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Cooling Problems (Already Searched)

Discussion in 'The Garage' started by 83ZZ502_Jimmy, May 28, 2003.

  1. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    As my screename implies, I have a ZZ502 crate motor in my Jimmy. I have had cooling problems with it from day 1 of the motor install.

    With my old motor (ZZ4) I had a brand new 3 core radiator installed with a single Black Magic fan (2800 CFM) with absolutely no cooling problems, in fact the same engine and cooling system is currently now in my 88 K5 with no problems. It will keep the motor at 180 all day long in all ranges of ambient temps. This motor runs a 40/60 coolant/water mix. No oil cooler.

    I have a 4 core radiator with the same Black Magic fan on my 83 K20 with a 650HP race motor. It has a 160* thermostat and runs at or around the 160-180 mark with little to no trouble. I usually run straight water or 10% coolant with Water Wetter to prevent corrosion. No oil cooler. This keeps the motor happy 95% of the time.

    Now onto my Jimmy..
    I have a 4 core radiator (brand new Modine) A 28k B&M tranny cooler not running through the radiator, and a small PS cooler. I have (2) two Black Magic Fans (total of 5600CFM) pulling air through the radiator. The motor will get way too hot, I never let it over 220 or so. But to keep it at 180-200 I have to run the fans all the time and let them run between rounds to cool it down to 180-200 to run the race.

    Things I have tried and have currently..
    ~Tried an Edelbrock water pump and a stock pump. The stock pump seems to cool better.
    ~Different T-stats 180 then 160 now none at all.
    ~Different mixtures of coolant. Brands, types etc.. Works best on straight water with Water Wetter
    ~I have checked timing and carb tuning
    ~I have 1 7/8" primary headers with 3" collectors and a full 3" dual system with H-Pipe
    ~New 115A alternator with yellow top optima to ensure full fan voltage. Fans wired on relays for optimal voltage as well
    ~I do not have a heater core hooked up.
    ~Would an oil cooler help?

    edit: I have a recovery bottle on all these trucks

    Someone has got to have an idea on this problem. I can run it to race by cooling it down, but driving it on the street is nearly impossible. Plus, I like to drive it every now and then for fun... /forums/images/graemlins/wink.gif

    I guess I could get one of those BeCool radiator and fan combos designed for 1000HP but that bad boy is like $1150 bucks. /forums/images/graemlins/eek.gif

    I think I should be able to cool this beast with what I have, but apparently not. I'm open to suggestions, comments.

    Thanks in advance,
    John

    ps. sorry for the long post.
     
  2. big pappa b

    big pappa b 3/4 ton status

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    Since it's a crate motor have you tried bouncing this same question to the GM tech guys? Maybe they are designed to run a little hotter /forums/images/graemlins/confused.gif
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Yeah, did that. They said it should run around 180 for best performance.

    Thanks,
    John
     
  4. slimlynn1

    slimlynn1 1/2 ton status

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    Have you tried a mechanical flex-a-lite fan with a shroud. Just a thaught.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    If you keep it at a constant speed, say 35MPH+, on flat ground, how does it cool?

    If you've got problems with the thing only cooling at low vehicle speeds, I'd look at the fans, since those seem to be the only real variable you haven't attacked, and cooling on the freeway, but not off, is typically an airflow problem. They SOUND adequate, but then, why isn't the engine running cooler? Perhaps there is a problem with one or both?

    You've verified whatever you use to monitor engine temp is correct?
     
  6. prjt_blzr

    prjt_blzr 1/2 ton status

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    Are you over or under driving the water pump? You should be over driving it up to 30% depending on what RPMs you turn the motor at. I doubt the BeCool rad would help, I'm running a lowly 454 with a custom 34x21 two row core from them with two black magic fans and will get to 210 in my garage at 2500RPMs.
     
  7. txbluethunder

    txbluethunder 1/2 ton status

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    stupid question...but...have you checked to make sure you water pump is actually pumping...and in the right direction? something that fkd up should be very simple to trace?
     
  8. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    No I haven't tried a mechanical fan cause I don't have a shroud to fit the radiator. If thats the solution, I'll get one, but throwing money at it is getting to be very $$$ spendy. I guess I could find a shroud in the J/Y

    Thanks,
    John
     
  9. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    I hear ya. It cools halfway ok at say 35mph, but man o man when I stop it heats up like mad. So maybe it is airflow, but geeze (my frustration is not directed at you) what does it take to cool this thing.? /forums/images/graemlins/rolleyes.gif I cant install more fans I'm covering the whole radiator now with these 2 fans.

    These are brand new fans, but I was reading where people say these fans suck (not literally /forums/images/graemlins/wink.gif ) Funny thing is that I have just one on my race motor truck and it cools fine.

    These fans seem to move the air, in fact the heat off the radiator is enough to burn your hand if kept there long enough. These fans seem to really air and lots of it, but I'm stumped.

    Yes I have checked the guage, its a mechanical Autometer. The factory guage is also still hooked up and is close to the same reading. I am reading the temps from the port on the head. Factory guage on one head, autometer on the other.


    Thanks,
    John
     
  10. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    I have a serpentine setup from a 91 burb with a 454. I do have the correct reverse rotation water pump for it. In fact tried an aluminum Edelbrock and it cooled worse.

    Thanks,
    John
     
  11. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    The pump is pumping because it does cool sorta. I mean I can get away with it right now b/c I'm just racing with cool down periods. I can run it for 5 minutes when hot and it will be ok to race with, but it definatly needs the cool down time.

    John
     
  12. prjt_blzr

    prjt_blzr 1/2 ton status

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    If you run the motor with the cap off and look at the coolant flow through the tubes, does the coolant just dribble out the tubes or do you get a reasonable amount of force? You need the force to stir the water in the cooling tubes to get good cooling. If the flow does not look strong enough, you could run a corvette short style water pump (IIRC Stewart makes a reverse rotation version) with spacers and some bracket work. Another trick would be to use a big house fan to push more air and see if that helps. If it does, then the black magic fans are not suffient.
    Good luck
    Mike
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, the thing should *easily* run at (or near) rated t-stat temp if the vehicle is moving steadily on flat ground above 25MPH or so (at least on my truck with no fan that was the case) if the cooling system is adequate. If you are seeing fluctuation even cruising, then the stat is bad, the coolant isn't moving fast enough/enough volume, or the radiator just isn't effective. Since you aren't even running a stat, if the coolant temp still is a problem at cruise, something else is going on. You aren't underdriving the pump are you? (and no chance its the wrong rotation pump?)

    How are the fans rigged up? Constant on, or can you shut them off at cruise? They shouldn't be running at cruise speeds, so that could a problem as well, just not for an idle problem.

    It sounds like the 'stat is working correctly if the radiator is heating up that much, but granted, it's hard to "guess" whats working and whats not when you can't physically see the work being performed.

    You said the radiator is new, how new? Read a thread about a year ago by some guy with a Camaro. Spent thousands(?) of dollars replacing/adding/ every single cooling item he could think of (water pump, fans, air dam, *heads*, etc) EXCEPT his "new" radiator which "looked good" to him. $125 after a new radiator, his problem disappeared.

    Radiators are deceptive. Usually the corrosion/deposits/ are the worst at the bottom of the radiator, and there is no way to see that. I've had a radiator that "looked fine" but tested to flow half of what it should have.

    BTW, you can hose down your radiator down to cool it off, might be easier than the house fan idea if you shut the fans off. (or maybe even if not?) /forums/images/graemlins/smile.gif
     
  14. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Well, I am running without the t-stat. As soon as I start the engine, with the cap off, I can see the coolant running out the top tubes in the radiator. Its not just dribbling out. Its coming out with a certain amount of force. Its not gushing out of the tubes but it definately not dribbling out either.

    Thanks,
    John
     
  15. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Dorian,

    I am running the stock setup from a 90-91 burb for pullies. No underdriving on any accessory. The radiator is big block radiator for a DRW K30. It is/was brand new, out of the box, from Modine (bought at NAPA) last year when I put the motor in.

    The fans are on an on/off switch. I can turn them off at speed and usually do at easy cruise 35/50 mph. The truck wont heat up too bad and usually will stay around 190-200* at those speeds, but will begin to slowly creep up even at those speeds..

    On a somewhat related/unrelated note, I had a 93 chevy with the 454 tbi. Granted I was not pushing nearly the power the Jimmy has, but I ran the A/C and towed the Jimmy behind it in 100* weather. I had a 180* t-stat in that and it would hardly ever get above 190 pulling hills in that heat.

    The Jimmy has got to be an airflow issue. It doesnt cool while not moving, and marginally cools when moving easy (30-50mph). Any ideas on fans that will move more air?

    You brought up the garden hose trick, at the track I usually have a garden sprayer with water and spray it down during rounds with the fans running. This really cools it down.

    So it must be airflow. Do I need a shroud and clutch fan? I know those fans move some serious air with the correct shroud. Just seems hard to believe that it will pull more air at idle than my current setup.

    I'm stumped. But, I really appreciate all the dialog we have been having. It gives me some new ideas to try.

    Thanks,
    John
     
  16. prjt_blzr

    prjt_blzr 1/2 ton status

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    It sounds like the pump is moving water and not cavitating anyways. The only other issue would be airflow. Do you have the factory seals around the fenders to the frame? If so, you could take them off and see if that helps get some heat out of the engine compartment. Another airflow trick is to remove the drip seal at the rear of the hood. Again, it is just trying to get heat away from the engine. Did you try pushing more air into the front of the rad to see if that helps? It really sounds like there is not enough airflow. Kind of hard to believe with two decent fans pulling air. You did confirm that they are pulling right? Other than that I'm about out of ideas.
    Mike
     
  17. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Haven't tried pushing more air in yet, but when I get home, if its not raining here /forums/images/graemlins/angryfire.gif I'll give it a try. /forums/images/graemlins/smile.gif

    Thanks,
    John
     
  18. bigmack

    bigmack 1/2 ton status

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    I know this is probably stating the obvious but it sounds like you've about covered everything else. Have you looked to make sure that both upper and lower hoses aren't pinched or collapsing in any way ? This one is from past experience, did you install a rubber like (adapter ?) on the upper hose where it goes on the radiator ? They are used when your hose is larger than the opening on the radiator. When installed, I have seen they get down into the path of the coolant and thus restricting flow. Just a couple of thoughts I wanted to run by you. Good luck.
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, to be honest, I have no clue what the factory fans pull.

    In my *opinion* properly setup/designed electric cooling fans are better at idle than the clutch fan will ever be, they are designed to move more air at a constant speed, as opposed to the clutch fan which is "stuck" with engine RPM. But since I've never found any testing on the clutch fan (CFM rating) I can't be positive this is true. But it makes sense, two large fans rated at 2500CFM is a lot of air, and you sure would expect it to cool ok. If they truly move that much air, at decent velocity, I think you will be hard pressed to find fans that move more.

    How about simple things like the air dam? In place? Possible to run in your application? Thats going to be a freeway fix only, but it may help.

    Removing the cowl seal should help with idle cooling, but since the cowl area is actually a high pressure area, at higher speeds, you'll probably be moving air INTO the engine bay from the back. You could always remove the seal and tape some string there to see /forums/images/graemlins/smile.gif

    If you are seeing temp variation at both idle and cruise, it's not the pump RPM's. It could be the pump itself (never really figured out if the SBC pumps were like some other GM makes, larger/smaller impellers based on engine, AC, etc) but IIRC, you tried two on this setup.

    How do you have your fans mounted now? If there is anything blocking the radiator (electric fan "brackets" that have been made out of sheetmetal for instance) they should be removed. As long as the fans have some sort of integral shroud for themselves. You see that on factory electric fans more than you do aftermarket...the factory fans (go look up LT1 or LS1 fan pics on ebay) have a fairly large "shroud" around the edges of the blades, which directs the air better, creating more velocity. Could be an issue as well.

    Your motor isn't overly bored or anything is it? You didn't mention it, but that can hurt too. I've got a motor that is .020" over what is "recommended" max overbore, and it heats up in traffic. It's not outrageous, but something that wasn't a problem on the same engine/cooling setup before the rebuild, and is now.
     
  20. MarcS

    MarcS 1/2 ton status

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    It does sound like a air flow problem, but I would put the t-stat back in because the water is never getting a chance to cool off in the radiator. Then try running it with no hood just to see if it still heats up. I have seen louvers put into hoods to help get rid of heat if no hood helps.
     

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