Thread: Head gasket failure or something else?

Hey y'all so I've been working on my 04 gtp trying to get the cooling system clean and I've done 2 hose flushes, 2 regular distilled water with flush treatment type flushes, and was doing my 3rd just now when after running it for about 25/30 minutes and turning car off, my coolant started overflowing out of my reservoir. I've never had this happen before even when driving it more than this, and it's also never overheated on me. I did notice the upper radiator hose was super hard like a lot of pressure when the car was idling after a bit at operating temp..is that normal? I'm super worried about a possible blown head gasket, my buddy thought I could have one because he said he smells lots of gas when idling.
I just don't understand why this happened after shutting car off, and it wasn't overheating either. Any ideas here before I start a compression test?

Have you replaced the thermostat after all these flushes? Could be clogged up with junk causing undue pressure. FYI the 3800 is RARELY known to blow a headgasket even if it gets overheated so I doubt that is the case. Where was the fuel smell coming from? The exhaust or somewhere else? Could be running rich if there is a vacuum leak.

Hey thanks for the reply
So this happened with the thermostat still out. Started freaking out because it didn't happen with flush 1 or 2 and I'm pretty sure I ran the car longer than I did on flush 3 when the coolant overflowed.
But someone told me that it probably happened because I had the thermostat out and the water wasn't cooling down at all, and when I turned off the engine and stopped the flow/circulation it expanded out? Seems to make sense I think right? Still confused as to why this never happened on my first 2 flushes though. I did a 4th flush and made sure to burp some air bubbles out for a good while too, and same thing happened once I shut her off, overflowing out my reservoir again. I've put the thermostat back in and plan to flush it some more to test the theory and see what happens. If it overflows again I know something is wrong.
And yea I've heard it's hard to blow a head gasket on these engines, but I tend to over worry lol.
As for the gas smell and running rich I'm not sure, I can't see any vacuum leaks and it seems to run good with no idle issues.

What you are experiencing sounds normal to me.

We must review several key properties of water to understand what is happening here:

1) water expands when temperature rises. If you run the engine with the pressure cap off, the temperature of the water will rise, and the water will expand, if you shut the engine off, the water flow in the radiator stops, and heat transfer to the air is halted, the water will instantly start to expand in proportion to the amount of heat that was put into the water by the engine.

2) The the hoses will feel hard when the pressure cap is installed and the engine is run to operating temperature, the cooling system is designed to hold pressure to about 16psi.

3) Water boils at 212 F @ sea level, and will boil at a lower temp. as altitude increases (lower atmosphere pressure). The pressurized cooling system raises the boiling point
of the engine coolant, this allows the water to remove more heat from the engine. The higher the pressure rating of the cooling system, the higher the water temperature before it boils.

Typical operating temperature of the cooling system in the 3800 is around 180-230 F, the preferred temperature is around 200-215 F. Anything over 230 would be considered hot, but as long as
pressure and coolant have not been lost due to hose rupture hose or other scenario, it's not overheated. Loosing pressure and coolant at temperature are what can cause damage.

On one occasion I have reached 240 F in my car, I was trapped in stopped traffic on I77 in Charlotte NC. It was a HOT afternoon day. The coolant temp went down when traffic finally started moving again, the car handled it with no problems.

If your really worried about a blown head gasket, watch for water in the oil, and/or get the coolant checked for combustion gases.

Sure your coolant sludge problem isn't oil in the coolant? Did you take the T Stat out? Bleed the air?

Hey man thanks for the reply and all the information about water expanding and stuff ..
Something is definitely off with my car though. Or I put way too much water in trying to do the flush. But I didn't use more than I got out originally, like 1.5 gal or so...
So yesterday is when I heard those awful noises when I shut the engine off after running for only like 25min, to try and get a good flush in and then it overflowed like crazy. After talking to my buddy he thought it was because my thermostat was out. It made sense at the time, so today I went to test the theory and put thermostat back in, and still had the same issue. Even gave what I thought was a good system bleed. Put my radiator cap back on and let idle for a while, and just kept seeing tons and tons of bubbles in my reservoir. Turned heat on and they seemed to subside for a min, but then came back just as bad. Car was at middle temp so operating I think, didn't go much above that which is what confuses me. I thought a bad head gasket would surely overheat? I seriously hope it's not a head gasket. Plan to order that block test kit now and see what that says I guess..

Any ideas why it's overflowing like this? Could I have a block somewhere in the system or bad water pump? Possible lower intake manifold gasket?
The oil looks clean, so I don't believe I have coolant in my oil...but the coolant might be getting oil in it I guess? This is just got me so stressed because I never had this issue before I started flushing it. Was running good with no overflowing.

I guess it's possible that I have oil in the coolant...seems more like rusty water at this point though. Or tiny amount of oil if that's what' it is.. oil cap looks clean though, so no coolant mixing there far as I can tell...
I did take thermostat out for the first 4/5 flushes and then started experiencing the above mentioned issues...so today I put it back in for another flush, and same thing is happening.. getting car to operation temp running for a few more minutes and turning off, and overflowing like crazy.

I did bleed the air out today. Maybe not every last bubble because it was taking a while and I got worried it was going to bubble over out of my leak proof funnel again. So I bleed what I could then let cool down, bleed some more and capped radiator. Let idle for like 20 minutes all while watching a ton of bubbles still coming up on my reservoir. Then turned engine off, and overflowed out the reservoir again. Something ain't right here...gonna get the block test kit I guess?

Hey guys so I ordered my block test kit today...ended up having the same problem with the coolant over-flow when turning car off...so on to some more diagnosis...
I did a pressure test today and I seem to have a slow leak somewhere...I think I know where so I will get to that soon and then see if I can complete the burping process...
But as for the block test kit .. question is can I use that with only having water in my system? I read that the steam may throw the test off?
And also since this car has that silly angled radiator neck, will the test work at an angle? Or do I have to find a way to go straight vertical?

Not sure why my last replies haven't been approved but upon removing the lower intake manifold I do think it could have been the oil/ coolant mix. Or rust from running water or both. I wasn't getting milkshake at my oil fill cap or in radiator but there was some around the coolant ports on my heads. The gasket was the original plastic one that fails. Even some of my intake manifold was chewed away where it meets against the head..like something had eaten away at the metal. Someone really neglected this car