I've been doing the timing belt and water pump on my 1990 E33A Galant GLSi hatchback with a 4G63 SOHC 8V engine.
I checked all the part numbers in the catalogue and ordered parts using the numbers. However, the water pump does not fit 100%. It's a Valeo 506617 and it should be compatible with my engine according to them, but I've got two issues with it.
First, the pipe won't go all the way in, and it seems like it is flush with the neck of the water pump. The old pump was slightly longer in the neck where the pipe inserts.
The image shows the water pump flush with the block, and the pipe is completely fastened with the original mounts, so it's not just pushed further back.
Second, the bolt holes for the pump is slightly different in that there is a short bolt on the new pump where there was a long bolt on the old.
I opened the parts catalogue and noticed this difference between SOHC and DOHC versions of the pump, see the drawing below.
It seems like I have the alleged DOHC version according to the bolts, but not the squared off end since mine is round.
Now for the confusion, the catalogue doesn't differentiate these part numbers, and I don't know which is which. There are two part numbers under "Water pump kit", MD997430 and MD997622, but wherever I look I see them as compatible with each other? On Amayama, MD997430 is permanently discontinued.
I've also tried googling both part numbers and check if I can see the distinctive differences, but I see some with two long bolts and some with one long bolt on both numbers. Also, it's quite hard to check if the pipe neck is long enough, but it looks to be as short on all of them.
The site I bought the water pump from lists it as a replacement for these part numbers:
I've looked at my 1985 L200 with a SOHC 8V and it has a completely different pump where a hose connects to the end, and a smaller pipe connects at the side. Probably due to it being mounted the other way as it's RWD/4WD. I also tried to look at the pump in my 1991 Galant GTi with a DOHC 16V but unfortunately I cannot see much due to the servo and pulleys being in the way.
So I think I need help, maybe someone else has experienced this. Unfortunately there are no stores nearby that sell Mitsubishi parts, so I have to order online, and that's pure gambling when there could be differences between parts. My only last resort would be to go to a Mitsubishi dealer and ask them if they could buy an original pump, however it's going to be expensive.