I'm having inconsistent, sometimes steady/normal engine temperatures.

Car has 43k miles

This is what I've done so far:
-Replaced thermostat with new OEM thermostat
-Replaced radiator cap with new OEM cap

With heat on, I've tried bleeding by opening the bleed cap by the firewall and the bleed screw on the intake manifold(radiator cap was on)

My most recent attempt was to just pop the cap off and let air come out. I had to stop because after the car warmed up it seemed like the coolant would erupt out as if air was coming out. I would've waited for a steady stream to come out or wait for the thermostat to open so the coolant would dip but it was making too much of a mess. If anyone has any tips for me to collect the coolant without it going all over the place I'll try this again.

I did a pressure test and no pressure was lost for all the 10 minutes I tried, so I'm assuming it's simply air bubbles in the system.

In the morning on start up I have slight white smoke for just a couple seconds. This is after sitting for at least 12 hours. I can stop and startup at any point later after and smoke will never come out.

Sometimes I can drive 30 miles to work and the temp gauge will be steady at 8 bars after warming up, other times it'll go up to 9 or 10 bars then back down to 8. I do know if I see it climb over 10 bars I can give it gas and eventually it'll have a steady drop until 8 bars.

Coolant has no oil in it, oil doesn't look milky, pressure tested good, new radiator cap, new thermostat, but for some damn reason I've got tons of air in the system some how. No visible coolant leaks anywhere on hoses or by heater valve.

Anyone think they know what the problem is and if it is air trapped, any tips on how to keep it from spilling all over the place when bleeding?

thanks, sorry for the long read...

 

don't bother with the cap on the firewall it is useless IMO. I've opened my system 3 times in 6 months (installed new hoses, new rad, and regular maintenance drain prior to that) and never had trapped air issues. Here is how I do it, it's never failed me yet.

Put temp switch to full hot for heater and remove radiator cap. Fill rad to the base of the filler neck if it is low. Turn on engine and Idle the car to 3 bars (ap1) or the equivalent bars on an ap2 whatever normal range is on it. Leave the bleed bolt at the manifold closed and do not open the bleed cap (firewall). Put lots of towels around the base of the rad filler neck, this method will result in spillage but it works, who cares about a bit of spillage or wet rags. As the car warms up you will see the level in the rad rise and fall at different times, and it will spill over the rad filler neck at times, thus the need for rags around the filler neck. I think that is how the air gets released properly as the fluid heats up and the level rises and falls so don't be alarmed as fluid rises and spills out. As soon as the temp guage hits normal operating temps shut off the car, if you need to add more coolant to get it to the base of the filler neck do it now and then install the rad cap. After a few seconds open the bleed bolt slowly until you get a steady stream of fluid coming out. The fluid will spray out so be careful and put rags around the manifold and bleed bolt. When you see steady fluid spraying out close up the bleed bolt and tighten to 8 foot lbs. Fill the overflow tank to the full hot level if needed. After it cools down check the fluid level in the radiator, open the cap and fill up as needed if it needs more fluid up to the base of the neck, fill the overlow tank to proper level if needed. You should be good to go , if necessary repeat this process a second time a day later if you think it still has air in the system. You should be getting consistent and very hot air out of the heating system once the system is properly bled and free of air pockets.

It's not the cleanest method but it works for me. Many people have had air issues after opening the cooling system, but I never have despite opening it up 3 times, so I'm happy with the results.

 

thanks, will try sometime this weekend

 

I was thinking about doing a radiator flush one of these weekends but this looks difficult. I just assumed when you filled it up it would be ready to go.

 

Run the car to 3 bars, plus 1 minute.

TURN ENGINE OFF.

crack the bleeder, just enough to hear it hiss. A load of air will come out.

Close bleeder, fill radiator, repeat until interior heat is red hot.

Trust me on this one

 

well I haven't done anything new yet, just got home, but this was the first time I've had a steady 8 bars(ap2) from cold start up to work and cold start up back home.

I'm thinking the few minutes that I did bleed some air out by letting the air/coolant just burst out of the radiator filler neck made a significant difference. I drove with air off, but set to heat, going to work. On the way home I had ac full blast and everything was steady.

Once it cools down I'll check coolant levels again, I'm getting tired of troubleshooting, hopefully this problem is over with.

 

I had this problem when I flushed the coolant on my ap1! I went through the same problems of trouble shooting until it frustrated me enough to wanna take it to the dealer but i eventually got rid of the stubborn air pockets.

 

when you warming the car up is the rad. cap on or off? and when warming the engine to 3 bars on a ap2 fine?

 

3 bars on ap2 is no where near warmed up

8 bars is normal running temp

 

I can not imagine why Honda would put that cap in the system on the firewall if not to use it.

Just the opposite of your methods, I top mine off at the filler on the firewall while the radiator cap is open. I have a small hose and funnel.

This method fills the entire system with no bubble left. No need to burp, fart, bleed or any of that other stuff. It is necessary to turn the heat on.

You can belittle the little access port on the firewall or you can use it to your advantage. No messy antifreeze soaked towels for me. For the record, I don't have the front manifold bleeder. Cut it off and welded the manifold shut.