bracket for the power steering pump and AC compressor are too long. Would anyone have a picture of that bracket, how it mounts? I am really kicking myself for not taking more pictures before disassembly. As many times as I have done this you would think that I would learn.......just a few seconds with a camera can save hours later..........

 

[1994ch]

wholesalegmpartsonline has some great diagrams/parts breakdowns. Think I figured out my problem with the AC bracket. I was trying to use a bolt and it was supposed to be a stud.

 

[1994ch]

Some people sit around and knit................ Others sit around and...........

 

[1994ch]

Tonight's progress was pulling the wires out of the tahoe's harness for the rear hatch and rear window wiper and washer. These wires will be added to the trucks harness that I am swapping with. Most of the swap was easy because the plugs that the wires went to on the tahoe were empty on the trucks harness, so it was as simple as unplug the wire from one and plug it into the other. So far I have only run into one wire who's hole was already taken on the trucks harness for something else, but there is still an extra empty hole in the plug so I will be able to add my own wire to the other side to match it up.

 

[1994ch]

Just curious.... does anyone know what this little box is?

 

[1994ch]

It is taped to the harness under the dash by the steering column.