Merc/Mariner 150 XR4 Repair

[MackDSM]

I recently purchased a boat that had a blown 1991 Mariner XR4 (2.4L) engine on the back. I don't have much experience with outboard marine engines, but pulling on past experience with other (automotive) engines, I would say that a connecting rod let go, or something similar.

There is a hole, clean through both sides of the block. I have found a few sources for parts, and was planning on purchasing a used block and starting to pull parts off the motor, inspect them, clean them, and start putting them onto the replacement block to rebuild.

Are there only certain year blocks that will interchange with my engine? I've been told previously that I can use blocks even from newer engines up to almost current, but I'm not so sure. I'm guessing I can use blocks from XR2's, XR4's and XR6's, since from what I've read, they are basically the same engines with some swapped parts, sleeved cylinders, etc. but I'd really like to know for sure.

Any other advice is also greatly appreciated.

 

[Dukedog]

Re: Merc/Mariner 150 XR4 Repair

You have whats called a "fat" block 2.4. Only year they built it (maybe a few in late '90) and last 2.4. Its a transition year from earlier 2.0, 2.4 to tha newer 2.0 and 2.5 blocks. There a few parts that will be little different. ie: center mains, dowel pin heads, rods n pistons ('93 up), exhaust divider plate, so be careful with what you're trying to replace.

You would be way ahead with a 2.5 drop on, adapter plates and tuner .......................JMO