My experience with an 1999 w4500 (Isuzu NPR)
My first advice is to get a very thorough inspection performed by an experience, reputable mechanic who is very familiar with NPR; pay the $150-200. if you have a sound and properly maintained NPR,NQR you have a vehicle that is bullet proof up to 300K-350K miles with no major repairs. I have heard some going as high as 500K miles. If you bought a lemon, it will cost you in repairs, more like break your bank!!! My first Advice in ownership of an NPR is to read the owner manual, lots of information that will save you money in long term unnecessary costly repairs. Most diesel motor are unforgiving when it comes to maintenance, so changing and maintaining the fluid level, filters and belts are key. For filters and belts stick with Isuzu.
Starting in the cold is like any other diesel, needs good glow plugs and a strong batteries; come stock with a pair of 750 CA, I recommend to go with a pair of 950 CA or better. In really cold weather like 0 degree F, I like to used my 1000 watt generator portable to warm up the oil pan, because it starts at an instance. In those temperature expect lots of white smoke. The diesel fuel does not completely burn when the motor is cold. Warming an NPR, NQR motor will take a while, so read the manual for cold weather starting. I usually like to warm the motor for a minimum of 8-10 minutes and then drive under 20mph until the temp is within the operating temp. Durning this time you will freeze your butt off in the cabin till the motor reaches operating temperature; Using an 12V electric vest helps a lot. Driving in the snow is no problem, meaning reasonable no problem. With my W4500 I went through 10" of dry snow, but that because I had decent tires for the task. Tire selection is important as it would for any vehicle. In Deep snow, carrying quality chains is also advisable, as with any other truck.
Isuzu are low cost maintenance and gets Excellent fuel milage. They are medium duty rated and tough. Make sure the Suspension and all the points are greased up, otherwise replacing those Kingpins are labour intensive, thus costly as I found out.
Driving an NPR/NQR is a joy with one default, your sitting on top of the front wheel; you will feel the bumps. I have taken my truck on logging roads and the road comfort was not a problem for me, as long I didn't drive aggressive over the potholes. There are some other weakness and the only one I can think of is the alternator which usually gives out at around 150k miles. The dog house will not work because of the cab tilt up clearance for maintenance and motor work.
I have converted my 1999 GMC W4500 into a toy hauler and a custom work vehicle, specific for my business. I wanted a robust, reliable and tough toy hauler/work truck with no down time. Inside the box is simple and comfortable in design. All the electrical, plumbing is mostly marine grade, the stove is a 375 lb commercial grade 30" gas stove; I like to really cook and the RV stoves and most of the RV equipment just don't cut it for me. My 16ft box has a 1600lb lift gate, one side doors with custom aluminium steps, insulated with 1/2 inch plywood that is completely sealed against moister (used a high quality oil paint). A 30,000 btu heater and roughneck air conditioner. For extra noise and cold weather insulation, I place insulation blankets over the doors and ceiling vents. Yes it is an overkill, but I am hard, not abusive, on my equipment and spend 3/4 of my work time in my truck.
I am in a process of building a 2004 GMC W5500 with roughly same configuration, since I have written offf my 1999 GMC w4500 late last year in a MVA.
