Is there a test to see if the water pump on the engine is still circulating enough water? My engine runs hot and my suspicion of a bad exhaust manifold is not panning out. Looks like they are fine. Not sure if water pump is circulating enough water. Do they get weak over time? Thanks.
Howdy,
In general, marine engine circulating pumps don't necessarily "fail". They might start leaking though.
If one was old enough, the cast iron impeller could be completely rusted away, but if that was the case, the water pump housing, the block, heads, and intake manifold would likely be so rusted that they would impede cooling water flow. If that's the case, it's time for another engine.
It's also important to know if the engine heats up only at high power settings. I.E., it's fine at low speeds and only overheats at cruising or WOT power etc.
In general, overheats are related to either a failed raw water pump impeller or system blockage from a previous impeller disintegration. WHen you replace those impellers, you need to find all the pieces. They sometimes block oil or power steering coolers, or if you're closed cooled, they (or other debris) blocks the heat exchanger.
A good preliminary test is to see if the risers are REALLY hot. poor flow through a riser will make it "too hot to handle" I'E., you cannot place your hand on the riser for any length of time at all. with adequate cooling water flow, you can put your hand on a riser and not get burned.
Now, having said all that, first verify your temp gage. They aren't infallible. Get yourself a one of those inexpensive IR thermometers (Harbor Freight, Enco etc) and point it at your T-stat housing (where your temp sender usually is) and see if the gage is anywhere near close.
It might help of you post your model number and if this is a salt-water or fresh-water (only) engine.
Regards,
Rick
