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More cooling Questions... Thoughts??

R

rx7gslse

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Hey gurus..

Got a question about the optimal cooling for my truck.. 89 Suburban, 350 4x4.

Alright, It runs right right on the thermostat temp (190) about 95% of the time... However, on my commute home I have this pleasant 5-55 min wait to cross the bridge back to the US from Mexico (mind you we are already nearing 100deg days here) and if I'm running the a/c the temp gauge will just slowly climb and climb until I turn the a/c off...

Current setup;
Stock Fan flex-fan
New HD fan clutch
New Waterpump
New 4 core Brass Radiator
190deg thermostat (also new)
Stock shroud (slightly modified to fit the 4 core)
Water wetter & new fluid...


Now... My questions are... WTH is this thing still running hot?? And more importantly, how do I fix it?

Elec fans?? (assuming a higher airflow at idle conditions)
I hear rumors of a 7 blade fan, but can't verify if there are any for the serpantine belt setups.. Anyone?

Since it's ONLY when the a/c is on too, and I know a/c doesn't help, but is there something that could be wrong with the a/c that's giving it too much load??

Dangit, I need my a/c! It's getting hot here! Gimme some help guys!
 
First off, the water wetter is thicker than water and can actually give you overheating issues. Secondly, if it is only getting hot while sitting in traffic but stays cool otherwise then i would add an electric fan as a backup for those sitting in traffic times, you could either hook it up to a thermal switch or run it to a toggle switch and turn it on whenever it is needed.
 
4x4HIGH - Antifreeze is thicker (more viscous) than water too - so what? 4oz of Water Wetter in a gallon of water isn't gonna change the viscosity of the water in any way that the truck will notice. Water Wetter works. It has never caused overheating in any of my vehicles, or any of my family's or friend's vehicles. I've had overcooling issues in the late fall, but never overheating.

rx7 - If you're running WW, I would NOT run 50/50 antifreeze/water, especially in your neck of the woods. Maybe 1qt antifreeze to 1gal distilled water (distilled is important with the WW, since it can cause the minerals in tapwater to turn to sludge).

Is your cap new? If not, replace it...

Is it a stock fan or a flex-fan? They are different, and IMO flex-fans are crap.

How is the fit of the fan shroud around the fan and the radiator? IIRC, about half of the fan blade should be exposed from the rear of the shroud. If the shroud doesn't fit well all the way around the radiator, the air is gonna take the path of least resistance to the fan and sneak around the radiator. Does you no good like that...

Is all the air purged from the engine/radiator? Trapped air can cause issues...
 
I understand that anti-freeze is also thicker than water, for that reason alone is why you do not want to run a 50/50 mix like people used to think back in the day. I also only stated that water wetter CAN give overheat issues not that it always will or definately would. I agree with you about checking the radiator cap and also the fitment of his shroud, this is all good advice for him.
 
4X4HIGH said:
I understand that anti-freeze is also thicker than water, for that reason alone is why you do not want to run a 50/50 mix like people used to think back in the day. I also only stated that water wetter CAN give overheat issues not that it always will or definately would. I agree with you about checking the radiator cap and also the fitment of his shroud, this is all good advice for him.
Click to expand...

JUst curious, but what is "water wetter"?
 
Never had to deal with AC before, but does your truck "compensate" for the load of the AC correctly, by maintaining roughly the same idle when the AC is on as when it's off? Most setups have an AC pressure switch wired into the setups, outside chance that's an issue.

If the engine is loaded by the AC and isn't increasing RPM's, coolant flow and fan RPM will be less. Not that hard to listen for.

A 4 core radiator reduces the effectiveness of a fan, so you are dealing with that problem as well I suspect. A *powerful* electric fan(s) may solve the problem, but that's a pretty extreme step. Personally I'd just swap over to all electric if I was thinking of that route.

Another thing, what IS the coolant composition? Did you use WW and antifreeze, or just WW and water? Water is a better coolant than antifreeze, if you've got antifreeze in the mix, you can always try running straight water to test (and just saving your current coolant in a bucket if you want to go back) and see if it solves the problem. I also doubt this will solve your problem, but it's a pretty easy test, and may at least help. Antifreeze companies would love to have you believe you need antifreeze for boilover protection, but that is (mainly) the job of the radiator cap. If it is working right, water won't boil until 240*+. Whatever percentage of antifreeze you need for freeze protection in your area (I mix mine up so I'll be ok down to around 0*, just in case) is the minimum I'd run. You still need SOMETHING as a corrosion inhibitor, so either WW or antifreeze, but straight water could be used to *test* as long as you didn't leave it in there.

I'd still lean towards the fan just not being able to pull enough air through the larger radiator, with the AC.
 
Ok, I'll try to answer some question here...

Yes, the radiator cap is new... It was replaced when I went to the 4 core radiator, at the same time the lower temp thermo was installed.

There is a small amount of anti-freeze inthe mix, but it's nowhere near 50/50. I doubt the coolant mixture is the issue given the way it's acting...

It is the 'stock' fan.. I guess I'm not 100% sure what a flex-fan is, but it's the stock 5 blade fan on a fan clutch that was replaced the same time as the stuff above (well, the next day)

When the a/c kicks in, the RPMs do rise a bit.. Nothing drastic, but maybe a couple hundred rpm or so... (no tach, just guessin)

I will look at the shroud a little closer.. It's just the stock shroud with modified mounting. It probably does sit a bit closer to the fan than original given the way it's mounted... An Issue?

I am definatly thinking airflow issue overall.. The 4core is a lot thicker than the stock radiator, so I'm trying to figure out how to compensate for that. Upgrade the stock mechanical fan setup? (and how?)
Add in an aux elec fan?
Convert to a full electric setup? (most I've seen for our trucks specify 'not for use with 4 core' is that a mounting issue, or an airflow limitation?)
Something else I'm overlooking??


FWIW, without changing anything mechanical, I was definately able to see a reduced temp just by running the water wetter setup. I like the stuff... :)
 
As to one of your last questions, I have no idea why they say not for a 4 core radiator. Should be plenty of room for a 5 or 6 core radiator and electric fans like the windstar setup. :)
 
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