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We cover all MG & Rover cars, We are the MG Owners Club & Rover Owners club, combined in one, from Rover 75 to MGZT, from Rover 800 to MGB, we are here for all your MG Rover MGR cars
 

How To's

How to Bleed the coolant after a radiator change

Unread postby luke83g » Sat Jan 17, 2015 9:42 pm

Hi, I'm about to change the radiator in my 1.4 k series rover 45. In the past I've gone on the basis of turn heater to hot and full, change radiator and slowly refill coolant using the expansion tank.

However with it being a k series engine I'm concerned that I may get a air trap and Blow the head gasket. Any advice over the above to avoid this? Is there a bleed tap on the k series and if so how do I work it? Thanks Luke
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Unread postby Blue Club 45 » Sun Jan 18, 2015 1:41 am

Hi

There is a bleeder on the coolant pipe that crosses over the top of the gearbox. Its an 8mm bolt! carry out everything as you have described heater tap to hot etc,

There is a "Giggle" valve on the plastic hose from the inlet manifold to the expansion bottle. this can easily get stuck! Remove the pipe from the bottle end and both "Blow and suck" on it to ensure the valve is free! if it is blocked you will not be able to fully bleed the cylinder head! = Over heating followed by head problems! If it is blocked you will need to remove the manifold to free it! Always use a new "Green" manifold gasket!

Please remember that coolant is poisonous so ensure you don't suck any in while checking the valve!

The coolant is drained via the bottom hose at the radiator. beware the water comes out pretty quick so watch out! While you have the hose off its a good idea to flush through the system. if you use a hose LOW pressure! The manual figures for capacity are "Guidance only!" its best to premix the coolant and water before trying to refill.

Once you have refitted the bottom hose and remembered to tighten the clip! remove the vent plug from the pipe, watch out for the special washer! it often sticks to the pipe until coolant starts to flow out then comes off and disappears!

SLOWLY add coolant to the expansion bottle watch the vent! When you get a clear bubble free flow. Refit the plug! continue filling SLOWLY until you have half filled the bottle. the systematically squeeze the large hoses and watch for bubbles and /or the level dropping. Continue filling and squeezing until the level remains constant! Tighten the pressure cap "effin" tight!

Start the engine and let it warm up until the indicator (I refuse to call it a temperature gauge!) shows normal. Have the heater fan running and make sure the heater is kicking out hot air! As the engine warms up and the thermostat opens repeat the squeezing (Remember the water in the pipes is HOT!)

If all is well allow the engine to cool. open the bleed plug enough for any air bubbles to show. If any do, repeat the bleeding from the bleed plug.

With any sort of luck you should have no problem. take the car for a 2-3 mile road test, leave the heater on fully hot! when you get back allow the engine to cool and top up if the level has dropped below the "Min" line! Retighten the cap (Remember effin tight) and you should be good.
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Unread postby Mal7921 » Sun Jan 18, 2015 12:38 pm

Good guide there, may well be worth adding to the 'How To' section
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Unread postby luke83g » Thu Jan 29, 2015 6:39 pm

Hi, I changed the radiator and the coolant return pipe that returns the coolant from the top of the radiator to the expansion tank (also connects to the inlet manifold). I followed your excellent instructions (thank you) slowly filling the system with fresh coolant and then slowly squeezing the hoses and also opening the bleed screw to reveal a stream of stead coolant coming out with no air.

Upon running the car upto temperature the air was not hot from the vents. I rechecked the bleed valve and hoses to ensure no air.

I was wondering, do you think the cabin vents were not hot because I was just running the car up To temperature whilst stationary? Or is there still a fault in the system? It must be noted that it was very cold today (snowed 3 times whilst I was doing this - fun!) and the bonnet was up so perhaps the car was fighting to get the temperature of the cabin vents up to par?

I simply did not have time to drive it round the block, so would appreciate any advice or suggestions prior to working on it again on Saturday. Many thanks Luke
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Unread postby Blue Club 45 » Thu Jan 29, 2015 9:35 pm

1/ Just checking you did have the heater set to hot when bleeding ?

2/ When you were pressing the top hose after running the engine, were there any bubbles coming into the expansion bottle?

If the answer was yes, there were bubbles then I would suggest re-bleeding.

If No, I suggest running the engine and feel the heater pipes to ensure that water is getting to the heater!

A question I should have asked previously! Why were you changing the Radiator?

If you can let me know I'll have a rethink and see what we can come up with!

Regards

David.
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Unread postby luke83g » Fri Jan 30, 2015 8:43 am

Hi David thanks again.

Yep the heater was on full and on hot when completing this procedure. The radiator had to be changed because the hose connector for the pipe that returns coolant to the expansion tank had been broken and was leaking.

When bleeding the system I did not get any air bubbles from squeezing the hoses.

I'm going to take her for a proper run out on Saturday to see if I can get warm air in cabin.

Any other suggestions?
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Unread postby Blue Club 45 » Fri Jan 30, 2015 10:27 am

Hi,

Thats an idea! Remember only a couple of miles!

Running the engine should have got the heater warm regardless of air temp!

You did test the Valve on the manifold on its own!? if you tried blowing and sucking with it connected to the rad you would have got a false reading!

Please let me know the result of your road test.

Regards

David.
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Unread postby luke83g » Sat Jan 31, 2015 6:30 pm

Hi took car for a run today, it ran up to temperature and hot air gust out of the vents. Slowly squeezed all hoses and they were warm. No coolant loss. Job completed I think! Many thanks for your help. Luke
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