Hello Ducato-friends! I will write in english, because my German is not good enough for these technical things. Feel free to answer in German if you like, I will understand
I have a technical issue that breaks my brain. I have a lot of experience with engines, I know how to repair things. I hope you guys have some tips for finding my problem.
Car is a J5 2.5 TD, Burstner A630, papers say 1991 so a late 280 model? odo 185.000 km. I bought it 'cheap' because of the overheating issue, because... I can fix things!
The seller told me it overheated after 2 hrs of driving, and after cooling down and putting water in, it worked again.
I drove 150 km with no problems. Then another 150 and I had the same overheating. After 30 mins waiting and fresh water, I drove home another 20km.
At home I did the following:
NEW waterpump, thermostat, belts
Flushed the cooling system with a chemical fluid from the car shop. (used the drain bolt on engine block)
Took the rubber hoses off to clean. Found rust in the hoses on back of engine to the round reservoir / oil heat exchanger
Flushed the radiator, it looked almost new so I think the previous owner had it changed.
This is the point where I thought I had flushed so much dirty water from the system, this must have been the problem.
We went camping 150 km, and 150 km back, no problems. Temp was steady just below 90 on the clock.
Went camping this weekend, 200 km with headwind and all. Steady 90 kmh, temp just below 90. Now I was sure the problem was gone.
On the way back after 100 km it started overheating again... within maybe 30 sec to a minute it would go steady up to 130 before we had a safe place to stop.
Water system was under full pressure, if I turned the cap the water sprayed around. We waited maybe 15 or 20 mins, and put extra water in that had sprayed. (we were on the highway with 2 kids in the rain, better to go!)
Now we drove another 20 kms with the temperature back at just below 90! And it started again...
At this point we had the ANWB take us home, because it was getting out of hand with the kids
But... WHAT is the problem? How can it overheat ramdomly, and ride good again, and overheat again? And probably If I ride it tomorrow nothing will happen...
No smoke, good power, good sound.
Clean cooling system, new pump, thermostat...
To me it feels like a sudden blocking of the cooling system behind the thermostat, but how? If rusty flakes jams the thermostat it stays open, not closed.
If rust blocks a pipe in the radiator, it will not overheat this fast, and it will not magically heal itself like this...?
please let me know any ramdom thought you have, it might take me in the right direction