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Closed20 replies

What the heck just happened?

G Guest
I just went for a drive, engine started fine (Idled pretty high as usual around 2400rpm initially then goes down when the engine warms) ran perfectly, after being out for 20minutes and after sitting at a standstill for about 3 or 4 minutes at a stoplight I pulled onto the freeway. This is only the 4th or 5th time the car has been driven but it ran fine for about a half or an hour last Sunday. I have been getting steam due to overflow through the water tank cap under hard acceleration - well I was getting steam billowing out the right side all the way down the freeway. The fan light came on. Engine ran fine all the way home which is about 3 miles but I had steam the whole way. Engine temp on the cockpit gauge read about 190 - it usually reads just over 160. When I parked the car in my garage steam just kept pouring out of the water tank - I used a towel to loosen the tank cap and the coolant was boiling. At this point I decided it would be good to release the pressure which probably was wrong thinking - I removed the cap entirely and am frankly amazed that I wasn't burned all over, it was like a volcano, I think all the coolant in the car came out in seconds, everywere in the garage including the ceiling.

So what's the deal? Do I need a new radiator, bigger fans? I can't help the fact that there is a red light now and again. What is wrong here?
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crazydavecrazydaveEFI Expert
One word, well two. Head gasket. Plan on getting down and dirty.

Combustion gets into the water jacket and really pressurizes the coolant. It also causes it to heat up quite a bit since you have so many bubbles in the coolant and bubbles dont work well as coolant. It blew the coolant everywhere because the bubbles expanded once the pressure was released.
joulesjoules"Racing is Life, anything before or after is just waiting" - Steve McQueen
quote:
If that's true though there should be coolant in my oil and oil in my coolant right?


Not necessarily as the head gasket may very (most likely) will be gone betwwen the cylinder and water jacket, so as Dave says compressive gases get forced into the coolant.
R 72red (Guest)
Ok so there's some consensus that I have a blown head gasket. V8Capri - what is this about a dead spark plug - how does it cause the gasket to fail? Panther - If I loosen a water hose from the bottom of the car and drain it there and then turn the engine over a few times - redrain - is that good enough or is there a special procedure? Can I really do this with the engine in the car? Does the carb and intake have to be removed? Obviously I've never tackled a job like this - I'm going to need to collect some information to figure out how to do it. Thanks for your replies guys.
cybomancybomanMember
quote:
Originally posted by 72red:
Ok so there's some consensus that I have a blown head gasket. V8Capri - what is this about a dead spark plug - how does it cause the gasket to fail?


I think what Paul (V8Capri) is saying about the 'dead plug' is that if you pull out the spark plugs on that side and one is rusty, it's a telltale sign that your getting water into that cylinder. Hence the headgasket diagnosis. The water/coolant will contaminate the plug (water/rust), and cylinder gases will take the same path out into the water jacket. Coolant will billow out of the tailpipe with a white cloud like you're 007 laying down a smoke screen! (Been there.) When you pulled the overflow cap off, did it smell like burnt gases?

Incidentally, if there were blue smoke coming from your tailpipe, it means you're burning oil (valve seals, piston rings, or head gasket), and black smoke would mean you're running rich (all the gas isn't burning completely in the combustion chamber).

Michael
marlinjackmarlinjackThe Machinist #5723 AMARGOSA MACHINE 'Running on Empty- Middle of Nowhere'
...So much BS here! IF You had a Blown Head Gasket, You would see Steam Coming out of the TailPipe OR/AND Find Coolant in the Oil Pan!! Excepting the Case where the Gasket is Blown Between Cylinders. Is There water in the Oil?? It would show up as Brown Slug on the Dipstick! You can check for a Blown Head Gasket with a Simple Compression Test. It is My opinion that You Just have a 'Weak' 'Pressure Tank' CAP, or a Cap that does not SEAL to it's Lip, Properly. It is letting the Pressure Release and thus causes Your Overheating. You also need a lesson in Physics!! You never Release the Pressure Cap When Hot or Even Warm!! The suggestion that Your Coolant System was Improperly 'Purged' of ALL Air; was Valid! Also A 50/50 percent Mix of 'Anti-Boil/Freeze' to Water, can make ALL the Difference and may 'Tip the Scales' into Your favor of a Steady Coolant Temperature. You never said where the Steam was coming from? Was it the Pressure Cap?; Or the Side of the Block/Head/Tailpipe? Take it for what it's worth! I've Been there!...
R 72red (Guest)
The admonition about the removal of the cap is appropriate, I was careful about it and didn't get any hot liquid on me but I was surprised to be sure. I will check the dipstick and drain the oil. I NEVER had smoke or steam out of the tailpipes, the steam came from coolant bubbling out from under the cap and running down the tank onto the exhaust header. I don't know how much pressure is in the system from the water pump and whether if you have a weak spring on the cap it is enough to blow fluid out the top of the tank? I did bleed the coolant system per the manual with the back of the car jacked in the air prior to use, ran the car, bled air again etc. What is anti-boil - is it the same as antifreeze - I am using a 50/50 mix of antifreeze. Again, help me in my ignorance, how does the inappropriate release of pressure lead to overheating?
Last edited {1}
crazydavecrazydaveEFI Expert
One way to tell for sure. Start up the engine with the radiator cap removed. Rev it up a few times. If you have a head gasket leak, you will start bubling out the radiator cap as the combustion gas leaks into the water jacket.

And no Jack, you dont always get coolant in the oil with a head gasket leak nor do you always get white smoke. It takes TONS of coolant to get white smoke and water in oil. You typically only see that kind of leak on race cars where the gasket blows badly and rapidly.

I have blown head gaskets from age on 4 different cars (2 302s, a 3.8 and a 1.8) and none of them had smoke or water in the oil. The only tell tale sign was a missfire at idle once warmed up.
panteradougpanteradougMember
Gentlemen. I think that you have a bad thermostat. Your temperature sensor is probably still in the expansion tank and not in the engine where it should have been relocated to.

If it was in the block you would have seen temperatures go up then down then up then down then finally on the ceiling.

Sounds like a classic thermostat failure to me. I certainly hope it is too. It's a hell of a lot cheaper to fix then a head gasket or a cracked block. Smiler
joulesjoules"Racing is Life, anything before or after is just waiting" - Steve McQueen
quote:
I NEVER had smoke or steam out of the tailpipes, the steam came from coolant bubbling out from under the cap and running down the tank onto the exhaust header.


When you said previuosuly you had white steam/smoke coming out the right side I assumed tailpipe. If this was only from the bottle then your problem may be much simpler and we should start with and eliminate some basics (still do the check for water in oil though);

1. Pressure caps fail, so check the cap, also check it is the correct cap as the Pantera bottles have a european neck and often people don't realize and put on a US cap that doesn't seal correctly.
2. Check that the engine has a Cleveland thermostat with the correct hat (a Windsor T-stat will by pass water around the block and overheat) This was my problem when I first got my '74, naively I changed radiator, fans and put on ahigh volume water pump before I was told the Cleveland had a unique T-stat.
3. Check the water pump spins okay and is functional (I've known impellers shear off).
Last edited by joules
moosomoosoMember
I had a similar problem with leakage at the overflow tank cap. After replacing the pressure cap, it still blew steam when hot. I examined the flange where the rubber cap seal is pressed down to seal the tank and discovered that it was scarred and uneven, resulting in an improper seal that would blow by when the pressure was high enough.
I found a large 1/2" drive socket that fit down into the cap "cup" on the tank. I glued sandpaper to the flat side of the socket (probably 180 grit), then I pressed down and turned it back and forth several hundered times until it was clear that I had a continuous, flat seal face. My tank was brass, so once I got through the chrome plating, it cut nice and even until flat.
It is just another detail to check. The system has sealed up nicely ever since.
Look in the past postings for detailed info on properly bleeding air out of the cooling system. This is the most important step to getting a cool running system.
Also, if you decide to replace the thermostat, check the past postings to make sure you get the right one. Do NOT trust an auto parts store to give you the right one.
R 72red (Guest)
My oil is clean. I looked at my cap - it is a 16lb Motorcraft cap. I sanded the top of the tank with an orbital sander - then put on a 13lb cap which fit snugly. No bubbling/smoking or spurting of coolant. Engine purrs like a kitten. Kind of a boring conclusion. Thanks everyone for your help though - part of the fun is learning about the car and how it works. Because of all of your suggestions I was able to think through the problem and come up with the simple fix rather than throwing money at the problem or throwing my hands up in frustration. I suppose I could still have a blown gasket, time will tell - I haven't checked the compression yet. Thanks again.
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