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Bleeding the K-Series Cooling System no longer a chore.

12K views 11 replies 5 participants last post by  Man in the Car 
#1 ·
Long since lost count of the times I've bled the Cooling System of Air from K-Series MG and Rover Engines.

There has to be a better way .... and there is as I discovered recently by trial and error.

I used my trusty Funnel and length of garden hose which for years enabled me to effectively fill the PG1 Gearboxes with little lubricant losses. This set up works well. :~



With that in mind and using a shorter length of garden hose with a Coolant Hose Off-Cut placed on the end. This locates over the 8mm Bleed Bolt Hole location on the metal coolant tube above the bell housing providing and effective seal.

Then, holding the funnel a shade higher above the Coolant Expansion Bottle with the garden hose located over the bleed bolt location ~ 8mm Bleed Bolt removed of course ~ pour coolant in until it rises and reaches the MAX Index in the Expansion Bottle. Then, immediately remove the hose from the Bleed Bolt location and quickly replace the 8mm Bolt. It works remarkably well. Just be patient adding a little coolant to the Funnel each time until correct level is reached.

Done this to three 1.8T K-Series ZT-T engines now. Wish I'd sussed out this speedy method years ago. This is the simple Funnel and short piece of Garden Hose arrangement. You may need to find a rubber hose ( old piece of coolant hose Off-Cut of suitable dimensions is what I used ) to fit on the end of the garden hose for some bleed bolt locations as the size varies from car to car. As it happens, the Garden Hose off cut alone fitted over it without the need for the rubber hose off cut on one car. :~



Here it is in place at end of topping up bleeding process. :~

 
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#2 ·
I've bled a few K's as well. Tbh I've never really had the problems (airlocks etc) I see written about here though. I do wonder if there are other faults in the cooling system when these problems happen.

Usually I'd flush well, and with the heater on full, I just fill up through the expansion tank with the coolant rail bleed screw removed and pop the screw back in when the coolant reaches that level, then continue to fill to the max level and replace the cap. Run, for a bit, top up if necessary, then keep an eye on the level for a few weeks, topping up again if required.
 
#4 ·
Lost count of the number of K-Series cooling systems I have flushed, charged with fresh coolant and bled over the years. Fiddly time consuming job rather than difficult.

Accessing that 8mm Bleed Bolt is not easy as so many things in the way.

This simple technique just makes bleeding the system so much more effective and efficient. Seeing the coolant rise to the MAX level in the Opaque Coolant Expansion Bottle on K-Series 75s and MG ZTs is so reassuring.

Here is the simple stuff I used to good effect :~



 
#12 ·
As said before - the one that switches the radiator fan via the engine ECU is the one that points directly forwards from the coolant elbow. On a Rover 25 or MG ZR (which have a MEMS3 engine ECU) it should be a black sensor. The one underneath the elbow (blue) only supplies a signal to the temperature gauge in the instrument cluster.

A brown sensor won't work with the MEMS3 engine ECU as it is for the earlier K series engines fitted to the bubble Rover 200 and 400 (which had a MEMS 1.9 engine ECU) - if you have a brown sensor fitted to a MEMS3 2005 model MG ZR, this is why your radiator cooling fan doesn't work.

However, the fans rarely come on anyway in normal driving (unless you are in very slow moving or stationary traffic), so if the coolant is getting excessively hot under normal driving speeds, you probably have a more serious problem than just the wrong CTS.
 
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