5.3L Cooling issue

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Feb 15, 2011 | 10:47 AM

djbjess

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From: Dunedin Fl

5.3L Cooling issue

I have a LM7 5.3L out of a 2002 Silverado. The issue is a cooling issue. I am running a hypertech 160 degree thermostat. When I stop at a red light you can watch the temp climb it gets to about 210 (I don't let it get any more) . If I rev it one time (Small rev) it drops back down. to the 180 mark. Driving it never over heats. It is just stopped. I have put the Jeep up on step racks and let it run to burp it out. I have squeezed the hoses.

This is a new build I put the complete drive train in a 1988 Jeep. Went with a Brice Thomas radiator. (Because it had both inlet and outlet on the passenger side which works great with the LS1.)

When the thermostat opens I see the antifreeze rolling in the radiator. I am at a loss. The next thing is go to w high flow water pump.
Any feed back is welcome. I do not believe it is air locked

Butt I have not been able find this one

Feb 15, 2011 | 10:39 PM

southsidecox

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it sounds like an airflow problem to me,are you running ls1 elec fans? did you make custom panels to go around the radiator and force the air thru it,i know that if you leave gaps around rad it will not get enough air forced thru it, but this should also affect it at speed

Feb 15, 2011 | 10:45 PM

southsidecox

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also if your running a clutch type fan make sure it isnt "freewheeling", with engine off when you spin the blade by hand it should have a good amount of drag,it sounds to me like your fan isnt moving enough air thru,but at speed it wouldnt matter cause youve got plenty of airflow

Feb 16, 2011 | 08:24 AM

Pocket

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From: NC

Are you sure theres enough coolant in it? With it cold and running, pop the steam line off under the intake. Leave it off until a steady stream of coolant comes out

Feb 16, 2011 | 08:33 AM

pwrtrip75

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From: Janesville, WI

First of all the thermostat has nothing to do with how hot it will get. Second... who tuned it? What is the idle A/F ratio at? If its lean it will heat up....and heat up fast as you describe. Even if you had a poor cooling system it shouldnt heat up fast and then cool down while driving. The only thing making a spike like that im going to guess is the A/F is lean as hell idling.

With a good A/F at idle mine can sit in the driveway and idle forever before hitting operating temp.....and my cooling system is modified and probably not optimal. I have a smaller radiator tucked in and an intercooler blocking it.

Feb 16, 2011 | 08:34 AM

98666

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u got an air pocket or low on coolant

Feb 16, 2011 | 11:14 AM

djbjess

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From: Dunedin Fl

Thanks for all the input, I have bleed the air out using the coolant lines on the intake, and I do not believe that their is air in it. I went and looked at a friends last night and he has a lot more turbulence in the radiator than i do. I think it may be a faulty water pump. So I bought one today for a $122 (lot better than a $450 high flow). I have new coolant and new thermostat.

pwrtrip75 thank you for the programming issue. I had a guy at LT1 site do the programming. I have the HP tuner and I will have to figure out what it is set to and maybe fatten it up a little. I can run the O2 check against it and that should tell me how it is running. Thanks
I will let you know if this correct the issue.