80 Operating Temperature per FSM

[landtank]

Sure it will Rick, the coolant just doesn't get directed thru the radiator, there is definitely flow thru the block and head! It's just the closed loop circuit is bypassing the radiator when the thermostat is closed. Once it's open, it flows thru the radiator.

Scott Justuson

OK, but not nearly at the same rate as going through the radiator. I only want the coolant to circulate through the radiator to maintain the temp as governed by the T-Stat. This is how the truck works most of the months.

Again we are talking about Toyota's original design and what we should expect from it in a stock configuration. In my opinion we should expect a constant temp control throughout the year regardless of which month it is. I personally don't think 100* ambient temps should be considered extreme operating conditions resulting in 210* operating temps. Unfortunately I only recently realised I could scan my ECU for those readings as it would have been good to get that data this year.

For you or anyone who wants to run this truck in sub freezing weather at an elevated temp while driving around town will have to significantly alter the design. Needing to do so to achieve those results would indicate in my mind that you are working outside the design parameters of the truck.

 

[SUMOTOY]

And this is different from the fan doing the same thing how?

If the fan kicks in 10deg before the stat if fully open, it's the same thing as if you hit 45mph (or whatever speed is equial to fan flow) 10 deg before the stat is fully open.

Mr. Vogt:
The fan kicks in by control, ram air doesn't. It's not a correct premise to assume that ram air causes open loop operation. In fact it's quite the opposite, ram air is a primary closed loop function. Fan intervention is *defined* as open loop operation, OR it's specifically fighting closed loop operation.

Ram air is a variable to defining closed loop engine heat management -capacity-. Too much ram air closed loop, the thermostat will close, not enough ram air the thermostat will open to maximum 203F engine temp, then the (open loop) secondary fan operation kicks in.

Bottom Line: Ram Air is not a secondary function. It is a variable to defining total cooling capacity in closed loop thermostat operation.

ST

 

[turbocruiser]

Could it be a result of the location of your temp sender?

Well as much as I can conclude, the answer there is "no"; the sensor in that spot gets the full force of the heat from the block, from the head, and from the turbo. It is only three to five inches from where your sender is and if it was exactly where your sender is it would not calculate the amount from the turbo. Plus, it is prior to the radiator so except for a super small amount of dissipation from the aluminum neck (which is negligible) it is reading the coolant at its hottest and before any basic cooling from the radiator. At least that's the thought!

 

[SUMOTOY]

Just to note that the future of the cooling is coming. BMW in their new generation engines has gone to electric WATER pumps. The advantage is that they can get max cooling at low speed where needed, but minimize drag at higher speeds where it isn't.

More specifically, water flow is a constant and it's placement doesn't have to favor the front cylinders in cooling. Expect to see dual water system as the next step. 100C block temps for wear and combustion, and much less in head temps to reduce detonation.

SJ

 

[SUMOTOY]

OK, but not nearly at the same rate as going through the radiator. I only want the coolant to circulate through the radiator to maintain the temp as governed by the T-Stat. This is how the truck works most of the months.

Not sure I understand that. We can identify the ideal temp as the sum of all load variables where the thermostat is fully open, and engine temp is at 203F. That means the thermostat isn't governing anything. The problem you have is that the secondary open loop fan is operating in a VC fan system all the time. This is *actually* how the truck works all the months. Wouldn't it be best to have closed loop operation a separate entity? IOW, the sum total of load and heat exchange has no fan intervention at all at an engine temp of 203F. ABC's of Cooling Part V!

Again we are talking about Toyota's original design and what we should expect from it in a stock configuration. In my opinion we should expect a constant temp control throughout the year regardless of which month it is. I personally don't think 100* ambient temps should be considered extreme operating conditions resulting in 210* operating temps. Unfortunately I only recently realised I could scan my ECU for those readings as it would have been good to get that data this year.

For you or anyone who wants to run this truck in sub freezing weather at an elevated temp while driving around town will have to significantly alter the design. Needing to do so to achieve those results would indicate in my mind that you are working outside the design parameters of the truck.

I don't believe this to be correct at all Rick, btdt down to -40 at Steamboat. I only need to add electric fans to more accurately define closed loop operation, and separate it from open loop operation better. The problem with mechanical fans is they are operating in the engine thermostat closed loop system, and they shouldn't be. In the winter, excess capacity is addressed in the big rigs by blocking the radiator. Significantly altering the design with a couple pieces of cardboard? BTDT, in the 7-11 parking lot. I used a coke bottle to cover the oil cooler too. This past year, I ran 2 days without any fan at all, and never got close to open loop, that was a 4 nut 'major alteration'!

I encourage everyone to not overcomplicate this. Ideal temp has been identified, as have the primary and secondary cooling functions. My original post was to clearly identify stock 'ideal' temp in helping folks understand that tweeking the secondary cooling function can fight the closed loop circuit Mr. T designed. Again, *if* you want to target something below 203F as ideal operating temp, use a lower T-stat. Otherwise, tweek the VC to come in full bore at something over 203F. That's better heat management theory and practice, given the stock Tstat.

A bit of preamble to ABC's of 80's Cooling Part V...

Scott Justusson

 

[alaskacruiser]

For you or anyone who wants to run this truck in sub freezing weather at an elevated temp while driving around town will have to significantly alter the design.

Back in Fairbanks, AK and other places with similarly cold climates, we have grill covers (some use cardboard) and summer/winter thermostats to achieve this effect. Not a significant alteration.

 

[landtank]

I honestly don't know what you're trying to get everyone to beleive here. With a very high degree of certainty I can say that my truck would run at 185* temp 11 months out of the year before I touched the clutch.

If that's not what Toyota intended then what is broken on my truck?

 

[landtank]

Back in Fairbanks, AK and other places with similarly cold climates, we have grill covers (some use cardboard) and summer/winter thermostats to achieve this effect. Not a significant alteration.

so in winter you run at 210*?

 

[SUMOTOY]

I honestly don't know what you're trying to get everyone to beleive here. With a very high degree of certainty I can say that my truck would run at 185* temp 11 months out of the year before I touched the clutch.

If that's not what Toyota intended then what is broken on my truck?

Nothing is broken, it just defines excess cooling capacity Rick. It's not what I'm trying to get you to believe, it's how Mr. T designed the 80 heat management stages (1,2 and 3). 203F temps means that the heat load and heat capacity are at equilibrium. 100% thermal efficiency of the closed loop system as designed.

You mess with secondary function (VC tweeks), you decrease the thermal efficiency quickly below 100%, because you are using engine load (fan) to create more capacity when it's the *thermostat* that is effectively creating the heat load. See the fight? Reach capacity before you add more?

I didn't think this would be easy. But there really isn't debate here, only misunderstanding. Your truck is operating just fine Rick, you just have cooling overcapacity 11 months of the year. That doesn't change the ideal load vs capacity temperature. As Alaska and I say, just add cardboard! And/or ditch the radiator fan from the closed loop thermostat operation.

SJ

 

[SUMOTOY]

Is there anyone other than Sumotoy that believes the radiator can tell the difference from 2500cfm from a fan and 2500cfm from driving down the road?

I understand your confusion, but I don't believe that at all M. Vogt. Ram Air is a variable in defining the limit of closed loop COOLING CAPACITY = 180-203F. A radiator fan defines the limit of COOLING OVERCAPACITY = 203-226F. Then the computer takes active steps (A/C cutout) to redefine THERMAL LOAD. At 230F, the radiator cap relieves pressure to Define OVERHEAT.

These aren't beliefs, this is how the FSM describes the stages of 80 engine heat management. Not sure your point, I'm confident there isn't any disagreement, since Mr. T defines it. You want to lower the fan kick in temp below 203F so that it defines cooling capacity? Ok, as I said before, that's engine fan load (increasing thermal capacity) with a *thermostat* closing to increase heat (increasing thermal load). Most trucks on this list are already doing that. It will work, it's just not very efficient engine heat management?

ST

 

[cruiserdan]

Gentemen,

It is clear to me that Scott is not just inventing, ok I'll say it, "s***" to throw out at us.

It appears that some of us tend to discount anything he says just to do so.

I suggest you all digest his observations completely before you poo-poo them.

I have and I enjoy the mental excersizes.

 

[tarbe]

If we aren't careful, this is going to start looking like a debate between Calvinists and Arminians!

Me, I'm going to keep my fins clean, I'm going to continue to flush annually and I'm going to change my blue fan clutch the first time I don't hear the start-up roar.

 

[alaskacruiser]

so in winter you run at 210*?

Never had an aux. temp gauge on the ol' '92 Ford Aerostar AWD, but I know the stock temp gauge ran about 3 needlewidths higher all winter, and the vehicle warmed up a lot faster. So if you're wondering if the vehicle ran consistently warmer with a "winter thermostat" and the grill cover, the answer is yes.

 

[Epic Ed]

Well, I get plenty of mental exercise during other parts of my day. I'd just like the bottom freakin line. WTF is Scott talking about? Can I get a translator and someone to explain to me how this makes two-poops difference in my decision to add an electric fan in front of the radiator to improve my AC performance while moving at slow speeds/idle?

Scott you refered me to the post where I got this idea in the first place, but it seems (and I may be confused) you are admonishing us NOT to add another fan to help with perceived over-heating issues, but at the same time you're recommending I do that very thing to resolve my AC issues. Am I confused, or are you?

Bottom line, please. I could care less about debating the minutiae.

Ed

 

[alaskacruiser]

Epic- adding the fan will definitely help with idle AC performance. Do it. Don't worry about the other stuff for now. Remember, plenty of other vehicles use condensor fans, including the 80 in rear A/C configuration. Adding the condensor fan hasn't significantly affected my cooling system performance, anyway.

 

[landtank]

I still don't get how 203* was determined to be Toyota's target operating temp when the trucks clearly don't behave this way unless operating in extreme conditions. ie: under heavy load and in hot weather.

 

[SUMOTOY]

Scott you refered me to the post where I got this idea in the first place, but it seems (and I may be confused) you are admonishing us NOT to add another fan to help with perceived over-heating issues, but at the same time you're recommending I do that very thing to resolve my AC issues. Am I confused, or are you?

Bottom line, please. I could care less about debating the minutiae.

Ed

Ed:
Bottom Line:
1) Read ABC's of 80's Cooling Parts I-III. The aux fan is specifically to help cool the condenser and really has nothing to do with this thread. It works, as long as you don't expect it to decrease your radiator temps.

2) This particular thread has to do with those tweeking engine fan VC clutches to 'increase' cooling capacity at the expense of thermostat load.

The rest of this thread is chit chat controversy and debate over a concept that many find difficult to understand, but is exactly how Mr. T designed the 80 to work.

HTH

Scott Justusson

 

[SUMOTOY]

I still don't get how 203* was determined to be Toyota's target operating temp when the trucks clearly don't behave this way unless operating in extreme conditions. ie: under heavy load and in hot weather.

Rick:
Toyota designed excess capacity into the cooling system, that's all. The 80 heat management conditions are as follows for a stock 80 thermostat:

Closed Loop Thermostat Operation (T-stat generates Heat Load)
Engine Temp < 203F means Engine Heat Load < Total Cooling Capacity
AND Thermostat < 10mm open

Closed Loop Ideal Thermostat Operation (ideal)
Engine Temp = 203F means Engine Heat Load = Total Cooling Capacity
AND Thermostat = 10mm open

Open Loop Radiator Fan Operation (fan generates increase Cooling Capacity)
Engine Temp > 203F < 226 means Engine Heat Load > Total Cooling Capacity + Fan (overcapacity)
AND Thermostat = 10mm open

*Overheat* Open Loop Radiator Fan Operation (A/C shutdown to reduce Heat Load)
Engine Temp > 226F means Engine Heat Load > Total Cooling Capacity + Fan (overcapacity)
AND Thermostat = 10mm open

*Overheat* Open Loop Radiator Fan Operation (Radiator cap pressure relief)
Engine Temp > 230F means Engine Heat Load - A/C load > Total Cooling Capacity + Fan (overcapacity)
AND Thermostat = 10mm open

This is not complicated! Exactly to the point, why add Fan (overcapacity) to scenario 1 when the thermostat is less than 10mm open?

Scott Justusson

 

[Nay]

mental excersizes.

I bought this truck to not have to worry much about this kind of stuff, but I think this is the best general explanation of engine heat management I have seen.

Thanks

 

[turbocruiser]

Ouch!

I've exercised my mental as much as I can now someone please share the friggin final answer; I've got two tubes of 6000 cst ready to rock, do I use em for my fan or use em for my, well, nevermind!