I am trying to get information about the compatibility of putting a 2001 5.3L engine in a 1991 Silverado C/K 1500 that has a 5.7L engine that needs replaced. Is this a drop in replacement or a major problem to do this?

 

Your 1991 Chevy pickup has OBD I, so an OBD II ECM will be needed for the 2001 5.3 liter motor.

 

Thanks for the detail. So if I take the 2001 5.3L engine along with the ECM OBD II module , this should be close to a plug and play? No issues engine mount or transmission interface issues? thanks again.

 

If you’re still needing answers -

No, this is not close to plug and play.

The locations of the engine/trans mounts might be the same (I can’t say for sure) but the designs are different. The 1991 uses a 3 bolt U shaped steel plate that bolts to the frame mount isolator (rubber) using a single bolt as a pin. The 2001 uses a single piece mount that can’t be separated. At the very least the frame or engine side of the mounts will need adapter plates or bolt relocation. There might be some aftermarket solutions available but I don’t know what’s available.

As for the electronic side, an OBD 1 to OBD 2 swap will require some modifications of the wiring harness and custom programming for the PCM.

The OBD 1 PCM’s were stand-alone controllers - they only focused on engine controls for emissions management (primary function); ABS and/or theft deterrent systems (if equipped); but otherwise no communication was required for them to operate.

An OBD 2 PCM requires communication with at least a body control module to allow the engine to start. The security system (pass lock) from that era will cut fuel injectors off without the anti-theft signal from the BCM.

Again there may be some aftermarket solutions in terms of control module programming or replacement modules, but I don’t know where to go for them.

 

Thanks those are the technical details that I was looking for. So this would be a major job and no guarantee that it would work well at all or ever. Starting to sound like a money pit. I m thinking a new 1991 engine is the way to go to guarantee a proper fit up and successful replacement .

well I guess I’ll just need to sell the good 2001 engine to someone that needs that model .

thanks again

 

As the saying goes “Where there’s a will, there’s a way.”

It wouldn’t be impossible to make the swap happen - I’m sure plenty of people already have - but it wouldn’t be a project to start with the expectation of getting it done in a weekend either. I think a conservative estimate for something like this is at least 6 months, assuming it’s only being worked on a few hours per week.

It’s something that you’d want to plan out on paper as much as possible to figure out what you have vs. what you need and then how to make it happen. That gives you some degree of preparation as opposed to just starting the swap only to run into one frustration after another.

Nothing is impossible for those who desire to succeed.