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Old 12-11-2016, 09:39 AM   #6
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Re: 2005 Yukon Denali slight coolant leak at Y connector

Originally Posted by Cusser View Post
Then over the weekend I noticed some some dried ATF on the metal lines running near the transmission on passenger side, and also noticed some ATF leaking (level was still above "Low"). So since the transmission was overhauled in April and still under warranty, it goes to the transmission shop today.
It's always something.
Guess what - wasn't ATF, the red leak was Dexron coolant. I saw the red leakage on the transmission housing last weekend after Mrs. Cusser's friend said she "smelled coolant".

Then when transmission shop couldn't look at it Monday, and I then changed that thermostat Monday, never dawned on me that the red Dexron coolant (added by shop at the Y-connector repair) might be the source of the leakage. So I picked up the Yukon at the tranny shop and took it to the mechanic's shop, and one of the brand-new proprietary connectors at the firewall was leaking, so he did a warranty swap of both.

When I asked if "old-school" barbed fittings and hose clamps at the original Y-connector and at the firewall would've prevented all this, he responded "yes".

So no charge from either place.

Where I used to work, I could've captured one drop of the leakage and used a spectrophotometer to identify. At home, I maybe could've added some to water, as coolant would be miscible and ATF not.
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