I need experienced help re: Water pouring out exhaust

[Daniel Abbott]

After a 100 mile trip my 2003 Tahoe 5.3L vin Z engine started to overheat prior to my intended return trip home. I poured water in the reservoir while the engine was running and it was pouring out of the exhaust in the rear of the Tahoe as fast as i could pour it in.
I left the truck at my families house, and had it flatbedded home. I never let it overheat beyond the first time it got hot. I got to it before it pegged the temp. guage.
Put it in the garage at home and tore it down to the head gaskets and did not see what i thought i would see. There was NO water in the oil, the oil was fresh and not contaminated at all. this kind of stumped me. I dont like assuming, but I seen no visual indication that should have stood out given how quickly the water flowed out the tailpipe?
Alas, to the point of my post here. I have 360,000 miles on this engine. It runs like a top and has no misfire. Just a huge water leak...
Common sense says just replace the engine. I am willing to gamble and just replace a cylinder head. My question is this:
IS THERE ANY POSSIBLE WAY THAT THE BLOCK COULD BE CRACKED TO CAUSE THS ISSUE? In my mind, it has to be a cylinder head that is somehow cracked between the exhaust port and a water jacket, or else i would have water in the crankcase.I also have no misfire so I am to think it is not getting into the combustion cylinder(s)... any wisdom here? I appreciate it.

 

[OR VietVet]

Please tell me you did a compression test before tear down and did not post the results here.....

I believe there are some threads about problematic heads with a stamped Castech head but have never seen where that caused water flow out of exhaust. The exhaust attaches at the heads. To get the water/coolant there the exhaust valve/area has to be involved. I think what you were seeing was coolant/water in the exhaust from a head gasket problem but that does not explain the statement you made here..."I poured water in the reservoir while the engine was running and it was pouring out of the exhaust in the rear of the Tahoe as fast as i could pour it in".

The compression readings would have helped a lot and so would a cylinder leak down test.

 

[Daniel Abbott]

I appreciate the response, thank you. I did not do a compression test due to the large loss out of the tailpipe.I just ripped into it expecting the obvious. I did not want to get too involved in this since it has 360Kmi. on the engine.My mistake. The engine shop near me wants $300 just to do a pressure check on the heads, and they are a month wait, I can buy a used pair of 862 heads (whichmine are 862) for $200. I just dont care to spend more than gaskets head bolts and replacement heads, but am willing to gamble that much.
My main concern was doing the head replacements only to find the block is cracked. I welcome thoughts on that. I'm with you on thinking it absolutely has to be a cylinder head. As i said, it runs too perfect to have a compression problem. There was no water in the valve covers like the castech heads seem to have. I think i simply have a rare crack between exhaust port and water jacket or else i would find water in the oil, which i do not.

 

[OR VietVet]

Ok, but, that crack would need to be huge to "pour" out the exhaust as fast as you were pouring in. In your case, I think your guesstimation is likely ok.

If you decide the go the engine route, think of this, gonna keep the rig till it falls completely apart or just drop an engine in and sell it? Used engine at that point or full blown rebuilt if rig is worth the keeping of it.

Lots of times those decisions are made knowing what else may need to be done to the rig before throwing money at it.

If that had water/coolant coming down there like that amount, the catalytic converter and sensors may be trashed too.

 

[corvette744]

Seems like you dont have many choices here.You can gamble and replace the heads and hope for the best.Or you can just replace the complete engine with a used lower mile one and everything is newer and use yours for parts.360k miles its your call i know what i would do.

 

[Tonyrodz]

I appreciate the response, thank you. I did not do a compression test due to the large loss out of the tailpipe.I just ripped into it expecting the obvious. I did not want to get too involved in this since it has 360Kmi. on the engine.My mistake. The engine shop near me wants $300 just to do a pressure check on the heads, and they are a month wait, I can buy a used pair of 862 heads (whichmine are 862) for $200. I just dont care to spend more than gaskets head bolts and replacement heads, but am willing to gamble that much.
My main concern was doing the head replacements only to find the block is cracked. I welcome thoughts on that. I'm with you on thinking it absolutely has to be a cylinder head. As i said, it runs too perfect to have a compression problem. There was no water in the valve covers like the castech heads seem to have. I think i simply have a rare crack between exhaust port and water jacket or else i would find water in the oil, which i do not.

I've read that 862 heads can be prone to cracks. Pretty sure I have a crack in one of the 862 heads on my 4.8 Express van. I'd have to refill the overflow bottle once a month because it would get low. I used some Blue Devil last summer, and it's been fine since.

 

[SnowDrifter]

I appreciate the response, thank you. I did not do a compression test due to the large loss out of the tailpipe.I just ripped into it expecting the obvious. I did not want to get too involved in this since it has 360Kmi. on the engine.My mistake. The engine shop near me wants $300 just to do a pressure check on the heads, and they are a month wait, I can buy a used pair of 862 heads (whichmine are 862) for $200. I just dont care to spend more than gaskets head bolts and replacement heads, but am willing to gamble that much.
My main concern was doing the head replacements only to find the block is cracked. I welcome thoughts on that. I'm with you on thinking it absolutely has to be a cylinder head. As i said, it runs too perfect to have a compression problem. There was no water in the valve covers like the castech heads seem to have. I think i simply have a rare crack between exhaust port and water jacket or else i would find water in the oil, which i do not.

Quick and dirty test time

Put the heads back on

drill+put a an air tool fitting in the reservoir cap, connect up the coolant hoses or plug the holes, set the pressure regulator to 8-10 psi

don't bother connecting the exhaust headers


Yeah it might take you a couple hours to do, but in the absence of clarity - this'll give you a solid path forward

 

[OR VietVet]

These have been known to help too.

 

[Daniel Abbott]

Well, she is parked until spring. I will likely abort and just find a low mileage used engine. I am seeing some decent 90 to 100Kmi. engines in the $1,000 area.
I appreciate the responses. Especially MO VietVet who has me concerned about the catalytic converters now...I didnt drive it since the failure, hopefully they just dried up. I have no choice but to find that out in my later chapter.

 

[SnowDrifter]

These have been known to help too.

View attachment 361210

Help with what? A leak's a leak. Making a clot around a hole won't fix the hole.

Might be a handy thing to keep in the glove box if you're off the beaten path, but I'm not sure I'd use those as a fix.