Last weekend, I had the engine running in Park for about 15-20 minutes. I noticed after a while that there was a wet spot right below the tailpipe from a drip. Is this a tell tale sign of possible cracked head? My 04 Tahoe Z71 5.3 has "862" casting # heads and I haven't seen any reference to this particular head being a usual cracking candidate. Tahoe has over 250k on it, so who knows. I do have to top off the water every so often, but I also have a water pump leak that I've been watching. I will be replacing the water pump soon, but haven't done it yet so I just assumed the missing water was from the water pump weep hole, however, it now has me wondering if the moisture/drips out the tailpipe may be pointing to other, further issues. Thanks.
Moisture out the tailpipe, sign of cracked head?
- Thread starter mattt
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Condensation, very normal
David Smith
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My vote is no. I think it is normal. I agree with Galante. It is condensation.
Like a glass of tea. Cold on the inside, hot on the outside, the glass sweats.
Your exhaust is hot on the inside and cold on the outside.
Like a glass of tea. Cold on the inside, hot on the outside, the glass sweats.
Your exhaust is hot on the inside and cold on the outside.
HiHoeSilver
Away!
How does it smell?
Thank you for all the replies. I know that condensation out the tailpipe is typical. The reason I asked is because it seems to be a tad more than I have seen typically in the past. I thought I saw a post here or on GMFS about that possibly being a tell tale sign.
Is there any other test or way to know if you have a cracked head besides pulling a valve cover and possibly the rocker shaft?
Just want to make sure all the water/coolant I am loosing is from the water pump and not a bum head.
Is there any other test or way to know if you have a cracked head besides pulling a valve cover and possibly the rocker shaft?
Just want to make sure all the water/coolant I am loosing is from the water pump and not a bum head.
zraffz
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Coolant in oil? Loss of power? Bum compression?
No... Don't worry.
No... Don't worry.
Some of those early motors had intake manifold gasket probs, make sure your oil is clean and look around ontop of the block under the plastic cover for coolant. Really though its just condensation... the more you idle in cooler weather the more you’ll make
Kelsda
Full Access Member
Preasure test your coolant system after you fix your leaking water pump or do a leak down test through each cylinders spark plug holes,nothing to remove but spark plugs. Blown head gaskets can blow a white smoke out of tailpipe all day
What you don’t want is to hydro lock your motor if your not getting rid of it
What you don’t want is to hydro lock your motor if your not getting rid of it
iamdub
Full Access Member
Smell it. Don't snort your exhaust fumes, just waft some towards you until you can get a few good sniffs. You may be able to soak up some of the puddle off the concrete and smell that, but that's not quite as fun as huffing exhaust (everybody likes their own brand, don't they...). If it's sweet, it's coolant.
Next time I see it, I'll go in for a wiff.
It does seem a bit down on power, but it also has 250k on original everything, except tune up parts.
I thought the intake manifold gasket problems were in the prior generation, 99 & earlier Vortec 350, not in the LS based 5.3 engine.
retiredsparky
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The 5.3 motor has a dry intake manifold made from plastic, no coolant in the manifold. But GM makes up for it by using the castech 706 heads many of which form small cracks around the head bolts. Small amounts of coolant leak into the rocker arm area through these cracks.
Since you have 862 heads, they should not be a problem. As noted above, just have your engine pressure tested after replacing the water pump.
Since you have 862 heads, they should not be a problem. As noted above, just have your engine pressure tested after replacing the water pump.
bsamole
Member
There is a tool called a combustion leak tester. Most automotive parts stores will allow you to borrow the tester or you could buy your own. The tester will test for combustion gases leaking into the cooling system. However I agree with others it is probably condensation.
I think that it is condensation. When I drive, I frequently see moisture coming out of the tailpipes of cars in front of me. It is normal. My understanding is that all cars need to be driven on the highway occasionally for an extended period in order to eliminate, or at least reduce, the condensation in the engine.
If you have 250K miles, it means that you have an outstanding vehicle.
axekick
Full Access Member
Water is a reactant from the chemical process of burning fuel and air.
C8H18 + 12.5 O2 -> 8 CO2 + 9 H2O
C8H18 + 12.5 O2 -> 8 CO2 + 9 H2O
I know, right. And an owner and previous owner that takes care of it.
Finelinetoy
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I'm surprised with all the replies that no one has figured out the cause. No it's not a "cracked head", it is perfectly normal and is caused by the ethanol added to the gas at refinery. Nothing to worry about except shorter life of the exhaust system .
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