Coolant leak, rear engine area

Hello guys first time here, came over from ls1tech I have an 04 tahoe with 214k miles I changed my oil pan gasket today and noticed There was coolant in the top of the tranny oil pan front area, note this is only the passenger side, it gets there through the outside transmission oil dipstick tube, the tube itself is dried in the top engine bay area, but gets wet somewhere down the line and carries the coolant to the tranny oil pan top area. So, my question is what is in the back of the engine block/heads that could leak? I was suspecting maybe a freeze plug in the heads or a coolant pipe in the back? or are those just blocked and capped at the back in these engines? I just wanted your 2 cents if any of you have had a similar experience or seen this before. Pic not related that's me stripping my oil pump pick up tube bolt, I got that taken care of. things do happen.

I'm looking forward to learn a lot about this gen of suv's in this forums!
Thanks in advance

Freeze plug, crossover pipe, heater core hoses or fittings, headgasket. Only things that'll leak back there. My money is on the heater core fittings at the firewall, they suck.

Z28TWITCH said:

Freeze plug, crossover pipe, heater core hoses or fittings, headgasket. Only things that'll leak back there. My money is on the heater core fittings at the firewall, they suck.

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Now that you mentioned the heater hose fittings those do run next to the tube, it could be possible that it's leaking there. I will check that once it stops raining.

I was just in this boat.... I had just put on a new tranny pan with a lube locker gasket...noticed tiny bit of coolant dripping shortly afterwards....my leak was the quick connect fitting on the heater hose to the heater core - replaced and no leak... 180K miles on my 04 Yukon

If you have rear ac/heat...Parts needed - Dorman 800-414 and 800-413 and 2 Gates Brand 28500 part # (see my last thread....) This is if your leak is at the heater hose/connection

Oh and prepare for sore fingers when you remove the fitting..... not fun... plastic is hardened and no longer flexible or cooperative.... Next time I will just replace hose and eliminate the QD plastic crap.

Coatwolf said:

I was just in this boat.... I had just put on a new tranny pan with a lube locker gasket...noticed tiny bit of coolant dripping shortly afterwards....my leak was the quick connect fitting on the heater hose to the heater core - replaced and no leak... 180K miles on my 04 Yukon

If you have rear ac/heat...Parts needed - Dorman 800-414 and 800-413 and 2 Gates Brand 28500 part # (see my last thread....) This is if your leak is at the heater hose/connection

Oh and prepare for sore fingers when you remove the fitting..... not fun... plastic is hardened and no longer flexible or cooperative.... Next time I will just replace hose and eliminate the QD plastic crap.

Click to expand...

I'm actually hoping its this instead of something even more major. Those things look like a pain in the butt, I replaced my charcoal canister not too long ago to cure my p0455 and it made my fingers hurt for two days pressing those tabs, and those look soft in comparison to those dang adapters you linked! I will check it out once weather allows me to. Will update you and check your post regardless. Almost forgot to add it is a rear a/c and heated vehicle Thanks for the precious insight.

Just to update it ended up being the two quick connect fittings, it was a pain to remove but the install was easy and quick!