496 mag temps

[270cook]

I have an 05 496 mag. With bravo 3 390hrs All stock except captains call exhaust. What I noticed yesterday is while running wot or close to it 4000 RPMs + , my temp teachers high as 186°f . Of course I slow down and came to an idolle the temp went back down to 170 168. While running about 3000 RPMs I have 9 PSI and temp is around 170-175 , which is the norm since I have owned it. I'm around 2psi at idle which has been the norm. I have owned it a year and dealer says new impeller was installed when I bought it. I didn't get a chance to run wot for an extended time the rest of the day. All the temps and psi are from my smartcraft displays. Are those pressures acceptable,? This is the first time I've noticed it. I plan on changing coolant, I don't think it's related , but then I'll know it's fresh. Any advice is appreciated .

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[paulswagelock]

Normal pressures are all over the place. Those seem a little on the low side. On my 496 with a new water pump, and the out drive pulled and new water pick up tube and press in fitting (to cure bravoitis) I am 1-2 at idle, 16 at cruise, and in the 20's at WOT.

boat used in salt water? Heat exchanger clean?

 

[270cook]

Normal pressures are all over the place. Those seem a little on the low side. On my 496 with a new water pump, and the out drive pulled and new water pick up tube and press in fitting (to cure bravoitis) I am 1-2 at idle, 16 at cruise, and in the 20's at WOT.

boat used in salt water? Heat exchanger clean?

Fresh water . I haven't had a chance to check exchanger this season . Opened before winter last year and seemed pretty clean. And have been out maybe 10 days this year.

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[Jeremygavin]

I have had a problem with debris (mostly seaweed) getting stuck in the oil cooler and blocking the water flow. The PS cooler is on the back of the engine and doesn't have any honey comb so the debris goes right through that and oil cooler is the first cooler that has honey comb. If you take the cooling line off the PS cooler on the back of the engine and then the line off the heat exchanger as is comes up from underneath the alternator after it exits the oil cooler and back wash this line with hose water I tend to get stuff out of it every year. I now do this as normal maintenance. This is the issue with not having a strainer on the intake because it is coming through the drive and not through a strainer.

 

[270cook]

Ok I'm gonna open it up tonight and take a look around. I went ahead and ordered new thermostat, and end seals for the exchanger. And will be draining anti freeze, and pulling the raw water pump to have a look see.

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[270cook]

Here is some of what I have found so far. Opinions welcome, think I will be getting a hardin marine stainless pump.

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[paulswagelock]

Those end gaskets do not look very good. New ones are flat....What does the inside look like?
also, pump scoring seems minimal and certainly workable - does the shaft leak or wobble? Not sure I would throw $$ at that.

 

[Jimmy Buoy]

Yikes! Those rubber gaskets look like they were getting pretty hot on the ends of the exchanger.

I've got similar signs on one of my engines. Not anywhere near THAT hot, but about 7 degrees warmer than the other. I know that the pump housing has the same type of wear that you're seeing. Apparently it really affects the pumps ability to pull water in. In my case, I have inboards with scoop fittings on the bottom of the boat. They actually ram the water into the large hoses to feed the pumps while on plane. Yours has a more indirect route to the pump and uses a smaller diameter hose which would only compound your issue of low water flow throughout the system.

After considering the $500 Harding pump, I also looked at a $110 rebuild kit from "Aftermarket Marine" which uses a drop in stainless plate on the inside of the existing pump, a special impeller cut a bit shorter to account for the stainless plate, a new o-ring for the outside of the pump housing, another steel plate to place on the o-ring, and a rubber gasket that fits over this steel plate. Your existing end cap with the water feeds bolts on as usual. This way, both ends of the pump that have all those swirl marks are covered by replaceable stainless wear plates. If the plates aren't too worn by the time it needs service, the impeller + o-ring + rubber gasket is sold as a kit for only $35. I decided to try the $110 option and will report how it goes. Should be getting the parts in a week or so...

Just thought you might like another option since you probably realize like me that just putting in a new impeller isn't going to solve the issue. I have no affiliation to this company either.

 

[paulswagelock]

I have used SS pump repair kit previously with success.

 

[270cook]

The heat exchangers actually very clean from what I thought it would be I found a small piece of seashell and that was it I plan on maybe trying to blow it out it was wet last night when I looked at it. And just make sure there's no instructions but yes the gaskets and thermostat are on the way. I believe the gasket could have been blocking that one hose on the end. I would like to do the cheap fix on the pump, but most people I have talked to online tell me to just get the hardin pump. It is such a pain the get to down there with all that crap on the way, I want it to be fixed when I bolt it up.

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[paulswagelock]

There are some threads with people with failing Hardin pumps - read through them. Seems if you press on the pulley they are more likely to fail, but other failures maybe unrelated as well.
I did a ton of research and came to my decision to replace the pump with OEM this time.
Honestly - your pump did not look as bad as many that I have seen and I am skeptical that is the reason for the issue. I would also be checking the water inlet path from the drive to the pump for obstructions, collapsing hoses, leaks, etc.

 

[270cook]

If it were your boat would you run that pump housing? At minimum I will put a new impeller in it even though that one is good. It is just a pain to get to.

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[paulswagelock]

What does the other half look like? Hard to tell in the pics, how deep is the scoring?
What I did was replace it with OEM, and rebuild the old one with the SS plates and saved it for my spare in case this one wears. Mine was much worse from what I can see in your pics. However, as it turned out, the pump was never my issue anyway. Inlet obstruction was my issue.

 

[Jeremygavin]

I just had 2 Hardin pumps fail with 152hrs of use on the first one and 158hrs on the second one. Hardin stood by the pumps and replaced both of them with brand new ones. They did tell me that I must have ruined the bearings when I pressed on the pulley but I used a threaded pulley press so I don't think it is that. They said that they have a much higher failure and return rate on the pump bearings when they sell them without the pulleys. I paid the extra $70 per pump for the new ones to come with pulleys.