extra cooling fan on radiator

[Keith V]

>That example exactly demonstrates why it's better to have a higher temperature thermostat.

your argument makes no sense. The engine temperature will still get to 195, it will just take longer to get there and since it took longer to get there will have a lower peak temp, or if it's a really long pull will have the exact same peak temp.
Your argument implies that a 180 stat will end up with a higher peak temperature which is impossible

I've run both 195 and 180 and have tested the behavior so I know this is true.

 

[Tom Katzenberger]

Guys,

I have a situation where my coach is running at 212° when I am on the highway. During stop and go or slow travel the temp comes down.

I am installing the FlowKooler thermostat today and also putting in Zirg Ultra Cool additive. The additive was per the advice of a performance engine builder who owns and engine shop and is a good friend. He also claims the aluminum radiator is the way to go.

My question is: if this doesn't reduce temps, what are your thought on the aluminum radiator? I don't know why they claim they are cooler, but manufactures claim they are about 30% cooler. I do know aluminum is stronger and allows for larger cooling channels.

I am very open to opinions and ready to get educated.

Thanks in advance and take care,
Tom K.

 

[Tom Katzenberger]

Guys,

I put the above question in a new post. This was done so that future personnel can do a search and hopefully find your answers. It may help other down the line and I won't have to hi-jack someone else's thread.

Stay healthy,
Tom K.

 

[tmsnyder]

>That example exactly demonstrates why it's better to have a higher temperature thermostat.

your argument makes no sense. The engine temperature will still get to 195, it will just take longer to get there and since it took longer to get there will have a lower peak temp, or if it's a really long pull will have the exact same peak temp.
Your argument implies that a 180 stat will end up with a higher peak temperature which is impossible

I've run both 195 and 180 and have tested the behavior so I know this is true.

Nope, I never said that the 180 would end up at a higher peak temperature. It would end up at the same peak temperature as the 195. But in the process of getting to the higher temperature with a 180F thermostat you'll be subjecting the engine to a lot more temperature swings; not good for the engine in the long term. That's the "stat" in "thermostat"; constant temperature. The engineers wanted the engine temperature to be static, at the thermostat temperature.

If a coach is having trouble overheating, that is caused by the cooling system not shedding heat at a fast enough _rate_ . That rate is proportional to the DeltaT of the water temperature and the outside air temperature. If you decrease DeltaT, you decrease the _rate_ proportionally.

Putting in a lower temperature thermostat actually makes the underlying problem worse, instead of fixing the actual problem. It's not even a band-aid fix, it actually makes the situation worse. There's not much to these cooling systems, it's either the fan/clutch failing to engage, or stuffed up radiator, or a thermostat failing to open fully. Or, very unlikely, a worn out water pump.

I'm not sure what else to tell you except go talk to someone familiar with heat transfer principles.

 

[Keith V]

Todd,
What do you base your knowledge of the temperature swing requirements for the GMC on? Besides less is better, how much less is how much better?
Is this documented somewhere? How does temperature swing affect engine life as measured in engine hours?
How does this effect compare to cold start wear and other issues?

 

[kidjedi]

Nope, I never said that the 180 would end up at a higher peak temperature. It would end up at the same peak temperature as the 195. But in the process of getting to the higher temperature with a 180F thermostat you'll be subjecting the engine to a lot more temperature swings; not good for the engine in the long term. That's the "stat" in "thermostat"; constant temperature. The engineers wanted the engine temperature to be static, at the thermostat temperature.

If a coach is having trouble overheating, that is caused by the cooling system not shedding heat at a fast enough _rate_ . That rate is proportional to the DeltaT of the water temperature and the outside air temperature. If you decrease DeltaT, you decrease the _rate_ proportionally.

Putting in a lower temperature thermostat actually makes the underlying problem worse, instead of fixing the actual problem. It's not even a band-aid fix, it actually makes the situation worse. There's not much to these cooling systems, it's either the fan/clutch failing to engage, or stuffed up radiator, or a thermostat failing to open fully. Or, very unlikely, a worn out water pump.

I'm not sure what else to tell you except go talk to someone familiar with heat transfer principles.

I'm wondering... isn't the engine pretty much on an upward climb from the moment you start it until it stabilizes at an upper limit that won't fluctuate much because of thermal retention (I know it can change some, but changing the temp of that much metal takes some serious work)? The coolant tries to keep it cool, but all that metal is retaining a lot of heat, so essential the coolant is helping to resist/stabilize a *quick* change. The coolant temperature will fluctuate, but it will take quite a bit of time for the temperature of the actual engine to change (and you probably won't really see it *fluctuate*). If my FiTech monitor is correct, when my coolant goes from 186 to 200, the cylinder temperature maintains a constant 143F unless I stay at the upper coolant number for a *long* time (an hour or more). Of course this won't be true if you kept the engine under high and constant load for hours, but hopefully the upper limits of "load" are only being put to the engine for half an hour or so at a time, and there is meaningful cooling happening in between. My thoughts are mostly anecdotal, so I am prepared to be wrong.

 

[Matt Colie]

I'm wondering... isn't the engine pretty much on an upward climb from the moment you start it until it stabilizes at an upper limit that won't fluctuate much because of thermal retention (I know it can change some, but changing the temp of that much metal takes some serious work)? The coolant tries to keep it cool, but all that metal is retaining a lot of heat, so essential the coolant is helping to resist/stabilize a *quick* change. The coolant temperature will fluctuate, but it will take quite a bit of time for the temperature of the actual engine to change (and you probably won't really see it *fluctuate*). If my FiTech monitor is correct, when my coolant goes from 186 to 200, the cylinder temperature maintains a constant 143F unless I stay at the upper coolant number for a *long* time (an hour or more). Of course this won't be true if you kept the engine under high and constant load for hours, but hopefully the upper limits of "load" are only being put to the engine for half an hour or so at a time, and there is meaningful cooling happening in between. My thoughts are mostly anecdotal, so I am prepared to be wrong.

Kid,
Your reasoning and observations are sound, and yes the the coolant out temperature will rise with engine load and in actual fact will be substantially be proportional to engine load. This is why there is no huge difference as far as the engine is concerned between a 180 and 190 thermostat. This is also why it is best to not thermal cycle an engine nay more than you have to.
Matt

 

[Keith V]

Well since there is metal betwen the fire amd the water, some metal has to be getting hotter.most likely the cylinder jackets,
I do know the exhaust temp goes up quite a bit.
Im suprised the head temp doesnt change tho, so im wondering where that cyl head temp gauge is

 

[Matt Colie]

Keith,
Actually, it is not the liners (cylinders) that get hotter, most of the heat change come from the cylinder head at the combustion chambers and the exhaust runners. Quite a number of engines have a hole through the fire deck (top of the block face), head face and gasket to put jacket water at the exhaust runners. Because you have to have studied any engines coolant flow path, there is no way to what represents the head casting temperature. We used to use this to predict the motion of the head relative to the block. Yes, there is thermal motion there.
Matt