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  1. #1
    El Diablo
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    Guerrero's take on H3 cooling

    I am Oscar, from Spain, my nickname here is Guerrero (my surname), I am going to post my investigations, current mod, and discussion about some wrong thoughts that is written here:

    First of all, is that Hummer H3 i5 Cooling System DOESNT have problem, or something about undersized, I live in Spain where outside temps are usually in the 70F in average, a lot of humidity and in Spring and Summer we can see Outside temps climb from 90F to 110F temps in hot days of Summer, I travel a lot with my 2006 Hummer H3 3.5 to sahara desert in Maroc, doing desert dunes in 90F outside temperature, with stock cooling setup except Dexcool being replaced, and that is why I can tell that all the current and past cooling issues the majority of us experienced are due to TWO things:

    -Dexcool Coolant Fluid: Dexcool is what is inside our trucks from factory, and from factory we received the 180F thermostat too...a lot of us experience in general 1/2 gauge temperature, but under high demand of power, or towing we can see 3/4 of the gauge...We here made the experiment with a 2008 Hummer H3 3.7 from a friend, with very low myles and 180F thermostat from factory and Dexcool about coolant. He usually saw 1/2 gauge except in long highway inclines, where the gauge climb to 3/4 (220F).....we flush and replace the Dexcool with Quimzel 50% Organic red colour coolant, we made the experiment again in the same highway and driving than before and the gauge NEVER climb over 1/2 of the gauge. I made the same experiment with 3 Hummers h3 more here, and the same result (only with the ones with 180F thermostat) so for me its clear, the system itself is very capable, the problem with running 1/2 and sometimes running 3/4 under high demand is due to poorly flow dexcool, if you flush and replace dexcool you will achieve a very stable temperature range of 190 to 195F water temperature with factory assembly line 180F.

    -Thermostats: GM decides to replace factory assembly line 180F oem thermostat, with 195F thermostat in something like 2010 or 2011 I believe, with this thermostat Hummer H3 is ALWAYS running in the 200-210F coolant temp range (No matter what you do), if you let the Dexcool with this 195F thermostat the temp range usually opens to 220 or 225F under high demand.

    Responding to EndeavoredH3 I tried the shim method in my 195F GM thermostat and achieve a little lower temp range, from 200 to 205/207F coolant temp range, so is a improvement and stabilizies the temp a little but is not a definitive solution to the H3 195F thermostat problem.

    So...what is the solution?

    Well first step is to consider how the stock Thermostat Housing is mounted, someone here said that OEM thermostat is mounted in the Outlet Hose of Engine, so its better to control temperature....well that is totally wrong..the Outlet Hose where OEM thermostat is attached is the OUTLET HOSE OF RADIATOR, meaning that is the INLET HOSE OF ENGINE, where cooler coolant reaches, making the thermostat always delayed respect of current engine temperature, that equals to a hotter coolant in engine. This mean that a Thermostat placed in the REAL OUTLET HOSE OF ENGINE (UPPER HOSE) will control better temperature of coolant, because the Hot coolant from engine reachs the thermostat, opening faster than placed in Lower Hose like OEM is.

    So despite that GM introduce again the 180F thermostat (not going to happen) I am going to post my own solution, based in the solution of some guys in **** forums:

    -SUSTITUTE CURRENT THERMOSTAT (removing the thermostat from oem housing and eliminating anything that cut flow), for another 180F one with its own housing, placed in the UPPER Hose (outlet hose of engine):



    I selected Jegs 53260K1 Inline housing Kit with thermostat and clamps: https://www.jegs.com/i/JEGS/555/53260K1/10002/-1

    To Mount this Inline Housing kit you need to first, remove OEM thermostat, and empty the housing, here is a picture of a thermostat housing empty next to a one not empty:




    After you empty the OEM Thermostat Housing placed in the lower Hose, you just reinstall it with new oring and install the lower hose back into the radiator, now you need to move to the UPPER HOSE, remove hose and take out metallic Outlet Water from Engine (I installed exhaust headers at the same time, if not, the lower bolt in the outlet water housing is difficult to remove), and you need to cut it almost 3 inch to allow enough room to place new Inline thermostat housing:




    After you cut it out, reinstall it, and place the NEW THERMOSTAT HOUSING cutting and adapting the new hose, so it makes the turns allowing the engine movement (I bough a longer hose from acdelco that rockauto offer, and cut that hose, not the OEM used one). VERY IMPORTANT to place the THERMOSTAT IN THE CORRECT DIRECTION, facing it considering that the flow of coolant in the UPPER HOSE, goes from the engine to radiator.

    An this is the result:




    I installed at the same time Exhaust Headers and a efan conversion, using DUAL FAN SETUP FROM A DODGE MAGNUM V8 (2008) or Chrysler 300c v8, need to cut and adapt the shroud to radiator, and use some screw to attach it, very low amp draw (20 amps of both fans) and g8





    These are ORION HEADERS, awesome finishing and performance after install, in that picture you can see it next to my previous setup, the stock exhaust manifold gutted with some exhaust wrap for lowing exhaust noise that removing catalytic made.









    This is the EFAN conversion setup that I used, based in EndeavouredH3 is experiences, and the experiences of one guy in Facebook that has this same setup in a Hummer H3 v8 configuration with 500hp and no cooling issues.
    The Fans is a APDI PRO #6015103 and the fan controller is a Davies Craig #0444, amazing fan controller with programmable temperature to start and with the feature of one fan start and after 5 seconds start the second one (like soft start).

    Finished engine bay looking:








    WELL! AND THIS IS THE RESULT:

    First picture is the normal TEMPERATURE WITH OEM 195F thermostat (with shim, to try to open it a lower temperature) and with STOCK CLUTCH FAN:



    This second picture is THE CURRENT temperature, after INLINE THERMOSTAT MOD, EFANS and exhaust header:


    Like you can see the improvement is HUGE with stock radiator, and stock water pump and hoses, all of this is due to thermostat (considering that a clutch fan is always better about cooling that a efan setup)

    Yesterday I datalog my Hummer h3 for a retune due to new mods, and drive it very hard, at WOT, highways inclines, traffic, city and temperature NEVER climbs over 190F, so this is totally a WIN. I need still to test this in Maroc Desert with 90F or more of exterior temperature in October, or this Summer here, where temps climb up to 110F sometimes.

    Here are some pictures of my truck, with a lot of other mods, 2.0 Fox shocks, Moog parts, Tranny upgrades, outfitter design kits, etc, that I can talk about with some new threat:







    I can talk too about Performance upgrades and result, but you can imagine than differences are awesome, with 33 inch tyres is in the low 9 seconds from 0 to 60 mph, before the necessary retune, so I expect this 3.5 to so a high 8 seconds from 0 to 60 mpg after retune, we will see.

    My truck is prepared for fast desert driving, reliability and performance doing offroad desert, some trails, and daily driving.

  2. The Following User Says Thank You to alrock For This Useful Post:

    Guerrero (06-15-2020)

  3. #2
    El Diablo
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    Moved to new thread as requested though I accidentally deleted it in the process. Hope I recreated it correctly.

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    Guerrero (06-11-2020)

  5. #3
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    Quote Originally Posted by alrock View Post
    Moved to new thread as requested though I accidentally deleted it in the process. Hope I recreated it correctly.

    Thanks so much Alrock!!

    Yes, everything seems perfect!

    I have a lot of research about h3, in all my years and always wanted to create a massive thread about: Commons Problems and Solutions with h3 - Performance Mods for a definitive fast, strong and reliable stock style h3

    I will take patience and do something in the near future, again thanks!

  6. #4
    All Terrain
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    This was a great, interesting write-up on H3 engine cooling. Some of the mods wouldn't be legal in Calif. or some areas of the US unfortunately. About all I can add is that engine cooling was never an issue on my M5-equipped 3T, even in 117 degrees going through Needles, Calif. in the summer. The temp needle always stayed below the second hash mark and I also monitored the functions with a diagnostic tester.

  7. #5
    a.k.a. "The Jackal"

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    That Quimzel organic coolant is interesting. I have never heard of it
    Squeaky3: 06 H3 ALPHA D70 front/Eaton HO72 rear 5.13 gears, custom crossmember for long arms, lockers, 4:1 T-case, v8 swap, hybrid cage, Warn 12k Custom bumpers....do it all vehicle

    "H3 front axles are like drunk cheerleaders....just use em until they get mouthy...then toss em and get another." -anonymous


  8. #6
    a.k.a. "The Jackal"

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    Do you have a link to the coolant used?
    Squeaky3: 06 H3 ALPHA D70 front/Eaton HO72 rear 5.13 gears, custom crossmember for long arms, lockers, 4:1 T-case, v8 swap, hybrid cage, Warn 12k Custom bumpers....do it all vehicle

    "H3 front axles are like drunk cheerleaders....just use em until they get mouthy...then toss em and get another." -anonymous


  9. #7
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    Quote Originally Posted by 06 H3 View Post
    Do you have a link to the coolant used?

    http://catalog.quimxel.ae/index.php?...roller=product

    That is one link, the Antifreeze made by Quimxel is a Spanish product I think, without international sales I think... nevertheless is not necessary to use that exactly product...there are a lot of Organic Antifreeze at 50% in red colour out there

    Is just to avoid using Dexcool (is a awesome brand about durability but I tested that is not any good about flow)

    Hope this help!

  10. The Following User Says Thank You to Guerrero For This Useful Post:

    3Hummers (06-15-2020)


 

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