GM Experts Step Inside - Chevy 5.3 Leak Identification - 2003 Tahoe

[ClarksHillGA]

Guys, Need help identifying the source of this leak. It's on the front left (driver's)side of the engine, right above the oil pan. Engine is a 2003 Chevy 5.3L Vortec.

It looks like oil, but is sweet to the smell like antifreeze. I checked the oil and it does not smell like antifreeze and is not milky.

Any help is greatly appreciated!!

Photos attached, but here are link to high resolution copies for more detail.
https://www.dropbox.com/s/g7ur8h5m8h..._4970.JPG?dl=0
https://www.dropbox.com/s/wkgjjg7eff..._4972.JPG?dl=0
https://www.dropbox.com/s/uw1hwc822m..._4973.JPG?dl=0

[old373guy]

Looks like the freeze plug is rotten and leaking. That should be an easy fix.

[Big Bass Man]

Check your heater hoses that go through the firewall. They have plastic housing that connect them to the firewall. The hot one will eventually get weak & break off. Most start leaking before breaking completely.

[okiebass]

2nd it on the heater hoses---my 1999 5.3 did same thing ---not a hard fix

[mactlman]

coolant check water pump and gaskets also

[07SkeeterZX225]

Freeze plug

[gehol]

Heater hose and firewall? I see a picture of the left front of the engine with a freeze plug leaking as was mentioned by old73.

[smghaley]

Definitely freeze plug leaking.

[Mike Thompson]

Water pump gasket.

[ClarksHillGA]

Thanks for the help! I've ordered the parts and wanted to provide the next steps should someone else stumble on this thread with this same issue.

The GM part # is 12561663, less than $10 for this threaded coolant plug, and you need a 17mm allen socket to remove it. I ordered both today from SummitRacing and will put up with the small pool of coolant on the garage floor until it gets here. I did note after looking at the leak again following the group's feedback, that the coolant was a little lower in the reservoir.

I topped it off just to be safe since this is my bride's vehicle. Thanks again, all!

[greenfshrmn]

Excellent pictures, but I'm not so sure it's coming from that threaded plug, coolant seems to be running down to it from above. I'd be tempted to scrub the area clean, "brakekleen" would help...and then go for a little drive before checking again.

[ClarksHillGA]

Here's the rest of the story. I had a new ACDelco water pump installed at the shop I have used for decades some months ago. This leak was leaking at one of the water pump gaskets. It doesn't appear they cleaned the surface very well and/or used inferior gaskets. So, I tore into it yesterday and did it right.

So far, no more leaking. It's been too long since the water pump replacement to request a warranty repair. There's still something said for doing it yourself and doing it right, but I don't have the free time like I used to...

[humanseine]

Yep, the ol water pump/gasket. Have seen hundreds like that.

[tbassz21]

Gm tech for 31 yrs !
Its the water pump gaskets !! but if the pump hasn't been done do it while your in there

[Bass AHolic]

some engines the dang timing chain gasket will leak antifreeze front of block, behind the water pump. I got that project to do near future, so when I do, its all getting replaced all gaskets, may as well put in new timing chain and tensioners, new water pump , thermostat , fan clutch, belt, idler and tensioner pulleys and be done with it, put new radiator in 4 yrs ago