Hello !

I installed a new impeller kit (upper part of pump, impeller and gaskets) on
a 29 year old Mercruiser 140. The old one was burned and the engine
overheated.
Test by flushing the engine was good.
During a test trip abuot 5 miles in the marina aerea the new impeller
burned again.
We used the old nuts because inch sizes are not common in Europe and must be
ordered from Merc.
And I remember that the long screw of the water pump did not tie (it was
loose).
In my opinion the impeller sucked air(or exaust gas) and overheated because
the bolts were not tight enough or we put a gasket in the wrong position.
The water inlet was not blocked..
Is this a common fault ?
Any ideas welcome!
The boat is still in its place (in the water) in Italy, we can examine it
only in our next holidays in July .
So I try to gather information in this group.
Please excuse my bad English.

Thank you!

Best regards

Friedrich.