Just joined the diesel fraternity and glad to be here with such a great group of folks. I bought a D250 about a month ago. Great truck and lots of power. Problem is that top speed is about 65 t0 70 mph with right foot putting dent in floorboard. I see several things to start checking from reading thru this forum. Great info. I need to install a boost gauge and egt monitor. My question is am I damaging the truck driving it in this condition? Most driving is less than 50 mph. Only twice since I bought it has it been on the interstate for very short periods (less than 20 minutes each time). Is there any way to check the turbocharger without a boost gauge? Thank You.


89 D250 180000 miles and seems to be just getting broke in.

 

A 3-speed auto, right? They only go about 74mph from the factory. Have someone put the fuel pedle to the floor while you check the throttle linkage to see if you have full travel. It should travel all the way to the stop.

No you are not hurting anything. The stock gov. is at about 2500rpm. The 3-speed auto's could use an overdrive on the highway, but I did get along with mine till I put an overdrive tranny in.

Paul

 

Mine can get up to 85, but it defuels at 80 and can only freewheel to 85 if I'm moving across flat land. (Actually I got the thing to 90 once going down an 8% grade, but at that speed you are beginning to reach the maximum of the Dodge's suspension... )

I thought that all 727 transmissions came coupled to 3.07 open differentials? You might have a bigger gear in there, or maybe it's just the difference of the year. (Although my engine is an 89'...)

Maybe the problem is that you don't have enough miles yet... They get faster as they get older, don't you know...

 

put bigger tires cheap way to fool with the gears get thin ones so they dont hurt fuel mileage

 

I've had mine up to 120 with no suspention problems , at least I dont think there was any.might have 4:10 gears in the old girl, that would hinder the top speed a bit.

 

Your truck isn't stock then. Everything stock the 727 with 3.07 gear truck will not do 80.

 

Actually, it should do just 80 on level freeway. Don't try passing above 70 though if the traffic is heavy. It sounds like the linkage is the problem. First you have to get all the slop out at the pedal and make sure the pedal is getting full travel. You don't want to cut the cable and rely on a stopper. I made a bushing to fir between the stock stopper on the cable and the pedal arm. Some even bend the pedal arm. Then go ahaead and adjust the linkage on the pump so it gets full travel. Make sure the linkage makes contact with the stoppers there when at full travel. If you let the pump stop itself, it can become damaged from the shock. For the other guys, the gears are not interchangeable without machining. The whole axle housing has to be swapped out. This only applies to the 3.07 gear. If you put in the replacement gov. spring it'll help your top end. Don't worry about running at top end frequently, at $3.10 a gallon, you won't like driving over 70 very often.

 

Redleg is right about running top end. It should suck fuel quick 70 and above. I drove mine about 65-67 and did fine. I did not drive 70 much, But I bet I lost 2-3mpg from 65.