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496 HO temp questions


496 HO temp questions

Old 06-14-2021, 12:51 PM
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Default 496 HO temp questions

Hello, I own a cobalt 343 with twin 496. I believe one of them is running a bit hot please see below

running temp: 160
water pressure: 20

running temp: 175
water pressure: 30-35

I'm assuming since pressure is up I may have a bit of a blockage. My questions are should I be concerned with the starboard temp and pressure or is this ok to run for a season? Is 175 something to be worried about even if no temp alarms have gone off? Is there an easy way to trouble shoot this?

Thanks is advance!
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Old 06-14-2021, 04:57 PM
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You could keep running it, 175 is about what mine used to run before I modified my cooling system when I added more HP. Or if you want to, take the end caps off the heat exchanger and take a look. It's easy to do, you won't lose any coolant when you do that. You may find the rubber end cap gaskets are warped and not flat anymore. Replace them along with the small Orings that go on the end bolts. Easy to do. Those heat exchanger end cap gaskets are a common item that cause what you are experiencing.

Last edited by 87MirageIntruder; 06-14-2021 at 04:59 PM.
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SB (06-14-2021)
Old 06-14-2021, 07:52 PM
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I would also check the oil cooler for debris
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Old 06-14-2021, 09:21 PM
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No, you need to get this sorted out. 35 is too high, and could wreak havoc somewhere. First place to check is to order new Heat Exchanger end cap gaskets, remove the end caps off of your Heat Exchangers, check for debris, make sure all the tubes are clear, and re-install the caps WITH NEW END CAP GASKETS. You CANNOT reuse them. Once you remove the end caps, you will see how the gaskets actually go bad, and can CAUSE blockage issues.

Good gasket:
Name:  18-0389.jpg
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BAD gasket:
496 HO temp questions-he2.jpg

Solid info here:

496 HO...full impeller service, stainless pretty much the only option right?
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