Why is the Coolant in reservoir boiling over.
 

It happened when I went to the auto-x also. :o Today I actually opened the hood and noticed that the coolant in the res. was boiling over. :eek: I have a Black Magic but have never had a problem with it before. The wierd part is that the guage inside was about on the "R" in NORMAL when it happened. Any ideas?

I would suspect a blown head gasket. The most common reason for pushing excess amounts of water (more than normal thermal expansion) into the resevoir is cylinder pressure driving it there. This usually means head gasket problems. Since your temperature doesn't seem to be excessive, it'd also seem to say that cylinder pressure is pushing the water out.

what he said

If no oil shows up in the coolant, then a cracked head/exhaust port etc allowing exhaust or combustion pressure directly into the coolant.

My POS Cavalier did this, I changed the head gasket and it was fine and the head was very straight, But lots of green dried stuff on one piston, then started loosing coolant. Eventually the cat converter plugged up with coolant residue.

Good point. Not quite as common, but definitely another way for the coolant side to get pressurized.

:eek: :eek:If the head gasket is blown, will it push the coolant out all of the time (when the T-stat is open)? It only seems to happen after I drive it for a while.

Possibly a simpler explanation.?.

Couldn't he just be boiling his coolant. I know my car has done this periodically in the past when I was dealing with overheating issues secondary to underdrive pullies on my modded motor. Of course, my temp gauge read higher than LOCASH's, but then again, the factory temp gauge isn't all that accurate.

Occam's Razor: one should not increase, beyond what is necessary, the number of entities required to explain anything.

Just a thought.

--nathan

just thought of this, try a new cap...

had a similar situation once, and it ended up being a weak cap.


maybe not, but it's worth a try...

I was really hoping someone was going to mention that!

Try a radiator cap.

The cap is designed to hold pressure in the radiator. The more pressure water is under, the higher it's boiling point. If your cap is week, your boiling point is low, possibly as low as 212 degrees, the normal boiling point for water. It is not uncommon for an engine to run this temp., therefore the pressure cap is necessary.

Your water is simply boiling because it's hot, not because of some supercalafragalistic cylinder pressure. Who ever heard of 5.0 blowing a head gasket anyway? Come on guys...

I am not being at all sarcastic-could someone explain how a bad rad cap would cause my res. to fill with boiling coolant? I think it may happen when I really get on the engine. It happened once at the auto-x and it happened again today when I was trying to get away from the Italian Police. I saw them parked on the side of the road and it was really obvious that I was speeding. As soon as they pulled out I floored it for about 2-3 mins. to make it home. I drove the car to work and back (about 15 mins. one way) earlier the same day with no problems though. I'm sure you guys know more about this than me, but does it still sound like a head gasket? Thanks alot for all of your help. I really appreciate it.

I was too! I was writing while you were replying. I have one on the way but I will try the Auto store on base. I really hope its just the cap. (Who wouldn't?) Thanks for the explanation also.

I replaced the cap and it hasn't happened since. Thanks to all of you for taking the time to help a stranded Stanger. I really appreciate it. :D