3.7 Mercruiser

[sticks]

i have a mercruiser 3.7 (just recently bought) which will not reach temperature, the gauge rises just above the bottom mark. My worry is that the thermostat may have been removed. Can anyone tell me if thats likely and if so where the thermostats located and is it much of a job to replace.
CHEERS

 

[tashasdaddy]

Re: 3.7 Mercruiser

sticks, if you want to work on your boat, you need a manual for your specific engine and outdrive. hope you have it winterized if you're in the cold. not familar with your engine but should be above the water pump, the stat could be stuck open, changing it requires gasket set.

 

[imported_sharkin95]

Re: 3.7 Mercruiser

the thermostat is located on the exhaust manifold on the right side of the engine.you will see a thermo heat switch with one brown wire next to it.there is a 1 1/2 hose going to it.if the thermostat is o.k. it's probably the heat switch.The 3.7 224 cu. is an anti-freeze cooled engine.I had one for years and i finally gave up on it and replaced it with a 4.3 v6

 

[JoChek219]

Re: 3.7 Mercruiser

I have the same thing on my boat, was thinking about looking into the stat, is it ok if I leave it the way it is , or should I look into it in the spring?

 

[Bondo]

Re: 3.7 Mercruiser

the thermostat is located on the exhaust manifold on the right side of the engine.you will see a thermo heat switch with one brown wire next to it.there is a 1 1/2 hose going to it.if the thermostat is o.k. it's probably the heat switch.The 3.7 224 cu. is an anti-freeze cooled engine.I had one for years and i finally gave up on it and replaced it with a 4.3 v6 .

d

Yew,.... Boy,........... Welcome Aboard Stickes........
I Wish you'd have found Us,.... Before you just Bought that ole 470........
You've got the Mercruiser's Mistake driveline..... 1 of those Ideas that Look Good on Paper.....

As tashasdaddy says,..... You Really Need the Factory Manual for that Baby,......
Maybe Don will know where to find 1.....

We need to know Much More info on your conditions,....
Is the coolant level Full,..??.....
Are you running it In the Water,.. Or On the waterhose,..??.....
How many Degrees is, "the gauge rises just above the bottom mark.",..??.....
And,.... How Mechanically Inclined,+ Equiped are you,..??.......


Btw,.... JoChek219,....... All these same Questions apply to Your Questions......

 

[imported_sharkin95]

Re: 3.7 Mercruiser

MERCRUISER MANUAL #8 I THINK...CHECK E-BAY OR PAY ABOUT 60.00 THRU MERC.

 

[DJ]

Re: 3.7 Mercruiser

Your engine has a closed cooling system. In other words, it has a small radiator (heat exchanger) that is cooled by sea water.

Because of that, the closed system runs a mix (50/50) of anti freeze and water, just like a car.

First off, as suggested, make sure that system is full. As I recall, there is a small tank on the top/front of the engine. I has a cap that looks like a radiator cap. Check it cold.

 

[sticks]

Re: 3.7 Mercruiser

the thermostat is located on the exhaust manifold on the right side of the engine.you will see a thermo heat switch with one brown wire next to it.there is a 1 1/2 hose going to it.if the thermostat is o.k. it's probably the heat switch.The 3.7 224 cu. is an anti-freeze cooled engine.I had one for years and i finally gave up on it and replaced it with a 4.3 v6 .

d

Yew,.... Boy,........... Welcome Aboard Stickes........
I Wish you'd have found Us,.... Before you just Bought that ole 470........
You've got the Mercruiser's Mistake driveline..... 1 of those Ideas that Look Good on Paper.....

As tashasdaddy says,..... You Really Need the Factory Manual for that Baby,......
Maybe Don will know where to find 1.....

We need to know Much More info on your conditions,....
Is the coolant level Full,..??.....
Are you running it In the Water,.. Or On the waterhose,..??.....
How many Degrees is, "the gauge rises just above the bottom mark.",..??.....
And,.... How Mechanically Inclined,+ Equiped are you,..??.......


Btw,.... JoChek219,....... All these same Questions apply to Your Questions......

 

[sticks]

Re: 3.7 Mercruiser

thanks for the info. No problem mechanically or toolwise, just brand new to boats.
cooling system is closed type and the test was on muffs. The gauge rose about 1/4'' from the bottom stop.

Thanx again

 

[JoChek219]

Re: 3.7 Mercruiser

I have a ?, since I recently found out what a mistake it was to buy that boat and motor...I planned on doing the tune up and rebuild the carb in the spring... but i'm wondering if its worth spending more money on it or just to drive it and try to sell for a newer boat with a 4.3...any advice is greatly apprecitated

 

[Don S]

Re: 3.7 Mercruiser

JoChek219, you really need to start your own thread with questions like that, no need to hijack sticks thread to find out info on your boat.
Besides, no one will probably see your question after a couple of replies and your question is buried in the middle of the thread.

 

[imported_Chrisb]

Re: 3.7 Mercruiser

Hey sticks, I have owned a 3.7 for four years now. They are challenged with overheating issues. On mine, the factory heat exchanger just can't keep up on a 90 degree day. When the engine compartment gets too hot the fuel vaporizes before it reaches the engine and the boat won't run. The engine is also prone to flooding.

I would bet that somebody removed your thermostat to keep the engine cool.

My solution was to install an extra blower in the engine compartment (total of 2) and run the suction tubing from both to the front of the engine compartment. I run my blowers almost nonstop. I also cut about a ten inch circular hole in the front of my engine compartment and installed a cooling fan behind a homemade door. On hot days I open the door and turn the fan on (provided the top is down).

Boat has run like a champ ever since.