Strange information from a parts store

" I called a local Mercury par

" I called a local Mercury parts supplier about the correct part number for a water pump rebuild kit. The person who took my call asked me if the bottom piece of the old water pump housing looked like it had melted. I said it did not appear to be melted, but asked the person how that could possibly happen. I was told that if the water pump got too hot, the rubber impeller could melt and stick to the steel insert, and the pump housing could partially melt.

But that didn't really answer my question. How could a water pump that is normally operated submerged in water possibly become overheated? I can see if the motor was run without any water (e.g. water hose muffs) - maybe. This just sounds bizarre.

Anyone ever heard of a water pump being melted?

870xprs "

"Mercurys are not my line of e

"Mercurys are not my line of expertise, however the problem you speak of would pertain to any outboard. If underway, and your heat warning system was faulty or so weak that it wasn't noticed..... and your lower unit picked up a plastic bag, that cuts off the water supply immediately. The results are that the impeller continues to spin at a rather speedy rpm, and the friction actually melts the impeller, making a real mess of everything connected with it.

The other side of the coin is that when you asked for a specific water pump kit, or mentioned the exact engine you have, the possibility exists that Mercury had produced a certain amount of w/pump kits that were faulty... or that the engine itself (if fairly new) had a flaw and Mercury had a recall warranty program in effect to take care ot it.

Hopefully some of the Mercury techs here can shed more light on the statement you received.

Joe "

" I agree with Joe. In additio

" I agree with Joe. In addition to the plastic bag senario, I can add to the theory. I have seen many "experienced" boaters(even pro bass fishermen)start their engines on the trailer just before launching-Out Of The Water! Their reasoning is that they want to be sure everything is OK before launching. Back in Merc tech school(way back!)the instructor told us to attach the flushette even for a compression check. When questioned about it, he had a student drag a dry impeller across his hand to demonstrate the heat generated due to the friction involved. Try it-it does get hot. Most Merc pump bases are a plastic material and will melt if run dry.

I don't know of any recall involved in the Merc water pumps, the parts guy was probably trying to help you get all the parts you needed-and increase his sales. "

" Ok, now I see. The plastic

" Ok, now I see. The plastic bag scenario had not occurred to me. The closest I've gotten to that would be some weed beds I tried to motor through, but the prop usually clogged up with weeds fairly quickly and I shut the motor off to clean it.

Anyway, the plastic bag thing gives me one more reason to install a water temp or water pressure gauge for the motor.

Thanks for the explanation.

870xprs "