Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Coolant system flush and antifreeze change.

Just getting ready to put my Mog to bed for over wintering. It's a plus 4 2010 car with a Duratec engine. When doing the checks I noticed that the header tank, a Ford item had started to show some brown sediment sticking to the upper surface of the vessel where the Radiator return pipe enters, That's one of the two small pipes that enters on the medial side at the top. This is a sure sign that the coolant has started to break down, so a coolant change is required. Now this will be the second time I will have changed my coolant ie. the third fill from new.

So I prepared to change out the fluid. Mine is filled with the Motal Ford product, the red stuff! so I ordered 5lt of that and 10lt of distilled water to do the job.
Unfortunately a lot of Morgans just don't get regular enough coolant changes or services as people assume that such low milages..... well the'll be ok won't they!
This is the first time my car has shown any sediment build up so I decided to do a cooling system flush as well and ordered 1lt of Prestone coolant system flush at the same time.

Now to the job in hand and really why I'm posting this. The modern Ford engined cars all seem to not drain down fully so this is the method of how I have worked out how to do the job without the chance of damaging anything.

I warm up the coolant a little, not enough to have the heating system at operating temperature or the thermostat open, say 3/4 minutes at idle, this tends to combine light particular matter into the solution as the water pump circulates it. This is done with the cabin heater on full and full fan, I then switch off the engine, make sure the rad is still cool and remove the header tank cap. Then under the car I open the drain cock and drain the fluid into a drain pan. Now the fluid drained out and looked like new. I tested it and it was within the required parameters, well it's five years old and needs to be changed anyway. Next I removed the header tank and flushed out the stubborn sediment which has a rubbery soft cheesy feel and is very sticky. OK, so that will mean that that sticky sediment from 15 years of coolant breakdown is coating a multitude of surfaces that I can't see.

So I decided I'm going to flush the system, It's a 10 lt capacity system but you can only manage to drain down about 6lts! Unless you start dismantling the cooling system, pulling hoses from everywhere, you will not get anymore out, especially as that tricky little heater matrix and pipes are holding the rest. Now in the old days you could pull hoses and pop off thermostat housings with gay abandon but these modern equivalents largely made out of plastic.... well that's not the way to go!
When you have drained as much as will come out, refill with tap water and run the engine. This time you do need to reach operating temperature and the themostat needs to open. When this has happened switch off and let the car cool down, when cool re-drain the system. Again you will get the 6lt's out. Next is the flush. Empty the 1lt bottle of Prestone flush into the header tank and top up with tap water, now run the engine for an hour and then let it cool down. Now here's why I choose Pestone coolant system flush. Not only is it possibly the best coolant cleaner in the world but it guarantee's to be non harmful or corrosive to any of your heating systems materials and it also offers a two stage option. You can stop here and drain it down then flush the system with plain water and refill with antifreeze or you can leave it in for 300 miles and then flush and drain it out if the system needs a heavy clean. However I have found over the years that a slightly different method works for me the best!
So back to switching off after running for an hour. I then leave it in overnight and in the morning I start the car up. reach operating temperature with the heater matrix and fan on full and after about ten minutes I shut the heater selector fully off until the engine thermostat opens and hot coolant enters the radiator. I let it run until the stat closes and I then open the heater matrix fully. after a few minutes I switch the engine off and wait for it to cool enough to drain it down.

Wait until you see just what comes out and the colour of it. You will also see by the associated foaming that it has cleaned the system. You will now have to go through the flushing process probably three more times ( remove all evidence of foaming ) and on the last flush when you are happy the drain off is showing clean, top up this time with distilled water. You want to remove as much of the tap water as you can. Now drain down for the last time. you will still have the retained roughly 4 Lt's, 2 being tap water mixed with distilled water.

Checking the drain cock is tightened and you have no leaks start to fill the system with concentrated antifreeze, You will get about 4 3/4 Lt in to the level mark, if you are struggling here start the engine and it will be drawn in. I mixed the last 1/4Lt with an equal part of distilled water as a top up should I need it!

Couple of points:

I'm not sure my system holds the full 10Lt's I think anomalies like pipe lengths will vary the capacity so don't panic if it all won't go in!

If you still have the original Radiator, I do and my car runs at a perfect 90' c ,which I'm happy with. A lot of owners who have alloy replacements are finding it hard to achieve this and are always running cool. The original has the modern trend of plastic end tanks and on the lower left of the radiator it has a drain cock with a cross in it to undo etc. Many say not to touch this drain cock as its vulnerable to failure, This is not true! It is a perfectly functioning pet cock and has an 'O' ring seal fitted so only needs lightly tightening. To undo and tighten use a large slotted screwdriver not a cross head variant. Pulling at hoses and pushing to refit them is far more likely to damage these radiators than using a perfectly designed drain off!

Sorry, but have to disagree about the drain plug…the first time I ever tried to undo mine, it broke off leaving the threaded portion inside the rad! So I dumped it and got a Sifab ali one.
BTW, the latest Ford Superplus spec anti freeze (POAT) that I purchased has changed from orange to yellow but Ford say it can be mixed if necessary without any harm, for topping up purposes.
With ref to the OP, I thought that “Motul” was an independant French company rather than a Ford product?

Does it work to jack up the back of the car to get better drainage?

Yes that's correct. HOAT is the latest incarnation and has less potential contaminants within its solution that can cause corrosion as it ages. There are three classes still available IAT, OAT and HOAT. If you mix HOAT with OAT because that''s all you have to hand you should flush the system fairly quickly and refill with OAT or HOAT. HOAT lasts longer in the vehicle, 7 years or 1000,000 miles. OAT 5 years and IAT 2 years. Never mix IAT with an OAT variant, That's the old green stuff.

HOAT was extremely expensive when it first hit the market but now generic options are available and careful shopping will get you the higher spec option for not much more than OAT.

I have never seen and original fitment rad with a broken drain plug but have heard others report it. So, just reporting on my experience. If perhaps they were replaced and over tightened to much this could be a cause. I don't know!... They are plastic, metal socket though.

Ford product should be Fomoco, however Motul do have the identical product. Not made by either company just marketed under their own brand name.

John, It won't help to drain the heater matrix out as the heater pipes enter through the heater box and are really the highest point other than the header tank. I do it the way I have explained trying not to yank at the plastic components which can only become more fragile as the years pass and having to refit a thermostat or possibly replace what was a functioning item. This leaves only clean water retained in the system with the minimum of tap water which can hold corrosive or scaling properties.

Coolant variations are a bit of a minefield.
One might think it safer to go purely by specification number as recommended in the handbook, but its no longer that simple.
My 2011 Duratec had Orange coolant with the spec. WSS-M79B44-D which is an OAT coolant.
However, if you try to obtain it nowadays, you will be told that Ford have replaced it with WSS-M97B57-A1 which is coloured yellow.
That one is a POAT.
Ford say that although it can be used for a small top up in an OAT system, it is best to completely flush the system before changing, as POAT & OAT should not be mixed in larger quantities. It also appears that POAT and HOAT, although from a similar stable, should not be mixed either.
So sewins advice on flushing when doing a change, seems the only way to go to be safe.
As Sewin mentioned Motul, I notice that Motul Auto Cool is in fact an OAT and happens to be orange, so I GUESS that could be used to add to a Duratec with the original orange coolant that was OEM around 2010 time.

Spot on DJ! As I tend to change my coolant on a time basis rather than milage I am happy staying with the original spec OAT. Ford as you say have upgraded and say this is compatible for use in their previous systems specced for OAT. But I've been around long enough now to have seen the reports that only time can show up where components breaking down due to reactions have happened. E10 fuel for example, blimey what a mess that created.
But I was surprised to see the sediment issue my car had thrown up this time. Its low milage and well serviced. Thinking about it, it was probably due to the OAT coolant mix throwing sediment, (Looked much like a red wine that had thrown a sediment in the bottle), over the total life of the car. When all surfaces were coated the new sediment found it harder to adhere to the already coated surfaces so made their way to the header tank. Now the latest coolants don't hold an electrical charge, the older types do, in fact you can use a multimeter to read it! So, when the metalled surfaces were coated, a little like powder coating paint finishes, the sediment then remained in suspension in the fluid. Well, I don't know this to be the case, just a theory. The hoses incidentally were as clean as when new but the initial drain down produced a new looking coolant mix yet the subsequent clean with the flush washed out like filthy ditch water and took three more flushes to run clear. Over the years I have flushed many a system using the old hose method and didn't achieve much in the way of discolouration to the water. Since using Prestone for the last few years on our cars as they aged I have been very pleased with the results of how they cleaned the system...... however I was not expecting a 10,000 mile mog to produce anything much... Oh how wrong I was!

Sewin
Interesting. My 2011 Duratec has now done 56.5k and has never had any signs of sludge or deposit.
I first changed the OAT orange coolant in 2021, after 10 years use!
It all came out clean and I changed the rad at the same time.
As I wanted to stick to the Ford specification, I replaced the coolant with the new yellow POAT.
My flushing was certainly not as thorough as yours and I have since noticed that the coolant is looking more orangey than yellow!
However, here we are about another 16k miles and 4 years on, and still no sludge nor deposits. So it's a bit of a mystery as to why yours was sludgy. First thought that comes to mind is whether you have owned it from new or whether it is possible someone topped it up with an incorrect product at some time in its life?
It’ll probably remain a mystery!
Looking back, think I should have stuck with OAT, albeit a different brand as Ford had stopped supplying it in about 2018 I believe..

Edit: noticed from your post that your Mog is bedded down over winter, whereas I use mine all year round; wonder if that has any effect?

My Roadster went white sludgy in the header this year and after a couple of changes. I suppose at 20 years old things like this will happen. Only a patchy deposit on the plastic though, like condensation. The coolant looks the same.

Deejay,

Think it might look orangey because the new coolant is shifting the deposits in the engine and they were red coloured from the OAT coolant. Mine didn't show a lot of sediment but just small deposit areas in two places in the header tank. As I said when I initially drained the old coolant out it looked perfect, right colour, perfectly clear. It was only through experience that I knew I must have some level of yuk within the cooling system to allow the deposits to reach the header tank. What surprised me was just how much muck the flush shifted when to all intense and purpose it would to most look like it was a clean system.


Dave.

Is your roadster running with the green antifreeze? It has a lot of silicates in it and its these that might be causing your deposits. Another thought is are you mixing your antifreeze with tap water. If you are in a hard waster area it might be calcium deposits.

The original Ford A/F was a sort of dark lilac blue. The latest colour is more orange tint if I recall that right, but stays almost clear in the header.
I always use water from the dehumidifier.