Welcome to the H4O - HUMMER 4x4 Off Road.
Page 1 of 4 1234 LastLast
Results 1 to 15 of 47
  1. #1
    Bald Tire
    Join Date
    Mar 2021
    Location
    Dallas, TX
    Posts
    20
    Thanks
    0
    Thanked 1 Time in 1 Post

    H3T Alpha won't run cool...at wits end!

    2009 H3T Alpha
    It had all original parts including a leaking factory radiator. Temps would rise continuously if idiling in anything warmer than 60 deg temp. If moving or raising rpm, temp would drop to about 200. In warmer temps this helped, but not as well. In 109 degrees nothing worked, even when driving without ac at highway speed.

    I tried replacing the thermostat first, just to see what impact it would make. Zero change. Then I tried removing the thermostat and temp peaked at 170 in 80 deg temps. This made me think the water pump may not be performing well since the restriction of the thermostat caused it to heat up.

    Here is where I decided to do a full cooling system upgrade. Replaced water pump, thermostat with a 180 deg unit, belts, hoses, tensioner, idler and fan clutch. Upgraded radiator to a thicker, 2-row all aluminum piece with a new cap and of course new 50/50 coolant. I also disconnected the trans cooler lines from the radiator and installed a remote cooler under the truck behind the psgr seat.

    It has been burped VERY well, so no air in the system. Condenser is clean and undamaged. Shroud fits perfectly. There is no sign of any issues with a head gasket.

    I can't imagine anything else I can possibly do short of upgrading to a racing water pump, which shouldn't be necessary.

    After all that it was about 60 degrees today when I tested it. I use a scantool for temp measurements. It idles at 202 degrees and drops to 195 at highway speed. If I raise the idle rpm to 2000-ish it will drop to 197 deg. Basically unchanged overall, even with the 180* stat. If the cooling system weren't having an issue, it should be settling at 180* or at least close to it.

    I'm concerned how it's going to behave in the 100*+ summers. Any ideas at all?

  2. #2
    Mud Terrain
    Join Date
    Jun 2012
    Location
    Cabool MO
    Posts
    967
    Thanks
    6
    Thanked 141 Times in 97 Posts
    By design it should run 200 to 210 degrees.

    A 180 degree thermostat starts to open at 180. It will not fully open until about 200 degrees.

    GM wants all new vehicles to run in the 200 to 220 degree range to improve emissions.
    2007 Hummer H3, 3.7L, auto trans, adventure transfer case. Rear locker.
    315/75R16 Nitto trail grappers, Thor parts frt/rr bumpers, 10,500lb winch, OEM rock rails, ucp, rear disconnects, blah, blah, ect.

  3. #3
    Bald Tire
    Join Date
    Mar 2021
    Location
    Dallas, TX
    Posts
    20
    Thanks
    0
    Thanked 1 Time in 1 Post
    If that's true, the factory stat would open even later but it doesn't. Are you saying I should go with a 160 if I want it to run at 185-190? That would at least give me a little headroom to allow for warming in traffic.

  4. #4
    Mud Terrain
    Join Date
    Jun 2012
    Location
    Cabool MO
    Posts
    967
    Thanks
    6
    Thanked 141 Times in 97 Posts
    That is the only way to get it closer to 180, is running a 160 thermostat.
    2007 Hummer H3, 3.7L, auto trans, adventure transfer case. Rear locker.
    315/75R16 Nitto trail grappers, Thor parts frt/rr bumpers, 10,500lb winch, OEM rock rails, ucp, rear disconnects, blah, blah, ect.

  5. #5
    Bald Tire
    Join Date
    Mar 2021
    Location
    Dallas, TX
    Posts
    20
    Thanks
    0
    Thanked 1 Time in 1 Post
    Anybody know of a high flow thermostat for the 5.3L? All I can find are for older engines with a 2.12" diameter. These are 2.20" and the smaller ones won't work.

  6. #6
    Mud Terrain
    Join Date
    Jun 2012
    Location
    Cabool MO
    Posts
    967
    Thanks
    6
    Thanked 141 Times in 97 Posts
    2007 Hummer H3, 3.7L, auto trans, adventure transfer case. Rear locker.
    315/75R16 Nitto trail grappers, Thor parts frt/rr bumpers, 10,500lb winch, OEM rock rails, ucp, rear disconnects, blah, blah, ect.

  7. #7
    Mud Terrain
    Join Date
    Jun 2012
    Location
    Cabool MO
    Posts
    967
    Thanks
    6
    Thanked 141 Times in 97 Posts
    If you run a 160* thermostat and don't change the tune, timing and fuel multipliers your gas mileage may drop a little.
    2007 Hummer H3, 3.7L, auto trans, adventure transfer case. Rear locker.
    315/75R16 Nitto trail grappers, Thor parts frt/rr bumpers, 10,500lb winch, OEM rock rails, ucp, rear disconnects, blah, blah, ect.

  8. #8
    Bald Tire
    Join Date
    Jan 2020
    Location
    US
    Posts
    14
    Thanks
    1
    Thanked 0 Times in 0 Posts
    What's the max temp it's getting to that is causing concern? 220 is normal on most vortec v8 that I have owned before.

    Flush everything out and I use distilled water or ready to pour dexcool and I add water wetter. I tow 3k lbs with ac on in florida weather no over heat issues.

    Sent from my LM-V600 using Tapatalk

  9. #9
    Bald Tire
    Join Date
    Mar 2021
    Location
    Dallas, TX
    Posts
    20
    Thanks
    0
    Thanked 1 Time in 1 Post
    If I let it idle or its 100 degrees or better it will keep increasing. Highest I let it get to before shutting it off was 240...and climbing.

    It's VERY flushed out after all the work I've done. Nothing but 50/50 Dex in her straight from the jug.

  10. #10
    Bald Tire
    Join Date
    Mar 2021
    Location
    Dallas, TX
    Posts
    20
    Thanks
    0
    Thanked 1 Time in 1 Post
    Thanks, good info. I did exactly that to verify the thermostat was good before installing. The 180 stat starts to open at 190. So much for accuracy. The previous one did the same. Yes, I tried multiple thermometers as well.

  11. #11
    Bald Tire
    Join Date
    Jan 2020
    Location
    US
    Posts
    14
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Quote Originally Posted by Hubbs View Post
    If I let it idle or its 100 degrees or better it will keep increasing. Highest I let it get to before shutting it off was 240...and climbing.

    It's VERY flushed out after all the work I've done. Nothing but 50/50 Dex in her straight from the jug.
    Yea that's past comfort level. Water wetter isn't a miracle additive just something I have used to bring me down just a few degrees on other vehicles.

    If I think of anything worthwhile I'll reach out

    Sent from my LM-V600 using Tapatalk

  12. #12
    Baja
    Join Date
    Feb 2012
    Location
    Wisconsin
    Posts
    1,062
    Thanks
    8
    Thanked 129 Times in 109 Posts
    Are you certain that the pump is not a reverse rotational pump? There are some that are labeled as such and will cause a lot of trouble.
    Also, how was the head gasket determined as good or bad?
    One of your pulleys causing extra drag? Such as AC or alternator, PWS pump ?
    Are you using a scan gauge tool to assess your temps?

  13. #13
    Baja
    Join Date
    Feb 2012
    Location
    Wisconsin
    Posts
    1,062
    Thanks
    8
    Thanked 129 Times in 109 Posts
    And why ask about rotation is I've run into threads while reading where people have installed what they thought was correct pump to later find out that it was miss labeled and sold incorrectly as correct .
    Meaning if you buy pump and need normally clockwise rotation they got counter clockwise.

  14. #14
    Bald Tire
    Join Date
    Mar 2021
    Location
    Dallas, TX
    Posts
    20
    Thanks
    0
    Thanked 1 Time in 1 Post
    I assume its correct since it cools just as it did with the original pump.

    Head gasket: no bubbles or oil in coolant, no water in oil, no steam or smoke from exhaust, no hard starting.

    No reason to think there's extra drag anywhere. Nice and quiet and all works well. Belt looked perfect when I replaced it.

    Yes, using a scan tool.

  15. #15
    El Diablo
    Join Date
    Sep 2011
    Location
    Scottsdale
    Posts
    9,751
    Thanks
    768
    Thanked 3,546 Times in 1,794 Posts
    Quote Originally Posted by Hubbs View Post
    If the cooling system weren't having an issue, it should be settling at 180* or at least close to it.
    What's your basis for this assumption? Just because it opens at 180 does not mean the system can keep it cool to 180, or is supposed to.

    As for the temp while sitting, I'd double check that the new fan clutch is working properly. It's also possible that the new radiator is not as efficient as a new OEM unit. Also, do you have anything in front of the radiator, from winches to lights to aftermarket bumpers that might restrict airflow?

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

    bebe (03-31-2021)


 

Similar Threads

  1. is this cool or a hoopty, stretched h3 alpha
    By Rockhound in forum Online Finds
    Replies: 6
    Last Post: 03-02-2020, 08:42 PM
  2. Cool Rig
    By Bigunit in forum The Firepit
    Replies: 7
    Last Post: 06-15-2015, 01:47 PM
  3. Cool shirt!
    By 4speedfunk in forum Online Finds
    Replies: 3
    Last Post: 09-17-2014, 02:13 PM
  4. Cool key for our H3/H3T's
    By 2010H3TAlpha in forum HUMMER H3 2006-2010; H3T 2009-2010
    Replies: 39
    Last Post: 07-22-2014, 06:08 PM
  5. Somewhat cool...
    By 4speedfunk in forum Online Finds
    Replies: 3
    Last Post: 04-28-2013, 01:39 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Logout