best way to bleed cooling system

[avacado11]

Is there a standard or proper way to bleed a cooling system?

I've always just idled the car with the radiator cap off. After a few minutes I top off, close, drive, and check level again once cool. I've also heard of squeezing the upper radiator hose to help purge the system...is this necessary? Lots of cars these days don't have radiator caps anymore. Just pressurized overflow tanks. Does the same procedure work?

Is there any other way that works better?

 

[clinebarger]

The best way is to use a Coolant Refiller that draws a vacuum on the system.....Bleeding is usually not needed at all using this tool.

 

[FCD]

Yes the same procedure works for pressurized overflow / expanion tanks

 

[Railrust]

I think it really depends on the car, some are easier than others, but I like it when a car has a bleeder valve or two...makes things go much quicker/easier. Just crack that valve and wait for the coolant bubbles to come out. My last car had a coolant valve that was big enough that I could remove it and pour coolant right in it's port, it was at a real high spot and it would take quite a bit of coolant.

 

[demarpaint]

Originally Posted by clinebarger
The best way is to use a Coolant Refiller that draws a vacuum on the system.....Bleeding is usually not needed at all using this tool.

+1 They work great.

 

[eljefino]

The right answer is following the manufacturers directions.

If I get a stubborn one, I disconnect the top radiator hose at the rad, hold it high, and pour coolant into it until it dribbles out the radiator nipple. Takes a long torturous journey through the engine and water pump before it gets out that way, and the added height adds pressure to force it through.

 

[Lubener]

I drill a 1/16 inch hole in my thermostat's flange to allow any trapped air to get by and get belched out, otherwise you have to raise the nose of the vehicle substationally while idling for a while to belch out the air.

 

[ofelas]

Most engines have a bleed screw that can be cracked open, or a "jiggle valve" that allows trapped air to purge itself when the engine is off.

Drilling a hole merely increases warmup times.

 

[ZebRuaj]

+1 to whatever the manufacturer recommends. The interweb is great for leaked service manuals when available. Harder to find for newer cars.

Most vehicles I leave nose high with the Lisle no spill funnel in the rad. Hold RPMs at 2000-2500 and let it burb itself out, then go for a drive. I still do the same when there's no rad cap and just overflow access. Bleed it out a bit while nose high, do some short drives and check the level.

My G35 had bleed valves that needed to be open while you refilled with coolant otherwise you would never get all the air out.

 

[Chris142]

Depends on the car. Some are easy. Just let them idle. Others have a procedure,rev to a certan rpm etc.

 

[Driz]

I just drive all of mine and check them. That's worked for me for 40 years without any problems. The only cars I ever saw that gave you an actual bleeder were Hondas.
My favorite trick if you wanna call it one is filling as much of the engine as I can read through the upper radiator hose. I just take the hose off at the radiator and then pour that thing until it's absolutely full and stuff it on again. I don't mind the mess. Then I fill the radiator and overflow bottle to the line and just keep an eye on it for a bit.

 

[zzyzzx]

I just drive it and keep checking the overflow tank and refilling. The first couple of trips are short trips where I just drive it around the neighborhood enough to warn it up.

 

[emmett442]

When possible, I fill the engine BEFORE installing the t-stat to a level just below the housing. Then install the t-stat/housing and fill it the rest of the way up. Prevents stubborn trapped air behind the t-stat.

It also helps to have the highest point possible open/disconnected while filling. Often, that's a heater hose connection That way, coolant can push the air out and there's minimal to no bleeding to do.

 

[ZZman]

I like the Lisle kit I bought.

 

[GoldDot40]

Varies per vehicle. As stated, the ones that have a bleeder screw work great.

 

[N Heat]

Jack up front, fill through top hose, run with cap off for a little while. Never had a prob doing those things.

 

[JeffKeryk]

Yup. Get the nose up.

 

[Omahaug]

Some cars have arrangements without bleeder screws because the neck of the radiator is the highest point, even higher than the water jacket in the head. For these all you really have to do is make sure the car is level or a little nose up on the radiator side.

I too just drain the coolant, fill it and idle it a bit, then rev to about 2000-3000RPM until the cooling fans come on. Periodically I'll gently squeeze the hoses and feel them for heat. Once the lower radiator hose gets really hot I know the thermostat opened up. Then I'll button everything up and drive it with a little extra coolant in the reservoir to accommodate any being sucked back in to replace displaced air. I usually don't have any major residual air when I do this.

I always follow the specific service manual though for whatever car I'm working on. For example some Infiniti cars have multiple bleeder screws, one on the radiator, one on the hose lead to the heater core, whatever and they have a very specific order of when to close each one such as open both, fill it until you see it run out of the lower one, close that, then fill until it runs out of the higher one, close that, et cetera.

 

[cb_13]

Originally Posted by clinebarger
The best way is to use a Coolant Refiller that draws a vacuum on the system.....Bleeding is usually not needed at all using this tool.


This 100%! I've tried all sorts of crazy methods but unless the vehicle has a bleeder screw nothing I've found can compare with the time savings and confidence that the job is done right that the vacuum refill tool provides.

 

[slacktide_bitog]

The Lisle coolant funnel is awesome