I have an '87 Chevy Step Van with a 6.2 liter diesel and new automatic transmission. It has 170,000 miles on the odometer and runs great. It gets lousy mileage, anywhere from 8 to 11 mpg, and it seems to do much better around town as opposed to highway mileage. It burns about a quart of oil every 2000 miles, and there is often a smell of diesel fuel around the vehicle, but no visable leakage under the engine or fuel tank etc. I don't have a tachometer in the vehicle, but it will only do about 60 to 65 mph max., and then it sounds like it is wound-up and running at a very high rpm. I am wondering if the poor mileage is due to the rear-end gear ratio and if this is why I can only go about 60 mph. It seems "comfortable" going about 45 mph. This step van was origionally a Postal vehicle, so I am wondering if that has something to do with the rear-end gears possibly being so low, it was designed to haul mail, not haul ass? Anyone have any ideas on how to improve mileage? http://www.dieselplace.com/forum/smileys/Disapprove.gif

thanks, hearddee

hearddee, see if you can find the data sticker. A GM dealer can tell you the RR ratio from that or the tag on the rear end. I would bet it is geared low. In any case a step van catches a lot of air. I doubt it will get much better milage. I higher ratio may help if you were to drive it 55, or less. Good luck. Mike

Is that brand new transmission an Overdrive? doesn't sound like it. sounds like a T400 with 4.11 gears. If that's the case your mileage is not that far off.

The fuel return line, the rubber ones on the injectors drip on the exhaust when leaking, many times it will never reach the ground. you shouldn't smell raw diesel at all, you have a leak.