How to fill and bleed the coolant system. - MG-Rover.org Forums
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post #1 of 90 (permalink) Old 21-11-2009, 17:37 Thread Starter
CJJ
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How to fill and bleed the coolant system.

The following is based on the TF but should be similar for the F as well.

There are several reasons why you would need to refill the coolant system.

The first is due to the age of the coolant. It should be changed every 60,000 miles or 4 years, whichever comes first.

The second reason to fill the system is post intrusive maintenance, such as changing the head gasket, the under floor pipes, any part of the cooling system, radiator, heater etc etc. All of these would involve draining the coolant and refilling once complete.

The problem with the F/TF is that the cooling system is quite complex and has many areas which can trap air. If the system was left in this state you can get hotspots in the engine, lack of cooling and other problems which could very easily lead to the dreaded head gasket failure (HGF).

It is essential that you bleed the system and purge it of any air.

The recommended way to fill the system is to use a vacuum filler. This essentially sucks out all the air, creating a vacuum, which then sucks in the coolant. The following process is the more common DIY method, which assumes you do not have a vacuum filler.

To drain the system, there isn't really a proper drain to use.

First take the coolant expansion tank cap off.



This will help the coolant drain faster.

The best place to drain the coolant off is at the front end of the underfloor coolant pipes. Remove the clips by pressing the ends together and sliding them along the pipe away from the connection. The rubber hose will be stuck on the metal pipe after years of sitting in place. I loosened them by gripping them with mole grips, or similar, and turning until the seal is broken.



Rather than pulling the hose straight off and getting soaked I slid a screwdriver down the inside of the hose to create a small bleed.



Now just leave that to drain. Check once in a while to make sure that the container doesn't overflow.

Be careful as it is easy to get the coolant in your eyes. Obviously I didn't, being the professional that I is. I said I didn't, right. And it stings, er, or so I heard somewhere.

You can aid the draining by opening the bleed points.

There is one at the top nearside of the radiator. Be very careful when opening this one as it is only plastic and often shears off. If it does shear off then one of the ways to remove the remaining threaded portion is to heat up a screwdriver end to F hot and melt it into the plastic bolt, let it cool and screw it out.



While you are under the bonnet, remove the plastic cover on the bulkhead and you will see another bleed point for the heater matrix. Make sure that you have the heater set to hot to allow the coolant to drain.



And one in the engine compartment, above the starter motor.



Once all the coolant is drained you can carry out whatever maintenance/repairs that you need to.

If you are simply changing the coolant then you should now reconnect the front coolant pipes.



Next you need to prepare your coolant. MOST of the Fs and all of the TFs specify a 50/50 mix of OAT (Organic Acid Technology) coolant and demineralised water. It comes in many colours but generally looks very bright. Common colours are green, orange and blue. Normal water should not be used as it contains minerals etc that can cause deposits in the engine and radiator (just look in your kettle).

Some older Fs recommend you use ethylene glycol, which is the more traditional coolant. Many people have converted to the better OAT coolant, but if you do, make sure that you thoroughly flush the system first as the two coolants do not mix well.

You can get OAT from most automotive car shops. I got mine from Halfords. You can buy 50/50 ready mixed or concentrated and a seperate container of demineralised water.

I mixed my own in a suitable container.



Close all of the bleed points opened previously and fill the expansion tank untill it won't take any more coolant, leave the expansion cap off.



Next you will be bleeding any air out of the system. Ideally it is a 2 person job as you need to make sure the expansion tank does not empty as it will introduce more air. I did it on my own and it is fine as long as you keep checking the coolant level and top up as necessary.

First, loosen the radiator bleed screw



and then loosen it further with your fingers (do not do this with a hot engine as you will scald your hands).



You should hear hissing as the weight of the coolant forces the air out of the radiator. Tighten the bleed screw regularly and check/top up the coolant. Go back and loosen the screw again. Do this as many times as it takes until coolant starts to come out without any bubbles. This may take some time as the radiator will be full of air.

Once the radiator is bled, move on to the heater bleed screw. As mentioned earlier, this is behind a plastic cover which should be removed and is roughly above where you fill up the windscreen washer fluid.



Make sure that the car heater is set to fully on (hot) and undo the screw until the air starts coming out. Again, keep checking the coolant level and continue until no more air comes out. You should just have coolant with no major bubbles coming out.

Next, you should slacken off the bleed point in the pipe above the gearbox.



Again, bleed until only coolant comes out.

Fully tighten all bleed points and check the coolant level.

Cross your fingers (I did and think it is an essential part of the procedure ) and start the engine. Let the engine run for a couple of minutes, switch off and then go around the bleed points to bleed any air that has worked it's way around the system. The coolant shouldn't be hot yet, but take care just in case.

Check the hoses where you disconnected and reconnected earlier for any leaks.

Wipe up any coolant around the bleed points.

Recheck that the bleed points are correctly tightened.

Run the engine and check for any leaks.

You have now changed your coolant.

You will suffer from coolant induced paranoia for the next month, this is normal.

DO, check your coolant level regularly for the first couple of days (Before and after every run). ANd then revert to normal checks after that.

If there is still air in the system you will get tell tale signs, such as no heat from the blowers in the car, erratic coolant level, sudden drop in level as the air escapes.

If you suspect there is air, then re bleed the system.

If you feel the need, then the torque settings for the bleed screws are:

Radiator Bleed Screw......................5Nm
Heater Bleed Screw........................7Nm
Radiator Return Line Bleed Screw......9Nm

The cooling system takes 10.5 Litres from dry.
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post #2 of 90 (permalink) Old 21-11-2009, 18:00
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It should be noted that a torque of 5.1 nm on the rad bleed screw will rip the head clean off of the screw leaving you with a leaking plastic lump.
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post #3 of 90 (permalink) Old 21-11-2009, 18:02 Thread Starter
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Quote:
Originally Posted by Dyshipfakta View Post
It should be noted that a torque of 5.1 nm on the rad bleed screw will rip the head clean off of the screw leaving you with a leaking plastic lump.
The voice of experience?

I just nipped it up, but I thought someone might want to know the correct torkses.
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post #4 of 90 (permalink) Old 21-11-2009, 18:30
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very nice info and pics
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post #5 of 90 (permalink) Old 21-11-2009, 18:52
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"You will suffer from coolant induced paranoia for the next month, this is normal."

Oh hell, not another one!!
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post #6 of 90 (permalink) Old 22-11-2009, 06:10
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Excellent 'how-to" (again) I paid 175 for my radiator to be replaced at a garage - just for paranoia of not bleeding the system correctly. WIll do it next time myslef now.
Will a vacume brake-bleed system - (you connect to an air compressor) vacume fill / bleed the coolant system I wonder?

Last edited by jonathanharding; 22-11-2009 at 06:16.
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post #7 of 90 (permalink) Old 22-11-2009, 08:28
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Yes, vacuum is the way most garages do it.
It does put strain on potentially old rubber hoses though when it collapses them.
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post #8 of 90 (permalink) Old 22-11-2009, 10:02
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Good job CJJ.
I report my personal experience after PRT installation, I managed the job in order to loose the minimum of liquid, I lifted only the rear wheels, so I lost only 5 liters and retopped the level and tested on the road, perfect.
The day after I parked the car in the very inclined ramp of my garage, when I restarted the expansion tank level switch beeped !! I added 200-300 cc.
The inclined ramp has favored the last bubbles escape.
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post #9 of 90 (permalink) Old 30-11-2009, 06:33
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Thanks for a great guide CJJ - I was looking at my tank the other day thinking "ooo - thats getting a bit low"

Time to do something about it
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post #10 of 90 (permalink) Old 01-01-2010, 15:12
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Thanks for this excellent guide Clive. I have changed the geadgasket etc over Christmas and couldn't find the bleed point in the engine bay.

Another excellent "How to"
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post #11 of 90 (permalink) Old 01-01-2010, 15:18 Thread Starter
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Oooh. You know how to celebrate christmas don't you.
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post #12 of 90 (permalink) Old 01-01-2010, 15:24
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I was allowed Christmas day off lol.

Had a couple of issues with what I have done though, I have broken the plastic connector that the rubber hose fits on for the Charcoal cannister (not the manfold one) and also the fuel guage isn't working..................but knowing the wife there is probably no petrol in it. , but I would expect it to move slightly
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post #13 of 90 (permalink) Old 01-01-2010, 16:00
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Champion of a bump thanks clive
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post #14 of 90 (permalink) Old 02-01-2010, 16:51
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For lazy folk like my good self the engine bleed screw can be reached through the engine inpection grill in the boot. Thus saving 30 mins removing the sound proofing & 15 ish bolts that hold the big engine cover on
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post #15 of 90 (permalink) Old 02-01-2010, 21:31
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when bleeding the second time do u recomend doing it with the engine running? to move the coolant or is this a engine off job??
or is this a silly question?
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post #16 of 90 (permalink) Old 03-01-2010, 06:40
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Send a message via MSN to X-P0WER
There are no silly questions. Just silly people. And im one of them so id like to know the answer too lol
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post #17 of 90 (permalink) Old 03-01-2010, 10:37 Thread Starter
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Once you have bled all the air that you can out of the system I would start the engine for about 30 secs and rebleed. The thermostat won't have opened yet so will only be circulating around the engine. Rebleed.
Once you are happy then take the car for a gentle drive, enough to get to temp, be aware thou that if a large air lock decides to let go then your coolant level will drop suddenly, so keep an eye on it.
Once the car has reached temp, I would let it cool and then bleed again.
If everything is OK then I would run the car for a week and rebleed.

This is just what I would do, someone else may come along and suggest something else.

Remember that the heater must be fully on at all times while bleeding.
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post #18 of 90 (permalink) Old 10-06-2010, 16:43
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how did you make the coolant change colour from red to green? ( you do magic)
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post #19 of 90 (permalink) Old 10-06-2010, 17:08 Thread Starter
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post #20 of 90 (permalink) Old 17-06-2010, 09:49
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Quote:
Originally Posted by CJJ View Post
The recommended way to fill the system is to use a vacuum filler. This essentially sucks out all the air, creating a vacuum, which then sucks in the coolant. The following process is the more common DIY method, which assumes you do not have a vacuum filler.
If you dont have a vacuum filler and fancy one take a look at this:-

Vacuum Filler
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