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What temp should I be running at?

J

jtoma878

Contributing Member
With a 5.7L and a full closed FWC system, my temp gauge reads 175 (right in middle of gauge) while idle speed and then at WOT it jumps to at or below 200. Is that too high? It never goes above 200. From what I understand the t-stat is supposed to open @ 180.

Can someone straighten this out for me?
 
jtoma878 said:
With a 5.7L and a full closed FWC system, my temp gauge reads 175 (right in middle of gauge) while idle speed and then at WOT it jumps to at or below 200. Is that too high? It never goes above 200. From what I understand the t-stat is supposed to open @ 180.

Can someone straighten this out for me?
Click to expand...

If the water temp is 80deg f or higher this can occur..

most likely the impeller is getting a little worn/distorted..causing a slightly lower flow volume..it should run at WOT around 185-190deg f ...

as time passes it will gradually get up to 200 or higher then you must cleanout the coolant system and replace the impeller..


if the engine temp drops after the WOT operation /operating at lower RPM's I would say this is your problem..
 
j cat said:
If the water temp is 80deg f or higher this can occur..

most likely the impeller is getting a little worn/distorted..causing a slightly lower flow volume..it should run at WOT around 185-190deg f ...

as time passes it will gradually get up to 200 or higher then you must cleanout the coolant system and replace the impeller..


if the engine temp drops after the WOT operation /operating at lower RPM's I would say this is your problem..
Click to expand...

Impeller / outdrive water pump was all replaced last May
 
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T-stat if over a year old change it run the motor still does it? Then you might have a heat exchanger clogged up, each one has to be checked if it's clogged.

Say none of the exchangers are clogged then you got to look to the risers, and flappers, yank them, and check the flappers.

Post back your result we want to know how things work out.
 
Sending unit.............

Or as Chief says a Partially clogged heat exchanger.

What type of water? fresh or salt,
What year is the motor/boat
how many hours?
 
This motor maybe has 50 hours on it. It was a brand new motor as of last May. Full, closed FWC kit, only saltwater touches the stainless risers and h/e. Rest is cooled with antifreeze.

FWC, t-stat, and all plumbing is new as of last may as well. I can't remember for the life of me if I was running at this temp last season, when I was in NJ. I have since moved to FL and the boat is now running in the warm waters of Biscayne Bay
 
Ok Fl thats a whole different dog altogether.

Ain't NJ and the salt if the worst there. Risers SS last year i would not believe them to be the problem yet !

Flapper fell down maybe, consider this, the motor got hot more then once, very possible they melted off one or both.

Maybe blocking the exhaust, seen this so much volvo stopped using them and has issued a bulletin to remove them if you had them.

The donor boat i purchased had one blocking the exhaust, and the owner couldn't figure out why is was always overheating, i bought the whole boat trailer for 400 bucks.

So t-stat first, you got check balls, it's time to check them, make sure if equipped your balls are working ok. HAH.

Listen i just came back to edit this post, this boat sits in the water ? If yes i would first make sure beyond a doubt the the water intake ain't clogged.

If it's a drive they even have mussels that grow in the intake don't even see them from the outside.

If you got screws then your intake could be clogged.
 
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intake on drive is clean.

dont quite get the tstat balls comment....

boat sits in water.

what temp should i be at? 175-185? 200 is too high in these waters?
 
jtoma878 said:
not what i wanted to hear. is that the same even in warm waters? the bay temp here is well above 80
Click to expand...

the water temps above 80 deg f in florida NOW ! that is most likely the reason for this to occur ..I doubt you have any componets defective ...I would replace the thermostat just to be sure, they can be bad out of the box ....

check the heat exchanger it is possible to pick up weed etc...
 
I troubleshot a 470 closed cooling system many years ago. Not the same motor as you but a closed system with a 160 degree thermostst same as you.

Motor would idle all day long at 160-170 degrees. Throttle up and it would jump over 200 degrees. Checked and double checked everything. Outdrive water pump assembly, gaskets, everything!!!

Finally took out the temp sender and got a new one out in stock, boiled water and checked the resistance rise between the two.

The motor/old sender would jump when it reached a certsain temp. The new one was linear in resistance rise.

Answer........sender was faulty.

One last question, When was the water pump impeller in the outdrive last serviced or touched?? A torn gasket in the impeller assembly will cause air bubbles in the water stream and this will cause a high/higher speed over heat issue.
 
kghost- last may the impeller was changed.

chief- i trim the drive all the way up and make sure the intake is unobstructed every time before I take her out. I also had some underwater divers come clean the underside and drive last week
 
Put an infra red thermometer on it to be sure what temp you are at. Gauges and senders can vary quite a bit.
Bert
 
The balls comment i made are about the poppit balls right in front of the t-stat you might not have them but if you do they stick, could be the reason right there just something for you to check.

Glad you take the time to make sure your intake is clear, sending the diver is good, i just dive under and take a look.

Theres a guy i know here pulls the boat for work for 200 but only for people he knows. People he don't know i bet it's a whole lot more.
 
ok, so i was able to get out on the bay yesterday. good thing is, she was only running at 175-180, so I guess I'm good there.

Problem is, I am running 32mph @ 3400 rps @ WOT! I'm guessing this is due to wrong prop size or the fact that it is chipped/bent.

Suggestions on prop size???
 
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