Moisture out the tailpipe, sign of cracked head?

[mattt]

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

I thought the intake manifold gasket problems were in the prior generation, 99 & earlier Vortec 350, not in the LS based 5.3 engine.

 

[drowssap]

I can definitely confirm that it happened to the vortech 7.4's as well

 

[retiredsparky]

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.

 

[bsamole]

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.

 

[mattt]

Thanks for all the posts and info. I may look for that tool as it sure beats pulling a valve cover and all that entails. The recent lack of power has me concerned, but it could just be age thing too.

 

[JWBGMC]

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.

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.

 

[JWBGMC]

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.

If you have 250K miles, it means that you have an outstanding vehicle.

 

[axekick]

Water is a reactant from the chemical process of burning fuel and air.
C8H18 + 12.5 O2 -> 8 CO2 + 9 H2O

 

[mattt]

If you have 250K miles, it means that you have an outstanding vehicle.

I know, right. And an owner and previous owner that takes care of it.

 

[Finelinetoy]

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 .