so mileage and test update-
Yesterday I needed to take a fridge down to a rental property in southern CT from RI. I was excited as this was an ideal test run and shake down cruise.
I went first to a diesel station, and filled to the brim, then drove down to the property, completed the job, and drove back to the same diesel station, same pump, and filled to the brim.
On the way down I did all highway, and the way back I came cross country through hills and two lane back roads. The objective was to see how it performed on both.
I then later went into google maps and duplicated my route to get accurate mileage.
The trip down I traveled 157 miles, and the way back 141 miles for a total of 298 miles. When i filled up I had used 10.14 gallons of diesel, which is an astonishing 29.4 mpg for this thing in its first real trip! The best I had ever done before was 23 mpg, but more typically with the 4.3 the mileage was 18-21mpg. If I had done all highway, it might have broken 30mpg.
This represents a high water mark and I do not believe its sustainable, as the gearing is just not dialed in and its not super easy to drive, too much top end gearing, not enough granny gearing. It got great economy due to the diff, but it could not at any time pull 5th unless downhill and drafting, and is slower than a stock NA 240 sedan, but not by much, mostly first gear.
Most of the trip was done in 4th in 1-1 ratio, and hills are rough with the current gearing and lack of power, requiring you to wind it out a bit and downshift early. One thing I really need is a tach, the sound level is so different in this tin box of a vehicle with most of the insulation stripped and multiple holes in the floor, that im not sure if im running redline, or just barely touching 3grand rpm. A tach will solve this problem.
When I got back and parked the van, I jumped in my DD 240, and was astonished at how peppy it was and how quiet.
As far as temp, the engine maintained a very steady 170 degrees even though it was about 95 all day, and I went over some really bad stretches of road and today am going to to a check of all custom brackets and fastners, as I rattled the heck out of this thing.
Issues noticed are the suspension settled a bit and the camber of the RF tire is horrendous, so bad it actually skids when you make a right hand turn under any speed. An alignment should take care of that.
First gear takeoff is still a real problem. Its hard to describe, but basically its like starting off a regular 240 in 2nd gear. You have to rev high, and still its a slow start, and you are close to the stall line until you are moving a bit. This is my biggest concern at the moment, its definitely drivable, but absolutely not possible to tow with this thing until I improve the gear ratios. First the diff, then Ill see how it does with the transmission, also going to drop tire sizes same time.
I think monday I will be going to the dump, so ill get a new weight measurement after the conversion and see how its changed, and how much heavier this van is than a regular 123.
Im also trying to research what rear end came in the 207D Mercedes TN vans that used the same engine to find an appropriate compromise based on the next weigh in.
