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Water pump ?s

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 1Blazin71, Nov 7, 2001.

  1. 1Blazin71

    1Blazin71 1/2 ton status

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    I have a ZZ4 in my first gen with a new 4 row radiator and a Permacool BlackMagic (2600 CFM) electric fan. With a 160 deg thermostat and a Autometer mechanical probe in the head it runs 170 deg in all conditions...as long as I keep the RPMs above 1200.

    Below 1200 for more than 10 minutes i see the temp creep up to 210 or so and then come down as soon as I get the idle up.

    This usually isnt a problem but I wonder if I shouldnt consider a larger water pump pulley or maybe an electric pump?

    Matthew Meyer
    matthewm@inhollywood.com
    '71 Ochre K5 - 4" Lift 35"s
    ZZ4 350 - 700R
     
  2. 1986Blazer

    1986Blazer 1/2 ton status

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    Check for low coolant or bubbles in the coolant system. I am not all that familiar with the ZZ4 but a buddy with a similar engine in his vette tells me the entire coolant system is pressurized and all bubble have to be removed (bled out). This is the same as it was in my Mitsu Eclipse Turbo - if there was any air in the coolant system the temp would spike when I was at idle but it would go back down once I reved the engine or kept the car moving. I may be wrong.....just my input!

    <a target="_blank" href=http://www.geocities.com/keywestk5/KeyWestK5.html>http://www.geocities.com/keywestk5/KeyWestK5.html</a>
    So I says to him, I said, "get your own monkey."
    1986 K5, 350 GM Crate, 700R4, NP208
     
  3. chevyracing

    chevyracing 1/2 ton status

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    A larger pulley would slow the pump down and flow less through the radiator. You may think about getting a high flow plate for your pump. It is about 7 bucks and all you do is pull the back of your pump off and it pop rivets in then put the back on your pump. They make the pump flow about 50 or 60 percent more water then.
    The other side of the boat on that one is you need an efficient radiator so the water cools down. Sometimes high flow is not good, mainly with a half plugged radiator because the water does not have time to cool off.
    Out of curiosity why would you be under 1200 RPMs for so long.

    John

    Like to go sloppin' 'round in da mud in a rapid fashion....=) &lt;img src="http://coloradok5.com/forums/images/icons/cool.gif"&gt;

    &lt;a target="_blank" href=http://community.webshots.com/album/23622937JIJjTHhZPo&gt;http://community.webshots.com/album/23622937JIJjTHhZPo&lt;/a&gt;<P ID="edit"><FONT class="small">Edited by chevyracing on 11/07/01 11:33 AM.</FONT></P>
     
  4. 1Blazin71

    1Blazin71 1/2 ton status

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    Thanks...good suggestions....

    Sitting idling at the bottom of the hill waiting for J**ps and Toyotas to get out of the way is mostly why I end up idling for so long. Also...sometimes on long crawls I just let the thing idle up the hill and will get wheel spin if I give it much more than idle...and I always notice my temp start to rise...but then drop as soon as I get the RPMs up again.

    Matthew Meyer
    matthewm@inhollywood.com
    '71 Ochre K5 - 4" Lift 35"s
    ZZ4 350 - 700R
     
  5. prjt_blzr

    prjt_blzr 1/2 ton status

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    You may want to try using the plate on the back of your water pump impeller as a quick low cost fix. The other option is to use a stewart components water pump. I changed the pump on my BBC (BBC tend to run hot with the long style pump) and my temps dropped to a constant 180*. their web site is www.stewartcomponets.com
     
  6. HarryH3

    HarryH3 1 ton status Author

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    Clicky: <a target="_blank" href=http://www.stewartcomponents.com>www.stewartcomponents.com</a>

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
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  7. HarryH3

    HarryH3 1 ton status Author

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    I had read some stuff on that site a long time ago and couldn't remember the site. They have some great tech tips, including the debunking of the myth about "if the water flows through the radiator too fast, then it won't have time to cool".

    Here's an excerpt of the info that can be found here: <a target="_blank" href=http://www.stewartcomponents.com/techtip3.htm>www.stewartcomponents.com/techtip3.htm</a>

    A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

    Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it.




    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
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  8. prjt_blzr

    prjt_blzr 1/2 ton status

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    I avoided this discussion as it has stirred up a few people in the past. Bottom line is the stewart pump works. My BBC ran hot in town on 90* days and forget towing on hot days. I run the 4 core 34" wide rad with the stock HD GM fan and clutch. With the stewart pump I can tow an 8,000LB trailer plus 1,000LBs of gear over the mountain passes at speeds above the legal limit and not get over 200*. The only complaint that I have is heat soak. If I work the motor hard over the pass and then pull in for fuel and shut the truck off, when I fire it back up my temps are about 230*. It drops as soon as the truck is running again. Of course that may have something to do with glowing exhaust manifolds.
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Sounds like you are running on the lean side of the fuel mixture (or way off on timing). Great for power, but bad for heat and longevity. Glowing manifolds are not a good thing. Just my $.02


    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot> click here </a>
     
  10. sosamantx

    sosamantx 1/2 ton status

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    hmmm, could also be the fan itself (electric)?? I mean normally they are not enough to cool the engine, but mostly used as an aid?? or, it could also be that there is no fan shroud?? if it's cooling as your moving, your obviously sucking in more air flow, and also your waterpump is flowing more water. Do you have a stock thermostat??, maybe try a Robert Shaw, hi flow thermostat?? Anyway, just my 2 cents worth. Also, the way I got the air out of my system was to drill 2 tiny holes on the thermostat itself, and that would let the bubbles out.

    <font color=blue>Steve Sosa a.k.a. "sosaman"</font color=blue>
    <a target="_blank" href=http://sosaman.home.texas.net/carpics.html>http://sosaman.home.texas.net/carpics.html</a>
     
  11. prjt_blzr

    prjt_blzr 1/2 ton status

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    It may be running lean. I've not meesed with the edeljuck carburator as I'm trying to get the real truck up and running. The guy that built this motor thought that he was driving a vette and not a K30. It has 10.25:1 compression and a large cam with some good oval port heads. It will tow well if you keep it above 2,000 RPM though. The only time that the manifolds get that hot is after about 20 minutes of the 4 barrel open and turning 4,500RPMs. It is a hoot to see the look of people in their rice burners as 15,000LBs blast by them going up the passes.
     
  12. HarryH3

    HarryH3 1 ton status Author

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    Ooh! Glowing manifolds are not a good thing. [​IMG] Just noticed that you're also in Colorado Springs! I'd like to check out the big block K5, as I'm about to drop a 454 into my Suburban. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
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  13. prjt_blzr

    prjt_blzr 1/2 ton status

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    The K5 is not mobil at the moment but the K30 has a similar set up. The BBC will drop right into your sub. Where about in COS are you??
     
  14. 1Blazin71

    1Blazin71 1/2 ton status

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    I'm pretty sure it's not the fan. That thing pulls 2600 CFM and if I just drop it into neutral and rev it a bit, the temp comes down in a matter of a few seconds. Hence my questions about water pumps.

    I'm not ruling out air pockets and may try to investigate that.

    I've seen people jackup the front end and run the engine with the radiator cap off to try to get the air out but I'm not sure if that's the best method.

    One thing I notice about the thermostat housing on my '96 impala is a brass fitting on the top, about 1/4" in diameter, which seems to be a vent of some kind. Perhaps to let air out or perhaps as a steam escape in the event of over heating?? Not really sure but the idea of drilling holes in my t-stat housing sounds scary.

    As far as the thermostat itself, its the 160 deg stat that came with the crate ZZ4 motor I put in a year ago, so yeah it's stock.

    Matthew Meyer
    matthewm@inhollywood.com
    '71 Ochre K5 - 4" Lift 35"s
    ZZ4 350 - 700R
     
  15. prjt_blzr

    prjt_blzr 1/2 ton status

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    A couple of other thoughts. Use the robert shaw T-stat and drill 2 or 3 small 1/8" holes into it. This is really easy to do. Did you swap pulleys?? If the temp goes down with a few more RPMs you need more coolant flow. A better water pump will help.
     
  16. HarryH3

    HarryH3 1 ton status Author

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    Sent you a PM. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     

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