Coolant boiling in reservoir

My girlfriend has a 89 civic si, the upper radiator hose blew yesterday so I
changed it and bleed the air out of the system. At the same time I changed
the radiator cap. Now after 15min drive, the coolant is boiling in the
reservoir but the engine is not overheating. The thermostat is two months
old, the fan is working.

Anyone know what it could be??

 

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It's just trapped air expanding past the cap and bubbling into the
expansion tank. When the engine cools down, it will suck some of the
coolant into the rad and the level in the expansion tank will drop, so
you must check it tomorrow A.M.

'curly'

===============

 

To get the air out of the cooling system, wait for the engine to cool down
and remove the radiator cap. Make sure the coolant is level with the bottom
of the "radiator neck." If not add more coolant and make sure the coolant
mixture is 50/50). If it's already at the right level or you've filled it
enough, squeeze the top radiator hose to remove the air from the system and
also suck in the coolant. If there's air in the coolant system the level of
the coolant will drop so you have to add more coolant.

Let us know how it goes.

--Viktor

 

On of the best ways to bleed the air out of a cooling system on a Honda is
to use the bleeder valve. On an '89 Civic the bleeder valve is on the top
of the water pipe bolted to the left side of the head.

 

You received some great advice. I just wanted to add that regardless of
how you solve the problem--you should check the radiator coolant level
about once a day (for the next two weeks) when the engine is cold and
refill it with a 50/50 mixture if it is low. Also, make sure the reservoir
is about half full. Once you find the level up to the cap for two straght
days--you won't have to check it anymore--your problem is solved and air
is now out of the system. Don't feel bad--you would be amazed how many so
called radiator experts that own or manage radiator shops make this same
mistake.

 

Yeah. Change the rad cap.

 

Thanks everyone,
I've added some more coolant with the bleeder valve open and
ran the car for 15min and checked the reservoir, there are still
some buble but way less. So I suppose that if I keep sufficient
coolant level in the reservoir the air will be expulsed to the reservoir
and be replaced with coolant when the engine cools.

Am I right in my suposition?

Thanks.

 

Yes, that is true. However, it's still a good idea to check it when the
engine is cold for a couple of weeks to make sure the air is out of the
system. I had this same problem a couple of years ago. I made the mistake
of believing the owner of the radiator shop that flushed out my cooling
system knew how to bleed the air of the system.

 

(T. Nelson) wrote in broad-158.snlo.dialup.fix.net:

If, for some weird reason, you filled the radiator with long life Dexcool
coolant, be extra sure to remove all air from the system because air will
cause rust.

 

And make sure you have the heater on when filling the radiator. Thats
the source of air in the majority of cases. Air can also be dissolved in
the water, depending on temperature, so check after letting it cool
that it has gaased of and filled those points where it collects. Rev the
engine slightly to move it about while having the bleeder open. Make
sure it isnts too hot > Burns are common. Best to have a drink of coffee
while waiting for it too cool down. Unless you like pain!!! grin!!

 

Your radiator cap was shot, even though there is no change in
appearance.

Go to GI Joes and buy a new one for 10 bucks and that should fix it.