www.iFourWinns.com

My 190 Horizon has a fuel injected 302 and runs at 140 degrees F. That seems cold when compared to over 200 degrees that my truck runs at. Why is it that boat engines run so much cooler?

I have had overheat issues with my 460 V8. So I recently installed an electric temp gauge.

How do I know whether or not it is accurate?

What is the maximum allowable temperature, in degrees Farenheit? At what point do I become concerned and turn off the A/C and crank the heater? (There are many different opinions on this topic.)

Thanks, Steve

140 is low. 175 seems to be the norm for fresh water cooled motors. That tells me your T-stat is open, possibly blocked open by debris. If it was me, I would run the boat on the muffs (clean water) to flush the system until temps stabilize, and see what that is. Then pull to inspect/replace the T-stat. It's an easy, inexpensive job, and as a Ford owner that's common place. My boat is 7 yrs old and has not needed it replaced yet, only flushed. However, I do have a replacement ready for that day.

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Walt B
"Debt-Charged"
Black '07 H210SS
6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.

Because they have a constant supply of 70-80 degree water running thru the engine/manifolds. In a closed cooling system (radiator), it is the same water run thru the block and back to the radiator to be air cooled.

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

It has always run at 140F, (maybe a little over but certainly not 175.) I replaced the thermostst 4 or 5 years ago because I was seeing elevated temps.

R, Steve

What was the "elevated temp"? I agree with Walt, sounds like your T-Stat is open. Try replacing it, they are relatively cheap and easy to install. 170 seems to be the "sweet spot" for my engine, runs like a champ.

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

On Monday mine was running where it always does around 170
until about the last 15 minutes I was out. Then it was about 140.
I'm assuming my thermostat is messed up and ordered one today.

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2002 Horizon 190 5.0gl

Actually, mine has dropped a few times as well. Usually this time of year (start of season), when the water is barely 50 degrees. Try it a few more times and see if it drops.

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

I was going to let it warm up again just to make sure and take it's temperature.
Don't remember it dropping that much in the past.
It's the original one so I figure wouldn't hurt to at least have one handy.

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2002 Horizon 190 5.0gl

Well since you asked, in an open or raw water cooled system the coolant is not under pressure like in a closed system or in vehicles. That 15 lb pressure cap and a 50/50 mix of AF and water raises the boiling point to about 265*F. In an open non pressurized system you can get localized boiling in the hotter parts of the system as low as 200*F. So most newer engines use a 160 stat to keep it cool which allows a safety margin.
Closed cooling costs more and there is more to go wrong but it is superior for engine longevity.
Marine engines are also under constant load with little to no airflow. The exhaust being enclosed and needing to be water cooled is another factor.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Do you guys consider $80 cheap???

http://www.iboats.com/mall/partfinder/? ... =837692315

WOW!!!

18-3656 thermostat is what comes up for my 1996 5.0FI engine. It is listed as a 60*C thermostat...that's 140*F.
So, 140* seems to be where they want it to be and that's what it has been running at except for when it went up that one season. (I replaced it immediately and I don't remember it being so much $...$40 comes to mind.)

And they say there's no inflation.

Steve, my '95 190 with the same Omc/Volvo 5.0 EFI Ford had a 145 deg F thermostat. I replaced it once or twice with the same temp thermostat because the cooling system apparently got a little bit of sand or something in it. A tiny grain of sand would hold the thermostat open just a tiny bit and cause the engine to run at less than 120 deg. Car and truck engines do run a lot hotter water temp, but keep in mind that the boat engine does not have an engine oil cooler or any natural ventilation so oil temps run higher when it is working. You may have seen other posts about low oil pressure at idle when hot........

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Surface Interval: A scuba diving term for that time between dives to relax and prepare for life's next great adventure.

Current boat: '02 FW 268 Vista
Previous boat: '95 FW 190 Horizon

Ok, first, iboats is notoriously expensive. Here is the same T-Stat for $26: http://www.marinepartsexpress.com:8080/mpeCart/details.faces?productId=3856961

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

Thanks NC. I did a Google search for this part number and all the prices were high. Even $28 is more than double what a quality t-stat is for a car/truck. So, thanks for the link. I'll get a spare.

Thanks SI. I can see where sand could easily do what you say.

R, Steve

Yeah, a T-Stat for a Ford 5.0 in a 'stang only costs $2-3 bucks, but a Ford 5.0 in my boat, $26. Prob cause it is a "specialty" part made for lower temps. Oh, and of course it says MARINE on it, so immediately the price is quadrupled, lol...

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

175 solid all day err day.

140 is too low.

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1981 Columbia 8.7
2015 Yamaha FZR - 87mph - sold
2006 Yamaha GP1300R - sold
2003 Chaparral 215 SSI - sold
2009 Stingray 195CS - sold
2000 Four Winns H180 - sold
1976 O'day Daysailer II - sold
Rick's Four Winns H180 Mods/Upgrade Thread