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Discussion Starter #1
i am working on a 96 deville overheating problem. already changed the cap thermostate and waterpump. but no dice the car will get to 230 at idle. i need to check the purge line according to the searches i've done but i'm not sure what that is. any help would be great. when the car gets hot it blows the antifreeze out the overflow line next to the cap. but you can't feel any flow through the top rad hose. hope this is enough info
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White Diamond '03 DHS (with DTS floor shift)
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The purge line is the 3/8" line that runs from the water pump housing to the surge tank. I think on the '96 it runs along the front cam cover, under the silver beauty cover. Just disconnect it at the surge tank with the engine at idle (cold). There should be coolant flow. Flow will increase with RPM. If not, locate and clear the obstruction. If it flows, check the coolant for exhaust gases.
 

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Discussion Starter #3
will that line make the car run hot? i unhooked mine and ofcource there wasn't any fluid running. so i think i got it cleared but now my battery is dead so i have to wait till tommorrow to try it.
thanks
 

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White Diamond '03 DHS (with DTS floor shift)
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will that line make the car run hot?
Absolutely. It purges air from the system. Air pockets in the cooling system will cause it to run hot.
 

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Discussion Starter #5
well i got the purge line unpluged and it now spits air/antifreeze i let the car warm at idle shut her down and refilled the surge tank. shortly into a test run 30 mph the temp shoots right up to 230 then will keep going if i don't shut her down. i'm not sure what to look for as far as exuast in the coolant. anything i should try or is it probably the headgasket? i'm thinking maybe a rad and hoses next.
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Discussion Starter #6
when i pulled the top rad line it was bone dry. there is a new waterpump and therm. maybe rad is cloged but i can blow thru the top line easly and antifreeze will come out the bottom.
weird huh?
 

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When you have overheating it can be somewhat difficult to purge the system. It souldn't be nearly impossible though.

You might want to remove the radiator and flush it with a hose, visually inspect it for clogged fins, damage, leaks.

Reassemble and te:tisk:st, making sure the purge line stays clear.

If that doesn't improve things have an exhaust gas test done. A radiator shop does them the quickest and cheapest. You can buy the kit at NAPA, that would let you do it yourself multiple times.

You have to drive the car with the coolant awhile for the test to be accurate. It might be a good idea to have the test done before putting all new coolant in.

If you have fresh coolant in you'll get a false negative.
 
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