Tracing a coolant leak, or at least trying to

TollKeeper

Original poster
Supporting Donor
Member
Dec 3, 2011
8,047
Brighton, CO
So I am trying to find a coolant leak on my XUV 5.3. It has a new Radiator, new water pump, and hoses. This leak is not coming from any of those as they are all dry. The leak is coming from the front lower passenger side of the engine, it appears to be either behind the AC Compressor, or just above it, cant tell, not a lot of room under there. Any suggestions on what it might be?
 

northcreek

Member
Jan 15, 2012
3,310
WNY
Good luck!, my 5.3 did that for the 7 years that I owned it. I looked everywhere and tried everything, even block sealer. I was still smelling the AF the day I traded it in.
Let us know if you find it, I would love to know what drove me nuts all those years.
 

Reprise

Lifetime VIP Donor
Supporting Donor
Member
Jul 22, 2015
2,724
You've probably checked, but in that area, check your t-stat housing.

I had replaced mine, torqued it up to the 9-10 ft/lb spec'd (w/ new gasket), and after long, heavy tows cross-country, it loosened.

Took it up a couple of extra ft/lb and put some blue locker on the front few bolt theads. Solved my problem, at least. Also, if you replaced hose clamps, especially w/ the gear-style, make sure they're tight enough.

PS: you may need to remove air box & washer reservoir to 'see' the area properly. I think at the time, I was looking to see if the coolant reservoir had cracked (known issue); mine was ok.
 

Mike534x

Member
Apr 9, 2012
894
I had a similar issue, mine was coming from the front passenger side. The hose clamp leading to the T-stat was a little loose and was allowing coolant to slow pool down the side. I got that fixed, but now my upper radiator hose keeps backing off the housing to the radiator. :Banghead:
 
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Boricua SS

Member
Nov 20, 2011
3,080
Ohio
I was in the same boat with the SS and all the motor swaps. So i sat there for about an hour until i saw a drip... Mine was coming from one of the the heater hoses above the compressor. Instead of just replacing the clamps, I just opted for a whole new heater hose assembly since the motor was tinkered with so much.
 

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BRomanJr

Member
Dec 9, 2011
371
Had similar issue with 2 different 5.3's. They had subtle leaks under the thermostat area at the block. First my 04 XUV, I ended up doubling the paper gaskets on the Water Pump (IIRC). The second one, my brothers' 06 SWB TB, we tried different Water pumps and finally added washers under the Water Pump bolt heads, they seemed to be bottoming. Tried silicone sealer with both style gaskets, Only stopped after using washers. Used the GM style Alum/silicone gaskets.
Both are leak free right now.
 

Sparky

Member
Dec 4, 2011
12,927
I was in the same boat with the SS and all the motor swaps. So i sat there for about an hour until i saw a drip... Mine was coming from one of the the heater hoses above the compressor. Instead of just replacing the clamps, I just opted for a whole new heater hose assembly since the motor was tinkered with so much.

More patience than I would have!
 
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Boricua SS

Member
Nov 20, 2011
3,080
Ohio
More patience than I would have!

I was tired of smelling coolant! Lol... after 2 water pump swaps, new t stat, new radiator, and new hoses at the time of my cam swap I was determined to find the perp!
 

linneje

Member
Apr 26, 2012
404
There is a somewhat common problem with the 5.3 L where a electrically controlled valve starts to leak. It is hidden on that passenger side of the engine. You have to remove a fair bit of stuff in order to be able to see it and get at it, but none of it is that hard to remove (like the coolant resevoir). On mine it started out as a small leak, but over the course of a month got worse and worse. I had no idea what it was. Took it to the dealer and they found the valve - already had it apart so I just had them replace it.
 

linneje

Member
Apr 26, 2012
404

Sorry, it is not just the 5.3L - I think that it is the extended models.
 

Kelly@PCMofNC

Member
Mar 16, 2013
184
Local parts stores sell UV Dye, you put into the coolant and run the vehicle for a bit. Then look at it in the dark with a black light, and it really helps you figure out where it is coming from and saves a lot of time!
 

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