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Old 05-02-2013, 03:41 PM   #1
Indy-Vert
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Default Another coolant leak question

Got a 99 GT vert stock automatic 108k miles. Noticed the coolant light on about a year ago. Topped off the coolant level, glanced over the engine bay for leaks and/or odors...nothing. Valley looked dry (from one glance with no light). several thousand miles later....coolant light on again with light and occasional coolant odor in the cockpit. ~16 0z. coolant missing from the system. Coolant residue is evident in the valley, but very light. Rear passenger side spark well may or may not have vague signs of coolant collection. No evidence of coolant dripping or leaking onto anything else, no pooling on the ground, no wet carpet, no wet undercarriage parts, no wet reservoir cap, no white smoke, no coolant in the oil, no intake manifold cracks around the thermostat....nothing. Only heavy throttling produces the symptoms. What are the most probable causes here?
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Old 05-02-2013, 03:44 PM   #2
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BTW, the water pump weep holes are bone dry and no noise out of the pump.
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Old 05-02-2013, 07:11 PM   #3
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Old 05-03-2013, 01:56 AM   #4
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I know you said the weep holes were dry but the engine gets so freaking hot that it would dry up before you would notice it. I had an 03 gt that was doing this to me and I changed the water pump and it stopped. But I dont recall smelling the odor in the cabin.
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Old 05-03-2013, 08:36 AM   #5
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Wrong section, moved you from the 2005+ to the 1996-2004.
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Old 05-03-2013, 01:21 PM   #6
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The 99 manifolds crack mine did the same thing
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Old 05-04-2013, 11:43 AM   #7
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Quote:
Originally Posted by brandonfoursix View Post
I know you said the weep holes were dry but the engine gets so freaking hot that it would dry up before you would notice it. I had an 03 gt that was doing this to me and I changed the water pump and it stopped. But I dont recall smelling the odor in the cabin.
I agree but there would be some evidence of leakage there(i.e. watermarks, white or green calcified, dried coolant reacting with the aluminum... ofwhich there is no sign).

Also, take note that there IS evidence of some light puddling in the engine valley under the intake manifold.

After reading through oodles of posts the likely culprit is either a compromised intake maifold gasket, a crack in the intake manifold tucked away somewhere that I cannot see w/o pulling it off the car or a blown head gasket(again, with the failing point of the gasket tucked neatly away from inquisitive eyes.)

I just need an experienced concensus to tell me what they think.
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Old 05-06-2013, 11:55 AM   #8
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Being a 99,it probly has the plastic coolant crossover which is prone to crack. If it is cracked, replace it with one that has a aluminum crossover.
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Old 08-17-2013, 10:43 PM   #9
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Ok, yanked the mani in July and found evidence of leakage near the driver side rear coolant transfer port/head mating point draining down into the valley. No signs of cracking on the mani itself, nor was there direct evidence of gasket failure. The manifold deck on the head looked great. Logic demanded the gasket failed, although ever-so-slightly. Replaced it with the Ford Racing composite mani with the aluminum crossover. I've pushed fairly hard for the past month with no leaks.

Oh, and THX to JimC for moving me into the right section!
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