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Mercruiser 502's Water Pump by-pass

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Mercruiser 502's Water Pump by-pass

Old 05-02-2008, 03:40 PM
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Originally Posted by pasquesi
Can somebody answer my question above? TIA
I would think it has to do with the drag that it creates on the crank.


I put a crossover on my modified 454 and have no issues at all. I am also not running a T-stat right now.
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Old 05-02-2008, 03:44 PM
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Both of my engine builders say to always run T-Stats - unless your running big HP blower motors and plan on turning them over 4500 constantly. But if your the average Joe and plan on cruising at say 3400 - 3600 , you'll never build enough heat to remove the moisture in the crankcase ... so they say.
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Old 05-02-2008, 03:54 PM
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Originally Posted by BY U BOY
I would think it has to do with the drag that it creates on the crank.


I put a crossover on my modified 454 and have no issues at all. I am also not running a T-stat right now.
20 HP? So has anyone dyno tested the same engine with a water pump vs. a crossover and seen a 20 HP increase?
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Old 05-02-2008, 04:05 PM
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Originally Posted by txriverrat2001
Both of my engine builders say to always run T-Stats - unless your running big HP blower motors and plan on turning them over 4500 constantly. But if your the average Joe and plan on cruising at say 3400 - 3600 , you'll never build enough heat to remove the moisture in the crankcase ... so they say.
My temp never gets above 110* and i never have a problem with condinsation in my oil,but i run at 4k most of the time. With that said I do plan on running a 140* this summer.
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Old 05-02-2008, 05:26 PM
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Originally Posted by pasquesi
I just have to ask; is it really possible that the engine driven water pump uses 20 HP? I really find this impossible to believe. I have 3" gasoline powered pumps that we use to pump out foundations and manholes. They move infinitely more water (319 Gallons per minute) than a little belt driven water pump. And the Honda engines on these pumps are only 7HP.

I dont really think its apples to apples ....but to answer your question ......no .....
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Old 05-02-2008, 05:51 PM
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Actually it will run too cold, too much flow. Leave it as is.
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Old 05-02-2008, 10:10 PM
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I doubt you'd gain enough hp to notice a difference. Maybe 5 hp..... maybe ??
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Old 05-02-2008, 11:18 PM
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Pasquesi,
You are right. After re-reading, I was thinking of the seapump when I stated the 20 hp number. I was thinking of running the engine with and without the seapump. That pump is worth almost 20, not the circ pump. A lot of builders will not run the sea pump to get a few extra on the dyno. The circ pump is not worth 20 hp. Glad you caught my mistake. I hate giving false info, even if by mistake. Sorry for any confusion.
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Old 09-27-2010, 06:32 PM
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where could I buy one of these water pump delete kit for 502mpi like just the website???
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Old 09-28-2010, 09:46 AM
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I think your 502 mpi will not respond well to a crossover due to the enrichment function on the EFI that adds fuel when the water temp is cold. If you don't get above a certain temp while running you will end up with poor fuel economy, soot on the transom, plug fouling etc.. Reprogram is possible but a lot of inconvenience for little gain.
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