Mercury 525 seawater pump
06-30-2019, 05:48 PM
#1
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Mercury 525 seawater pump
Apparently I need to change the oil in the reservoir of my seawater pump. Can someone tell me how to do that please? Do I just remove the lower plug to drain and fill from the top hole, or remove the top plate and fill from there?
07-05-2019, 09:09 AM
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I just looked closely at my seawater pump, instead of pictures online. My seawater pump has a fuel pump attached to the top on it, and only on plug on the side. I'm assuming that plug is the fill plug? How do I drain the old oil out? Do I just dump it out when I install a new impeller?
Sorry if these are stupid questions. I've had the boat for 3 years and just found out about the required fluid change in the seawater pump.
Sorry if these are stupid questions. I've had the boat for 3 years and just found out about the required fluid change in the seawater pump.
07-05-2019, 09:22 AM
#4
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I had a pair of these that I sold, I dilled and tapped a 1/4 npt hole in the bottom and put the plug in, this way you just remove the drain plug and refill from the upper plug,
07-05-2019, 09:51 AM
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Installing a drain plug is the best way to do this service. Next best way is to completely remove the pump every season then you can r&r the impeller housing, impeller, and the lube in the reservoir on a bench. Use drive lube in the reservoir. On 525/600/700 it is extremely important to consistently run a fresh impeller and housing for 100% water flow, not water pressure, to keep the headers as cool as possible for longest possible header service life.
Last edited by VoodooRob; 07-05-2019 at 09:54 AM.
07-05-2019, 10:06 AM
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07-14-2019, 01:47 AM
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I use a good size hospital syringe, with some clear tubing attached to the end. I fish the tubing into the plug hole suck out as much fluid as I can. Then, switch the clear tubing to a fresh piece and fill syringe with gear lube and push in to fill. Kinda tricky, to fill with one hand and have plug ready to go in the other very quickly. Of note, when you pull the plug, its got like 2 threads, so very short. Have bucket or towels underneath as very thin gas laden gear oil will come flowing out. Its the fuel contamination in the pump fluid that happens as to why it must be changed. The gear lube integrity gets compromised... Good Luck!
