I do not make the statements about the DR400 cooling system without some knowledge of the basics, this is the second DR400 I have owned and both show much the same cooling characteristics.
Apart from checking the baffles the calibration of the CHT, oil temperature probe and EGT have all been checked.
The fact is for performance reasons the DR400 is close cowled and the cooling restricted to give just enough cooling at cruise speed and power. All aircraft design is a compromise and Robin decided that cruise performance was paramount , OK I have to step climb on a hot day but I will still lift more payload out of a shorter runway and cruise 15 kts faster than a PA28 with the same engine.
I had to add a couple STC‘ed extras to cope with the heat. I went through pain and tears over trying to cool my left engine side. CHTs of over 400dF were the norm.
I know for a fact that although airflow over the cylinder fins only accounts for ca 10% of cooling, it can make a big difference. Correctly installed baffles are an important factor in any airplane, and more often than not old or worn baffles are the reason for overheating. The pressure differential between the upper and the lower part of the engine is not great anyway, so especially with the small intakes in the front, so any small hole in the baffling can effectively destroy the airflow and the air then circles over the upper engine side without being able to flow through the fins to the downside part.
Another item may be the fuel flow – check the fuel system if there is enough fuel being fed to the cylinders to cool them internally via incomplete combustion.
Engine defects aside the DR400 engine temperature issues at high OAT fall into two category’s CHT caused by high power at low airspeed or high oil temperature during the climb at best ROC speed for long duration.
None of these problems can’t be solved by good engine management practice .
I fitted a B&C full flow oil filter to my DR400 and because of the extra oil capacity it slows the oil temperature rise in the climb a little, I have been considering fitting a large aluminium heat sink around the oil filter, these are available from the Motor racing industry to see if this improves the situation during the summer.
When the temperatures were in the high 30s / low 40s last summer, I took the aeroclub DR400/120 for a 2 hour local to do touch and goes at 5 airfields. Just before leaving, one of the instructors ran over and said to keep an eye on the temperatures, especially in the climb. The engine had been having cooling problems and using a lot of oil recently. The club thought the reason for this was someone running the engine at redline in high ambient air temperatures. At reduced power and shallower climb it was a struggle to get over the Haut Folin (2,000ft in 9nm). In this case, the warning/advice was done informally by a quick word from an instructor. Shortly afterwards the DR400 went for a 100h service where it transpired the engine had to be replaced completely (I’ll ask what the problem was).
I have flown the Regent and the Remorqueur. They are very nice airplanes with an excellent view, and wonderful climb rates, especially the latter. I have friends who fly them regularly, in clubs, on tour, in towing, sightseeing, you name it. Never has anyone complained about heat issues and I haven’t observed any, nor can I find anything on the internet when I google the topic. Which I think I would, if this was a persistent problem.
Peter
If you buy a basic Robin the instrument and radio fit is just about good enough to Fly around the circuit at Dijon. So the buyer will spec the aircraft for their own operational requirements and it is almost unthinkable that if buying a glider tug you would not make sure a CHT indicator was fitted, an EGT gauge is almost useless for the glider towing task as the aircraft is inevitably run full rich most of the time.
Those of us who use the aircraft for touring need both as EGT is critical for cruise engine setting and CHT is a limitation if you are trying to hit the best angle of climb 70 kts rather than best rate at 92kts
It says a lot for the Robin DR400 airframe that it can perform such diverse tasks very well but it does require good piloting technique to keep the engine within the limits as the OAT climbs.
Without a CHT gauge, I can see all sorts of “operating limitations” going around, because everybody is working blind.
Yes it climbs very well, but the oil temp and CHT (we have a single gauge) climb just as fast 
Let’s take aside for a minute whether the aero club is right or wrong.
Let’s also take aside the unlikely effect of terminal damage by 1or 10 ovetheated climbs.
However I’d like to focus on why ‘this is utter nonsense’ and similar comments are necessary. Owners of several years experience, and other knowledgeable on type Pilots have added comments that a closely cowled ‘fantastic in group’ aircraft can suffer quite significantly, if not handled with care in high ambient temperatures.
Are you saying it’s not possible to run the CHT or OIL into the red? That the idea of doing so and being an issue is nonsense? That there is no chance to ‘Certify’ such an appalling design?
Try any high performance piston aircraft and find similar issues.
Jujupilote, the 1st time you get to try a DR400/180 with newish engine and only 2 people you will have a smile on yoir face. She will climb like a homesick angel. ;-)
Thanks for the answer A and C. I’ m not alone to have a hard time make robins climb 
