Head Gasket leak/hissing noise

[tommy_1812]

Earlier today I got home and turned my stang off. I saw smoke coming from the hood, so I popped the hood and saw smoke coming from underneath the passenger side valve cover/head gasket area. I also heard a hissing noise coming from this area (sounded like pressure being relieved). I noticed a small amount of antifreeze on top of the passenger side "Ford Motorsport" valve cover. Head gasket leak perhaps?

I've checked the oil and it seems fine. It is running Royal Purple 20W50 oil. It's a 1990 5.0.

 

[dragnazz5.0]

probably not a head gasket if its on top of the valve cover. do you have the coolant lines hooked up to the egr spacer? it could possibly be coming from there. or maybe the coolant pipe that runs along that side of the intake sprung a leak

 

[tommy_1812]

I will check along side the intake coolant pipe to see if it leaked. What concerns me is the hissing noise coming from this area after turning off the car. It sounds like a radiator blowing off pressure.

There is also oil leaking from either the head gasket or the valve cover which is running down to the header causing smoke.

I don't know if the hissing is coming from the coolant pipe next to the manifold, or from the apparent gap in the valve cover or head gasket.

The engine runs fine, no known difference in the way it runs today and last week.

 

[Mustang78]

does it overheat? the hissing coulda been the radiator cap leaking a little..check the compression and cylinder leakage test to find out if it's a head gasket, there are some smarter guys here that would be of more help, hope its not a head gasket!!(but hey, if it is those heads needed porting anyway, right? haha)

~Mark~

 

[TheBocSez]

probably not a head gasket if its on top of the valve cover. do you have the coolant lines hooked up to the egr spacer? it could possibly be coming from there. or maybe the coolant pipe that runs along that side of the intake sprung a leak

I had a similar issue and it was the gasket at the EGR spacer. I never noticed the hissing noise, but then again, I never listened for it.

Makes sense, its part of the cooling system so it would be pressurized like the rest of it. So if its leaking coolant and the system has 16lbs of pressure, its gonna hiss a little.

Then again, could the hissing be the sound of the coolant hitting the header and burning off?

Either way, its does not sound like a head gasket issue.