New Truck(to me anyways)
 

New to this forum from the Square body side.

I just bought a 1989 K2500 XcabLB with the 7600 GVWR and have some issues and questions.

1. The HVAC controls are not working right. The blower is stuck on low. The blower is spinning but the control will not change the speed. The other controls work as far as I can tell. Can anyone point me in the right direction?

2. The BIG problem is that I am only getting 10 MPG at this time. Some of it could be that the truck needs a major tune up and the fan clutch is stuck. I may convert to electric fans if that is easy to do. Can some one give me a REALISTIC mpg figure I can expect or shoot for?

3. The axles are 4.10 ratios. If this is the greatest affect on my gas mileage, I am willing to change to a higher ratio to get better mileage.

4. I am looking at a 94 K1500 Suburban with a blown tranny as a donor vehicle if the ratios are 3.42 or 3.73. Will the axles/differentials swap in without too many problems?

The reason I am looking at the suburban is that I can get a chrome grill and the better instrument cluster as a bonus.

Thanks for any help and pictures will be coming soon!
Steve

Re: New Truck(to me anyways)
 

Bump

Re: New Truck(to me anyways)
 

Uh 10 mpg sounds pretty crappy. I use to have an '88 long box regular cab with a 2" lift and 33"s and I got some where in the neck of 12-13 mpg like that in town and getting on it sometimes. I would start with a tune up like new plugs wires and cap and rotor along with a new fuel filter. As far as the HVAC goes I wonder if you need to replace the entire unit there or if it's something simpler.

Re: New Truck(to me anyways)
 

to answer a few questions,

(1) hvac stuck on low,

it sounds like one of two things. i would check the blower motor resistor. these are a common issue and are not hard/expensive to replace. that is the number one culprit of those symptoms. if that does not fix it, i would check into the switch itself. make sure it is functioning properly

(2) i would start with a tune up first. that will do a lot for you. a realistic mpg is 12 city 14 highway. these engines are not mileage savers but they have good power and are dependable.

(3) is this light 6 lug 2500 or the 8 lug 2500hd? the gears you have are good for towing and low end power but not the best highway gears. my '93 suburban has 3.73 gears and it has good pulling power (this has been the workhorse pulling a '72 stock trailer that ways alot empty) and cruises highway at about 2100 rpm. but keep in mind rpms and mileage depend on the use and where you are driving.

one thing that i love about these trucks is that it does not matter if im driving on the interstate or pulling a loaded trailer, i get 14 mpg. does not matter. i like that i can depend on it.

(4) i can not say if they will swap right over without knowing which 2500 you have, but if it is a 6 lug, should be a direct swap on rear ends. the difference if i remember right is mainly in the suspension. if you have the 8 lug 2500, thats a different cat.

aside from certain drivetrain parts, everything else is pretty much a direct swap and easy to do. sorry for the short novel. hope it helps

Re: New Truck(to me anyways)
 

It is the 6 bolt light 3/4 ton with a 9.5 14 bolt rear end.

12-14 MPG I can live with. My old carbureted truck got about that with light loading. I still want to change from 4.10s to something lower as I don't really need that much lowend torque.

As to the HVAC the control switch does not change off of low on the digital display, no matter which way I push the fan switch.

Steve

Re: New Truck(to me anyways)
 

it should be an esy bolt in swap then and depending on the model, will give you 3.73 gears. it may have the 3.42 gears.

if the display never changes from low and the fan speed does not change, i would start t the switch and make sure it is working first