06-18-2021, 03:41 PM
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#31
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Quote:
Originally Posted by Bad Luck
Have you tried cleaning your condenser? They can get clogged up and restrict airflow to the radiator.
One thing to consider when switching to electric fans is the additional electric load required. There is still a load on the engine in the form of increased load on the alternator. You may need to upgrade your alternator in order to keep up with the demand. There's no such thing as a free ride.
The Koyo or Champion radiators are a thicker radiator core (advertised 33% thicker) which will greatly increase heat transfer. Combine that with a 170 degree thermostat, fresh coolant with water wetter, and a properly functioning fan clutch and I don't see a reason for electric fans. I don't think Koyo or Champion have provisions for an internal transmission cooler, and they may require a different radiator cap.
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My AC Condenser is relatively free on debris but it wouldn't hurt to give it a cleaning. I think I will probably go with an aluminum radiator, probably the Koyo because I don't want to deal with the fitment issues of the Champion.
After some thought, I don't think I want to do the electric fan mod. Seems like a lot of work with maybe not much benefit over the regular fan clutch.
I'll run a bigger stand-alone trans cooler when I go with the Koyo aluminum radiator. My trans temps can spike too under the right conditions.
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06-18-2021, 03:43 PM
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#32
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Quote:
Originally Posted by Pyral
It appears that the water to antifreeze ratio can also have an affect on heat transfer. [...] but be warned that there is some disagreement if running pure water can lead to it boiling and becoming steam. The antifreeze raises the boiling point of the water, but the system is pressurized so it should make it more difficult for water to turn into steam.
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You're right, a stronger mix of coolant does raise the boiling point. The difference in boiling point between a 50/50 mix, approx 225F by this chart, vs a 25% coolant mix boiling at approx 218F is not particularly large. This would not be one of my primary concerns, especially since the increased cooling capacity of the mix with less coolant would also keep temps lower.
Note these boiling temps are also at standard atmospheric pressure.
Last edited by PrinceValorum; 06-18-2021 at 03:47 PM.
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06-18-2021, 03:45 PM
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#33
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Do you have an automatic transmission? if yes, you might like to add an inline aux atf cooler with fan to help lower the water temp in the lower tank of the rad.
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06-18-2021, 03:46 PM
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#34
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Quote:
Originally Posted by PrinceValorum
A simple thing to try would be to drop the mix ratio of coolant to water. 50/50 is recommended for optimum freeze protection with minimal heat transfer losses. A lot of race/track cars will run 25% antifreeze, or even 10% antifreeze, to maximize the cooling efficiency. Fortunately you don't have to worry about freezing, but even 10% antifreeze is enough to protect down to 26F.
If it were me, I would try running 25% coolant and see how that went.
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I have thought of this option. I'm currently running the usual 50/50 mix.
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06-18-2021, 03:47 PM
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#35
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Quote:
Originally Posted by PrinceValorum
You're right, a stronger mix of coolant does raise the boiling point. The difference in boiling point between a 50/50 mix, approx 225F by this chart, vs a 25% coolant mix boiling at approx 218F is not particularly large. This would not be one of my primary concerns, especially since the increased cooling capacity of the mix with less coolant would also keep temps lower.
Note these boiling temps are also at standard atmospheric pressure.
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Boiling point increases with pressure. OEM radiator cap is 13 psi. Boiling point of straight water at 12 psi is 242*F. Boiling point of 1/3 coolant/water at 12 psi is 253*F. Boiling point of 50/50 coolant/water at 12 psi is 257*F. I don't see any problem with running a 25/75 coolant/water mix.
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06-18-2021, 03:52 PM
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#36
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Quote:
Originally Posted by JZiggy
Lots of good ideas in here, Tim. Here are some of my own ideas and my take on some of the suggestions offered here.
Regearing -- agreed this is likely to make the most difference as it will reduce strain on the drivetrain = less heat generation. Less torque converter slipping, engine running at higher RPMs and more reasonable loads rather than being bogged down all the time.
Electric fans -- A pusher fan in the front of your radiator can help a good deal. My little 1000cfm one certainly does. I would NOT change your mechanical fan to a primary electric fan. I have also personally had bad experiences with this approach.
Mechanical fan -- I know your fan clutch is new, but have you actually confirmed its operating correctly? It is also possible to change the viscosity of the fan's silicone oil to make it hook up more. Reading these two links it sounds like the factory units are sometimes underfilled with silicone oil as well!
Coolant -- Good idea to try a higher water % in your coolant mix as water is a much better heat transfer fluid than ethylene glycol. Redline's water wetter or similar is a strong surfactant and helps the coolant reject heat into the radiator more quickly but I'd leave this as a last resort.
Radiator -- Sounds like a lot of people are suggesting an upgraded radiator. Makes sense to me.
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Yeah, the pusher fan might happen.
I'm going to start with the re-gear because the extra power is seriously needed and I know it will help drop the coolant temp.
Next will be an aluminum radiator with a big stand-alone trans cooler. I think I will lessen the coolant/water ratio, maybe a 40/60 or 30/70.
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06-18-2021, 03:55 PM
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#37
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Quote:
Originally Posted by phattyduck
I'd still suspect the cooling system just a bit - the radiator cap. If not new and OEM, change it out.
I had slight overheating issues when I had a weak radiator cap - it got up in the 210*F range in ~105*F heat with a medium load (32's, armor, 3 dudes w/ backpacking gear) on long hills. It was always fine around town, in traffic or on regular freeways (rock solid at 191*F). After replacing the cap, no issues with the same or higher load in harsher conditions. I already had a new radiator, new water pump, new thermostat and coolant (all OEM).
The OEM cooling system is incredibly good, I think it might be as simple as the radiator cap.
-Charlie
Edit: PS. I always run about 40% coolant / 60% water - it has been ok down to as low as -10*F temps on my Subaru, and I'd assume the 4Runner would be fine that way too.
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The radiator and cap were replaced 20k ago so I wouldn't suspect an issue with the cap. I think I'll follow your suggestion and go to a 40/60 coolant/distilled water mix.
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06-18-2021, 03:57 PM
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#38
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Quote:
Originally Posted by Pyral
Your rig has a cold intake right? That probably helped you out.
It appears that the water to antifreeze ratio can also have an affect on heat transfer. That's because water is a better conductor of heat, but be warned that there is some disagreement if running pure water can lead to it boiling and becoming steam. The antifreeze raises the boiling point of the water, but the system is pressurized so it should make it more difficult for water to turn into steam.
But the long term fix is upgrading radiator and fan. This is probably a good idea anyway because it appears that these heat waves will happen more often.
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No cold air intake. I have the stock set-up.
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06-18-2021, 03:59 PM
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#39
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Quote:
Originally Posted by Bad Luck
Boiling point increases with pressure. OEM radiator cap is 13 psi. Boiling point of straight water at 12 psi is 242*F. Boiling point of 1/3 coolant/water at 12 psi is 253*F. Boiling point of 50/50 coolant/water at 12 psi is 257*F. I don't see any problem with running a 25/75 coolant/water mix.
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I agree.
Just to clarify for anyone else who may have slept through thermodynamics, the boiling point of water is 212F at 14.7psia (pounds per square inch absolute, absolute being in reference to complete vacuum). The radiator cap rated at 13psi is 13psi g (pounds per square inch gauge, like what you measure with your tire gauge). Gauge pressure is what the additional pressure is on top of atmospheric pressure, so a 13psig cap would be able to hold 14.7psi + 13psi = 27.7psia.
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06-18-2021, 03:59 PM
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#40
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Quote:
Originally Posted by HiluxSurf SSR-G
Do you have an automatic transmission? if yes, you might like to add an inline aux atf cooler with fan to help lower the water temp in the lower tank of the rad.
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Yes, auto trans and I do have an auxiliary trans cooler that is running in-line with the radiator trans cooler. I don't have a pusher fan though.
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06-18-2021, 07:01 PM
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#41
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Quote:
Originally Posted by RotaryDreamz
Thats a unique idea. But I feel it wouldn't really help, as I feel the water would just simply, fly through the radiators fins going highway speeds. If somehow the fins of the radiator would somehow capture the moisture and let it absorb somehow, I can see something there.
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That's an interesting point you bring up. I suppose it would depend on how finely the sprayers atomized the cooling water, and how densely packed the fins were. If the mist passes through the rad without touching it obviously that doesn't help, but if it is in contact with the rad before getting blown off by the incoming air while driving, it will pull heat out of the rad with it, ie. evaporative cooling.
I typed 'mist radiator' into youtube and found several videos, to my mild surprise. The ones about radiators didn't really have much in the way of hard data, but this quick vid by Might Car Mods showed some numbers for their Miata spraying the intercooler with water. There would be a lot more heat to pull out of a radiator vs an intercooler because water has more than 4x the heat capacity that air does, but the temperature delta will be much greater between a radiator vs ambient air compared to their intake air vs ambient air, which would assist in cooling a radiator.
Ambient air was 86F during their test, and with 104F IAT, the sprayer took it down to 97F, giving a temp delta of 7F. When they had the car under higher load and intake temps were 118F, the sprayer brought temps down to 104F, giving a temp delta of 14F. Not insignificant improvements.
https://www.youtube.com/watch?v=O0MY0diHo4U
As several of the people who installed the radiator sprayers mentioned, there are some pretty significant drawbacks, including limited reservoir capacity, having to refill the tank frequently due to the limited capacity, the potential for mineral deposits if you don't use distilled water, and the fact that this is kind of a big bandaid fix in the first place, etc, etc. Still pretty novel idea, imo, especially if you just need it for a few sections of climbing in a trip vs needing it for the entire trip.
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06-18-2021, 07:15 PM
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#42
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Quote:
Originally Posted by mtbtim
I think I will probably go with an aluminum radiator, probably the Koyo because I don't want to deal with the fitment issues of the Champion.
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FWIW, the only "fitment issue" I had was that the ears that hold it up while you line it up for bolting it in just won't work. 30 seconds with a hacksaw and a file make that problem go away. That's it.
Sleepydad had some bad rivnuts, mine were fine. By drilling his out and just using nuts on the backside, his fit fine ~ mine needed a couple washers on one corner (but I know my 4r has been in an accident too, so it's likely a little twisted) to sit right.
The potential issues with the Champion are minor, especially when you consider that the Koyo is twice the price... though I "get" that $200 means less to someone with a $200k/year income than to someone like me with a $30k/year income, so it may be a non-issue from the finances standpoint.
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06-19-2021, 12:10 AM
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#43
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the stock air intake system is a "COOL AIR" intake because it sources the air from the inner fender, not from inside the engine bay. I would prefer this over some aftermarket air intake systems that call their intake system as "COLD AIR". COLD AIR is a misnomer because the intake air isn't COLD and in fact some of them, like the pod-type air filters, source the intake air from inside the engine bay which is actually HOT AIR.
Quote:
Originally Posted by mtbtim
No cold air intake. I have the stock set-up.
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06-19-2021, 10:45 AM
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#44
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Get a Desert Water bag like they use to use. The canvas actually allows water to seep out, which then aids in cooling the radiator through evaporation.
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06-19-2021, 10:55 AM
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#45
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My feeling is the re-gearing will probably provide the best results, assuming there isn't some underlying issue with the motor. A heavily loaded vehicle with probably minorly compromised airflow from the armor has to work a lot harder. Add in the increased ambient temps and you don't have a good way to extract all that extra heat.
Just like running trails in 4Lo, the engine/trans, etc has less work to do so it's not putting more heat into the system. The lower (probably more correct for the tire size, etc)gearing will probably also net a little better fuel economy, once you do the mileage/speed corrections.
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