How hot is too hot?

[Aloysius]

Re: How hot is too hot?

QC asked the pertinent question..just how ACCURATE is your measuring device???

 

[thumpar]

Re: How hot is too hot?

My equipment might not be the most accurate but I can say that once it warms up it sits a tick before the 160 line and never moves all day. We run hard 45 minutes to our "spot" and it sits rock solid.

 

[Brentathon]

Re: How hot is too hot?

My raw-water cooled 5.7 Merc (w/ 140 T-stat) runs a little hotter during cruising rpm's (as compared to slow/idle rpm's), and then drops back down when I slow down.........usually takes approx 30 sec to come back down. Unfortunately, my gauge does not have numbers on it.....but it really doesn't rise too much.....no where near the "red zone", so I'm not too worried.....just yet.

 

[Friscoboater]

Re: How hot is too hot?

I was looking at my truck temp gauge tonight and it fluctuates about 15 degrees depending on the cycle. I also spoke with a guy at the marine shop (a real old timer) and he said that some marine gauges are very fast to respond to temp changes, and others are slow. Being that I have new everything, including the gauge, he said my boat is just telling me every little degree change.

I do plan on making the change over to the center riser manifold this winter (if the budget allows) and retire the logs.

 

[thumpar]

Re: How hot is too hot?

I was looking at my truck temp gauge tonight and it fluctuates about 15 degrees depending on the cycle. I also spoke with a guy at the marine shop (a real old timer) and he said that some marine gauges are very fast to respond to temp changes, and others are slow. Being that I have new everything, including the gauge, he said my boat is just telling me every little degree change.

I do plan on making the change over to the center riser manifold this winter (if the budget allows) and retire the logs.

Cars and trucks run the same water over and over so fluctuations are normal. My boat runs new water and spits it out. Even closed cooling boats have the convenience of new water running over the exchanger that is much more efficient that air over a radiator.

 

[QC]

Re: How hot is too hot?

Roger that ^^^^ especially open cooling. And they are also much less affected by ambient conditions, 80 degree water is still 80 degrees cooler than engine temp. Can't get that with a typical radiator and 80 degree air.

 

[Philster]

Re: How hot is too hot?

So, to sum it up: Fluctuations are normal. 15 +/- degrees = very normal

I've noticed cold-water boaters (ya Northerners) are less likely to see a temp gauge rise. Well, excuuuuuse me! Well, Well, Well, run 58 degree water through an engine and she is more likely to stay within 2 degrees of the t-stat's opening temp!! I'll take plus-80 degree water temps and 10-15 degrees of cooling water temp fluctuation, thank you very much!

They key is to know the normal nuances of your boat, and when something starts to deviate from that norm, you know to check something out. If I ran at 190-195.... yep, I'd lose sleep that night, but not because I hurt anything, per se, but because something isn't doing its job as efficiently as it was before.

.

 

[Aloysius]

Re: How hot is too hot?

There has to be waterflow AT the thermostat for it to function properly, even when it's closed! Most cars cycle water through the heater core to provide a constant circulation of water around the t'stat "pellet", while most marine thermostats will have a small hole in the flange to promote water circulation.

Of course the t'stat has to be installed correctly, not upside down!!

 

[jmarty10]

Re: How hot is too hot?

Good thread. My 4.3l warms up to about 170-175. Of course its hard to tell if the gauge is exactly accurate. Engine cools down to 150 at idle speed, heats up to about 175 at acceleration and drops to about 165-170 cruising. I watch that gauge pretty closely all day.

 

[bobhol]

Re: How hot is too hot?

Good thread. My 4.3l warms up to about 170-175. Of course its hard to tell if the gauge is exactly accurate. Engine cools down to 150 at idle speed, heats up to about 175 at acceleration and drops to about 165-170 cruising. I watch that gauge pretty closely all day.

__ But what thermostat are you running?

 

[sethjon]

Re: How hot is too hot?

I just saw a post that scared me. He said that 200 was too hot for a boat. For those of you that have not seen my thread, I just rebuilt my boat. New 5.7 new manifolds risers and impeller. When it was really hot out (104) my engine would touch 200 when we were really hammering on it or a wot run across the lake. Once you slowed down it went back to the 140 to 160 range. I can still put my hands on the risers. This past weekend we had a big cold front that came through and the water is cooler. The boat never gets over 180 now. Do I have an issue?

Do I have an issue? Duh! Thats a trick question, right. 200 is way too hot even for a few seconds. 180 is also too hot. You have a clog somewhere. Find it before you use the boat again or get ready for a new motor.

 

[sethjon]

Re: How hot is too hot?

no ,
all normal to me ......

at wot the engine goes warmer : normal .

do you have only the impeller in the outdrive to bring water in engine ?
if so yes it `s normal to raise to 190 on hard drive !

190 is not normal.