Hi, Can anyone shed any light on why my 2005 2.8 CRD is running hot? From cold, gauge gets to just below half way, then starts to rise, gets to three quarters, then drops down to just above halfway. continues to rise and fall between half and three quarters. It has always run steadily just below halfway, but has recently become erratic. I have had to top up water level a couple of times and had hi temp light come on. Could it be a thermostat problem? Thanks in advance...

 

I had pretty much those symptoms . With mine I found there was no flow and that the radiator was blocked solid .
Initially I tried all sorts of flushing, then I swapped it out for a new one from Eurocarparts £170......the cheaper one did not fit.
Just disconnect the bottom hose to see if anything comes out.
Then I went down the route of a new thermostat ( it is a complete housing unit ) about £65................£125 to fit.
There is a much quicker and cheaper way around replacing the stat housing , by inserting a new stat in the rad hose.... plenty of posts and pics on here.
Since then ............. all running great , still not the greatest warmth over winter but much better and the needle never moves from just below halfway, even on a five hour non stop run.

 

It does sound like a blockage or something in there causing water flow problems, depending on mileage it might be worth looking into the water pump too, has that ever been replaced? (It's generally a good idea when you get the timing belt done around 100,000 to get water pump done too).

I did a video on changing the radiator and replacing/flushing coolant through it that might help you out

 

I wish I had seen your vid before I swapped mine out !!!!
I did it the hard way without removing the headlamp or bumper..........
Lots of jiggling but eventually I won.

To be honest I had all my problems ( should I say noticed all my problems - as I was only doing short trips ) about 4 months after the cambelt /tensioner and water pump were changed , and I had the stat done within 2 months after that.

It does seem to be something that is becoming more common place to read about , the more I delve into 2.8 CRD 2005

Again good luck

 

Blocked aluminum radiators are the result of NOT CHANGING THE HOAT ANTIFREEZE* on time, usually 5 years. This happened to me because of neglect of the previous owner. I paid someone else to replace mine and there wasn't much change out of £300:00
The thermostat will jam open under these blocked radiator conditions as it is intended to in design, and believe you me, it's an absolute pig to get at and replace. So after replacing the rad., you go from excessive see-sawing temperatures to running cold and uneconomical, as usual with a diesel. So....see my mod. involving placing a regular thermostat into the top hose, a pretty easy job, and leaving the wide-open original in place. Mine's worked ok for a couple of years now.
Don't waste your time attempting to flush the rad. It won't because it's blocked by aluminum oxide. They aren't at all like the old copper and brass ones. If you observe the rad. when it's out, you'll see a slight curve on it. This is the dead giveaway it's blocked due to corrosion -- told to me by the man at Northern Radiators in Leeds here.
Leedsman.
*HOAT" = Hybrid Organic Antifreeze Technology. Always use this kind with aluminum rads.