Time for a Radiator Upgrade...?

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Bextreme04

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isnt a big block usually an exception, to my understanding they get hot in pockets that the gauge isnt at, but running a hotter t stat could mean too hot in those hot spots?
Not necessarily an exception, they just generally have more cooling issues. That's one of the reasons the Gen V & VI BBC have a different cooling flow pattern and therefore needs different head gaskets. It's also why the Gen VI has built in oil cooler ports, so that the engine oil can be pulled up to temp faster and kept at a reasonable temperature even under a heavy load for extended amounts of time. Having the engine cooler is almost always better for full throttle performance but has disadvantages that have been discussed earlier. These disadvantages are negated in full race vehicles because generally don't run under very extreme temperatures and generally run for much less time. The oil change intervals are generally much shorter and they aren't really asked to do more than one thing very well. A street vehicle needs to operate well in a wide variety of conditions and also for a very extended amount of time comparatively. Everything is a trade-off, so for a street vehicle it makes sense to sacrifice a few horsepower on the top end to stabilize the engine oil and transmission fluid under most operating conditions and also to allow the engine to run a bit more efficiently. The funny thing here is that due to how heat transfer works, the hotter your engine coolant is, less heat is pulled from the engine(once the thermostat is fully open) and MORE heat is transferred out of the radiator. So a thermostat that opens fully earlier will not necessarily allow the entire cooling system to function better, but might allow the engine to transfer more heat out and the radiator to transfer less. The engineers that designed the system most likely sized the radiator, pump, and thermostat temp to match as closely as possible so that the engine running at 100% throttle for 10 minutes or so will not produce enough heat to overcome the rest of the system.

When we have these old cars that we have made so many modifications too and that are using reman parts or upgraded speed parts, its almost impossible to match the system properly anymore. A good alternative is to just put the biggest, most efficient radiator you possibly can on it. Then you can size down the thermostat, get a higher flowing thermostat, or get a higher flowing pump to compensate for any issues with heat transfer through the engine. A cooler thermostat gets you better heat transfer out of the engine and the giant radiator compensates for the loss in thermal transfer from the lower temperature coolant. If you are running just a bit over stock power levels and have a clean, well tuned engine though, you will get more reliability and longevity from running a stock pump and thermostat and an adequate radiator.
 

7900_Blazer

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Thought I'd post a quick update as the thread starter...

I happened to be at Oreilly's for something else (I'd removed the thermostat completely, which lowered the temp enough for me to drive it - but clearly I needed to do something).

I still hadn't decided which direction I was going to go... rot out the original, buy an aluminum radiator, try to find an OEM etc...,

I happened to ask the guy if they could order a replacement and to my surprise, they had a replacement in stock (plastic reservoirs - cheap-0)... for $140 so I bought it along with a 180 degree thermostat.

Those are super easy to install... runs cool as a cucumber...

Still have plenty to do (factory reservoir, clutch, fan etc...) but wanted to mention that Oreilly's stocks a replacement... cheap...

Concerning my 'stranded' thread - mentioned here... In my opinion, cooling the engine was needed but not to solve that issue necessarily. My goal there is a return type fuel sending unit along with a return type mechanical fuel pump and a return line...

For now though, the top is off, it was 77 today in Texas and it's purring like a kitty cat...

You must be registered for see images attach
 
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AuroraGirl

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Thought I'd post a quick update as the thread starter...

I happened to be at Oreilly's for something else (I'd removed the thermostat completely, which lowered the temp enough for me to drive it - but clearly I needed to do something).

I still hadn't decided which direction I was going to go... rot out the original, buy an aluminum radiator, try to find an OEM etc...,

I happened to ask the guy if they could order a replacement and to my surprise, they had a replacement in stock (plastic reservoirs - cheap-0)... for $140 so I bought it along with a 180 degree thermostat.

Those are super easy to install... runs cool as a cucumber...

Still have plenty to do (factory reservoir, clutch, fan etc...) but wanted to mention that Oreilly's stocks a replacement... cheap...

Concerning my 'stranded' thread - mentioned here... In my opinion, cooling the engine was needed but not to solve that issue necessarily. My goal there is a return type fuel sending unit along with a return type mechanical fuel pump and a return line...

For now though, the top is off, it was 77 today in Texas and it's purring like a kitty cat...

You must be registered for see images attach
I compliment you on your changed course for return. Sure we are all pinheads in our own ways but it’s a sign of intelligence and truly the least stressful way to live, and a lot of people will never get to that point lol so it’s rare. But I’m glad you got a new rad, that tells us it was very inefficient inside. Have it now you can fill some clr shake, then drain out and see what comes out? If you still have it, put her on a shelf if you ever decide to keep it or donate to someone who could and just be apart of maybe a couple other parts you Toss in for a trade on some stuff. Assuming you have the room.


Nice looking truck too.

If you go and do return stuff you can buy a premade return line molded like the factory Ones for 73-80 trucks. If you’re supply line looks bad old crusty, I suggest buy the pair or at least burst a bit of air to clean it out. When disconnected ofc.

If you’re into gambling I got a few random sbc pumps, all prob original :) lol.

Do you still have same shroud snd fan? Frankly you might be able to cheat those other changes for a while if you do that good and Texas winters are colder enough like today was 77 you said. But it’s a great goal wrapping that gas line too to keep engine and road heat deflected a bit too
 

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@AuroraGirl
I probably wouldn't categorize adding a return line as a 'change of course'. My problem was I had no course at all :)... and thats why this site and you all are so helpful.

In consulting with one of the guys I follow on Instagram 'MrChevyGM'... (check out his profile - does unbelievable work restoring 1st Gens...) - He's run these trucks and Blazers for years and years in the desert - rebuilt them for years... and is completely fine with the factory setup (no return line)...

I also considered just going EFI... everything is pressurized etc...

Over in my 'Stranded' thread - I had ended my posts with my two goals... 1st being to get the temps lower... so that's accomplished; the 2nd is to put in a return line as that seems to most common-sense solution given that I want to drive both my Blazers (with my son) to Alaska but still want to keep both Blazers as 'stock' as possible.

At that time, I hadn't considered returning the fan to stock, adding a clutch etc... as I was just trying to get to Colorado and back... but those items are now on my short list.

Also, concerning my 'truck'... it was such a basket case when I picked it up last August. You can check out some of work on it with my son on my Instagram profile - search for @fwilliamjohnson. While you are there.. search for @mrchevygm.... seriously beautiful work he does...
 
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AuroraGirl

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@AuroraGirl
I probably wouldn't categorize adding a return line as a 'change of course'. My problem was I had no course at all :)... and thats why this site and you all are so helpful.

In consulting with one of the guys I follow on Instagram 'MrChevyGM'... (check out his profile - does unbelievable work restoring 1st Gens...) - He's run these trucks and Blazers for years and years in the desert - rebuilt them for years... and is completely fine with the factory setup (no return line)...

I also considered just going EFI... everything is pressurized etc...

Over in my 'Stranded' thread - I had ended my posts with my two goals... 1st being to get the temps lower... so that's accomplished; the 2nd is to put in a return line as that seems to most common-sense solution given that I want to drive both my Blazers (with my son) to Alaska but still want to keep both Blazers as 'stock' as possible.

At that time, I hadn't considered returning the fan to stock, adding a clutch etc... as I was just trying to get to Colorado and back... but those items are now on my short list.

Also, concerning my 'truck'... it was such a basket case when I picked it up last August. You can check out some of work on it with my son on my Instagram profile - search for @fwilliamjohnson. While you are there.. search for @mrchevygm.... seriously beautiful work he does...
If you needed a 5 blade or a 3 blade metal fan I have what I think are Oe fans, just need a new clutch because they have been layinf down for years. But without you mocking up a fan on the water pump it will be hard to know if you need a different shroud. I could measure the length and you can measure from your spacer base to the base of the flex. One thing to note is I do believe flex fans were made to match the water pump pulleys speed rotation which means a different crank and water pump pulley could change the the speed and that might mean it flattens out at lower rpm than intended too
 

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A auto mechanic explained how best to figure out what temp thermostat to use. The first question is "Do you know more about the design of this engine than the engineers who designed it? Have you studied the scientific reasons for the original engineer that designed this engine to use a 195 degree thermostat? If the answer to either question is "No" that means you should leave things as they were designed, or design an engine that works the way you would like it to work.

From that point on I considered the engineer had reasons to design the device the way he did and changing something I didn't fully understand based on opinion might not be the best idea.
 
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AuroraGirl

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A auto mechanic explained how best to figure out what temp thermostat to use. The first question is "Do you know more about the design of this engine than the engineers who designed it? Have you studied the scientific reasons for the original engineer that designed this engine to use a 195 degree thermostat? If the answer to either question is "No" that means you should leave things as they were designed or go to engineering school so facts are present in the decision process.
I mean if youre doing something you know will be effecting things enoguh you can plan and act accordingly but that frankly requires a lot that most arent doing or the effort to change could have been augmented by something like a better choice part
 

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One gramer/spelling question I have, I have always ASSUMED that when you have a radiator serviced they will "rod" the core, which I ASSUMED meant they would push rods through the core to clean/scrape out the tubes going through the core.

I keep seeing the word "Rot" used in this description, can someone better at English than I am clear this up? I am asking because I have assumed for more than 40 years that the term is rodding, without actually knowing the facts.
 

WP29P4A

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@AuroraGirl
I probably wouldn't categorize adding a return line as a 'change of course'. My problem was I had no course at all :)... and thats why this site and you all are so helpful.

In consulting with one of the guys I follow on Instagram 'MrChevyGM'... (check out his profile - does unbelievable work restoring 1st Gens...) - He's run these trucks and Blazers for years and years in the desert - rebuilt them for years... and is completely fine with the factory setup (no return line)...

I also considered just going EFI... everything is pressurized etc...

Over in my 'Stranded' thread - I had ended my posts with my two goals... 1st being to get the temps lower... so that's accomplished; the 2nd is to put in a return line as that seems to most common-sense solution given that I want to drive both my Blazers (with my son) to Alaska but still want to keep both Blazers as 'stock' as possible.

At that time, I hadn't considered returning the fan to stock, adding a clutch etc... as I was just trying to get to Colorado and back... but those items are now on my short list.

Also, concerning my 'truck'... it was such a basket case when I picked it up last August. You can check out some of work on it with my son on my Instagram profile - search for @fwilliamjohnson. While you are there.. search for @mrchevygm.... seriously beautiful work he does...
Replacing the flex fan for a standard fan/clutch combo should also substantially reduce fan noise.

 

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4 months later. Lol. I could have solved your problem with that pic when you were in Colorado.
 

SirRobyn0

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4 months later. Lol. I could have solved your problem with that pic when you were in Colorado.
Why? He provided an update is that such a bad thing? Next time one of us has an issue maybe we should PM you so you can solve lol. I'm just picking on you...
 

Bextreme04

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Replacing the flex fan for a standard fan/clutch combo should also substantially reduce fan noise.

It reduces the "fan noise" because it isn't really moving any air. Do yourself a favor and just don't do it. If you are having a constant fan noise, you likely have a bad fan clutch.

Old radiators got "rodded out" by removing the tanks and actually pushing rods through the cores to clear out all the junk. A radiator can also be "rotted out" as in corroded and falling apart. Modern aluminum core radiators can no longer be serviced because the design of the core is too thin with internal ridges and fins that act as "turbulators" that ensure the flow through the core remains turbulent to maximize heat transfer. This is how a modern aluminum radiator(aluminum is less efficient in heat transfer than brass) can have the same overall efficiency as old brass radiators while being lighter and cheaper. The downside is that they are not serviceable and have to be thrown away and replaced when they get clogged or spring a leak.
 

WP29P4A

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It reduces the "fan noise" because it isn't really moving any air. Do yourself a favor and just don't do it. If you are having a constant fan noise, you likely have a bad fan clutch.

Old radiators got "rodded out" by removing the tanks and actually pushing rods through the cores to clear out all the junk. A radiator can also be "rotted out" as in corroded and falling apart. Modern aluminum core radiators can no longer be serviced because the design of the core is too thin with internal ridges and fins that act as "turbulators" that ensure the flow through the core remains turbulent to maximize heat transfer. This is how a modern aluminum radiator(aluminum is less efficient in heat transfer than brass) can have the same overall efficiency as old brass radiators while being lighter and cheaper. The downside is that they are not serviceable and have to be thrown away and replaced when they get clogged or spring a leak.
It reduces the "fan noise" because it isn't really moving any air. Do yourself a favor and just don't do it. If you are having a constant fan noise, you likely have a bad fan clutch.
I mentioned the fan noise because the pic the OP posted shows a flex fan with "NO CLUTCH". So yes having a correct fan and working thermal clutch will reduce noise. Which I believe is what I said. In my experience a fan without a clutch sounds just as bad a fan with a bad clutch.
 

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I mentioned the fan noise because the pic the OP posted shows a flex fan with "NO CLUTCH". So yes having a correct fan and working thermal clutch will reduce noise. Which I believe is what I said. In my experience a fan without a clutch sounds just as bad a fan with a bad clutch.
im pretty sure a flex fan itself IS the clutch, at high speeds it spins flat, pulls nothign air wise
 

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im pretty sure a flex fan itself IS the clutch, at high speeds it spins flat, pulls nothign air wise
Yeah that's how a flex fan works, so basically not very well, they are sharp so it's easy to cut yourself on and known for flying apart at high rpm. The thing is a clutch fan engages and disengages with heat. A flex fan flattens out as you increase rpm, so they are great at idle, usually depending on rear end bearing ok at cruise but terrible at high rpm, like going up hill or towing. We do a far bit of work on squares at the shop and I've removed a few flex fans and installed fan clutches and 5 blade fans to solve cooling issues. The reason we typically install the 5 blade fans is they are easier to get than the 7 blade.
 

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