Replacing Impeller - Just the impeller or entire assembly?
#21
Registered
If your mechanical fuel pump bolts to your block disregard, but if your mech pump bolts to your impeller housing then follow along-
Unhook the lines from the mech pump and then unbolt it from the impeller housing. In that cavity there is the impeller shaft and on it the cam lobe that actuates the fuel pump foot. This cavity should be filled with merc gear lube, but in some gases gasoline can leak from the mech pump and dilute the oil. This will ultimately result in failure of the fuel pump to do it's job properly. So whenever you pull your impeller you should pull off the fuel pump. pull out the old oil with a syringe or similar and refill with gear lube.
Attached is a pic of my fuel pump after I lost a seal and evacuated the gear oil to my bilge via the v-belts. Different cause, same end result. Please note wear on the pump's foot.
Unhook the lines from the mech pump and then unbolt it from the impeller housing. In that cavity there is the impeller shaft and on it the cam lobe that actuates the fuel pump foot. This cavity should be filled with merc gear lube, but in some gases gasoline can leak from the mech pump and dilute the oil. This will ultimately result in failure of the fuel pump to do it's job properly. So whenever you pull your impeller you should pull off the fuel pump. pull out the old oil with a syringe or similar and refill with gear lube.
Attached is a pic of my fuel pump after I lost a seal and evacuated the gear oil to my bilge via the v-belts. Different cause, same end result. Please note wear on the pump's foot.
#23
Registered
If I have the whole assembly off , I rebuild the whole thing. Housing , impeller, seals , bearings , fuel pump gasket, even the wear collar the cam lobe rides in for the fuel pump. Too much of a pain to remove to not go thru it completely. Do it every other season.
#25
Registered
If I have the whole assembly off , I rebuild the whole thing. Housing , impeller, seals , bearings , fuel pump gasket, even the wear collar the cam lobe rides in for the fuel pump. Too much of a pain to remove to not go thru it completely. Do it every other season.
#26
Registered
iTrader: (1)
Am I the inly idiot to change out the sea pump, start the engine, shut it and the water off only to restart it a few minutes later without the water frying the brand new pump? Brilliant. :|
#27
Registered
If I have the whole assembly off , I rebuild the whole thing. Housing , impeller, seals , bearings , fuel pump gasket, even the wear collar the cam lobe rides in for the fuel pump. Too much of a pain to remove to not go thru it completely. Do it every other season.
#28
Banned
iTrader: (9)
Mercruiser years ago compared their impellers vs aftermarket impellers - Actually and I will agree they found that THEIR OEM impellers pumped the best compared to anyone else. Apples to apples testing. Globe blue implellers did not pump as much water volume as Merc OEM impellers.
#29
Registered
Platinum Member
Always some fuel in cavity - I change mine at the same time I change my engine oil, about every 20 hrs. Replace impeller and housing every season.
#30
Registered
Yes , one seal keeps the water on the water pump side and the other keeps the gear lube on the fuel pump side. They are installed opposite each other, pay attention to the way they face when you press the cam / impellor shaft out. Bam has a good exploded view on their website if you don't have the factory service manual. Bam also sells the manuals, best $ you will ever spend on your boat!