94 ls auto
So I was driving up some small hills to my parents house. I parked my car. I walked around the front and noticed smoke / steam from the passenger side hood, so i popped my head and noticed my coolant reservoir was BOILING. My engine never overheated.


Could this problem be due to a bad thermostat??

 

change your radiator cap NOW!

 

Really ? Not the thermostat?

 

Check and make sure your fans are working, easy way to do that is to flip the a/c on and check. Keep an eye on your temp . second make sure your water is circulating once it's up to temp by checking for pressure in your radiator hose. If the thermostat isn't opening the rad hose will be limp. Also check your radiator and make sure it isn't filled up with a bunch of crap , you might want to do this before getting the car warmed up.
Do you have a 50/50 water/coolant mix? i believe it slightly raises the boiling point but not much. The coolant acts as a lubricant and prevents corrosion so you may have a clog somewhere as well. There are a few more things to look for but if thats the case your better off getting a repair manual and trobleshooting or take it to a trustworthy mechanic. Hope this helps

 

Thanks ! I'm going to change the radiator cap and fill up with some coolant. Then ill check fans

 

If the water was boiling in the reseviour i'd imagine you would hear hissing if it was the cap and probably some leaking of coolant around the cap and top of radiator and your car would have probably ran hot by then.. just my opinion tho.

 

It sounds like your cooling system is purging air. Was the car running when this "boiling " was occuring?

 

Yah not sure how long it was boiling / overflowing. I noticed it when I was parked.

 

Check your radiator cap. I suspect a head gasket. Start it cold and see if it bubbles.

 

My motor is a Jdm replacement with 60 k on it I hope its not a head gasket it was fine till I started goin up the hills by my parents house

 

The coolant would not boil in the reservoir. It is most likely a gas escaping from the cooling system. You may have just had an air pocket. Has the coolant level been dropping in the reservoir?

 

No the level never dropped. Just happened yestetday.

I'm waiting for a friend might do a coolant flush . New cap n thermostat. Then take it from there.

 

Your problem will be solved. Do that.

 

i just had the same problem with my integra where it was boiling and overflowing in my reservoir and not overheating but i just installed a brand new rad cap. i did notice my reservoir was empty the other day and this is not long after i just refilled all my fluids. do you have any updates ?