Water pump impeller clearance

I also just found a part number for a thicker water pump housing gasket to adjust the impeller clearance. It too is in my heavy maintenance class info and not found in the illustrated parts manual otherwise I would have installed one. The spec. on this gasket states the original gaskets are 0.5mm thick and this newer style is 0.8mm thick. I will order one of those and install it and that should put the impeller clearance in the perfect range.

If you have free play back and forth on that shaft replace it. It means it's too worn.

Murray

The gasket change is for all water pump gaskets, there are not 2 different ones.  If you find old stock they are the thinner ones.  All the new parts are now thicker.  

Cheers

Hi Roger.

The free play I am seeing is Axial, not radial; a worn shaft won't create Axial movement. Either the gear is worn thinner, or the housing is worn to create a gap big enough to give more end play. I just wish there was a spec on how much gap (shown on item 14 in the picture in previous reply) is normal. I can't see how replacing the shaft will change this. 

Just to be clear on my method, when I push the impeller in and out, it takes some effort, and I can feel slight movement against the seal spring and then it moves back on its own when I release this pressure. What I am feeling is the drive gear moving back and forth in the gap in the housing. I haven't measured yet, but it is barely enough movement to be felt, I am guessing less than .005" and I can't get any radial movement. 

Thanks for that info, I will check to see which gasket they sent me, most likely the thicker one if that is the norm now.