Possible head gasket leak after overheat

[alvocado]

I had a rear heater line come off a couple of weeks ago on a highway trip and blew all the coolant. The temp gage spiked with no warning and I immediately pulled off the highway, shut it down and opened the hood.

Since the trip, there's been a noticeable but slight tick on the passenger side of the engine that has developed. It's not uncommon for me to hear a tick at cold start when outside temps drop after installed a Dorman manifold clamp on the exhaust manifold. Although not present immediately after the overheat, I'm now getting a lot of moisture out of the tailpipe with clear water puddling under the exhaust exit. There's some steam but it doesn't smell like coolant.

I did a block test today and surprisingly, the fluid stayed blue and no sign of exhaust gases in the coolant. I don't know if there's a chance for a false negative on the block tests.

The next step is a cold temp pressure test to see if it holds. How much pressure is needed to detect a head gasket leak so I use enough but not too much?

 

[Joseph Garcia]

If you immediately pulled off the road and shut down, you 'probably' did not do any serious damage. Much the same, when one on my heater hoses grenaded in the engine bay. And, of course, you did not try to put any water into the radiator, while the motor was still hot.

Definitely, a coolant pressure test should be performed.

Did you check to see if any other exhaust manifold bolts may have snapped?

 

[j91z28d1]

I've over heated a ls3 like crazy, like to the point it blew the entire radiator out thru the overflow. I was sure I killed the engine. but let it cool, replaced the belt, filled the radiator and hasn't had a issue. I sent off a oil sample to black stone labs and no sign of any damage.

you very well. might have gotten away with it. I woold change the oil quickly after the over heat though. oil can break down from high Temps. I didn't of course since I was a 1000 miles from home. I drove it back on the black oil that looked like water lol.

water out the tailp ipe is a side effect of proper combustion. if it doesn't smell like coolent. I wouldn't worry to much about that alone.

 

[alvocado]

It took some time to source water so the temp was down to around 170 degrees when I refilled the reservoir. I finished the trip (about 600 miles) and changed the oil and coolant as soon as I arrived home. I didn't notice any water out of the tailpipe for the first couple of weeks after the incident.

Exhaust manifold bolts are in tact. They have all been replaced with ARP bolts.

I know a little bit of water at cold start is normal since it's a combustion by product but I'm producing much more water than ever before and it continues to drip out even after the truck reaches operating temperature.

I got a pressure tester on it at 15 psi and aside from coolant leaking out of the hose from the throttle body at the radiator, I didn't see any other leaks. The Harbor Freight tester was the only thing leaking from the pressure release so I couldn't confirm if pressure held. I'll swap it for a replacement and try again later.

 

[j91z28d1]

if you're seeing that much water. you might see something on the plugs. maybe even a hard crank over first thing in the morning.

do you see any missing coolant in the Reservoir?

 

[donjetman]

@alvocado
if your consuming coolant you have a problem.

 

[alvocado]

if you're seeing that much water. you might see something on the plugs. maybe even a hard crank over first thing in the morning.

do you see any missing coolant in the Reservoir?

There has been a small amount of missing coolant but I discovered the clamp on the rear line I replaced wasn't tight enough and was leaking. I replaced the clamp yesterday and will need to monitor.

The system was pressurized at 12psi and held for 15 mins with no visible leaks. Oil on the dispstick looks normal and still like brand new - not cloudy, no coolant smell and there's no accumulation under the fill cap.

I'll watch the coolant level in the reservoir for a couple of days and see if it holds.

 

[mikez71]

Stock cap is 20psi, so I'd go over that just a little bit..

 

[Marky Dissod]

...next step is a cold temp pressure test to see if it holds. How much pressure is needed to detect a head gasket leak so I use enough but not too much?

Stock cap is 20psi, so I'd go over that just a little bit.

Thought stock cap was 18psi, close enough. No need to go over 20psi either way.

... little bit of water at cold start is normal since it's a combustion by product but I'm producing much more water than ever before,
and it continues to drip out even after the truck reaches operating temperature.

Why do I have this strange feeling, that you can pump it up to 20psi cold, and then go round the back of the exhaust and listen for a hissing?
Or maybe get someone ELSE to pump it up to 20psi cold while you listen for a hissing at the back of the exhaust?
Actually, if I'm right, you can just attach a balloon to the exhaust and then pump it up to 20psi cold. If the balloon expands ...

 

[Fless]

Actually, if I'm right, you can just attach a balloon to the exhaust and then pump it up to 20psi cold. If the balloon expands ...

Or use a nitrile or latex glove.

 

[RST Dana]

Coolant out the tail pipe only means trouble. Did you, or did you not add cool liquid to the super hot engine? My money is on the “yes”!

 

[solli5pack]

Fix any and all coolant leaks and then monitor the reservoir to see if your losing coolant.If your not losing anything then your good.If your head gasket is blown you will have white smoke out the tailpipe and you'll smell it. Also you'll have some misfires due to coolant in the combustion chamber.

 

[alvocado]

Coolant out the tail pipe only means trouble. Did you, or did you not add cool liquid to the super hot engine? My money is on the “yes”!

The engine cooled for a half hour with the hood open before I added water and it was 65 degrees outside. Temp gauge was almost down to the min.

 

[Big Mama]

For my own knowledge, would you see some oil in the reservoir if the gasket blew?

 

[j91z28d1]

I honestly think you're fine.

you can also start the engine with the gauge on it and Rev it up. you'll probably see the pressure go up quickly if you have a leak.

the pressure will rise slowly at it gets hot. but a blown gasket will show. quickly and with revs. at least normally

 

[Marky Dissod]

For my own knowledge, would you see some oil in the reservoir if the gasket blew?

More likely coolant in the oil, but this'd be obvious, when the oil pressure goes down down down so low so quickly,
that he won't need any advice from us, he'll just pull the dipstick and smell coolant or unscrew the oil cap and see latte froth.

Thought of one other thing you can affix to the exhaust tip, but if I type it the forum censor will get all up in my asterisk.

 

[alvocado]

Here's where I'm landing on this. The truck passed both the block test and held pressure at 15 psi for 15 minutes (20psi cap but reco is to stay below max pressure since that's an emergency vent pressure.) After a few trips yesterday, the water discharge from the tailpipe eventually stopped. I suspect that the rear resonator somehow filled with water as I could see water dripping from the back weld seam as well as out the exhaust tip. The trapped water was also causing the excessive steam and dripping even after the truck warmed up. I never had the smell of burning coolant.

The exhaust is bone dry today with no discharge, no steam.

The only scenario I can think of is there must be a hole or rusted weld on the resonator that allowed a lot of water in. For now, it seems to be fine and I'll see if this repeats particularly after some wet weather.

 

[Joseph Garcia]

Glad to read that it appears you're truck's going to be OK.

Friendly hint: Change out ALL of your coolant hoses, so that you don't have to be concerned about a repeat of this event for the next 100,000 miles.

 

[alvocado]

Joseph, the irony is I proactively changed a slightly wet rear heat coolant line in the back to prevent this and didn’t get the quick connect fully snapped in, resulting in the highway nightmare 5 hours into a trip and the overheat. Good intentions gone bad.

 

[j91z28d1]

Joseph, the irony is I proactively changed a slightly wet rear heat coolant line in the back to prevent this and didn’t get the quick connect fully snapped in, resulting in the highway nightmare 5 hours into a trip and the overheat. Good intentions gone bad.

I've done stuff like that. I hate fixing things till it's broken lol.