Why no service on fresh water pump?

[Bowdrie]

Originally Posted by MWGDVC

Bowdrie,
A modern timing belt driven overhead cam engine is a very different animal from your old work truck. The water pump on many (most) modern engines is driven by the timing belt. A water pump failure will result in a timing belt failure, with catastrophic results. in order to meet emission and CAFE standards most engines will be interference types. The pistons will collide with the valves, resulting in bent valves, possibly damaged pistons, occasionally cylinder head or cylinder damage. Weigh the risk/reward.

I'll not argue that.
My understanding is that this thread was about the coolant circulating pumps on the smallish diesel engines we typically use in our boats.
Those pumps are typically driven by either a V-belt, or a Serpentine belt that is external and independent to the operating of the camshaft.
I try not to chase down rabbit holes of esoteric "what ifs" which can go-on infinitum.

[Rumrace]

Okay so whole new world of pumps. Ford GM BMW you get a rebuilt or new one. You’d need a 2 ton arbor press to assemble one so parts are not made for the public.
BMW use an awful plastic impeller and the pump is 385$. A rebuilt with a bronze impeller after market 250$. Go figure.
Same goes from pumps you can drop an impeller in eventually expire.

[Rumrace]

I had a pair of Turbo 395. I bought aftermarket pumps cause Cummins has no imagination to increase volume without increase pressure. The impeller is cast but the aftermarket one is bronze with very sharp progressive veins. Push more volume and balanced for its bearing and housing.
They are tricky special tool just for that version of a pump casting. Then the parts are pressed together with a hydraulic press.
It’s been popular to replace Yanmars pumps with electric and I can’t tell you why but it’s not a great idea. It’s an average pump depending on what year or maker of the block. Some have a weep hole most don’t do rule of thumb is 1500-2000 hours. $125.00 rebuilt exchange.
An out board needs an impeller annually $27.00 Average. Yanmar need a pump every 8 years average. Winterizing, dirty bilge, poor oil changing habits and so on anyone’s guess. Maintaining hoses debris in heat exchanger maintain fluid levels all play on the pumps life span. The antifreeze has lubricant in it which expires. Detergents which no longer clean. Like oil they need careful changing
Hope this helps

[Rumrace]

If you want to make your Yanmars cooling system more fun add a Bosch liquid cooled Alternator. It’s water pump is amazing the alternator and pump expire together. Get re- built together. 100$ exchange for a good casting. Bosch actually has a parts list for the beasts for rebuilders. They don’t mention you need $10,000.00 in tools to rebuild one.
Wasn’t designed for boats but monster trucks nascar drag racing and common huge SUV. You can get a V belt on a Bosch they would allow it.
I dirty bilge eats V belt pulleys and starts to chew belts fast. Belt burn. Water cooled alternators can be seen on racing and performance boats back in the late 30’s from Delco. Absolute terrors to rebuild and no parts. Serpentine pulleys in anodized forged aluminum are the ticket. The anodizing is so hard it destroys cutting tools. Runs belt cool and are much better suited 2 speed alternators like a 250/400.

[Searles]

In fact if the engine is installed well under the waterline a centrifugal salt water pump is often used to cool the heat exchanger,some modern centrifugal pumps are in fact self priming,these units have a verry long life ⛵️⚓️