So I am looking at a 1987 d150 with the 318. The truck is lifted 8in with 35in BFGs. The truck is rusty but it will be a project for the winter and the summer. I have a class in which we rebuild engines so I will work I the engine there.

My question is:
The guy says that it has a bad sensor for the 4x4. What sensor is that and about how much will it cost to get a new one? Does it have to do with the transfer case or the front differential? Could I pull it off a truck that has been scraped or would it be frozen up and not work?

I am 16 but I am mechanicly inclined with this type thing. Also I am working on a limited budget but I am good with finding good parts for cheap.

All help will be appreciated,
Thanks,
Alex

 

To start with a D150 is not 4 wheel drive. A 4x4 is a W150. Which do you have?

Do you have manual hubs, automatic hubs, or smooth caps on the ends of the front axles? Look on top of the left front axle tube near the drivers feet for a housing with a vacuum motor on top of it. Do you have that? You will have to trouble shoot it electrically and mechanically to find what the actual problem is. What are the symptoms of the problem?

 

The truck has auto locking hubs the guy says. Also he said that he can throw it in 4x4 but nothing happens. That's all he could describe it as. He did say it was just a sensor though Seal.

 

There is no sensor that can stop the 4x4 from engaging so I would have to question the owners knowledge/honesty. The only sensor is the switch that operates the dash light and that won't stop the 4x4 engagement. If you can look at the front hubs see if they have a cap that has screws holding it on or if it is smooth with no screws around its outer edge. You can also look for the vacuum motor on the axle tube I told you about. Most of the usual problems with the 4x4 are easily repaired for less than $200.00. There are major things that can cost much more but they are unusual. With the work you are planning this shouldn't be a deal killer but you can use it for a better price. If you don't want to take a chance you could always tell him to replace this sensor he says is bad and add the price of the sensor to the sale price. I will bet he won't take that offer.

 

If I had to guess, Im thinking you have a vacuum Central Axle Disconnect (CAD). You probably have a torn diaphram in it or dried out, cracked vac. lines going to it. As SEAL said, there is no sensor that would cause 4X4 to fail.