Possible impeller replacement, any damage done?

[borderboat]

Well, I was working on my 1993 Mariner 115 today. When I was done I brought out my barrel, put it under the leg, filled it up with water and fired it up. Ran good, but after a bit no telltale pee!!! I waited nervously and then the temp alarm goes off!!!!!! So I shut it down immediately. Would this indicate it is time to replace the impeller?

Have I done damage to the engine due to lack of cooling?

I just bought the boat this year and don't know when the old owner replaced the impeller last, so I'm gonna do it anyways to be safe. I've been using the boat almost every weekend, and this hasn't been a problem. I have noticed it take awhile before it starts to pee, but I've been told that is because the thermostat has to open up before it will telltale.

Now, I've read some posts that say put it into forward gear before pulling off the lower unit & others that state to leave it neutral. So, forward or neutral? Can I leave the oil in the lower unit? Any other tips would be greatly appreciated.

 

[j_martin]

Re: Possible impeller replacement, any damage done?

Yup.
Nope.
Maybe.
Neutral, with the CFO helping by rocking the engine flywheel with a strong arm. (safest and most likely to succeed for a newbie.)
Yup

hope it helps
john

 

[emckelvy]

Re: Possible impeller replacement, any damage done?

It's unlikely that you hurt the motor since you shut it down right away, and it was carrying little to no load in a bucket. Was the water level in the barrel high enough on the center section to fully flood the lower unit? You may have starved it for water. It's a good idea to have water level at least halfway up the 'leg' (exhaust tower aka center section) and this'll keep the pump well primed and lubed at all times.

Also check your thermostat and poppet. It's definitely time for servicing if you don't know when the impeller was last replaced.

Whatever gear (or Neutral) you leave the motor in, move neither the control lever or lower unit's shift shaft when you have the L/U down. As long as you do this, they'll stay in place and it'll be All Good when you reassemble. This motor does not have the pesky hidden bolt under the trim tab, as do older Inlines etc. But the hardware is likely metric so be ready for that.

Use liberal amounts of Mercury Anti-Corrosion grease or marine-grade boat bearing grease on all studs, bolts, and on the splines of the shift shaft/driveshaft but not the tops. This'll ensure the L/U will drop down nicely the next time.

Use this forum's Search feature and you'll find all sorts of Wondrous info on impeller replacement! And the Repair FAQ section at the root of the repair forums has much valuable maintenance tips and info, check it out.

HTH............ed

 

[borderboat]

Re: Possible impeller replacement, any damage done?

Thanks for the responses John & Ed, I had a sigh of relief knowing that I (possibly) didn't destroy my motor.

So I bought the complete rebuild kit today, assuming that the old one was toast. The old impeller was trashed, and it had also blown out the upper gasket. So all is good and fine, however there is an o-ring that was not in my water pump, and the vague instructions that came with the kit do not show where it goes but states "install all parts included with this kit when servicing any water pump". Is this o-ring for a different year of water pump? If not, where does it go? There is also a big flat rubber washer that sits on the copper tube and get sandwiched between the mid section case & the new water tube seal. Should I leave it in there? There wasn't a replacement one in the kit... Thanks in advance!

 

[awojo]

Re: Possible impeller replacement, any damage done?

that other o ring probably goes to the lube oil line. there is really only 2 things that go to your lower unit gear oil and water. The only other thing that it could be for is the shaft itself?? you'll know if this isnt it won't fit lol. be sure to put the "oil" o ring on if not you'll get water in your gear lube...very bad news. Search on that lower unit for a small indentation where that ring will fit it there. Good luck