Mercruiser 5.0 mpi... Urgent water pump help needed please!

[nauticool]

Just commissioning new belt driven sea water pump and it's not pumping. It's been bled and is all fitted below waterline.
I figure I've done one of two things wrong.

Plumbed pump incorrectly. Is the lower 1 1/2" pipe the inlet? I assumed this as it's larger than the outlet, 1 1/4". This is the way I have plumbed it.

Impellor fitted wrong way round. I removed, inspected and refitted it the way it came from dealer.

Please help as on the boat now and want to see if I've solved my overheating issues.

Thanks guys!

[HT32BSX115]

Howdy,

If it's hooked up backwards......it won't pump...


I had to go out in the shop and look at mine..... Inlet is the upper fitting and the outlet is the "bottom" one on my bravo pump...and unless you're running counter-rotating engines and this one is the backwards engine, you have it backwards.....


Cheers,


Rick

[nauticool]

Thanks, I assumed this was the case. Strange the larger hose is the outlet. I now have to step down the 1 1/2" pipe to 1 1/4" to fit the p/s cooler. However my overheating issue is gone

Thanks for your help

Glenn

[Don S]

Without knowing what year, or model or type cooling system or pump, any suggestions are just WAG's.
Post a Merc SN for your engine, and there are links to manuals to find the cooling system layout and what hooks where.