LB7: slow heat

dttproperties

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Dec 22, 2016
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my 2004 truck takes long time to heat up, and sometimes spills antifreeze,the gauge will stay at 180 for a long time until i rev up engine then it shoots up to 230 or so then calms down, i keep adding DexCool but getting expensive,could use some advise.
 

THEFERMANATOR

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Feb 16, 2009
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From the sound of your description, I'm guessing you mean it's spitting out the tank. If so you most likely have a compression leak, either a head gasket or injector cup is leaking. The lack of heat until you hit the throttle, then rapid spike up and going back down is air trapped in the top of the cooling system preventing engine heat from making it to them to open the stats, but when you hit the throttle it forces coolant up thats hot, and they open then the temp stabilizes back out when the air purges out. It's classic signs of combustion leakage into the cooling system.
 

dttproperties

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Dec 22, 2016
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It's leaking from reservoir, it passed the head gasket test, it's really weird
It seems like right after it leaks out and the low coolant light come on it runs fine, until nextday then I have to rev up again but it won't spill as much!!
 

dttproperties

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Dec 22, 2016
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I have heard possible air lock, but can't resolve I've tried filling then
Turning on heater to Max and go thru gears for RPMs to build up but when it
Starts to heat up it goes overboard and leaks antifreeze again
 

rgullett83

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Oct 27, 2008
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What head gasket test? Combustion leak tester? I have yet to see that test show combustion leak into cooling system accurately. Is your truck an lly or an lb7?

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THEFERMANATOR

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Feb 16, 2009
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I had one literally BLOWING bubbles out the degas bottle, and that block tester kit said it was fine. They don't work with diesels very well if at all. If it's pushing coolant out the bottle, that means something is putting something in there to do so, plain and simple. If it's getting air in it, then it's combustion gases or the SLIGHT chance you got a porous turbo housing(this was an issue on vgt trucks, don't think it affected LB7's).
 

TheBac

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Apr 19, 2008
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Moved this over to LB7 section. Starting to sound like headgaskets to me. Tstats been replaced? Rest of cooling system up to par?
 

dttproperties

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Dec 22, 2016
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Heat issues,

What head gasket test? Combustion leak tester? I have yet to see that test show combustion leak into cooling system accurately. Is your truck an lly or an lb7?

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. Yes my truck is LB 7 thank everybody for input, no I haven't changed thermostat yet but I'm going to do that next week and get that out of way, just trying to do some things that aren't that expensive , truck runs fine otherwise
 

rgullett83

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Oct 27, 2008
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Do you know the history on injector replacement? It could be a cup, or a head gasket. Does your surge tank appear black?

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IOWA LLY

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Feb 23, 2007
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If you suspect injector cups, pull all the glow plugs, pressurize the cooling system, then let it sit overnight. When you crank it over have someone watch for you and if any of the holes spit coolant out you have a leaking cup.

If it passes that test, with all of the other symptoms you describe, you have blown headgaskets. Font waste your money on thermostats yet. Wait and replace them when you replace your head gaskets.

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