I have a '88 GMC Sierra 2500 4X4 and I want to change it from a field truck to a road truck. It hasn't been above 15 mph for about six years and I plan on putting it back on the highway doing 60 mph plus. Right now the engine seems old and slow and I'm worried that it's going to blow up or something when put on the road. So, do you think I would be better off putting a new engine in the truck or is there something else I could do to get it back into road shape?
The first thing I'd do is wash it. This truck can't be looking very healthy after six years in the dirt. As far as the engine is concerned, the terms old and slow aren't giving me a lot to go on, but if there is a significant loss of power, diagnose the problem before flipping the bill for a new engine.
After she's running up to par simply go over the basic maintenance items like the belts, hoses and keeping all the fluids clean and full. Yes, there is the possibility of problems developing due to the drastic change in driving conditions, but let's not try and fix anything before it breaks.
Another important area to check out will be the ride quality of your pickup at highway speeds. Its first trip over 30 mph may resemble an earthquake. So let's make sure the suspension is tight and take a good look at the drive axles, shocks, wheels and tires. I'm sure that all those years of off road abuse have taken their toll.