overheating h1

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overheating h1

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overheating h1 - 4/8/2007 2:00:07 PM

Guy

Posts: 4
Joined: 2/9/2007
Status: offline

Need some advise , just rebuilt the 5.7 gas engine in my 1996 H1 hummer , everythings new , new water pump , thermostats, radiators clean , fan clutch is new , and she still overheats . with out the thermostat she runs between 150 to 220 with gas mileage is awfull at about 3 mpg . Have the timeing at 6 degrees What I don't understand is how it can run cold without a thermostat and overheat with . Have tried two Napa 190 s that were specked for the Hummer and one 180 runof the mill V8 that fit which worked the best . Any ideas ? what about air lock ? is there something I missed when filling her back up with water ?
Any help would be appreciated .

Post #: 1

RE: overheating h1 - 4/8/2007 9:07:28 PM

Linus Gump

Posts: 960
Status: offline

Have you checked you temp sending unit and guage to ensure they are correct? It may sound odd, but if either one of them are faulty you could be decieved into spending a lot of money. Aslo, is the fan engaged by a bimetal spring in the clutch, or does it have it's own sending unit? It may not be coming on when it gets hot.

(in reply to Guy)

Post #: 2

RE: overheating h1 - 4/8/2007 11:41:48 PM

kild1

Posts: 852
Joined: 12/26/2006
Status: offline

as long as ur filling up the coolant system then burping the coolant system (letting it heat up to normal temp then shuting it off and after cooling back down filling it up the rest of the way with
coolant)
i would have to agree w/ linus about the bad temp sender or a bad new fan clutch
why did ya rebuild the motor?
did it run hot and blow a headgasket ?
if so did ya have the head checked

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07 H3X Sonoma Red Metallic

(in reply to Linus Gump)

Post #: 3

RE: overheating h1 - 4/8/2007 11:47:24 PM

Guy

Posts: 4
Joined: 2/9/2007
Status: offline

Thanks for the reply we replaced the temp sending unit first thing and am going to put a second mechanical guage tomorrow , I can actually here the radiator getting hot , it starts to click like an old kettle when it goes to 230 degrees . today we got some air out of it and siting in the carport shes running between 190 and 225 degrees over a 1-2 minute period . but I didn't take it out for a drive .The fan clutch was bad and being Costa Rica with no replacement we welded it solid until I can ship a replacement . Any other thoughts ? any tricks to get out trapped air ?

(in reply to Linus Gump)

Post #: 4

RE: overheating h1 - 4/8/2007 11:53:26 PM

Guy

Posts: 4
Joined: 2/9/2007
Status: offline

Kid ,

I'll try your burping tomorrow we pushed the hose down below cap level that helped get out some air ,
The rebuild came from a low knock that turned out to be a spun bearing but even then didn't over heat , this all started after the rebuild , did have the heads done , new pistons , almost everything is new , runs great other than the heat , have the timeing at 6 degrees what do you think ?

(in reply to Guy)

Post #: 5

RE: overheating h1 - 4/25/2007 2:50:32 AM

midweststunters

Posts: 12
Joined: 4/17/2007
Status: offline

is that a 350 engine? arent those the same as a chevy 350, seems like replacing it wouldnt be to bad cost wise?

(in reply to Guy)

Post #: 6