Anyone know why I have a cream coloured sludge in my water reservoir?

It looks like an oily substance but clean? Did you touch it?

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2006 LTD Bright Silver loaded with all the needed mods, CCV intact.
Proudly supporting CRD vendors, and their development of quality parts and accessories.
Equipped with HDS thermostat, plenty of heat, faster warm-ups, increased fuel mileage.

Yes its a thick cream like substance, dont think its oil its to light.

I think I need to flush the cooling system is this quite easy to do?

Have you always used a HOAT coolant?

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2005 Limited CRD

What is a Hoat Coolant?

It's the only coolant safe for these engines. I wouldn't run it for even a second. I'd drain, and flush the heck out of it, and refill with HOAT 50%. The alternative could cost you $5k, or more. If you wipe the water pump and jump a tooth on the timing belt, it may destroy the engine, and then there's overheating the head, and probably other very bad things that I'm not thinking of.

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

Whats the best way to drain and flush the colling system?

Remove the fill reservoir at the overflow tank and twist and pull up on the air bleed valve on the top passenger side of the radiator. [Do all of this with the engine cold]

There is a small petcock on the bottom passenger side of the radiator that can be opened with an adjustable crescent (socket won't work, they designed it weird) wrench.

That's how you drain it, flushing, dunno.

I don't like radiator flushing, at all.

I would recommend 80/20 HOAT. Zerex G05 or Zerex Asian Formula is what you want to buy. (The Asian formula is actually a pre-mix 50/50 HOAT coolant).

HOAT = Hybrid Organic Acid Technology (If you were wondering, only type acceptable to our engines)

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Silver 2006 KJ 2.8L CRD Limited:
GDE ECO Tune / Fumoto Valve / E-Tecno GX3123 7v Glow Plugs / 2nd Gen Fuel Head / Mishimoto RED Hoses / Rockers/Lifters @ 114k / Hayden FC + 11 Blade Nylon / Sears P1 Battery / Transgo 45RFE-HD2 Reprogramming Kit / Timken Front Bearings

The sludge has been caused by the mixing of 2 different types of coolant (so I've been told) which was probably done by the garage who serviced it last year!

Hoat coolant is no longer available in the UK is there an alternative?

You cant get Zerex G-05? You need something that is approved for Mercedes Benz and Chrysler.

http://www.amazon.com/Zerex-ZXGO51-G-05 ... B0033QNZZ0

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2006 LTD Bright Silver loaded with all the needed mods, CCV intact.
Proudly supporting CRD vendors, and their development of quality parts and accessories.
Equipped with HDS thermostat, plenty of heat, faster warm-ups, increased fuel mileage.

Cant get Zerox in the UK either what about this one?

http://www.halfords.com/webapp/wcs/stor ... 55224#tab1

Its says in my OEM Manual Not to use Propylene Glycol Coolant!

Or will any 5 years Ethylene Glycol coolant be OK?

I am not sure of the difference of OAT, but do you have a Jeep dealer in the UK where you can get the right stuff?

For the flush, I would pull off the top rad hose, and one of the smaller hoses on the tstat, and push a lot of water through the recovery tank filler.

When my wife’s CRD lost coolant away from home, I told her to add water only and I would deal with the correct fluid later.

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2006 LTD Bright Silver loaded with all the needed mods, CCV intact.
Proudly supporting CRD vendors, and their development of quality parts and accessories.
Equipped with HDS thermostat, plenty of heat, faster warm-ups, increased fuel mileage.

This sound like a good replacement in the UK for the unavailable HOAT

http://www.amazon.co.uk/Comma-XHD5L-Xst ... uctDetails

Approved by Mercedes and Chrysler and contains Ethlene Glycol.

What do you think?

Also I think I have the flush sorted:-

1 Drain old coolant from bottom of Rad
2 fill with water and run for 10 mins with heater full on
3 drain again (When cold)
4 fill with water again add flushing fluid run for 10 min with heater on full
5 drain again when cold
6 fill with water and run for 10 mins with heater full on
7 drain again when cool
8 fill with 50% G05 Coolant and 50% deionised water to full level on reservoir
9 run again for 10 mins
10 top up if neccesary

Comments please?

Yep, MS9769, that's the stuff. The Comma website will provide a distributor http://www.commaoil.com/productsguide/view/6/354/XHD5L

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Have you tried contacting Valvoline in the UK to track down G-05. For a time it was hard to get here (not available in the retail stores) too and you could not import it through Amazon through their protection agreement.
This was because it wasn't sold retail for a time here but Valvoline would help you could find an engine specialist stockist who would sell to the public. Valvoline here were really helpful in sourcing a stockist who was a private engineer just a couple of corners from home.
Suggest avoiding de-ionised water and use distilled water for the final two changes.
Also, it depends how thickly it's gelled. The biggest issue will be in your heater lines/core. I'd be inclined to separate the 16mm id lines there and gravity feed a substantive quantity of water though these. Catch it am leave it settle so that you can check for more gel.
Then allow distilled water to run through these. As it always flows, the water and coolant will mix.
In the UK the tap water quality is probably good so you could get away with the first clearing fills and drains with tap water but be sure to drain and fill at least 3 times after with distilled water.
HOAT here was a different colour and I found I had to change the fluid I had to fill and release 4 times to get a reading of Zero on a refractometer. It was then washed/changed out with distilled water 3 times and then the final times gave zero so the concentration could be adjusted. Same process as you outline - just done more times.
I only ever gravity feed through a radiator unless I'm pressure testing and then I use a different process altogether or there are other issues being investigated.

For some reason Distilled water in the UK is very expensive.

I have been told De-ionised water is just as good and not so expensive.

It is expensive here also. De-ionised water is made by adding chemicals that cause the mineral content to flocculate and precipitate out and then pH is adjusted chemically to neutral with buffers. As I have a science background I'm afraid I can only rate it as a second rate product.

To give you an idea - I paid almost as much for 20 l of distilled water of which I used all in the coolant change over (and I might add had to chase it through the manufacturers to source a retailer as well) as I did for the Xerex. I was trying hard to avoid the issues you are having now in case the coolants were incompatible.
The HOAT that was in the Jeep was red/orange and the Xerex G-05 sold here is green hence, my care with cleaning.
Demineralised or de-ionised water can be had anywhere here.
I will readily admit it is not a cheap job even doing it all yourself in some parts of the world.
That's why I suggested the first couple of wash-outs in the method you outlined be tap water - to save a few coins.
I worked out how many flushes were needed to get it to a virtually undetectable level with the refractometer so I had enough to clean the system right out with the distilled water. By using the refractometer I had an accurate idea of how many wash-outs were needed to change over to a quite "clean" cooling system. Three with water got to an undetectable level - an I did four (4) with distilled.

The final 3 were to remove/dilute the tap water and the last one was to refill with Xerex and distilled.
I couldn't imagine doing the whole job with just distilled water given the cost of it here either.
I weighed/measured the volumes taken out and put in so I knew I'd topped off completely at the end of the job with no air pockets. I was sure there were no air pockets (which seem to trouble some folk when they do this) as I tracked it carefully.

It was tedious and expensive.

Oh well De-Ionised has got to be better than Tap Water!

UUUmmmh! I've added details to my post immediately before yours of 6.04 pm. Respectfully request you have another read and reconsider.
I'd also suggest in this case trying to get it out by using water rather than radiator flushing fluid. Try to do it by washing out first. (Radiator lavage )