Coolant system flush

[AceOfHearts]

I am currently re-commissioning a TVR 280i (Ford Cologne V6) and need to sort out the cooling system.

The heater matrix was leaking, and a previous owner has used rad-weld to stop it. I have now pulled the old matrix and sent the radiator and a new heater matrix off to be cleaned out and pressure tested.

The whole coolant system is filled with brown rusty water and a certain amount of sludge (i guess from the radweld). Should I use a radiator flush once its back together or just pull the thermostat and rinse the block out as best i can with clean water. I think the car has suffered from overheating issues in the past as the previous owner has also fitted two electric fans operated by a switch in the cabin.

[Auntieroll]

If you really want to do the job properly you should remove all the core plugs and clean out the waterways revealed, the problem is, there is a core plug located at the rear of the block, inside the bellhousing, which means removing the gearbox and clutch to access it.(amazing how much crud can gather in the bottom of the cooling jackets.)
Probably more realistic to back flush the block for a while, then try it with the new radiator etc; and see if it still overheats.
Good luck!

[AceOfHearts]

Haha don't tell me that, I only had the gearbox and clutch out last week!

I will see how well I can get it with a good flush. Thankfully there didnt seem to be any 'solid' rust out of the radiator but it just seems like the coolant has been sitting there for years. Fingers crossed it will clean out ok then.

[Auntieroll]

I would at the very minimum remove the core plugs on the block, you will probably be horrified just how blocked the waterways will be ,believe me, I've been there many years ago with Cologne V6's.

[GavinPearson]

You don't want to touch the core plugs.

What you need to do is use a cleaner that is designed to remove corrosion in cooling systems. The Ford product used on their diesels in the USA is called VC-9.
http://www.amazon.com/Genuine-Ford-VC-9-Cooling-Cl...

And here is somebody with a viewpoint:
http://www.thedieselstop.com/forums/f23/im-believe...

And here is a short video aimed at dealer technicians that shows them what to look for when performing flush procedures fixing a number of cooling system problems on trucks. Included are the comments on how to see if you have removed the VC-9 - absolutely critical to ensure the system works trouble free.
mms://multimedia.ford.com/seopts/WSM/Diesel_Coolant_Health_Final_Final.wmv

My Cologne 2.9 was treated with VC-9 and has been completely trouble free in ambient temperatures of up to 105F.