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shunter2005 06-27-2021 01:00 PM

Another Hardin SS Sea Pump Question
Have had continuing issues with alarm sounding when coming onto plane and at high speed. Not sure the exact pattern, but alarm stops as soon as the boat rolls over onto plane. Also wife says she hears the alarm steady when running at higher speeds. Cruising is fine. Replaced the OEM pump with Hardin SS pump previously. This condition has been persistent (but intermittent) ever since changing over the the SS pump. New impeller this year and the problem continues. Thinking about going back to the OEM pump as I never had this issue until I went with the SS pump. Working to find the problem, but I just can't help but think it could be this SS pump. Hoping to get the motor scanned in the next week or so.

I have read everything I can find here (and any other forums) and some say they have issues and some say the SS pump has no flow issues at all. I know some have the OEM pump with Hardin SS impeller housing, but has anyone gone the other way and kept the SS pump and gone back to the OEM plastic housing? Did it help any flow issues you might have had? Better yet, has anyone just R&R'd the SS pump with the old OEM Merc pump?

Just a caveat, but I am also checking the outdrive reservoir sensor for issues as well.

techman 06-27-2021 01:45 PM

Assuming a 496? Without knowing what the alarm is, you are throwing darts. What sort of gauges do you have, mechanical, Smartcraft? If this issue is really water pressure or water pressure causing temp alarms then you can dig into this a bit further. There is nothing wrong with the OEM pumps unless the brass gets deeply grooved and you see evidence of water pressure issues. Even with grooved pump housings, there are repair kits, even from Mercury, that replace the stock impeller with a smaller version with wear plates that eliminate the groove problems.

shunter2005 06-27-2021 02:08 PM

Sorry, should have elaborated a little more. 2001 502 mpi. Standard gauges. Seems to have decent exhaust flow as there is plenty of water out the exhaust and the risers are not overly warm. I do have a new water pressure gauge that I am going to install shortly to monitor water pressure in the future, but I just can't help but think that this SS pump could be the issue since it has only happened since I installed it. Never with the OEM pump. Also, the OEM pump is not the brass one, it has the plastic housing. I have a friend who is going scan it in the next few weeks and then maybe we can figure it all out. I am just frustrated with this issue.

F-2 Speedy 06-27-2021 02:31 PM

I think you answered your own question, put the OE pump back on and go boat..........I dont think the stock 502 mag mpi has water pressure gauge which means the ECM doesn't care unlike the 496, 525, it has 2 water temp sensors one for the ECM and the other for the temp gauge, low drive fluid will have a constant alarm tone.

shunter2005 06-27-2021 08:19 PM

I was thinking the same thing, but just wanted to know if anyone had kept the SS pump and went back to the OEM housing. Thanks

Griff 06-28-2021 02:42 AM

Very few things will set off the alarm on a 502mpi. Low oil pressure, high water temp and drive lube.
My guess is your drive lube float is acting up. Merc gear lube turns to pudding like sludge in the bottom of the drive lube reservoirs over time.

shunter2005 06-28-2021 02:48 AM


techman 06-28-2021 07:45 AM

Just curious, why did you install the Hardin pump to begin with?

shunter2005 06-28-2021 12:18 PM

Originally Posted by techman (Post 4795255)
Just curious, why did you install the Hardin pump to begin with?

As it turns out, that is a very good question. Several reasons initially. One, group deal from CPPerformance at a decent discount. Two, idea that no replacement of impeller housing anymore, so less maintenance. Three, it's much prettier than the fugly black pump from Merc. Thinking now, that I should have read all the threads about pump issues BEFORE I bought it, rather than after. Lol..... I had never had any issues with Hardin products in the past, so I had no reason not to buy it.

techman 06-28-2021 03:10 PM

I get it. I've been contemplating R&R my stock unit with the Hardin one too. But, I've managed to just re-engineer the stock pump to suit my needs. Engine bling is such a guy thing, eh? No one will see it, but you feel better knowing that pump is sparkling down there in the bilge!

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