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Radiator options?

Discussion in 'The Garage' started by jms, May 28, 2003.

  1. jms

    jms 1/2 ton status Author

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    Thinking about redoing my cooling system; the current one is o.k. for driving around on freeway or in town, but didn't quite cut it last year in Moab at BB'02.
    The motor is an '85 350 with vortec heads and headers; it runs a bit hotter, probably due to the increased compression.
    Cooling system is a Stewart water pump, 195 degree thermostat, 3-row radiator that has seen better days ('reconditioned" when I got the truck in '97), and two 14" PermaCool electric fans (that supposedly draw 2900 cfm each) with minimal shrouding. Tranny (700R4; 4.10's w/ 33's) is plumbed separately to a big B&M cooler; no engine oil cooler on the truck. Truck has A/C; condenser seems in reasonable shape and not plugged up regarding airflow.

    I've been looking at new radiators, essentially 28"x19" honeycomb area, either 3-row or 4-row. But from measuring a bit. it seems that I might be able to put a wider radiator in, if I move the evaporative canister a bit. When looking for other options, such as aluminum, I found that radiators for '94 and such come in a HD 2-row aluminum version. The tanks left and right, however, are plastic. Does anyone have experience with those? How do they hold up? Opinions welcome on which radiator to go with, and don't worry about overcooling the truck in the winter - no more road salt for this truck. Thanks for the input, michael

    Oh, yeah, I could go back to a belt-driven fan, but I really like the reduced noise - I'm just getting old, I suppose.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    I had looked into the later AL radiators myself, but from speaking with a guy that rebuilds/sells radiators all day, he told me not to.

    I don't know that the guy is necessarily a genious, but our truck frames flex a LOT, and those plastic tanks have a very hard time staying sealed if there is movement. Most of the new vehicles these are used in have a lot more rigid frames than we have.

    I have no idea how much "deflection" you'll see in the core support and frame rails up front, nor how you'd actually measure it, but I'd certainly hate to buy a new radiator and find out its too much flex.

    Great idea because they are cheap compared to a be-cool, but other than that, I don't think they are as durable as the plain old copper/brass.

    I'd guess your existing radiator is the problem. If a 2 core radiator can cool a stock 350 (mine does) then a good 3 row should cool a 350 with more compression and AC, if the system is working right.

    However, you could always remove the t-stat and see if it still gets hot. That will prove whether or not the radiator is the problem. If it still gets too hot, even with max flow through the system, you know the radiator isn't cutting it. And saying that the coolant flows through too fast (within reasonable limits, we aren't talking firehose velocity here) is a myth. The faster you get the fluid through the radiator, the better it will cool, as long as the radiator has enough air passing over it. What kinda t-stat? Some people have really had problems with the mr. gasket/robertshaw units FWIW.

    Aftermarket electric cooling fans have been pretty disappointing to a lot of people, you may think about switching to something else, or pull them off (for airflow concerns) and try the stock clutch fan just for the heck of it. Another easy "change" that won't cost anything if you still have the fan/clutch around, and will prove if the electric fans are adequate.
     
  3. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Check into the large tube 3 cores. Thick as a 4 core, but only 3 rows. I got one from a local guy (DesertDueler). I previously had a wide diesel 4 core (6" wider than gaser K5 radiator) and the new radiator cools MUCH better. Hottest days in AZ summer at 105*+, on the rocks, reving the engine and slippin the tranny 'cause my gearing sucks, and still it does not get over 200... If I had a catch tank, I wouldn't have to touch it at all...

    For fans, I say run a clutch fan. I was considering an electric only because I was going to move the radiator back, but figure out I could do almost as good with the belt driven fan in place. If you do electric, look into the 3.8L taurus 2 speed fans (check tech on PBB), they work better than any aftermarket fan from what I hear, and they are available for cheap, if you can find them, everybody wants them and they get stripped pretty fast...
     
  4. jms

    jms 1/2 ton status Author

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    Thanks for the ideas. The aluminum-plastic combo doesn't sound too great in terms of stability against flex.

    T-stat is from O'Reillys, no idea on brand or flow rate, but seems to open at 195-200, according to my two gauges (one stock in cyl head, the other aftermarket in the intake right next to the waterneck.

    Local yard has a fan from a Lincoln Mark VIII; I'm waiting for my 70Amp relay to come in. What bugs me is that every time I read up about the Ford electric fans, the amp draw goes up, right now we seem to be at 100Amp at startup, who knows how much it'll be a few weeks from now..... I wish someone would publish the electrical specs.

    I have upgraded the alternator a long time ago, and I liked the electrical fans; the truck is noticeably quieter without the clutch fan. After the vortec heads and headers, the motor is in the same temp range with the el. fans as with the clutch fan - that's in city traffic with A/C on (~210), freeway is no problem at all (200-210) . The trouble was mostly on the trail (~225-230). Maybe I ought to wrap my headers to reduce underhood temps.

    Any idea where to look for the large tube 3-core and what are they called in radiator-speak, since all those online places go by vehicle make/year/engine size?

    Thanks for the input, michael


    I almost forgot: I still have the clutch fan, right now it's being painted for an art project..... maybe I'll have to change the design /forums/images/graemlins/cool.gif
     
  5. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    In regards to the aluminum replacements: I have sold several of those units to fellow wheelers and have yet to take one back or hear about any leakage/tank breakage issues. I always have sold the AC Delco brand (p/n 20978), instead of the aftermarket (typically a derivitive of a p/n 730) units, which in my opinion have tanks that look to be of less quality than the Delco units. I would not hesitate to recommend a Delco replacement plastic/aluminum radiator to you, in fact the p/n 20978 is the rad I am going to run in front of my Cummins (with a different driver's side tank--hose size issues). Take this for what itis worth, just my $.02, but when it comes to cooling, I have had no better luck keeping things cool here in Phoenix than with an aluminum core. Good luck with your project!
    PS: The last Delco unit I sold was a bunch cheaper than the first one I sold a few years ago, so they may be competitively priced now (I don't remember how much though).
     
  6. bowtiepower00

    bowtiepower00 1/2 ton status

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    I just replaced the radiator in my 95, and wanted to avoid the plastic tanks for reliability reasons. After looking around I found a local radiator guy who changed my mind. I picked up a Moline radiator with dual 1" cores for a little over $300, and it has a lifetime warantee for the original owner. The aluminum radiators I looked at were double that cost, and didn't have the warantee. Since replacing my stock single row my temp gauge never moves after the truck warms up.
     
  7. LKJR

    LKJR 1/2 ton status

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    1-888-radiator


    www.1888radiator.com

    just got mine from there, seems to be a good quality unit. haven't abused it yet though.
     
  8. JDNobodi

    JDNobodi 1/2 ton status Premium Member

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    I just post on Zakk's thead about radiators. I might as well put my two cents here too. I don't know about 81/87 radiator mounting but I going to assume it is the same as 73/80.
    For 73/up, the four cores and maybe this "wide tube 3 core" are taller than standard 3 and 2 core radiators. All you need is the proper radiator support, gromments, and fan shroud. This probally all you need for what you want to do.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    The '81+ trucks also had "tall" 2 core radiators apparently (I have one in my truck) but not sure if that was standard, or something someone put in afterwards. (why??)

    Anyways, other than that, same idea as the '73-80 vehicles. 4 cores use a larger one piece top "plate", "tall" non-4 cores use two brackets at either end, and "short" radiators use two "drop" brackets that bolt in the same location as the tall non-4 core brackets.

    There are additional holes outside the "normal" width, but I can't recall if the extra wide diesel radiators used the same mounting points as the gas ones, or if they actually used the one side bracket mounted farther out. Only seen one of these "extra large" radiators, and its been awhile, they basically touch both battery trays as I recall.
     
  10. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    [ QUOTE ]
    There are additional holes outside the "normal" width, but I can't recall if the extra wide diesel radiators used the same mounting points as the gas ones, or if they actually used the one side bracket mounted farther out. Only seen one of these "extra large" radiators, and its been awhile, they basically touch both battery trays as I recall.

    [/ QUOTE ]
    The diesel 4 cores are short format and use separate arms. The driver's side uses the outboard holes. I've got one in my "junk yard", came out of my 1008 that I started with... I'm also using 2 separate arms with my tall-narrow format "wide 3 row". But I couldn't find issolators for them, so I made my own. Basically same as a standard 4 core tank wise. But my son's 77 has the plate on a 4 core...
     
  11. jms

    jms 1/2 ton status Author

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    Thanks for pointing out the Delco alu units, I did find them on the ACDelco web site, but no price. Any idea (ballpark) how much they run? I may have to go locally and see whether I can take some more detailed measurements of such a radiator.

    It's funny you and Russ mention the heat in Phoenix; I actually did a lot of AZ and SoCal desert trails when I lived in San Diego and Scottsdale. Never had any trouble with the heat at all (o.k., one cooked tranny in the Sierra). Of course, all that was before I hopped up the motor in the truck .... /forums/images/graemlins/smirk.gif but what is a guy to do in those midwestern winters but wrench on the equipment? /forums/images/graemlins/cool.gif
     
  12. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    Yeah, I guess I never had run-hot issues until I had other problems. I'm definitely not saying that a good copper/brass radiator will have problems (I have several personal customers who's vehicle I service that have copper/brass radiators that run at 1/4 gauge in summer). Just sayin' that since I have converted my fleet to aluminum, I no longer have any run-hot issues in any of my rides (knocking on wood).
    The 20978 radiator should be able to be had for around $250-$275 -ish. Prices will vary from supplier to supplier, but they should fall somewhere around there. A good radiator shop should be able to acquire one for you but beware, I have radiator suppliers that tell me, on a regular basis, that "this company (insert brand name here) builds all the radiators for Delco", but when they come in and I inspect them they do not look even close to what a Delco looks like. Just letting you know what to expect if you start calling around. Hold out for a Delco, in a Delco box, for best results.
    Good luck,
    Nick
    PS: This radiator should be thicker than the unit you have now. I have converted may trucks with different radiators in the '81 and up vintage. If you run into any issues, let me know and I can tell you what you need to get to make it work. The radiator support bushings (rubber inserts) for the thicker tanks are p/n 6264100, and are available from GM for small money /forums/images/graemlins/cool.gif.
     
  13. rigdonhome

    rigdonhome 1/2 ton status

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    Few things:

    1) Never run without a thermostat... Old Wives' tale. You will actually run HOTTER even though it will take longer to heat up. The coolant actually runs through the radiator too fast to cool off. Lots of complex math but try it if you don't believe me.

    2) A single-core aluminum radiator will cool better than a 4-core copper/brass. Hard to believe looking at them side-by-side, but I have experience with it. I have a 1992 G20 High-Top Conversion with every power option, TV, Fridge, VCR, Dual A/C, etc. Idle it through heavy traffic with the A/C blasting front and back, pulling a heavy trailer, all day long and it won't overheat. Has a big aluminum single-row radiator in it. I can get you one brand-new, AC-Delco unit for $150 plus shipping, still in original packaging. Still have 3 in my garage I bought at a clearance auction. I will even give you the radiator doctor warehouse with ebay feedback and you can see if you can get one yourself cheaper if you want. I think I bought all they had though.

    3) I can't speak for the point about flex with the strength of the aluminum vs the copper/brass radiators. No experience off-roading with an older truck. I had an aluminum radiator in an '84 V8 S10 4x4 that I beat relentlessly, but I built the mounts for the radiator myself so it probably held up better than stock for that reason.

    Let me know if you want more info or some pics of the radiator. It's pretty big but the apps say it will fit my K5 as well as the G20 Van.

    Cheers,
    Scott
     
  14. jms

    jms 1/2 ton status Author

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    Just a quick update: I went to a local radiator shop (Radiator Depot here in Omaha), and although they don't seem to have the ACDelco units, the fellow presented me with four drop-in options they have in stock:
    1. copper-brass 4-row, 3/8" tubes, high fin-count
    2. copper-brass 3-row, 1/2" tubes, lower fin count but better air and coolant flow
    3. aluminum/plastic 1-row, 1" tube
    4. aluminum/plastic 2-row, (probably) 1" tube
    Prices were reasonable, between $180 and $230
    I'm now trying to decide between #2 and #4. I'll get new brackets for the fans anyway to mount to the core support, right now they are zip-tied to the core, with one stabilizer bracket for each fan against vibration.
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    So he's saying there is an AL tank that is a drop in fit for your vehicle?

    Whats the manufacturer or Modine part number if he's got one? Just kinda curious if I can find the specs online for it. If others are able to run these things (in the same year trucks) that spend more time off-road than mine, I'll be happy to use one.
     
  16. jms

    jms 1/2 ton status Author

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    Yup, he said drop-in. Honeycomb is aluminum, tanks are plastic, though.

    I don't have the complete parts numbers, the gentleman gave me a yellow sticky with the numbers 716, 730, and 1599 scribbled on it /forums/images/graemlins/crazy.gif

    I won't be able to make it today, but I'll go back next week to have him pull #2 and #4 off the shelf so I can take measurements - I'll update the thread then. The number 730 jives with what was mentioned earlier in the thread by mosesburb.
     
  17. RATAH

    RATAH 1/2 ton status

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    www.1888radiator.com
    its a great place
    just goto select your vehicle
    then you go live with a tech, free advice and they
    will even call you,and beat any online price you get
    thats what they told me,,
     
  18. jms

    jms 1/2 ton status Author

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    Thanks for the advice, they used to have a cool website, but the way it is now, I really don't feel like "talking" to a computer online, especially when I can't check out the available options and can't get any tech specs or dimensions, and as soon as you get anywhere close to any product, the "dialogue" stops and you're supposed to call and talk to "George, our GMC specialist..." - all just a nice trick to turn the convenience of the Internet into a sales call - thanks, but no thanks, and by the way, I can get the same or better price locally.....
     

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