hey guys my coolant boils a little on hot days (after city driving) when i turn my car OFF... i'm sure this is not normal, but what can i do to fix it? and whats making it happen to begin with?

 

How do you mean boiling? Is it leaking out somewhere and boiling or what? If it's leaking out just fix the leak.

 

you probably mean that you can hear it boiling inside the radiator/engine. i've had the same thing before.

#1 check your thermostat.
#2 check for air bubbles in your radiator while the car is running (don't take the cap off while it's hot!!!)
if it's bubbling, most likely your coolant o-rings are shot in your engine. the combustion leaking into the coolant system causes the extreme heat.

 

i've left the car running with no cap on it. (its a new engine btw) and no air comes out.

its only if its really hot outside and it will only boil after i shut it off. also, by "boiling" i mean some overflow coming out of the overflow tank and a little steam coming out as well. you can hear the coolant boiling in the top of the radiator... new thermostat as well.

 

What's the coolant mix? 50/50, or something else?

The general reason for it happening is that when the car is shut off, the water pump (obviously) is no longer running. This allows the coolant to sit in one place, and if the engine is hot enough, the coolant in the hot places will boil.

One possible solution might be to let the engine idle for a minute or so before shutting it down, so parts can cool off. Not sure if you've tried that or not.

-=Russ=-

 

I would drain and clean the radiator.

 

Bad Radiator Cap.

Replace with good quality one (ie, OEM).

 

damn man I hate to say it but thats the same symptoms I have had on two of my 7's and they both turned out to be coolant seals. Is your engine a rebuild or a J-spec? But it could be a leak in a coolant hose. Allowing air into the system.

 

its an atkins reman. it could definitely be some tiny holes in the coolant hoses. they are getting old and brittle..

 

well lets hope so! Good luck and let us know

 

I'm with White FC- your cap is weak, allowing the coolant to boil at a much lower temp than it normally would in a good pressurized system...And like others have said, allow a couple of minutes at idle for cooldown, with e-fan on if available....

 

First, you need to verify what your coolant temps are.
Water boils at 212F @ sea level.
If you are at higher altitude, the boiling temp comes down.
You should be using some kinda anti-freeze / coolant mix, so this temp should rise.

You should not be hitting coolant temps over this (about 220F or so) unless we're talking 90F + degree ambients?

If so, there is most likely a leak in your cooling system.
You see, pressure helps the water / coolant mixture NOT to boil.
With a 0.9 bar (13psi) cap most widely used, the boiling temp gets pushed to like 240F.
If the system is not under pressure, it stays at 220F.

Easy test...
With the engine cold, start the engine and let it idle.
Keep squeezing the upper radiator hose.
Do you feel pressure?
Keep doing this until you feel the hose get hot - this is a sign the thermostat has popped open.
Do you still feel pressure in the hose?
BE VERY CAREFUL WHEN DOING THIS AS YOU CAN BURN YOU HANDS!

Even with minute pressure leaks, the system can still hold pressure enough to keep the upper radiator hose stiff.


-Ted

 

I seem to have a leak from the front cover just below the water pump. Is this repairable without pulling the motor?

 

That should be the water pump leaking....it's shot, replace it.

 

i'll second that. with the addition we've tested a bunch of stant caps and over half of them are bad out of the box, about 1 in 10 actually hold the rated pressure