Burping, radiator cap, general cooling question

[admstng]

My car has been over heating... it would reach 260* then fall back to 200*.. it seems like when i beat on it the car would get cooler? I changed the thermostat 2 months ago and the problem has progressively gotten worse. well, i did a little searching and i burped the cooling system.. now the car run at normal temp's...

Q1: how did my car get air in the cooling system? is there somthing i should look at?
Q2: after my car is turned off at normal operating tempature (and after the car running hot) i hear a "hissing" noise form the rad cap? do i need a new cap?
Q3: i do not see anywhere my car is loosing rad fluid, did it just evapuate becasue the car was running hot?
Q4: can air in the cooling system make my car run that hot? (200-260)
Q5: after and before I burped the cooling system i smell raditor fluid?
Q6: I will look at my overfill and it will be at a certain point, when i start the car and drive somewhere, i check it and it seems higher? is this normal?

sorry for all the questions, any help is appriciated.

-Adam

 

[TheUser]

I'll answer these now, and if anything is not explained fully or incorrect, HISSIN, Michal Yount, or someone else will probably catch it

Q1: how did my car get air in the cooling system? is there somthing i should look at?
I believe it can get in there when you the coolant in there; I've always heard to burp it after replenishing coolant. HISSIN says to raise the pass side of the car up so the thermostat is higher)

Q2: after my car is turned off at normal operating tempature (and after the car running hot) i hear a "hissing" noise form the rad cap? do i need a new cap?
You probably shoudl replace your cap. Also, your neck on your radiator could be un-even and/or warped. I'd replace the cap to see. Be sure to get the proper psi.

Q3: i do not see anywhere my car is loosing rad fluid, did it just evapuate becasue the car was running hot?
Are you running straight water or are you running a water/anti-freeze mix? Anti-Freeze raises the boiling point of the water. If you were running pure water, yeah it can evaporate once it reaches boiling point (of course, 212*F) If there was air in there, the "lost" coolant could simply be replacing the air.

Q4: can air in the cooling system make my car run that hot? (200-260)
Yep, if there's air, there's less coolant. I've had that problem. Air doesn't seem to cool as well
Q5: after and before I burped the cooling system i smell raditor fluid?
Do you smell it in the car? If so, check your passenger floorboard and/or your firewall for a leaking heater core. If your heater core is leaking then that could explain the smell and the loss of coolant/overheating.

Q6: I will look at my overfill and it will be at a certain point, when i start the car and drive somewhere, i check it and it seems higher? is this normal?
I believe so. That's why there's a line lower for "Cold" and then a line higher for "HOT." If you let it sit for a while after you drive it, you can go out and the vacuum in the cooling system should have pulled the excess from the overflow.

Also, the stock guage is notorious for being inaccurate. Most suggest to replace the stock guage w/ an autometer guage for more accurate readings. I was told that the car cannot run 260* and still "run".

 

[HISSIN50]

I'll answer these now, and if anything is not explained fully or incorrect, HISSIN, Michal Yount, or someone else will probably catch it

Q1: how did my car get air in the cooling system? is there somthing i should look at?
I believe it can get in there when you the coolant in there; I've always heard to burp it after replenishing coolant. HISSIN says to raise the pass side of the car up so the thermostat is higher)

Q2: after my car is turned off at normal operating tempature (and after the car running hot) i hear a "hissing" noise form the rad cap? do i need a new cap?
You probably shoudl replace your cap. Also, your neck on your radiator could be un-even and/or warped. I'd replace the cap to see. Be sure to get the proper psi.

Q3: i do not see anywhere my car is loosing rad fluid, did it just evapuate becasue the car was running hot?
Are you running straight water or are you running a water/anti-freeze mix? Anti-Freeze raises the boiling point of the water. If you were running pure water, yeah it can evaporate once it reaches boiling point (of course, 212*F) If there was air in there, the "lost" coolant could simply be replacing the air.

Q4: can air in the cooling system make my car run that hot? (200-260)
Yep, if there's air, there's less coolant. I've had that problem. Air doesn't seem to cool as well
Q5: after and before I burped the cooling system i smell raditor fluid?
Do you smell it in the car? If so, check your passenger floorboard and/or your firewall for a leaking heater core. If your heater core is leaking then that could explain the smell and the loss of coolant/overheating.

Q6: I will look at my overfill and it will be at a certain point, when i start the car and drive somewhere, i check it and it seems higher? is this normal?
I believe so. That's why there's a line lower for "Cold" and then a line higher for "HOT." If you let it sit for a while after you drive it, you can go out and the vacuum in the cooling system should have pulled the excess from the overflow.

Also, the stock guage is notorious for being inaccurate. Most suggest to replace the stock guage w/ an autometer guage for more accurate readings. I was told that the car cannot run 260* and still "run".

well done TU!

i think you meant to say (in Q1) to raise the drivers side (point being to get the radiator-cap opening as high as possible to allow the air to purge).

ill toss out general info, most of which TU already correctly hit (im too lazy to go back and forth).

if you hear 'hissin' and im not standing next to you, it is a pressure leak. as TU said, the cap and its mating surface is the place to look. but if you have a seam going on the rad, etc, it will hiss as well.

air in the system is bad - it can lead to cavitation and hot spots. water boiling, as TU said, can also cause steam pockets. also not cool (literally). it is normal to have air in the system once the system is open and coolant is removed/added. theoretically the system should self purge, but they often need some persuasion, as you have seen. besides, who wants to wait and then not know if the air is purged.

if you spilled coolant on the outside of the rad or motor, when that stuff gets hot, it will burn off and give off a nice sweet smell.

water transfers heat ~2.4 times better than antifreeze. but antifreeze is needed for lubrication, freeze protection, corrosion inhibiting and some boil-over protection (thought it is surprising how little antifreeze raises the boiling point). the pressure in the system is much more important, IMHO. for each psi of pressure, that raises the effective boiling point ~3 psi. now 3 psi * a 16 psi cap is about 50*F. and that temp delta is right in the sweet spot (boiling point goes from 212 to 260*+).

sorry to have been all over the place, but TU did a nice job so i did not go through each question - just added stuff to augment his nice post.

 

[HISSIN50]

oh yeah, a quality stat is a good thing. at a minimum it should have a bleed hole, which eases this whole situation you are going through.

 

[10HoleLX]

You will get air in the cooling system whenever it is opened such as when you replaced the T STAT.
Replace the cap if the seals look cracked or stretched.
Air in cooling system will make engine run hotter than normal-stock operating temp is around 200 degrees
After burping system use water to wash all coolant that might of spilled on timing cover,radiator etc-then check for leaks

The way I have successfully "burped" many cars is like this:
1.Fill cooling sytem
2.start engine and let it run for five minutes
3.Check for obvious leaks
4.Top off radiator
Fill reservoir to about half way
5.Take the car for a 3-5 miles run
6.After run and before opening radiator cap check for leaks
7.Open radiator cap slowly (without shutting off car) and Top off radiator to the top and TOP off reservoir to the HOT Line.
8.Wash all residual coolant off with water

Check your fan clutch operation
Check for excessive debris in radiator and A/C condensor

 

[admstng]

Thanks a lot guys... some great info... I do appogize however, i neglected to tell you that my heater core is "plugged" from the previous owner.. any more trouble shooting steps becasue of this? and would this be the problem or contributing to it?

Thanks again,
Adam

EDIT: just got back from autopart store... i got a rad cap, and no "hissing" so i guess everything is OK... thanks for your help..

 

[TheUser]

Thanks a lot guys... some great info... I do appogize however, i neglected to tell you that my heater core is "plugged" from the previous owner.. any more trouble shooting steps becasue of this? and would this be the problem or contributing to it?

Thanks again,
Adam

EDIT: just got back from autopart store... i got a rad cap, and no "hissing" so i guess everything is OK... thanks for your help..

What he probably actually did was loop the hose to the heater core back around to the return. No problems should occur from this except you won't have any heat

 

[admstng]

What he probably actually did was loop the hose to the heater core back around to the return. No problems should occur from this except you won't have any heat

yea, that is what he did, just didn't know the terminology....

OT: you know whats weird? i can't stand driving in other cars that have heat now. i always have them turn the heat off and roll down the windows... i think this is due to me driving in frigid temps during winter... lol...

 

[Look Its Aaron]

if you hear 'hissin' and im not standing next to you, it is a pressure leak.

LMAO you SOB.