1988 470 3.7 165hp low temp

[Galaxy2100]

Boat runs great but temp is way low like 130 all the time.
What is runing temp and thermostat temp suppose to be?
Thanks

 

[alldodge]

Re: 1988 470 3.7 165hp low temp

Thermostat should open between 155 and 162 degrees. Are you sure your gauge is accurate?

 

[stonyloam]

Re: 1988 470 3.7 165hp low temp

I suspect the gauge, mine (for the last 20 years) never reads over 140. The operating range is 165-200 degrees F. A properly functioning system should run in the 165-175 range and be steady over the entire RPM range from idle to WOT

 

[Galaxy2100]

Re: 1988 470 3.7 165hp low temp

I grounded the gauge and it pegged to other side. Is this an
Accurate way to test the gauge? Thanks for the replies.
Maybe my thermostat is stuck open?

 

[pyrotek]

Re: 1988 470 3.7 165hp low temp

What thermostat temperature is in your engine? I have a 143 degree (different engine) and I get about 130-140, usually more towards 130.

 

[CharlieB]

Re: 1988 470 3.7 165hp low temp

Your gauge tst only proves that the gauge works. The usual culprit is the sending unit, the resistance fails and the gauge reads low.

I agree, most likely your stat is stuck open OR the sending unit is faulty.

It never hurts to change an old stat, figure it could die any time, changing it now simply averts a problem later.

It the gauge then still reads low order a sending unit.

 

[stonyloam]

Re: 1988 470 3.7 165hp low temp

I grounded the gauge and it pegged to other side. Is this an
Accurate way to test the gauge? Thanks for the replies.
Maybe my thermostat is stuck open?

If the thermostat were stuck open the temperature reading would change with engine load, it would go up to a certain point at high rpm, then drop back down at idle. If the temperature stays steady over a wide rpm range then your thermostat is probably OK. You could try a temperature gauge radiator cap, or an IR thermometer to check.

 

[Galaxy2100]

Re: 1988 470 3.7 165hp low temp

I changed my gauge and sender, temp still 125 130
Only thing left is stat and cap. Will it hurt the motor
Runing at this temp?

 

[Galaxy2100]

Re: 1988 470 3.7 165hp low temp

And I will try an IR temp reading. I Guess
Take tem at the sender? Thanks

 

[alldodge]

Re: 1988 470 3.7 165hp low temp

I changed my gauge and sender, temp still 125 130
Only thing left is stat and cap. Will it hurt the motor
Runing at this temp?

And I will try an IR temp reading. I Guess
Take tem at the sender? Thanks

Your engine will not be hurt running cooler, just not as efficient.
Checking temp at the sender is a good place, check a few other spots (exhaust, intake) while your at it and see what the differences are.

 

[stonyloam]

Re: 1988 470 3.7 165hp low temp

Well I never worried about my 470 running too cool LOL count your blessings! Yeah scan near the sender, and scan the reservoir. If it is running low it could be the thermostat opening too early, but I would not worry about it too much, as long as it is running well and the temperature holds steady.

 

[Galaxy2100]

Re: 1988 470 3.7 165hp low temp

Well I checked the temp ON the sender 128-130 and at the coolant res top 135,
Then the manifold body it was 158-160. Talked to the Merc Mach and he
Told me I should have a 140 stat in there so I guess it's ok ��.
You all really have a good forum going here. Thanks for all
The helpfull posts. Peace of mind. Thanks again

 

[stonyloam]

Re: 1988 470 3.7 165hp low temp

Talked to the Merc Mach and he
Told me I should have a 140 stat in there.....

Hmmmm I believe your Merc mechanic is wrong. A 1988 Merc 470 should have a 160 degree F thermostat! part # 99155T2 Could be that you have the wrong thermostat in there.

 

[Eric 3.7LX Alpha 1]

Re: 1988 470 3.7 165hp low temp

deleted double posted

 

[Eric 3.7LX Alpha 1]

Re: 1988 470 3.7 165hp low temp

That's what I am thinking as well.

 

[alldodge]

Re: 1988 470 3.7 165hp low temp

Hmmmm I believe your Merc mechanic is wrong. A 1988 Merc 470 should have a 160 degree F thermostat! part # 99155T2 Could be that you have the wrong thermostat in there.

Agree, pulled it direct out of the service manual

 

[CharlieB]

Re: 1988 470 3.7 165hp low temp

While the motor will run fine at a slightly cooler temp the real issue is oil temp. We want to oil temp 'just' high enough to evaporate any moisture that normally condenses inside the motor, ideally 180, but 160 or above is acceptable.

I wouldn't worry about your motor.

 

[Galaxy2100]

Re: 1988 470 3.7 165hp low temp

You r correct. I'm going to change it today w/160
And see how she runs.