Hauled boat up on trailer today and ran for a few seconds with the lower unit out of the water. How long does it take to do engine damage or impellor damage while running dry??
Gradyrod
Gradyrod
Brad1 said:The best OMC mechanic in this area once told me that it takes about 10 seconds running an impeller dry to begin to cause it damage.
But why take a chance. Just don't run it dry.
I always replace my impellers at the scheduled intervals and the old ones ussually look like new. However, just because an impeller looks like new, doesn't mean it will pump water sufficiently. There can be a fine line between an impeller that provides sufficient water supply and one that doesn't. For example, an impeller that has taken a "set".
As a matter of fact, I just replaced an impeller on an OMC engine that was previously replaced 5 or 6 years ago, but had only been run about 20 hrs since then. But the motor had not been run at all in the past several years. As a result, the impeller took a set. The overheat alarm sounded at slow speed. Replaced the impeller. Sure enough, the old one looked brand new. But due to having taken a set the blades just couldn't provide adequate pressure against the walls of the housing.
An impeller is something you should replace BEFORE it goes bad, not after it goes bad.