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2004 Merc 5.0 water temp

S

sparkman

New member
I took out my (new to me) 2004 Trophy 2352 for a shakedown last week and my water temp held about 175 at idle and would go up close to 195 when running it on plane. It is a Merc 5.0 with the fresh water cooling system. Is this temp normal? Previous owner claims it has always run that temp.
Thanks in advance.
 
Re: Merc 5.0 water temp

when you say fresh water do you mean, closed cooling system with a heat exchanger?
Or just raw water from the outdrive?
 
Re: Merc 5.0 water temp

Typical closed cooling systems have a 160 degree thermostat so I would say ~ 170 at idle is OK.

195 is a bit high in my opinion. I would say 180 to 185 would be the max. 190 on a very hot day and running it hard.

Also a 5.0 litre pushing a 23 footer is a bit underpowered. BUT at idle it still should run around 165-170 all day long.

Seeing as the previous owner said it has been that way I would say at the very least a thorough cooling system check would be in order.


Is it salt water used or fresh water and how was it used by previous owner, salt or fresh?

1. when was the outdrive impeller replaced last?
2. what does the heat exchanger look like on the inside? remove end caps and take a look. if there is a power steering cooler in the incoming fresh water supply line maybe it has some stuff inside it restricting water flow, remove from water hose and take a look.
3. how many hours of use?
4. if salt water use then maybe the risers/elbows are clogged?
5. Thermostat? is it 160 degree or maybe higher? marine? correct for the motor?
6. sender or guage could be off 5-10 degrees, verify with a infared heat gun pointed at the sending unit.

Answer some of the questions and we can supply more answers

INFO INFO INFO!!!
 
Re: Merc 5.0 water temp

Some more info:

The boat came from the Potomac River in VA. (brackish?) It will be in fresh water from now on. The engine only has 150 hrs on it and has never been checked for an overheating condition.

Answers:
1.As far as I know it has never been looked at.
2.The heat exchanger has never been disassembled and inspected.
3. 150 hrs.
4. Needs to checked.
5. Needs to be checked too.
6. I plan on taking a heat gun with me the next trip.

As you can see, The boat does not have much time on it and with me being new to the I/O's I am just trying to make sure I don't have a problem brewing.

Appreciate your help.
 
Re: Merc 5.0 water temp

I'd check out the heat exchanger on that boat first off. Running on a brackish river , it may have picked up some sand or debris and has limited flow.
Bert
 
Re: Merc 5.0 water temp

I have a 220HP 5.0L Merc running in a 21' boat. My idle runs around 170-175, at full throttle right about 190. So I'd say you're probably within tolerances.
 
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