View Full Version : Mercury 70 HP Thunderbolt 1979 Not Peeing at Low Speed

Danielle Lord
05-24-2003, 05:54 PM
" Our Mercury 70 Hp Runs Fine, and Pees at High Speed, but as soon as we bring it down to an idle, or very low speed it stops peeing out the tell tale. It appears to steam. Havn't run it for very ong like this as afraid of burning something up. Any suggestions as to what might be causeing this problem, and how to troubleshoot it. Water also appears to be coming out of the exhaust at low speeds.

Thanks for any help. "

05-25-2003, 06:25 AM
" Water pump impellers are made of rubber.It is not a permanent material and the impeller should be replaced on a regular basis. Water conditions( temperature, silt or sand ) .It is by far the most neglected item and has resulted in many scrapped motors.Not pumping at idle is a sure indication of a bad impeller. "

05-25-2003, 11:03 AM

Sparky is correct, but I would advise you to replace the entire pump.