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shaggydog



Member Since: 12 Aug 2012
Location: Kent
Posts: 3346

United Kingdom 1991 Defender 110 200 Tdi USW Arles Blue
Holts Rad Flush- Any experiance?
Hi Guys,

As the summer is now well and truly dead down here (heating is on, stew in the oven, girlfriend in fuzzy jumpers) I thought it good to sort out doing a coolant flush on my 200Tdi as a last chance thing before resigning myself to doing the head gasket.

So bought Holts 2 part rad flush as it was recommended to me via here.

However, the instructions are a bit unclear and sound like it will do more harm then good.

Part 1;
1. Thoroughly drain radiator and engine block, flush with cold water.
2. Refill with water and add part 1 to system.
3. cover filler pipe with damp cloth.nb, for systems with an overflow tank replace cap on radiator and cover overflow tank opening with the cloth. Product should not be added to expansion tanks but directly to main system.
4. Run engine at fast idle for 30mins- do not allow to boil?
5. Switch off engine and drain radiator and engine block and flush thoroughly?
6. Refill with hot water.
7. Run engine for five minutes on tickover before using part 2.

Part 2;
1.Refill system with cold water and pour contents in radiator
2. Cover filler pipe with a damp cloth
3.Run engine at fast idle for 15mins- do not allow to boil
4. Switch off and drain radiator and engine block
5. Flush system thoroughly, by removing thermostat and directing clean water into thermostat housing, so that it circulates in a reverse direction through the engine block then up the radiator and up out the top hose.
6. Continue until the water runs clear


Now, seems simple enough but what worries me is the draining hot coolant out and then putting cold flushing water back in?

Surely that's a recipe for thermal shock or warping your head or cracking it?


Also, how can you make sure your coolant doesn't boil?

And when it says put a damp cloth over the filler, does it mean don't allow the system to pressurise? Wont that do damage?

Any pointers welcome- I may just be over thinking it Thumbs Up Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter Very Happy
Post #452733 6th Sep 2015 12:04pm
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shaggydog



Member Since: 12 Aug 2012
Location: Kent
Posts: 3346

United Kingdom 1991 Defender 110 200 Tdi USW Arles Blue
Anyone? Rolling Eyes

It doesn't sit right with me to be flushing a hot engine with cold water - or am I being over cautious? Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter Very Happy
Post #453024 7th Sep 2015 1:26pm
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rfkdemon



Member Since: 02 Apr 2015
Location: Staffordshire
Posts: 64

United Kingdom 2000 Defender 90 Td5 Silver LE Zambezi Silver
I have used this on my other half's Seat Leon 1.9 TDI that I did the head gasket on for the reason that she hadn't put coolant in for some time which meant everything was furred up with corrosion.

I too was a bit worried about the thermal shock that running cold water through a 90 degree engine would cause but from what I can tell so far there haven't been any symptoms from this and she has done a fair couple hundred miles since. I am not entirely sure how it works but I assume it converts the corrosion rather than removing it fully as you would expect damaged rubber pipes/alloy if it was caustic based etc.

However, I had just done the head gasket so if you think the trueness of your head or integrity of the head gasket is already questionable then it may well finish it off and stretch/warp components further.

The other argument is that if you already suspect head gasket failure then you probably don't have much to loose and in fairness changing a HG on a 200tdi is a straight forward job so t isn't the end of the world if it does need doing.

Matt
Post #453240 8th Sep 2015 7:40am
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Happyoldgit



Member Since: 14 Sep 2007
Location: Norfolk
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United Kingdom 2015 Defender 110 Puma 2.2 USW Corris Grey
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Owned numerous Land Rover vehicles of all shapes and sizes over the decades.
Current Defender: A non tarts hand-bagged Puma 110 XS USW.

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Last edited by Happyoldgit on 8th Sep 2015 11:54am. Edited 1 time in total
Post #453304 8th Sep 2015 10:45am
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rfkdemon



Member Since: 02 Apr 2015
Location: Staffordshire
Posts: 64

United Kingdom 2000 Defender 90 Td5 Silver LE Zambezi Silver
It isn't a magic head gasket repair, it simply flushes any deposits that have built up in the coolant system over the years. The hope being that the cooling system will work more efficiently. Hence why I used it myself after doing the head gasket to make sure the coolant system was all in order Smile

I agree, those miracle HG repair fluids are a waste of money, unless you simply need to get home. They end up causing more harm than good unfortunately.

Matt
Post #453318 8th Sep 2015 11:41am
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shaggydog



Member Since: 12 Aug 2012
Location: Kent
Posts: 3346

United Kingdom 1991 Defender 110 200 Tdi USW Arles Blue
The reasoning behind it being is that every pic I have seen of a 200tdi head fresh off the block is that the coolant gallery between the cylinders is blocked.

If it is blocked then there could be a lack of coolant in the head which is causing it to create a hot spot and when the engine is turned off it is boiling and then venting through the cap.

I haven't flushed the engine or coolant for 3 years at least so its probably due one anyway (and as I found out isn't part of a service coolant change Evil or Very Mad)

Sound reasoning or ridiculous lip wiggling? Running Restoration Thread http://www.defender2.net/forum/post323197.html#323197

Self confessed mileage hunter Very Happy
Post #453319 8th Sep 2015 11:45am
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grumpy old git



Member Since: 16 Nov 2013
Location: United Kingdom
Posts: 153

United Kingdom 
I did my old Td5 disco and SWMBOs 300tdi with it, to be honest the drained water wasn't that hot and I left it to cool before filling and flushing. Each time was a leisurely process carried out over the course of the day around doing other things. That was some times ago and we've had no issues Thumbs Up
Post #453460 8th Sep 2015 9:03pm
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