Coolant Overflowing when Gas Pedal Released

[intheheartofit]

So about a month ago after driving home got out and all of a sudden heard a waterfall coming from under my truck. Looked and coolant had leaked out. It was a nasty rusty brown colour.

Flushed the rad, etc and made sure the water was clear. Also used a rad flush product. Then filled it back up with 50/50.

Everything seemed good till a couple days ago when driving on the highway got a "check gage" as the coolant temp gauge hit red and then went back down just as fast. The heat then cut out and only came back on about 5 minutes later.

Changed the rad cap and "burped" the rad as the top hose was collapsed/flat.

When burping the coolant was a tad bit frothy and was once again rusty brown. Also whenever I would let the gas off from having rev'ed the engine the coolant would overflow from the top of the rad (literally boiling out). I could get it to go back down by rev'ing again.

Have no idea what might be wrong. I'd replace the thermostat but stripped a bolt and it's stuck solid even after trying stripped bolt remover, etc.

Did a search, but didn't find anything to help.

Right now oil is clearish. A bit dark, but I just changed it. Tends to go black fairly fast though and gets a pint-quart low a month or so if that could be connected.

Any thoughts so I can drive without worry and with heat?!

Thanks,
Derek

 

[Iceman21]

Head gasket... Cracked head... Thermostat. Start small... Figure out the problem before you destroy the evidence. Is there water flowing through your hose that goes into the block? To me it sounds like your thermostat but... If your bolts are stripped.... Kinda screwed.

 

[Road Angels]

To get the bolts out find a local welder have him weld a nut on top of the old bolts then as soon as the weld stops glowing take a wrench to it, the high heat will expand the metal, allowing the bolt to come lose be sure he puts his ground as close to the weld area as possiable, and it would not be a bad idea to unplug your ecm, you can also take your truck to an emissions station and have him check for co emmisions from the radiator using a sniffer with means a bad head gasket or cracked head

 

[RonD]

There is a very simple test for a head gasket/cracked head issue.

The glove test:
Cold engine
rad cap removed
Overflow hose removed
Unplug Coil, you want a "no start"

Put Latex glove or balloon over rad cap opening, seal it with rubber band if needed.
Block overflow opening, vacuum cap or finger will work.

Crank engine and watch the glove, if it moves you got a leak from cylinder to cooling system.

Video of a Glove test here:
http://www.youtube.com/watch?v=vFGquUimXro&feature=youtu.be

He found a "new type of balloon" but it worked, and he did have a blown head gasket.

If your "glove" moves then you can find out which cylinder is leaking by removing 1 spark plug at a time, and cranking engine each time, when "glove" stops moving the last spark plug removed was the leaking cylinder, put it back in to confirm.


The rusty brown color is a sign of exhaust gas in the coolant, so head gasket leak.
Overheating and then cooling down is also a sign of "air" in the system, which could be exhaust gas, it air locks the system then releases when enough pressure is built up, so heats up then cools down as "air" is purged from the head, but it can go to the heater core so no heat for a bit.

But overheating could be a bad t-stat.
Collapsed rad hose is a bad rad cap