Bleeding the coolant system question

[Dalejandrino]

Hey r3v.

So lately I've had cooling problems with my car. Just recently I've bled my coolant system 3 times in the past week. The reason being my engine overheats relatively easy. I just went on a test drive and I checked my coolant level which was fine. I squeezed the tubes to check for air and the highest hose had no coolant whatsoever inside. I could tell because it was really easy to squeeze and usually when I squeeze any other tube you can hear slushing of the coolant inside the hoses. I thought that this was odd so I drove it 10 miles; 3 miles on the road and 7 on the freeway.

The heat gauge never went past a quater of the way, which is good, but im still confused. It is ok to have some are in the cooling system or do you not want any air at all? I can't seem to get all of the air out no matter what.

When I bleed the system I turn the heater on full blast, bring it up to operating temp, then I open up the valve and rev the engine to 2000 RPMS until I stop seeing air bubbles. I don't use the normal bleeder valve because the bolt is stripped, so I use the 19mm hex bolt closest to the radiator to bleed is which I was told is fine to do. I guess on autos there are sensors connected to those bolts.

Even after all of that there is still air in the system. I want to fix this ASAP because it's starting to get hotter outside and I don't want to have to worry about my car overheating.

Thanks.

[EatsHondas]

When you're blasting the heat, do you actually get heat? If not, your heater core has no coolant running through it.

Have you tried jacking the front end up at least a foot? This helps also.

Those bolts on the thermostat certainly aren't for autos (I used to have one), but maybe for s/etas?

You don't want any air in the cooling system at all. That's the whole point of bleeding it.

It took me a couple tries one evening to get my system bled for the first time, but it wasn't too bad. When you're filling her with coolant, keep the bleeder (or whichever bolt you're using) open until coolant dribbles out. Stop adding coolant, close the bleeder, and fill the reservoir to the line. Start her up, let her get to operating temp, then crack the bleeder for a few seconds. Close it and hold the throttle open like you said you were doing. If you can do this for a few minutes without the gauge going past the middle, she's bled. Over the next couple of days, crack the bleeder at idle when the car's at operating temp for a second or two to release any small amounts of air that may have been jarred loose by driving.

Do you have a new or relatively-new thermostat? An old one could be stuck closed, preventing coolant from circulating.

Also, you might as well check your fan clutch. With the engine idling, gently poke the fan with some rolled-up newspaper. If the paper gets shredded, your clutch is good. If it stops or greatly slows the fan, you need a new clutch.

[Dalejandrino]

When you're blasting the heat, do you actually get heat? If not, your heater core has no coolant running through it.

Have you tried jacking the front end up at least a foot? This helps also.

Those bolts on the thermostat certainly aren't for autos (I used to have one), but maybe for s/etas?

You don't want any air in the cooling system at all. That's the whole point of bleeding it.

It took me a couple tries one evening to get my system bled for the first time, but it wasn't too bad. When you're filling her with coolant, keep the bleeder (or whichever bolt you're using) open until coolant dribbles out. Stop adding coolant, close the bleeder, and fill the reservoir to the line. Start her up, let her get to operating temp, then crack the bleeder for a few seconds. Close it and hold the throttle open like you said you were doing. If you can do this for a few minutes without the gauge going past the middle, she's bled. Over the next couple of days, crack the bleeder at idle when the car's at operating temp for a second or two to release any small amounts of air that may have been jarred loose by driving.

Do you have a new or relatively-new thermostat? An old one could be stuck closed, preventing coolant from circulating.

Also, you might as well check your fan clutch. With the engine idling, gently poke the fan with some rolled-up newspaper. If the paper gets shredded, your clutch is good. If it stops or greatly slows the fan, you need a new clutch.

I'll try doing what you said this weekend. I have no clue about the thermostat. I guess it's pretty old because I haven't changed it since I bought the car, and I have no idea abou the history of the car before that. The heater does blow out hot air as well. The fan clutch works fine, but I havent done the newspaper test. I'm pretty sure the P.O. replaced the clutch before he sold it to me, but I'm no 100% sure.

I'm going to try again this weekend. Thanks for all the help.

[EatsHondas]

No problem man, best of luck to ya.

Unless you know them well or they're a regular on a well-known forum, P.O.'s are generally worthless and should not be trusted. Nothing is for sure until you czech it out yourself.

[jlevie]

The right fix in this case would be a new thermostat housing and bleed screw. But a workaround would be the get the front of the car at least 1' higher than the rear. Then remove the small hose where it attaches to the top of the radiator. With the engine off and cap on, blow into the hose until coolant comes out of the radiator. Put the hose back on, run the engine until it reaches normal operating temperature and the radiator is hot. Set the heater for max hot and bring the engine to 2500rpm a couple of times. Shut off the engine, crack the cap to release pressure, and repeat "hose bleed". It may take a couple of iterations to get all the air out.

BTW: this is a good way to purge air from the system while filling. When filling a cold engine, have the bleeder open while you blow into the hose, and close the bleeder when no more air comes out. Continue to blow until only coolant is coming from the radiator. Then continue with the hot portion of the bleed procedure.

[Dalejandrino]

Ok so today I followed what you said EatsHondas, and Everything seemed fine. I did exactly what you said and the needle on the gauge never went past half way. It went the slightest bit past halfway, but it should be fine considering its super hot out today. Now I just half to see if there air in the system when it cools down. I checked the fan clutch and that worked fine. It shredded the rolled papers I held to it. And the other fan turned on and blew air fine when it was supposed to. Everything went well! Hopefully it stays this way.