1994 Diesel Suburban Build

[ECO-AKJ]

Looks like it's coming along great!

[grabowski]

Hello Everybody!

I popped over from Diesel Place 6.5 from fellow member deejaay.
Back in August 2013 I picked up a '94 K2500 burb, brought it back to life and strived for 20mph. My Build Thread is '94 Suburban 3/4t 4x4 TD, can't post hyper links yet.
Have you a way to adjust IP timing?
Highest MPG was low 18s. My good friend John at Quadstar Tunning and I were working on economy tune with his custom OBDI switcher.
If you have any questions, feel free to get a hold of me!

Scoty

[aardvarcus]

Fordman,
Thanks for the encouragement.

Grabowski,
Glad to have you here, I spend a lot of time lurking and reading swaps over at diesel place and a few other sites before I embarked on my adventure. I looked through some of your build thread, sorry it didn’t seem to go as planned. I haven’t looked to deep into the timing yet, I have been pretty focused on just getting everything swapped over. I am converting over to mechanical fuel injection using the Optimizer IP that came with my engine, so no OBD interface for the engine any more. I have been able to work out most of the hiccups so far, I was laughing that we both seemed to come up with the same solution to the oil pan (cutting it out) versus replacing the oil pickup. Funny you are going from a Suburban to a Tacoma and I am doing the exact opposite (hopefully).

[grabowski]

Going mechanical will be simple to do with all the right parts and as you are going in with the manual, that will help. My neighbor has a '94C2500 that must have 3.7x gearing, with the auto and she says on the highway, 65mph with cruise control on she sees 23mpg. I have heard rumors of manual tranny 3.4x geared C2500 getting 25-27mpg.

The frontal area of the 2wd is much lower to the ground and a bit of less weight vs the 4wd chassis. With the factory air dam, my mpg did go up.

Why put the heavier and wider 255 tires compared to the 235s?

[deejaaa]

here's what i've heard over the years:
Push in on advance lever with engine at idle. If engine stumbles/fishbites it's set properly. If engine just slows a bit then it's too far advanced, if engine shakes or quites it's too far retarded.

[aardvarcus]

Grabowski,
I mainly used the 255/85R16’s because I had them lying around left over from another project. I like the additional diameter of the 255s, but I have not yet found a tire tread pattern that I really like in that size. So unless a manufacturer decides to produce a less aggressive tire in 255/85R16 I will be using 235/85R16’s on the Suburban when these wear out. I have run several sets of 235/85R16 on my Tacoma, Michelin LTX M/S 2 and Cooper ATW.

Deejaa,
Thanks for the advice on the timing, I will give that a shot when I get it going. I would love to someday switch to the gear driven timing set to replace the chain, as I have heard that will allow you to advance the timing further due to less slop.



Over the weekend I only had a few hours here and there to work on the Suburban. I managed to get the flywheel dust cover on, after some significant modification to make it work with the 6.5L as it was designed for the 350 the NV4500 was previously mated to. I will probably replace it with a milled piece of aluminum in the future, but it should keep gravels at bay for now. I got the starter (and the important rear starter brace) bolted on and the clutch slave cylinder installed.

I used the Humvee 90 degree oil filter adapter in lieu of the stock adapter from the 94 as it positioned the filter a little further from the drivers exhaust manifold, and moved the filter over a bit to drip less directly on the front driveshaft. Also got the transfer case shifter lever reinstalled.

[aardvarcus]

Progress has been slow due to other things taking precedence, managed to get more interior firewall insulation done, clutch master cylinder mounted, and the transfer case shifter. I had some issues with the lower radiator hose, bought a gates stock replacement piece, but it didn’t fit right and rubbed the frame and brake lines. Had to disassemble the piece (where there is a tee fitting in the center) and trim bits off of all four of the ends to get it to fit right without rubbing. That took forever as I had to install it and remove it multiple times until I was satisfied. Got the coolant overflow/reservoir tank mounted and the lines connected to it.

I started inspecting and test fitting the electric fans, as I mentioned in another thread, putting two 18” Thunderbird fans in a 34” radiator means they will overlap a bit on the sides and somewhat complicate mounting, but I don’t want to take any chances with cooling.

[aardvarcus]

Progress has been slow, mainly due to other priorities plus getting myself wrapped around the axle a few times on some details (such as the oil cooler lines) but now I believe I have that resolved.

I have gotten some pretty significant strides made towards the electric fan setup, I ended up deciding to lap my two 18” fans in the middle to get them to fit within the 34” radiator. In order to do that without making the assembly too thick, I cut away at the excess shrouding at the overlap point, leaving myself roughly a half inch of clearance between the fan blades and any other items.

I got the first round of heat welding (melting them together with old soldering iron) the shrouds completed, so the fans are securely attached together. I will have to do a few more minor modifications to get the shrouds to work together well with the core support at the bottom of the radiator as well as any modification to attach them to the shroud at the top.

Anyway, some pictures.

[aardvarcus]

Spent some more time working on the Suburban this weekend. Spent way too much time messing with the oil cooler lines, beyond frustrated on that front. The hoses I put together would have worked but were too thick to route through the gap between the differential and engine without being pinched or rubbing on everything. I didn’t want to have to run them under the differential, so I broke down and ordered PTFE/stainless hose and corresponding AN fittings in -8 size, shouldn’t have any issues routing those. Now I am just waiting for them to arrive, hopefully I can then put the oil cooler lines nightmare behind me.

I did get the radiator mounts replaced with polyurethane, the stock rubber would let the radiator move around quite a bit. Got the AC condenser installed and the bracket for the oil cooler modified to accept my new larger oil cooler.

[deejaaa]

good progress.
i got some tires and had them mounted Saturday.