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Michael Paceskoski
Experienced User
Username: forever_elegant

Post Number: 36
Registered: 7-2005
Posted on Saturday, 24 September, 2016 - 19:07:   Edit PostDelete PostView Post/Check IP

Just wanted to update everyone on my progress and maybe someone might have some valuable thoughts to share.

after starting the vehicle for the first time in many years i noticed that the water temp gauge was working. i embarked on cleaning up the cooling system and these are the things i have done so far.

-cleaned up water sensor terminals and threads, tested in boiling water and change in resistance, which passed the test. Does anyone know the resistance range for the sensor.

-removed thermostat with tool, cleaned from scale, tested in boiling water and opens fully to about 7mm just before water is boiling. thermostat is 76'C opening.

-back flushed radiator 10min, from bottom hose. clear water

-back flushed from both engine block taps out through lower water pump and thermostat for about 10min. clear water

-Ran car for about 10 15 min without thermostat, temp increased only slightly, but this was a test if the water pump was working. water circulating through top rad hose only at a higher rpm. Is this normal?

-Drained water, was very dirty at this point. Im thinking that the heat is breaking up scale and grime/crud. Has anyone ran a cleaning agent through the system to aid breakdown of scale successfully?

-Re-fitted thermostat and ran car for 10-15mins. car came close to normal temp and thermostat seemed to open. What is the normal time that thermostat will open in stationary position with light throttle?

-will drain and repeat above process until i get mostly clear running water.

-Im planning on running green Nulon coolant at 50:50 ration with water. any other coolant brand or type suggestions?

any suggestions guys will be greatly appreciated?
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David Hughes
Frequent User
Username: wedcar

Post Number: 61
Registered: 7-2004
Posted on Sunday, 25 September, 2016 - 20:34:   Edit PostDelete PostView Post/Check IP


This link was posted on the American RR website regarding cooling water system cleaning. It suggests fill the system using 1lb (.5KG) of citric acid per 1 gallon (5 litres)water then run the car for half an hour, then flush the system with water.

I have not had to use this myself however there are quite a few comments about the success of this treatment.

Trust that helps.

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Michael Paceskoski
Experienced User
Username: forever_elegant

Post Number: 37
Registered: 7-2005
Posted on Sunday, 25 September, 2016 - 21:26:   Edit PostDelete PostView Post/Check IP

Thanks David,

Iv just applied to register for the US RROC forum and ill have a look at the link when Its activated
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David Balfour
Experienced User
Username: sidchrome

Post Number: 27
Registered: 2-2009
Posted on Monday, 26 September, 2016 - 10:06:   Edit PostDelete PostView Post/Check IP

Hi Michael I have two thoughts on this. The first is any corrosion on the outside of the wet liners, and the second is corrosion of the aluminium alloy. A product like Evap-O-Rust will dissolve the wet liner rust completely into solution without introducing acids/alkalis to the cooling circuit which are not so kind to the rubber components particularly. They also produce a product for aluminium oxide, but I don't know anything about it.

The brilliant thing about the wet liners is that they transfer enormous amounts of thermal energy to the water jacket, and thus keeping them rust/scale free is critical. I've also heard when they do rust that corrosion can build up between the liner and the block in places where the clearance is in the mm region, putting lateral pressure on the liner and leading to liner distortion and possible mechanical engine damage.

On the maintenance side, an older club member told me he knew a guy that used to drain his cooling system annually and add dish washing liquid, run the engine until hot and then drain, flush and refill with coolant. He says his was the cleanest cooling system he ever saw on a car.

I gave the Evap-O-Rust advice to a former club member who had a chronic overheating problem with his Spirit. He bought and filled his cooling system with the ordinary stuff, they make one just for cooling systems too. After a drop in operating temperature progressively over 4 days, he drained and flushed the cooling system. I expected him to tell me the drained solution had turned black (was yellow when added), because as the iron ions bond to ions in solution, the carbon from the rust is liberated sending the mixture black. He said it looked like brown mud, which possibly suggests that as the rust formed, dirt and contaminants in solution was captured and held by the rust. In any case he was deliriously happy with the result, as no amount of chemical flushing/cleaning to that point had helped.

The manufacturer claims Evap-O-Rust is non toxic, neutral pH, and harmless to rubber base metals etc., which is important for our cars. I believe there may be at least one other similar brand of chelating solution on the market - start googling.

As for the alloy, I'm sure the citric acid will help clean that as does phosphoric acid. In any case, it would be wise to clean all prior to adding your inhibitor. Don't forget to make sure your heater taps are open, if they work, so you clean out the heater core(s) at the same time.
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christopher carnley
Unregistered guest
Posted From:
Posted on Tuesday, 27 September, 2016 - 02:48:   Edit PostDelete PostView Post/Check IP

Evap-O-Rust conains EDTA a chelating agent with a very long name. It has a ph of 6.1 and as an organic acetate, is mildly acidic.

It is used as a chelating agent by injection to precipitate lead and other heavy metals principally from the blood of workers employed in such trades.

It is also used to "rejuvenate" lead acid batteries.

(Message approved by david_gore)
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Marianne Dawson
Yet to post message
Username: maddy

Post Number: 1
Registered: 2-2019
Posted on Saturday, 02 March, 2019 - 04:45:   Edit PostDelete PostView Post/Check IP

To those forum members who are or have hands-on experience working on Silver Cloud III automobiles I ask for your help.

I have a 1963 Silver Cloud III LSCX397. I am a third owner from the factory. When I took possession of the automobile I was informed that there was a fire on the right side engine compartment. The previous did not know what caused the fire.

Even though work has been done to restore the automobile to running condition, my inspection of the coolant system has revealed there are no water tap actuators. I have purchased two used ones and refurbished and tested them. I see where they are fitted on the valance.

Since the automobile was routed to operate without the actuators I am not sure if I have the proper molded hoses or have all the piping necessary to reconnect the actuators properly. I can compare the hose and piping of my engine compartment to one that is properly routed by pictures if these pictures are exact and clear for me to use as a study.

Should any forum member have such pictures that can be attached to a reply in this forum it would be most appreciated.

Secondly, to refit the hoses to the heater/demister located behind the right side wing/fender is it necessary to remove this wing/fender? I presume so.

Marianne Dawson
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David Gore
Username: david_gore

Post Number: 3162
Registered: 4-2003
Posted on Saturday, 02 March, 2019 - 07:59:   Edit PostDelete PostView Post/Check IP


Welcome to our forum; I am certain one or more of our regular Silver Cloud/Bentley S contributors will be able to help with your request.
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David Balfour
Prolific User
Username: sidchrome

Post Number: 144
Registered: 2-2009
Posted on Sunday, 03 March, 2019 - 23:13:   Edit PostDelete PostView Post/Check IP

Hi Marianne, Perhaps just to simplify what it is you will need, can you perhaps upload a couple of images of your water tap locations now, and the actuators you have purchased. Does this mean you have the taps but the actuators were missing and you have now bought them? There are 4 identical actuators in your car (same as my late Cloud II). There is one tap bottom of the engine bay on the left and on the opposite side - on the right in about the same location. The two upper actuators located aft of the brake reservoirs are flap actuators. Can I confirm you are talking about the left and right down the bottom on the inner guard location and not the flap actuators?

I too had a fire on the RH side at the rear of the engine bay. The steel braided rubber fuel line failed and sprayed petrol all over the starter solenoid which acted as a lighter when my automatic transmission guy re-installed the transmission and started the car. He had to tilt the engine slightly to get the transmission out and the hose failed unbeknown to him. Luckily he extinguished it before the fire spread. Perhaps you car has had a similar issue.

If you would be good enough to upload some images that would help tremendously.
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David Hughes
Frequent User
Username: wedcar

Post Number: 89
Registered: 7-2004
Posted on Tuesday, 05 March, 2019 - 08:30:   Edit PostDelete PostView Post/Check IP


I read with interest your posts on the American website regarding the issues with your car.

There are several "youtube" articles by Steve's House of Speed on Silver Cloud 111 maintenance jobs.

The above is regarding the water tap actuators.

There are several other concerning fitting the parts back on the car. Hopefully they could assist you.

Regards David

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