Where's my coolant going?

[ToughBowtieTruck]

2000 Silverado 5.3 208k

I am slowly losing coolant. Takes 2 months or so for it to lose most of the reserve tank. And I can smell coolant from time to time. So I think it might be burning it. Oddly enough, I keep getting a "cat efficiency below threshold bank 1" . . . could that be suggesting I am losing coolant in the left bank of the engine?

Where are these notorious for leaking coolant ?

[Eroq]

5.3 and 6.0s always got leaky water pumps....   dont know why they changed from the old style water pumps... seems like they almost never fail...     look and see if its coming outta the weep hole on the top of the water pump... prolly hard to see if its leaking real slow.

[RIP_K52007]

if you smell it could be heater core or heater hose... pressure test it..

[buddman (AKA Mick)]

Starting to see more and more of those with leaking intakes. And the O2 code is usualy a symptom.

[71 Highboy]

My 03 did the same thing, heads were warped

[989F150904]

Starting to see more and more of those with leaking intakes. And the O2 code is usualy a symptom.

X2.     If you know a mechanic or take it in to a shop, they can do a pressure test on the cooling system and put a dye in it to see where it's coming from. I'd keep an eye on your oil. If it starts getting milky it means it's leaking internally and can wash a bearing out on you.

[ToughBowtieTruck]

Yeah I have those capabilities. I'll give it a pressure test soon and see what happens. I know my oil is good though. If I blow it up I might throw a Detroit in it or something cool . . .

[Boggen Joe]

if it has casttec heads they leak through the castings, to sume it up you will need new heads. I have changed a few like this

[Strapless]

I have also changed alot of intakes on the 5.3 and 6.0 for that code. Good news is it has a dry intake. For the code you need to scan it and check the O2 activity. seen alot with the mysterious coolant leak and cant never find it via pressure check. It mighy be what bogger joe was saying... Good luck

[Boggen Joe]

Starting to see more and more of those with leaking intakes. And the O2 code is usualy a symptom.

no coolant runs through the intake

[old school truck dude]

http://www.silveradosierra.com/vortec-5-3l-v8/5-3l-coolant-lose-t11033.html


There a link to a pdf file on that page, its like the 2nd reply, shows the head and stuff. Sounds like that might be whats goin on..  

[ToughBowtieTruck]

http://www.silveradosierra.com/vortec-5-3l-v8/5-3l-coolant-lose-t11033.html


There a link to a pdf file on that page, its like the 2nd reply, shows the head and stuff. Sounds like that might be whats goin on.. 

http://www.silveradosierra.com/resources/file/6330

Very good read. Thanks! Seems easy to investigate.

[Strapless]

Your right bogger joe but in the quote he was only referring to the code not the coolant leak.

[old school truck dude]

http://www.silveradosierra.com/vortec-5-3l-v8/5-3l-coolant-lose-t11033.html


There a link to a pdf file on that page, its like the 2nd reply, shows the head and stuff. Sounds like that might be whats goin on..  

http://www.silveradosierra.com/resources/file/6330

Very good read. Thanks! Seems easy to investigate.