View Full Version : Impeller debris in engine, 2001 Mobius

06-14-2010, 08:48 PM
I overtemped my motor today, because the impeller died. I couldn't get the RPM's much over idle, and when I finally realized it was overheating, the guage was pegged at 240. Removed the hoses, found debris. Removed housing cover, and impeller was shredded.

Here are my concerns:

1. I don't have a strainer in the water lines. How can I make sure I don't have rubber debris blocking the cooling of the engine? How can I get it out?

2. What concerns should I have after overtemping the engine? Are there any checks I can do? Any inspections? Any worries?

Thanks for your responses,

06-15-2010, 05:01 PM
Here is a thread with almost the same issue.



06-15-2010, 05:10 PM
Here is a thread with almost the same issue.



I did see that, but not much info.

I spoke with a mechanic today. He said the computer was cutting out my engine to protect it during the overheat. So, I feel that I probably did not hurt the engine internals.

I've gotten a new impeller. I took the thermostat housing off, and found no debris. But, I'm having a hard time finding a new theremostat kit with the gaskets, locally. Hard to find parts for the Indmars. It's frustrating, because I'm guessing the kit is sitting on a shelf in the parts room, but I don't have a Mercury number for it.

Mechanic said that if I don't find anything in the thermostat housing or the inlet to the engine water pump, there is really nothing I can do. The pieces will either settle to the bottom of the block, or be blown out the exhaust.


06-15-2010, 05:16 PM
You need to check where the water pump hose runs into the transmission cooler.

06-15-2010, 05:46 PM
Exactly what Phosphor said. Pull the hose on the inlet end of the Transmission cooler. It's got a strainer on the end of that. If any place is going to collect impellar parts, it'll be here. I've found an impellar paddel there once. Just stick your finger in there and feel around. Probably will be a few pieces at least!

Luckily, it sounds like your motor is still in good shape! Chock one up to the good guys!

06-16-2010, 01:08 PM
Good call on the transmission cooler. I had to go to Texas Mastercraft to get the thermostat kit, and that's exactly what the tech said. I guess parts can back flow to the trans cooler.

He also explained that my engine was in "limp" mode, specifically to protect it. I'm confident that the overheat did no damage.

Thanks for you help, guys.

Summary, if you trash your impeller:
1. Change it every year! Or, if you hear a wine from the engine compartment, check it!
2. Check all your water hoses for debris.
3. Remove the thermostat housing, replace the thermostat, and check for debris.
4. Check the transmission cooler for debris.
5. Carry a spare, in the boat.


06-16-2010, 03:43 PM
When I pulled the hose off of the OUTLET side of the transmission cooler, the screen was full of rubber debris. When the impeller fails, most of the debris flows back to the transmission cooler as the water drains from the engine, out of the boat. If I'd not gotten this debris out of the cooler, it would have flowed right into the new impeller, and destroyed it.