mercruiser 165 1987 B772088..Radiators

[sinkher]

Gentlemen, My 1987 165 4cly B772088 is having chronic overheating problems. I won't go into the boring detalis, but here is my thought. Why can't I just splice in a decent radiator with an electric fan to cool the radiatior and bypass alot the problem causers. The heat exchanger, the riser, the impellar in the lower end, all the possible leaks and crud accumulation etc. Just make the engine like an automobile engine closed cooling system. Or, if we need to use the impellar system why not route the cooling system like our outboard cousins. They suck the water in and then pump it right back out. No need for heat exchangers, risers, etc. My twin 1984 235 hp Johnsons V-6 run great on that system. Has anyone ever tried to incorporate a radiator to a 470 (165) to cool the engine? Your thoughts please before I go Frankstien on my (HOT) little motor. Glen

 

[jerryjerry05]

Re: mercruiser 165 1987 B772088..Radiators

Yea,you could put in a radiator. Just remember that ANY electrical accessories need to be Coast Guard rated if it's gonna be in the bildge of a boat.The radiator fan probably won't be acceptable.J

 

[bomar76]

Re: mercruiser 165 1987 B772088..Radiators

This idea is so bad it made my eyes hurt reading it.

 

[skargo]

Re: mercruiser 165 1987 B772088..Radiators

This idea is so bad it made my eyes hurt reading it.

x2.
If it were a good idea, you'd probably see at least one boat running a radiator.
I suggest you find out WHY it's overheating and fix the underlying cause.

 

[Don S]

Re: mercruiser 165 1987 B772088..Radiators

Gentlemen, My 1987 165 4cly B772088 is having chronic overheating problems. I won't go into the boring detalis, but here is my thought. Why can't I just splice in a decent radiator with an electric fan to cool the radiatior and bypass alot the problem causers. The heat exchanger, the riser, the impellar in the lower end, all the possible leaks and crud accumulation etc. Just make the engine like an automobile engine closed cooling system. Or, if we need to use the impellar system why not route the cooling system like our outboard cousins. They suck the water in and then pump it right back out. No need for heat exchangers, risers, etc. My twin 1984 235 hp Johnsons V-6 run great on that system. Has anyone ever tried to incorporate a radiator to a 470 (165) to cool the engine? Your thoughts please before I go Frankstien on my (HOT) little motor. Glen

Keep that kind of talk up, and I will move this thread over to this forum http://forums.iboats.com/forumdisplay.php?f=20

If this thing has overheated in the past, then you probably have a blown head gasket due to the open deck design. Fill the cooling system with water, leave the cap off, and do a leakdown test on each cylinder to find out where the head gasket is blown. (you will see bubbles in the expansion tank) You are probably getting air into the cooling system now causing your overheat.

 

[sinkher]

Re: mercruiser 165 1987 B772088..Radiators

Well I didn't hear a reason why it wouldn't work, but I wont try it. There are millions of engines with radiators, I don't see why a boat application wouldn't work. But obviously I'm not the expert here. But thanks for stopping me from creating a monster. I'll put my hacksaw away.

 

[Bondo]

Re: mercruiser 165 1987 B772088..Radiators

Well I didn't hear a reason why it wouldn't work,

Relatively speakin',.... There's No air flow on a boat,... Boats top out in the 40/ 50mph range...
Cars, 60/70mph...
And,...
As noted by Don,... That just Ain't your Problem....

The heat exchanger works just Fine as designed...

 

[skargo]

Re: mercruiser 165 1987 B772088..Radiators

Well I didn't hear a reason why it wouldn't work, but I wont try it. There are millions of engines with radiators, I don't see why a boat application wouldn't work. But obviously I'm not the expert here. But thanks for stopping me from creating a monster. I'll put my hacksaw away.

No need to take offense. many of us drive those millions of engines with radiators, just not in our boats.
To add to what Bond-o said, even it it were feasible to use a radiator and take advantage of the airflow, where would you mount it to get said airflow?
I doubt you'd find a "marinized" electric fan setup either.

Fix it right and you will love your HE, mine is awesome, and I am thankful the original owner had the foresight to order it, 32 years ago. How many 32 year old boats do you hear of running it's original engine?

Good luck!

 

[sinkher]

Re: mercruiser 165 1987 B772088..Radiators

Will do, thanks Don

 

[sinkher]

Re: mercruiser 165 1987 B772088..Radiators

Well, I could fashion an automotive racing type air scoupe on top on the engine cover and route the air flow to the front of the radiator. The scoupe would be just above the gunwale. It would have a dragster/racing boat look to it. Keeping in mind that at slow speeds the electric radiator fan (damn the Coast Gaurd, Full speed ahead) would engauge for slower speeds. Plus I will have lots of bagged ice to pack around the engine just in case. But seriously, I really do appreciate the time and trouble you guys invest in answering dumb questions. You never know till you ask.

 

[45Auto]

Re: mercruiser 165 1987 B772088..Radiators

From a thread about the same question last year:

The reason boats with closed cooling systems use water-to-water heat exchangers instead of water-to-air heat exchangers is because water-to-water is much more efficient. You have all that free water there anyway, why not use it? A rough calculation should show the difference.

The thermal conductivity of water is about .6, air is about .025. So water is 24 times more efficient than air at removing heat. That means with air you need 24 times the equivalent MASS of water to remove the same amount of heat.

Density of air is .08 lb/cubic foot, density of water is 62.4 lb/cubic foot. So to get the equivalent mass of 1 cubic foot of water I have to use 62.4/.08 = 780 cubic feet of air.

Since the water is 24 times more efficient, you need to move 780*24 = 18,720 cubic feet of air to get the equivalent cooling of 1 cubic foot of water.

Maybe that's the reason the radiator on my 300 HP Suburban is about 4 feet long and 3 feet high, while the radiator on my closed-cooling 425 HP boat is about 4 inches in diameter and 1 foot long .....

Another problem to consider with your air cooled-radiator is that the exit area MUST be bigger than the entrance area. Air expands as it absorbs heat. An automobile has the entire open area under the engine compartment for the heated air to expand into and escape. There were lots of overheating problems on early high HP WW2 aircraft (both liquid and air cooled) before they figured that out. Hard to imagine how you will do it on a boat without just sticking the radiator up in the air (like on an airboat). In that case you're adding a huge amount of unnecessary drag if you hope to get any speed out of your boat.

It's not impossible, there's lots of things you can do with flush mounted radiators and ducting, etc. The question is why? You're adding extra complexity, weight, drag, and expense to gain exactly nothing. If you want to do it just to be different, nothing wrong with that. Kind of like putting square tires on your car. People figured out a long time ago that round is better, but hey, it's your money and time!