Hidden Coolant Leak

Bob CT

New Member
Joined
Jan 31, 2011
Location
Connecticut
Had an obvious coolant leak on my 95,000+ mile 1/2 ton '03 Z71 Suburban so I replaced the reservoir, which took care of that problem. But now I've got a hidden leak which requires me to top off the Dexcool every 2-3 days. Guy at the shop said it holds pressure so it must be internal. What's the possible damage? Intake manifold? Head Gasket? Something else?
 
The intake is dry on that 5.3, no coolant runs through it, only the throttle body, so the intake gaskets aren't the problem.

Check your oil, make sure the level isn't rising/turning milky from coolant.

At 100k miles it is very common for the water pump to start going, it commonly leaks out the weep hole and is sometimes hard to detect, although is much cheaper/easier to replace than head gaskets.

How much are you losing in 2-3 days?
 
Thanks, will check oil, though I periodically get the 'check oil level' message telling me it's running a bit low. Hope it's something 'easy' like the water pump. Will post what I find out.
 
Bob CT said:
Thanks, will check oil, though I periodically get the 'check oil level' message telling me it's running a bit low. Hope it's something 'easy' like the water pump. Will post what I find out.
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An internal coolant leak would cause the oil level to "rise".

Also do you see any extra white steam coming out the exhaust that smells like coolant? (other than the usual condensation when it's cold)


By the way, I'm happy to help any way I can, but why exactly did you post your question on "this" site? It's not exactly a car repair, GM, etc site, its a local 4x4 site, and you apparently are from CT, not exactly local to NC :lol:
 
GCncsuHD said:
An internal coolant leak would cause the oil level to "rise".

Also do you see any extra white steam coming out the exhaust that smells like coolant? (other than the usual condensation when it's cold)


By the way, I'm happy to help any way I can, but why exactly did you post your question on "this" site? It's not exactly a car repair, GM, etc site, its a local 4x4 site, and you apparently are from CT, not exactly local to NC :lol:
Click to expand...


Well, first when I searched the internet for my problem, this forum came up as one of the top listings (and the one with the most detailed conversations). Second, I posted somewhere else (and asked a few local shops near me) and the initial response from those people was that it was an intake manifold problem. Now, I'm not a mechanic but even I know that the intake manifold in these engines is 'dry'.

Wanted to see what kind of response I got from 'non GM exclusive,' non-local people.
 
Bob CT said:
Now, I'm not a mechanic but even I know that the intake manifold in these engines is 'dry'.
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Well, pretty much all previous small block Chevys did have coolant running through the intake manifold, but on the LS series engines like your 5.3 they went to only running a small hose to the throttle body, nothing to the actual intake manifold.
 
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