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6.2 mercruiser too hot

M

Martinique33

New member
I have two, one 6.2 mercruiser closed cooling system. At 2500 rpm temp gauge reads 190, the other is ok at 170.

Over 2500 rpm, temp creeps ups. All cooling system parts are ok, new raw water pump, newsender, new termothast. Raisers ok.

Gauge temp is 190, but laser gum temp is 155.

Any want can't help!!
 
Swap senders

Not all senders have the same resistance.........some vary enough to show a 10 + degree difference.
 
So if you swap the senders from one motor to the other, then the high temp follows the sender????????
 
What is the serial number.
Were these engines factory Fresh water cooled?
What are they in? I/O or inboard?
If I/O what drive do you have?
Where do you store the boat, Trailer, slip or lift?
 
sandkicker said:
What point on the engine are you using for the IR (laser) gun?
When did this current problem start?
Click to expand...

In the sender, near thermostat, etc. With a laser 155, mechanical gauge temp 140 (inside heat exchanger). The problem start two weeks ago after increase rpm at 3400. Before the problem, at 3000 rpm was 165, now is 190 degree at 2500 rpm. I used a direct connection to check temp gauge (190).
 
So if you have two inboards, Both Closed cooling, A lot of the parts that are new. One is overheating/getting hotter than the other.

What does the incoming water system look like? Do you have a strainer system where the water comes thru the hull?
Is it clear?

Is the closed cooling system loosing any anti freeze?

I think some more information is needed here.

Because you have a known good (second engine) the key to finding a problem sometimes like in your situation is to use the parts from known good engine to check and see if the engine with issues same parts have any problems and if not no need to replace.

So every part so far has not been needed to fix your issue. Lesson learned!!


Now your description is hard to understand,

since the issue started what have you done?

list everything you have done.




In any marine cooling system there are 4 major categories,

Water in (pick up, strainer, impeller, hoses, rusted ports that the hoses connect)
Temperature control (heat exchanger and thermostat)
Temperature information (sender) (gauge)(wire harness)
Water out, (elbows, manifolds if raw water cooled)

Rarely does the engine mounted water pump (circulation pump) ever fail.
 
If this has a separate water pump (ie; not in the lower unit) there's a fifth thing to look into: Look for an air leak before the raw water pump. Aerated water cools poorly.

Jeff
 
fastjeff said:
If this has a separate water pump (ie; not in the lower unit) there's a fifth thing to look into: Look for an air leak before the raw water pump. Aerated water cools poorly.

Jeff
Click to expand...
....or a collapsed or kinked hose from the drive to the transom and hence to the engine mounted pump. IFNO engine mounted pump, issues with hose and fittings from drive to engine still a concern.
 
kghost said:
He has inboards........
Click to expand...
OOPS... missed that... THKS!

..,However... if it has raw water strainers, the gasket in the access port is often an issue, as well as improper reinstallation of the strainer access port on some types of strainers. (Bubbles usually visible @ speed.) All hoses on inlet side circuit of raw water pump need to be wire reinforced.
 
Last edited:
sandkicker said:
OOPS... missed that... THKS!

..,However... if it has raw water strainers, the gasket in the access port is often an issue, as well as improper reinstallation of the strainer access port on some types of strainers. (Bubbles usually visible @ speed.) All hoses on inlet side circuit of raw water pump need to be wire reinforced.
Click to expand...

Eel grass strainers are all you need on any boat. I take the inboard basket style strainers out, they are a restriction.
 
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