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1998 Deville
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Discussion Starter #1
I have a 1998 deville with a 4.6 northstar. When i'm driving, and give it gas,coolant comes out the overflow tube.eventually it looses all coolant and overheats.I have installed a new water pump, thermostat,had radiator checked for flow (ok), replaced all hoses (there are no leaks), heater core ok.
I've done a block gas test(blue liquid does not turn yellow).Compression test on all cylinders is ok.It seems like system is either creating too much pressure,or there is a water passage blockage.Any ideas?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Check the purge line for obstruction - remove the line from the surge tank nipple and take the cap off. Hold the end of the line in the tank neck and have an assistant start the car. Is there a constant flow of coolant from the line ? If not, find out why: this may be your air bubble problem.

Now go back and perform the block test for gas in the airspace over the coolant in the surge tank - again: Fill the surge tank to halfway, cold, with 50/50 DEXCOOL/water. Do not fill more than halfway. That is the full mark. Drive the car carefully for 10-15 minutes, return to your driveway, pop the hood and slowly release system pressure by barely cracking the cap. Now perform the block test and remember: any coolant which enters the test tube ruins the result.

The normal cold full mark for your coolant surge tank is halfway - at the tank seam - no more.
 

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1998 Deville
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4 Posts
Discussion Starter #3
I removed hose from purge line. It is not blocked.It's just dribbling water out,but spitting air.It also seems like my top rad hose has no water. The other day, I removed the coolant crossover housing to check for blockages.None found.Should I do a coolant pressure test?
 

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1998 Deville
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Discussion Starter #5
I did test again,it turned blue-green,not a solid yellow. Go ahead, give me the bad news..lol
 
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