Hi all.

I've successfully pulled out a motor with a thrown rod (fist sized hole in the side of the block), and dropped in a used motor.

The body is a '96, and the new motor is a '97, and it went in like a dream. Only a couple of problems to speak of.

First, the oil pressure gauge is pinned all the way to the right. I don't know how long the new motor sat at the wrecker, so I don't know if the sensor is faulty.

Could this problem be attributed to a faulty sensor?

 

This absolutely could be a sensor or gauge issue. When it comes to oil pressure I always say the same thing...Rent or buy a mechanical gauge and see what your pressure is with confidence. Then, depending on what you find take proper action.

 

Yep faulty sensor. Go to the dealer and pick up a new one

 

Will I need to drain the oil to replace it?

 

no but good idea to have a pan underneath to catch any that might be sitting in the port

 

Replace it with your engine cold and you won't have any mess at all

 

You should also beable to check the connector function. While running disconnect the electrical connector. If gauge reads zero/all the way to the left. Then the wiring should be fine. If you have access to a scanner for the OBD system, you can check pressure that was also.

 

If I don't clear up the problem, will the computer shut the vehicle down? I ask because I had been driving it for a couple of days, and the engine just died while I was driving. No bangs, no noise, no nothing. It's like I turned off the ignition.

Now it will crank but won't fire.

Could the computer be killing the spark to prevent any damage because the oil sensor is pooched?

 

No, there is no failsafe design on a bad oil pressure sending unit.You now have 2 problems. Most likely a bad oil pressure sending unit and a no-start.

First, concentrate on the no-start. Try a small spray of starting fluid or gas into the intake. If the engine starts and runs for a short period of time, that verifies that you have spark and your problem is a fuel delivery issue. If it doesn't start with starting fluid, although there are a number of reasons, the primary one is a bad crankshaft position sensor. If you do end up buying one of these, do yourself a favor and buy it directly from a Jeep dealer for the best reliability and longevity. Aftermarket crank sensors are "hit and miss", with a lot of miss.