Mercruiser 120 impeller change?

[kd6nem]

I've never had an I/O apart. Would changing the impeller on a Mercruiser 120 be just about like doing the same for an outboard? There are still rubber impellers, right? Always wise to have a manual, though I don't expect to ever do much to this rig (father-in-law's boat), can I get away without having one? Most of the more generic ones are half useless anyway. All advice welcome!

 

[Capt.T]

Re: Mercruiser 120 impeller change?

I changed the impeller on a 120 Mercruiser a few year ago. I would suggest using the manual. It took me about 2 hours to do the work following the manual. I got the lower unit off by myself, but I needed another hand to reinstall the lower unit. It is a bit tricky lining up the water tube and the drive shaft. Changing the impeller was the easy part, putting it back together was more difficult.<br /><br />Good luck with your project.

 

[Blk-n-Blu]

Re: Mercruiser 120 impeller change?

Bearcat, have a look at these instructions:<br /> http://www.mercstuff.com/waterpumpinst.htm <br />Good Luck

 

[kd6nem]

Re: Mercruiser 120 impeller change?

Good link! Thank you both for the tips.<br />I'm getting mixed signals about the correct lube- 90w gear oil or ATF? Anybody know for sure?<br />Do I understand correctly that the mercruiser 120 does not need any sealant applied for reassembly?<br />Will do a pressure test after getting it back together, though sounds like I won't have exposed any of the oil containing areas anyway. If anything this seems a tad simpler than my outboard, although a bit heavier.

 

[Trent]

Re: Mercruiser 120 impeller change?

Its 90w gear oil. Dont use ATF. ATF goes into mercrusier transmissions that have the (normally) Borg Warner Transmission. You dont have one on the 120.<br /><br />No sealant required. Look for the quad o-ring seal on the starboard side where the lower meets the upper. (about mid way)Dont loose it or just replace it with a new seal.

 

[kd6nem]

Re: Mercruiser 120 impeller change?

Thanks, Trent. Would any of these seals be predicted to need replacing anyway, or are most reuseable?