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Gotta get my temps down

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigk, Jun 18, 2001.

  1. bigk

    bigk 1/2 ton status

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    I constantly battle high temps on my 87. I've changed the thermostat a couple times, with no real good results. I'm getting ready to yank the radiator and have it boiled and checked. I've seen a write up on hi-perf water pumps coupled with 160 degree thermostats that was supposed to be the solution. Would it be alright to run that cool of thermostat in the winter? I live in west central Illinois and it gets cold.
    Thanks,
    Karl Anderson
    87 3/4 ton K5 185,XXX miles
     
  2. prjt_blzr

    prjt_blzr 1/2 ton status

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    The 160* thermastat will not help as it only controls the minimum temperature. High performance water pumps do help. I run a Stewart Componets water pump on my BBC and it made a big improvement in operating temps. You should also be running a Robert-Shaw type thermastat as they allow more water flow and an electric fan mounted in front of the rad would help if you run hot at idle.
     
  3. fr8train

    fr8train 1/2 ton status

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    I am thinking you have a tbi on your truck and they are set to operate optimally at a specific temp. So you might want to check on that. Also if you run a high volume pump with an ordinary radiator that isnt cooling suffiently to begin with. It will only draw water that is not cooled down at all, faster thru your system. Reason being, the high flow unit sends water thru at a faster rate, since hose diameter doesnt change only rate of flow. I was reading an article in hotrod about cooling blunders that were commonly made. This was a big one that was commonly made. It could be as simple as just getting your rad. core rodded out. I sawpped out to a 4-core radiator. It has more surface area to cool stuff down.
     
  4. 80blazer

    80blazer Registered Member

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    bigk, You need to find out what is wrong with your cooling system. changing the thermostat is not the answer. You also need to check your timing if it is too high they will run hot, are you running lean, do you run a clutch fan and is it working, and since you constantly have this problem do you have a fan shroud if not get one. Good luck Jeff

    Its time to lock them in!
     
  5. Emmettology 101

    Emmettology 101 3/4 ton status

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    Start off with having your radiator check and go from there. It may just be clogged...

    <font color=green>MIKE</font color=green> - "Hukd on fawnics,werkd fer me!"
    <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>
     
  6. newyorkin

    newyorkin 1 ton status

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    BigK,

    I went through the same thing on my S10. Constant near-redline temps all the time.
    First the obvious: Does your coolant level always stay the same at the same states (I.E. is it the same or lower level each time you check it at the same time every day like morning or whenever before drivng?)
    Have you tried to flush the system? If not, buy a flush kit and chemicals for $20 and give it a good cleaning (should be done every two years anyway). Also, this will sound very wierd, but there's a voltage (not resistance, voltage) test you can apply with a multimeter, negative probe on radiator, postive probe in coolant. I can't remember what voltage is good and what's bad, I just remember mine was way over the bad voltage before the flush. Use a digital, I think it requires pretty accurate readings. Anybody on the board know the correct voltage the coolant is supposed to show? I think it was in fourwheeler last month/june.
    Do you have an electric guage or gas? If electric, see if you can get a good mechanical/gas type to install temporarily (or permanently, your preference) just to verify your temps are actually high. You can get a cheap yet functional guage for $10 in Walmart (ok, everyone, I don't buy ALL my truck parts in Walmart, just the disposable stuff).

    In my troubleshooting, I found out that chevy changed the pump flow direction in '87 with a new belt routing and pump impellor (my s10 was an '86 w/crate goodwrench), but the housing looked identical. I don't know if this applied to full-size trucks, but know a lot changed in '87, so make sure you're feeling flow through your top hose anyway (unless this is an all-of-a-sudden problem). You can also sort of check this by opening the cap when COOL, starting the truck, and watching the coolant flow (do that just to verify that it's flowing at all).

    Also, after running it up to temp for a 15 minutes or so, shut it down and feel your radiator. Make sure every part of the surface/core is hot, to get a rough idea of whether coolant's flowing through the entire core or not. Then you may at least have a garauntee that you need to pull it out (if some places are hot and others are not).
    Grab your fan clutch and try to move it around on the shaft to verify there's no play in the shaft or the pump pulley. Possible fan may not be pulling enough air due to bad clutch. loosen your belts and try to spin the fan/pump pulley. It should be smooth as glass, if it's rough at all you'll have trouble there.

    How's it running? Smooth? It is also possible that a head gasket leak could be letting oil into the cooling system or coolant into the cylinders/crankcase, reducing your coolant volume/ability, while not dramatically affecting performance or showing any sysmptoms other than running hot...


    I swapped out 3 radiators, a dozen or so 'stats, water pump, all hoses, clutch fan, ran without the 'stat for awhile (too cool for TBI, ran terrible), flushed the system for hours a month... Then one day, out of the blue, it ran normal. Just before I was going to install dual electric fans and a 4 core radiator. Months of replacing everything in the cooling system, and it just "got better" on it's own. Me and nobody I know have any idea why.

    Good luck! Can I get the longest post of the year award yet?

    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**
     
  7. prjt_blzr

    prjt_blzr 1/2 ton status

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    The high flow pumps do carry away a lot more heat than the factory pumps. I've done this several times on my own vehicles and others. This is due to a couple of reasons. First, the larger the temperature difference between the water and the "hot" or "cool" part the more effective the heat transfer. The second is that you need sufficient water flow to create turbulent flow as opposed to laminar flow. This allows more water to come in contact with the hot surface or the cooling fins in the rad. This all allows better cooling. (A lot of people that bought performance pulleys that slow down things like the water pump have cooling problems)

    Lifted trucks with large tires require more HP to move them at a given speed than factory. This is even more of an issue in stop and go traffic as the motor "sees" more of a load especially if the gears have not been changed. As for the truck running hot, if the truck hasn't just been lifted or bigger tires put on recently, then something mechanical has changed to cause it to start running hot. The fan clutch, thermostat, rad corrosion, water pump failure etc could all be problems. Changing to a more efficient cooling system should only be done when you are certain that everything else is working correctly. Otherwise you can mask things like incorrect timing and head problems until it is too late.
     

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