TOPIC: Mercruiser impeller assembly

1977 mercruiser 165, looking to change out the water pump impeller assembly. Is there any way to know which kit part number I need without removing the parts. I have looked at marine engine.com and two different base housing are shown. Wanted to order and then replace rather than vice versa

Get the later kit, it will fit. But you should pull it apart first in case you need other parts.

Actually, the #1 took a different base than the MR/Alpha Gen1.

You need the upper kit 46-96148A-8, T-8 or Q-8. That will give you what you need except for the base. Fits all #1/R/MR/Alpha Gen 1.

Bases rarely get destroyed.

That is true, good point. The later Alpha, R and MR (not to be confused with the earlier 1 drives like your 165) do have different bases but as you say they rarely need replacing. Tops will interchange. BTW when you split the drive to get at the impeller, be careful to replace the little quad ring that seals the oil passage between the two halves. If it leaks, it is goodby outdrive as you will loose the gearlube and the upper gears will strip. Cost you a lot more than the ring would.

What drives me crazy is that most people, owners and mechanics alike refer to this model of Mercruiser as Alpha drives. Not so! There are many variations of this drive dating back from the beginning and outwardly they all look pretty much the same to the unpracticed eye. So when you are looking for parts or even a replacement drive, make sure you are aware there are differences, and use the serial number to identify what you have to avoid confusion. If you can't find it on the engine it is on the decal on the drive, and also under it as well. Find it, write it down somewhere and keep it safe!

Thanks for the Info.....indeed after more research the kit is the 46-96148a8 and I went and purchased the base as well.......hoping for a nice easy install....although probably going to be a pain in the but.....this is cheap insurance so to speak

I just did my impeller this past spring. It's not too bad. Just don't forget about the hidden Allen bolt under the trim tab . I had a duh moment after I had every other bolt out plus the tab removed and it wouldn't separate. I finally squatted down and saw the little devil