Ok the thermostat is in the tube and it works great now
At first the temp would not rise quick or high enough so I also blocked the radiator airflow with a piece of canvas (on the inside of the grille)
Now it runs great and it even gets warm enough for the radiator fan to kick in after an hour drive during 1-2Celsius (maybe I should reduce the size of the canvas a little)
I followed all advise given and it worked great (Thx Leedsman for the idea)
Some pictures:

 

Good 4 you !, glad you have it sorted.

 

If you want to get an idea of the simple cooling effect of the air blast over the engine body (not only the rad.) just stick your head out of the window at 30mph. in winter of below zero and see how long you can keep it there! This is what is blasting over your engine when the 'stat is closed for warmup.

As I've posted before, you can go through the whole year, summer included, with the fancy grill part of the front completely blocked for the diesel engine without needing to remove it. The airflow through the lower cowling part and side vents is quite enough, but the removeable blockage to the lower cowling does need to be removed in a hot summer.
Note: The engine produces the LEAST heat with motorway driving, the MOST heat in heavy stop-start traffic. So if you know you're going to be stuck in city traffic a lot in summer, remove the cowling blockage.

Your thanx is appreciated, I like to know someone is benefitting from at least some of my ideas -- which if I'm honest are mainly from the past. The main point is to get on with it it and do it. Apart from anything else, it's so.... nice to be able to turn on the heater in winter and keep your feet warm.

BTW, how much money do you think you've saved with my 'stat mod?

Leedsman.
n.b. See my postings, "Winterizing your GV".

 

Leedsman, I am an enthusiastic motorcycle driver since 1977 so I know how cold wind feels at low and high speeds

Today I made a 450km highway trip with an outside temperature of 0-3 degrees Celsius. The first half of the trip the airflow to my radiotor was blocked according to the Green lines in the picture.
I found that the temperature got too high, even on the highway because the fan of the forced cooling kicked in every 10 minutes to lower the temperature back to halfway the meter. Anyway that was living proof the new thermostat worked as designed!

When I arrived at my destination I cut some off the canvas at the sides and at the bottom according to the Blue lines and drove back several hundred kilometres.
Now the temperature was behaving perfectly! The needle climbed a little above halfway but did not rise to the height where the fan needs to kick in.
I say I keep it there till nxt summer

I think I saved like €200 to €300,- using the alternative thermostat trick. Money I don't even have at this moment as starting small business owner.. I already need to use my last resources to pay for the new crankcase seal I need..

 

Yes, I can see what you've done -- maybe the 2.5 diesel has a smaller rad. than the 2.8?
And maybe your air blockage was right up against the rad. itself, rather than the front grill?
Anyhow, your feet will be warm now, and you'll be using less fuel plus a heavier wallet.

Leedsman.

 

When I did my in-line-stat many moons ago. I always needed the reassurance of a reverse gear or 'get out of jail card', this is the 22mm connector I bought as a just~in~case

 

I am now in my 2nd winter using the Renault 5 thermostat in the top hose..... works absolutely great :-)


MG

 

- thank's for that, good for you, you saved hundreds of £'s and it, the mod, works just as well
- that's what happens when a good healthy active forum shares good advice and qualifying feedback !
- when I first came here as a poster there were only 3 or 4 CRD posters, now its much the bulk of activity on this sub forum
- and over that very short few years there has amassed a huge repository of information on Euro GV's and previously unheard of diesels

 

That Renault 5 thermostat without cutting down I take it.

 

That Renault thermostat is 43.5mm diameter and is not easy to push in the tube. The tube is like 42mm I believe (?)
But it is manageable, I used a little bit of grease and a flat screwdriver to "flip" the stat in the tube and pushed it down with a large pipe with 40mm diameter.