80 Operating Temperature per FSM

[PHAEDRUS]

Well I have avoided this little pile of minutia drivel for some time now.
Rick and Vogt and Sumo:
1. at what temperature will a fan clutch filled with 6000 cst (to properlevels as per ricks thread) engage and begin to draw More air in through the radiator. I do not give a s*** about ram air as it is not my goal to control total heat loads. or any other such minutae bull s***.

If anyone can answer that question again with 3000 cst and 10000cst fluid peopel should be able to replicate at what temperature their fan clutch will engage.

Sumo's point from what I see is that by making the clutch engage at a temperature lower than max flow at teh thermostat is couter intuitive. I agree.
Some may want more of an overload buffer than the magic 22 degrees though and may choose to have the clutch fully engage earlier.
Dave

 

[cruiserdan]

As I understand it the viscosity does not effect the temperature at which the clutch activates, it increases the ammount of "drive" at any given temperature.

 

[SUMOTOY]

As I understand it the viscosity does not effect the temperature at which the clutch activates, it increases the ammount of "drive" at any given temperature.

That's my understanding as well. Which means exactly what you need to know is at what temp does the timing of your specific VC cause fan intervention?

I can't answer this question, as it appears that is not a constant in a brand new factory delivered blue VC clutch. What does appear to be valid is, if you are switching VC fluid, 203F is a critical temperature to *consider*. Read Rick's excellent writeup of how to change fluid and engagement timing.

Getting caught up in the minutiae of 'choosing' VC fluid or engagement wasn't my goal, only to present that below 203F, changes to the secondary cooling properties will affect closed loop thermostat operation. More specific than 'counter intuitive' this approach appears to be a less than optimal target in 80 heat management.

I'm confident when the smoke clears, it's not rocket science.

ST

 

[Epic Ed]

Scott -- we're talking two different fans -- fan clutch vs electric fan. Got it. Can we all just go have a beer now?

Ed

 

[LandCrusher'70]

As I understand it the viscosity does not effect the temperature at which the clutch activates, it increases the ammount of "drive" at any given temperature.

More drive is good right?

More drive = more CFM?

 

[Darwood]

Let’s see if I understand what Scott is saying when he talks about modifying the viscous coupling. Pretty much at any time before 203F the thermostat should be the controlling factor in managing coolant temperature. This is due to the fact that it is not fully open before this temperature. Since the thermostat should be controlling temperature before 203, modifying the fan to turn on before 203 is a waste of energy. In essence the fan and thermostat are fighting each other. The fan is cooling off the coolant early which results in the thermostat closing prematurely to heat up the coolant. It works but it's not ideal. You want the fan to engage as late as possible to increase fuel economy. An active fan is pushing against the air which creates resistance which creates more load on the engine.

 

[SUMOTOY]

More drive is good right?
More drive = more CFM?

More drive = more engine load. 'Good' depends exactly on if you need the extra capacity. If more drive load then causes the thermostat to add more thermal load, I don't believe it's good.

YMMV

SJ

 

[SUMOTOY]

Let’s see if I understand what Scott is saying when he talks about modifying the viscous coupling. Pretty much at any time before 203F the thermostat should be the controlling factor in managing coolant temperature. This is due to the fact that it is not fully open before this temperature. Since the thermostat should be controlling temperature before 203, modifying the fan to turn on before 203 is a waste of energy. In essence the fan and thermostat are fighting each other. The fan is cooling off the coolant early which results in the thermostat closing prematurely to heat up the coolant. It works but it's not ideal. You want the fan to engage as late as possible to increase fuel economy. An active fan is pushing against the air which creates resistance which creates more load on the engine.

Good summary! Thanks Darwood, the smoke really is beginning to clear. The key is the 203F temp, and understanding what's happening before 203F in terms of load and capacity.

Understanding that, the fan can be fully locked up at 181F, it's just a bigger fight between primary and secondary cooling functions. The engine and FTU isn't going to care or know. Your wallet might remind you every couple hundred miles...

SJ

 

[SUMOTOY]

Scott -- we're talking two different fans -- fan clutch vs electric fan. Got it. Can we all just go have a beer now?
Ed

I'm always up for a beer, at whatever temp my truck is running at. Ed, you are looking for aux condenser cooling, that's ABC's of 80's Cooling parts I-III. Do note however, that in ABC's Part V (to be written), I am going after puller type electric fans (ditching the VC engine driven one) based on the principles of heat management I present in this thread.

If you got that, this should be a good beer weekend.



SJ

 

[LandCrusher'70]

More drive = more engine load. 'Good' depends exactly on if you need the extra capacity. If more drive then causes the thermostat to add more thermal load, I don't believe it's good.

YMMV

SJ

Hmmm . . .

 

[alaskacruiser]

Inventing - no. Misrepresenting yes. Misunderstanding, certainly.

He's stated twice now that there is a difference between air moving through the radiator that comes from driving at speed, and that which comes from a fan.

And we should have more confidence in what he says for exactly why?

Walking Eagle- SUMO responded *directly* to your question as follows:

"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."

What about this explanation does not make sense to you? Seems pretty clear to me. It would *really* help if you try to identify what, specifically, about SUMO's explanation doesn't make sense to you or what you do not agree with and exactly why.

And, speaking of confidence in what you saying, I seem to recall that, after trying to "call out" SUMO in a totally irrelevant and obvious flamebait post about "nulls", you were proven wrong and you then proceeded to make an excuse about it instead of admitting it. And we should continue to read your increasingly transparent flamebait posts why? Please do us all a favor and try to post about the topic instead of hashing out your personality conflicts with SUMO. None of us care.

 

[SUMOTOY]

Heat Management....

Baseline
I believe the confusion really revolves around the VC fan coupling and it's purpose. Prior to the application of the VC fan coupling, the direct drive mechanical fan was part of the primary AND secondary cooling functions in terms of *capacity*. Plain and simple you were way over capacity in the thermostat closed loop phase.

Better
Then the car/truck manufacturers discovered that the addition of the VC meant that you could better manage engine load vs fan overcapacity. With the VC there wasn't fan lockup capacity added during warmup or closed loop thermostat operation. Since a VC can't disengage, there is always fan capacity in the primary thermostat closed loop operation, but it can be significantly reduced (I am after elimination with electric conversion)

Best
The third step car/truck manufaturers have taken is to use either electric fans or on/off mechanical coupling fans to eliminate the fan load on the engine all together during thermostat closed loop operation. These newer systems have the advantage that they are engine temp activated (active not reactive) overcapacity devices.

Back toward baseline
Where an 80 owner runs into trouble by tweeking the VC, is possibly taking a step back towards too much overcapacity in the thermostat closed loop phase. Increase the lockup of the fan before 203F, you are adding overcapacity when it's not needed.

I see this as specifically negating he benefits of the secondary cooling circuit as Mr. T designed.

SJ

 

[Walking Eagle]

Walking Eagle- SUMO responded *directly* to your question as follows:

"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."

What about this explanation does not make sense to you? Seems pretty clear to me. It would *really* help if you try to identify what, specifically, about SUMO's explanation doesn't make sense to you or what you do not agree with and exactly why. .

Exactly what I don't understand is why it's so bad for cooling to have the fan enguage before the T-stat is full open. There are so many situations that there is more air going through the radiator from just driving than the fan can provide, also before the T-stat is full open. There is no difference in the effect of this on the cooling system. If having the stat only partially open due to the radiator having an abundance of airflow was so bad for the cooling system, we'd probably see alot of cars with variable slats in front of the radiator.

And, speaking of confidence in what you saying, I seem to recall that, after trying to "call out" SUMO in a totally irrelevant and obvious flamebait post about "nulls", you were proven wrong and you then proceeded to make an excuse about it instead of admitting it..

Humm.... Telling him I don't understand how he's using the term null and nulls, was trying to "call out" Sumo? Flamebait? I didn't understand what the heck he was saying cause he was using a term I wasn't familiar with. Proven wrong? Proven wrong? I asked how he was using it and he explained, and that proved me wrong? I hadn't made a statement to be proved wrong about! There was no wrong to admit. There also was no excuse, only some facts. Facts like in Six Sigma Black Belt traing they teach us not to get hung up in becoming statisticians cause we'll never accomplish our jobs. Even talked to our Site Master Black Belt to confirm - and he confirmed 'We did actually teach you about it in class, but we only spend a few minutes on it (out of 250 hrs of training which is probably why I didn't remember it) on purpose cause we don't want you using it'. Then a quote of facts from Wikipedia, and then the fact that I don't feel I need to add it to my toolbox. I don't see where the excuss was.

And we should continue to read your increasingly transparent flamebait posts why? Please do us all a favor and try to post about the topic instead of hashing out your personality conflicts with SUMO. None of us care.

Alaskacruiser, you're more than welcome to put me on your ignore list and not read my posts. I really don't give a flying rat's behind about Sumo's personality. I just want to know why he believes the fan kicking on at less than full t-stat open is any different, to the cooling system, than having far more air flowing through the radiator at a less than full t-stat opening. That answer he has not given.

 

[Darwood]

Exactly what I don't understand is why it's so bad for cooling to have the fan enguage before the T-stat is full open.

I thought I covered this in my post. It's bad because you are wasting energy. Wasted energy means decreased fuel economy. How much energy is being used might be negligible though. It's kind of like wearing belt and suspenders when all you really need was a belt. If your pants get too heavy use the suspenders but until then you're just wasting time when you get dressed.

 

[SUMOTOY]

I thought I covered this in my post. It's bad because you are wasting energy. Wasted energy means decreased fuel economy. How much energy is being used might be negligible though. It's kind of like wearing belt and suspenders when all you really need was a belt. If your pants get too heavy use the suspenders but until then you're just wasting time when you get dressed.

I like that one Darwood! 2500cfm of Ram airflow doesn't cost you any additional engine energy to create cooling capacity. 2500CFM of VC fan output always costs engine energy to create cooling capacity.

Engine Thermostat regulation of Ram Air cooling overcapacity is good heat management. Engine Thermostat regulation of VC fan generated cooling overcapacity isn't good heat management.

Bad engine heat management > fuel consumption increases


SJ

 

[tarbe]

Let’s see if I understand what Scott is saying when he talks about modifying the viscous coupling.

Saved bandwidth by not quoting the whole post.

You get it.

 

[landtank]

I don't see where running with the thermostat partially closed automatically means the clutch is engaged and wasting energy. The clutch is controlled by the air temp that is in front of it. And if that air is cooled to the pioint where the clutch won't come on then it will have no ill effect. This is often true when driving along where ram air provides sufficient cooling.

In my specific case I was running extremely hot during weather that exceeded 85* and towing. The cooling system needed help which I gave it.

Just because my truck is running at 185* now in 70* weather doesn't mean if I removed my clutch entirely that the temp would increase.

 

[ShottsUZJ100]

That's my whole point, it isn't a rpm variable at all, it has to do with how open the T-Stat is. All the RPMs in the world won't yield any flow with a closed T-Stat.

My new LX overheats in drive-thru's and when stopping at obstacles on the trail. The A/C then cuts out and kicks back in.
I did discover that while I'm waiting (at either place) if I keep the RPM's up to about 1500 or so, the A/C won't cut out.

What does this scenario tell you about my trouble? I just had the R134 system drained, leak tested and recharged. Install an electric fan? Check fo a bad ??? Thoughts?

Thanks!

 

[alaskacruiser]

Shotts- coolant flush, replace fan clutch, rad cap.

 

[landtank]

My new LX overheats in drive-thru's and when stopping at obstacles on the trail. The A/C then cuts out and kicks back in.
I did discover that while I'm waiting (at either place) if I keep the RPM's up to about 1500 or so, the A/C won't cut out.

What does this scenario tell you about my trouble? I just had the R134 system drained, leak tested and recharged. Install an electric fan? Check fo a bad ??? Thoughts?

Thanks!

It means you're running efficient evidently


Actually I'd rework the fan clutch. Take a close look at the temp spring and be sure it's in good shape and free of debris as this will stop it from working properly. After that do a drain and fill with new oil, I'd use 6K myself and see how the truck runs then.