Offshoreonly.com - 496HO T-stat

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Bravoitis is when the intake water hose going into the transom assy collapses from corrosion etc. It happens more in saltwater boats but does happen in freshwater too depending on the water it boats in. This is a common problem. Over time the engine will run hotter and hotter as it closes up. Mercury has now redesigned the water hose, so when you replace it with OEM parts it has a plastic tube going through the transom instead of the rubber hose.

https://cimg2.ibsrv.net/gimg/www.off...6afac7c376.jpg

You boat Cumberland… have hilltop clear the oil cooler and the heat exchanger. A solid backflush and removing the output from the sea pump will likely resolve the problem.

I know the lake and problem well.

Quote:

Originally Posted by Sunny32SSR (Post 4903062)

Sunny32SSR,

Honestly, if it’s coming from any lake, it is from Caesar Creek in Ohio. I’ve been boating on Cumberland my entire life and never heard of a debris issue. Cumberland is, by far, the cleaner of the lakes I boat on.

Thanks. Brad.

If you choose not to run a restrictor plate do use a high flow t-stat. Maybe a 120 or 140 and drill an extra 3/16 hole in it opposite one another. They look like this and come in 120 thru 180

Amazon

I agree with the 120 or 140, it will still run warm enough and likely run close to same at WOT. Double back and check with your blower supplier. Nickerson recommended a 120 high flow on my B&M 250 setup. When blower was removed I went to a 140.

Has anyone seen the 140 in this version available anywhere? I dug mine out of my parts drawer where it lived for years, not sure where I got it.

Do your drives have low water pickups?

Quote:

Originally Posted by Brad Christy (Post 4903063)

Quote:

Originally Posted by Sunny32SSR (Post 4903075)

Do your drives have low water pickups?

Sunny32SR,
https://cimg3.ibsrv.net/gimg/www.off...5276a82e5c.jpg

Thanks. Brad.

Put it back together with the 140°F that is recommended. I assume the Whipple thermostat is a high-flow version. Do not run the Amazon version and get the high-flow from CP Performance.
https://www.cpperformance.com/c-123-thermostats.aspx

Quote:

Originally Posted by Rookie (Post 4903147)

Rookie,

Appreciate the input, but I've already ordered the restrictor plate kit and will be calling Hilltop momentarily to make arrangements for the end of the month.

Thanks. Brad.

Quote:

Originally Posted by 87MirageIntruder (Post 4903026)

Yes the restrictor plate replaces the tstat. And you are correct a 1" hole is big, and is the largest one in the moroso kit (comes with 3 plates). If you look at the tstats they have 3 small holes to flow water, and this must be why the 1" restrictor plate works on a 496 cooling system. Meaning for this specific application, its the flow capacity of the tstat that is the limiting factor on cooling, not the heat exchanger itself. If you run a 1" restrictor plate, you'll run about 10-15 degrees cooler than with a tstat of any temp range. I hope I explained that good.

As an example, I just built a 496HO with a whipple for a friend. It has stock heads and a stock heat exchanger. I tried the 120 tstat then the 1" plate. With the plate it idled a few degrees cooler, and at cruise it was 10-15 degrees cooler than the 120 stat. I have a friend in Ohio that has built a few of these 496s also and he has found the same results. I was cautious at first with the concept of running a plate as old school teachings were to never remove a tstat but in the case of a 496 platform it actually works. I wouldn't do it to a completely stock one though, as they run forever if you leave them alone!

Not to hi-jack this thread, but I never knew about the 1" plate. My Whipple 496 has a 120 tstat. During the middle of the summer, it runs about 145-150 degrees running. When I come into a 5 zone, it goes up to maybe 160. I have forged pistons. Any benefits to switching to a plate on my setup?

Quote:

Originally Posted by Don_Juan (Post 4903390)