85hp force Impeller destruction

[Boathead 1]

Have an 1989 L-force 85 hp. Have over heating problems. Replaced the impeller and w/p housing. The lower unit is in a tub of water with the hose running (no prop) I started the engine with the thermostat housing off to check water flow-had water. Checked thermostat - opened at 146 Replaced thermostat & housing. Started motor & allowed it to run for 3-4 minutes. Over heat alarm went off. Shut down immediately. Removed L/U- impeller destroyed. This is the second one that has not lasted more than 5-minutes. I installed the impeller to turn clockwise-Am at a loss.....Only 2 impellers left!! HELP???

 

[pnwboat]

Re: 85hp force Impeller destruction

Make sure that the lower end is deep enough. To be safe, it should be covered up to the cavitation plate. Are there any signs that water has entered the water pump?

There are two types of water pumps used on your model. Make sure that the housing, base plate, and base plate gaskets are identical when comparing the original and replacements. You can also apply a light coating of grease to the impeller blades to help avoid scuffing upon initial start up. Be conservative on how much you use though. When looking at the impeller blades from the open bottom of the housing, which way are the blades bent?

 

[Boathead 1]

Re: 85hp force Impeller destruction

Make sure that the lower end is deep enough. To be safe, it should be covered up to the cavitation plate. Are there any signs that water has entered the water pump?

There are two types of water pumps used on your model. Make sure that the housing, base plate, and base plate gaskets are identical when comparing the original and replacements. You can also apply a light coating of grease to the impeller blades to help avoid scuffing upon initial start up. Be conservative on how much you use though. When looking at the impeller blades from the open bottom of the housing, which way are the blades bent?

Thanks so much- paragraph 1 nailed it. I saw water out of the thermostat housing so I shut it down and removed L/U.-impeller was ok (I used dish soap on it this time, tried grease & had no luck preiviously) so I loaded the boat up & took it to the lake Monday- I removed the plug on top of the thermo housing to check for water flow, it was good. I took a friend with me (In case we had to row!) chugged around for a little while near the docks waiting for the overheat alarm to go off- it didn't!! Opened it up & cruised at 30 mph to the other end of the lake, which is a couple miles, no problems & caught 2 trout (took the gear just in case we didn't have to row)

I would like to thank everyone that replies to the posts on this forum. This was my Dad's boat & I had no idea what I was in for when I "volunteered" to get it running. With all the topics available I was able to find ALOT of usefull information. Keep it up & happy boating.