1994 Diesel Suburban Build

[deejaaa]

Originally Posted by aardvarcus

......but yes I did put in new oil cooler lines.......

i got mine from leroydiesel yesterday and as well as a new cooler. nice having a supplier close enough to pick up parts from. drove the Jetta and used less than a gallon.
hoping to get them in today.

[aardvarcus]

Slowmover,
Good question. This vehicle is intended to replace my Tacoma as my daily driver. I drive roughly 20K miles a year for work, and then probably 5k miles a year for personal use. The Suburban is at 210,000 miles now. My lifespan plan for this vehicle is about 10 years/250,000 (more) miles at which I would cross another replace/ major repair decision point. My intent is to do the major repair option and continue to keep this vehicle on the road, but time will tell on that front. My driving is mostly highway and always done very carefully.

Deejaaa,
Glad to hear you are replacing the oil cooler lines, the stock ones I took off mine were rough looking and leaking which is pretty typical from what I hear. I also upgraded my oil cooler at the same time I did my lines, got one just like stock except taller.

[aardvarcus]

Made some more progress. Put most of the old interior back in, much of it I want to replace but for now it will do. All seats and seatbelts are back in as well. Hooked up a PWM speed controller to the HVAC fan so now I can dial the fan speed to whatever I want efficiently without resistors.

On the exterior, I reinstalled windshield wipers and cowl. Replaced the exterior window seals which were leaking. Removed factory grill, composite headlights, and light harness and swapped those over to the sealed beam style front end. Truck has an identity crisis between front and rear badging until I can get a GMC work truck style front clip to replace the Chevy one off my parts truck. This swap was in anticipation of a dot legal led headlight upgrade, plus I am one of the few who likes the older/dated look of the sealed beam front end.

Took the Suburban on a trip to a local park. Everything is working well, except the steering. I tightened up the steering gear, but there is slop in the pitman arm to the tie rod.

[COcyclist]

I converted my 90 Dodge Caravan to Ram van sealed beam headlights. Cheap and easy to replace and better lighting than the always hazed composite lights. Looking forward to the LEDs.

[cRiPpLe_rOoStEr]

Originally Posted by aardvarcus

My lifespan plan for this vehicle is about 10 years/250,000 (more) miles at which I would cross another replace/ major repair decision point. My intent is to do the major repair option and continue to keep this vehicle on the road, but time will tell on that front. My driving is mostly highway and always done very carefully.

Body-on-frame vehicles have the advantage of being easier to apply some upgrades when the time for a major repair comes. BTW have you ever considered fitting a more modern engine such as Chevy's downsized Duramax or the Cummins R2.8 if you go for another major overhaul?

[aardvarcus]

Cripple Rooster,

Honestly I picked this project/engine and had already bought them before the R2.8 was announced, had it been around I may have chosen a different project. At the time there were very few “legal” engine swaps, and the fact that the Suburban was a factory diesel was a major deciding point for me at the time. If I decided to pursue a smaller diesel, I would be more inclined to put a R2.8 or similar in a 90’s 4Runner than to continue with the Suburban. But assuming my lifetime prediction is accurate 10 years is a long time from now, so who knows what will be available and what I will need at the time.

Everyone,

In other news, I got the steering linkage, idler, and tie rods dropped out the Suburban, having ordered replacements. Still need to pull the pitman off the steering gear and finish separating the other steering parts. That should take care of my steering slop.

[deejaaa]

another engine option is the 4 cylinder diesel out of the older Isuzu NPR. Leroydiesel put one in his truck. said it had plenty of power but vibrations were harsh.
was selling the entire package but i couldn’t afford it at the time.

btw, got the cooler/lines in. hot idle is 30 psi. i was spared.

[cRiPpLe_rOoStEr]

The problem with the Isuzu NPR engine is that it's not emissions-certified for the same class of the Suburban, which would make ir harder to get it registered stateside. Well, unless you'd have the time to get approval from a smog referee who could give you a waiver claiming this engine would be equivalent to something else actually certified. I have already persuaded some rednecks to not attempt to import Brazilian MWM 4.2L straight-sixes to fit into F-250s and Silverados for this very same reason.

Originally Posted by aardvarcus

Honestly I picked this project/engine and had already bought them before the R2.8 was announced, had it been around I may have chosen a different project. At the time there were very few “legal” engine swaps, and the fact that the Suburban was a factory diesel was a major deciding point for me at the time. If I decided to pursue a smaller diesel, I would be more inclined to put a R2.8 or similar in a 90’s 4Runner than to continue with the Suburban.

Both engines have their pros and cons and, even though a smaller vehicle is likely to be considered as more suitable to the R2.8 than a full-size, it's not a bad choice. Well, even though I still enjoy much of the old-school Diesels that wouldn't require a computer to keep running, nowadays I can't deny the newer electronically-controlled ones also have their merits.

But assuming my lifetime prediction is accurate 10 years is a long time from now, so who knows what will be available and what I will need at the time.

Maybe you won't be even considering an engine overhaul by then. Who knows...

[aardvarcus]

It lives!

So after many short trips to prove it's worth, the Suburban made it's first long trip this morning taking me to work. No issues or problems on the way. I topped of the tank so I can get a baseline after a few trips.

After driving it a bit, I have found some areas that need improved. Below is my short list of currently needed upgrades:
CUPHOLDER!!!
Gearing is to low.
Lack of Aero Mods.
Lack of cruise control.

[aardvarcus]

As I mentioned previously, the gearing is too low, even with 10% oversized tires (LT255/85R16 vs stock LT 245/75R16). This will get worse when I put the planned LT235/85R16 tires on it, but the rolling resistance advantage of the Michelin Defender LTX will outweigh the additional 5-6% gearing loss.

Overdrive is 0.73, gears are 4.10s. RPMs are around 2100 @55, 2600 @70. With the low end torque of the diesel first/low gear on the NV4500 is useless on the street so I launch in second, unlike my old gas 350 truck.

My plan is either to stick with the NV4500 (but have it rebuilt as the 3rd gear syncro is on its way out) and convert the differentials to 3.42 (tallest stock gears) or switch the transmission to the (I’m sure very overpriced) RSG Tranzilla TR 6060 4x4 with it’s 0.5 double overdrive.

With the 235/85R16 tires, my RPMs for the various scenarios are as follows:

OD__Diff_Net _RPM 55_RPM 70
0.73 4.11 3.00 2213 2739
0.73 3.42 2.50 1841 2280
0.50 4.10 2.05 1512 1872
0.50 3.42 1.71 1261 1561

I think the 0.50 overdrive with the 4.10 gears is probably the best option, but I will have to see on price for that transmission. ( I could make it myself, it’s just a Corvette tranny with a SSR output shaft and a custom adapter plate.)