Bleeding/Burping coolant system, I'm stuck.

[NickM450]

Hi folks,

I recently had the cambelt and water pump changed on my '93 Toyota Carina, everything worked perfectly until a few days ago when I noticed small drops of water from one of the radiator hoses. No problem, a quick fix, or so I thought. I've now lost most the heat from the heater, I think I've probably got an an lock in the cooling system.

My mechanic is off until the 5th so I thought I'd tackle this myself. I have the basics, jack the car up, run without the radiator cap on and wait. The problem is I have come across conflicting advice, do I run the car with the heater set to hot or cold? Any other pointers would be appreciated, thanks

Nick

[curlie467]

Run it on hot then the water is getting round the whole system.
Keep feeling all the hoses for heat, they all should be hot. Have you fixed the leak first?

[Willy Nilly]

I don't know for sure, but would have thought you need the heater on to circulate coolant around the heating system that might be hiding bubbles.

[SuperHangOn]

Heater on hot. I squeeze the hoses to purge the bubbles. Whatever you do, don't pour cold coolant/water into a hot engine

[Fluid]

When I did my puma's heater control valve, I left the cap off and put the heater controls to hot, fan to full whack and left it running until hot. Giving the pipes a squeeze to dispel any air that was trapped.

[JakeT]

There's a ton of YouTube videos on it also. EricTheCarGuy has good videos for the DIY'er.

[eltax91]

Heater on full heat. Massage the hoses to try and purge the air. Do they all get hot?

[NickM450]

Cheers folks,

The top radiator hose is hot, bottom not so much. Didn't know about squeezing the hoses, hope this works

[john2443]

NickM450 said:

Cheers folks,

The top radiator hose is hot, bottom not so much. Didn't know about squeezing the hoses, hope this works

Bottom hose won't be so hot - hot water goes into the top of the rad, is cooled by the rad, goes out of the bottom and into the engine.

Someone said put the fan on full - doesn't make any difference what the fan is doing but you do need to have the cabin temp set to high.

[Ozzie Osmond]

Some cars have air bleed screws to assist the process. I've no idea whether your does.

As others have said, heater on and squeeze the hoses. I also favour doing all of this with the radiator cap(s) removed so that the system doesn't pressurise and you can see what's going on.

[NickM450]

Seems to have worked

Certainly restored some if not all the heat in the cabin, should at least be able to defrost the screen in the morning. Is it just a case of carrying on longer if I want to try and get more heat or am I kidding myself that it was hotter before?

[s p a c e m a n]

Nah, now that it's 99% there just keep a bottle of coolant in the boot and check the level every time it's cool enough to do for a couple of days, it'll sort itself out.

[B'stard Child]

s p a c e m a n said:

Nah, now that it's 99% there just keep a bottle of coolant in the boot and check the level every time it's cool enough to do for a couple of days, it'll sort itself out.

Or you could try the "italian tune up" method to restore it to 100%

[Superhoop]

Why does anyone think the setting of the heater controls has any bearing on whether there is coolant running through the heater matrix and therefore the cooling system or not?

Do you all think that when you turn the heater to cold, that engine coolant stops flowing through the heater matrix?

The only difference between the hot and cold settings on the heater, is how much air is directed over/through the always hot when the engine is hot heater matrix...

[B'stard Child]

Superhoop said:

Why does anyone think the setting of the heater controls has any bearing on whether there is coolant running through the heater matrix and therefore the cooling system or not?

Do you all think that when you turn the heater to cold, that engine coolant stops flowing through the heater matrix?

The only difference between the hot and cold settings on the heater, is how much air is directed over/through the always hot when the engine is hot heater matrix...

Depends on the car and the heater set up

Cars either have

servo operated valves that control the heat by controlling the ammount of hot water flow to the matrix

Or flap/servo operated cold air bypass systems that mixes cooler air with hot air coming thro the matrix

If you don't know what you have then the sensible advice is to always select max heat (just in case)

[ging84]

Superhoop said:

Why does anyone think the setting of the heater controls has any bearing on whether there is coolant running through the heater matrix and therefore the cooling system or not?

Do you all think that when you turn the heater to cold, that engine coolant stops flowing through the heater matrix?

The only difference between the hot and cold settings on the heater, is how much air is directed over/through the always hot when the engine is hot heater matrix...

Might be how your car works, it might be more normal on modern or exspensive cars particularly with climate control, but for years, the conventional way to control the heater was all the air through the matrix and a single cable operated valve on the heater matrix, which if left closed when bleeding, guaranteed you a nice big air pocket which then often gets shifted somewhere you really don't want it when the heater if first used

[B'stard Child]

Out of my cars - it's 50/50 on systems

BMW - servo controlled valve controlling water flow
Merc - As above

Monza - Air Flap control Matrix always at engine temp
Lotus - As above