Mr.Rubins schreef:

No, There is no flow

If there is no flow in your cooling system you have a blockage somewhere. Did you try to (reverse) flush your engine using a waterhose?

piping for heater: Hot water from right side of the head leaves via the black pipe to the bac wher it is connected to a hose 15 mm diameter that runs to the heater core. The other pipe from the heater core runs to the iron neck in the left side under the battery. That neck connects the lower radiator pipe (big) to the waterpump. The upper hose runs from the top of waterpump.
LAst there is a pipe running from back of waterpump to the inletmanifold bottom.

Just to be sure: when the head was off for rebuild, has it been cleaned internally? And how clean was the water jacket inside the engine block?

The cylinder heads on the DS can suffer from ‘rot’ caused by acids in old coolant, which causes small chunks of material to come adrift. This, maybe combined with crystallized chunks of old coolant and/or rust sediments that can be swirled up from the cilinder block when the engine is put back to use without further cleaning, can cause coolant passages in the head to clog up. Ask me how I know…

The heater core is indeed fed with water from the cilinder head, so no flow between the pipe along the head and the heater core might indicate blocked passages inside the head.

I’d mostly consider such a scenario a long way towards ‘worst case’, but by now I’d have expected this problem to be cured in any normal case so I might just as well put it out there, I guess…

Derk

benieuwd wat de uiteindelijke oplossing is.

Yes, there will be all revised finnaly. We also wait where problem.

Today mechanic changed one pipe. switch on car. 1,5 h working engine and all ok. But did not driwe because we have snow thease days.
when snow end he will drive car.

engine was cleaned. but maybe it need to be done more careful?
How You suggest to clean it? Maybe He will do it again.
No variants. need to fix this DS.
Soon is summer…

So now it kept cool for an hour and a half, mostly just sitting and idling? Because that wouldn’t seem to be bad at all…

Derk

Hi, mechanic opened radiator.
It seems that cleaning with chemicals did not help.
It seems that radiator is blocked.

A specialist can put in a new core. Much cheaper than a new/revised one.

However, it may still be wise to find out where that crud came from and if there’s any risk of more crud coming adrift. Just to be sure a new core won’t get clogged up as much as this one.

Derk

So there are two causes of the overheating?
- “Today mechanic changed one pipe. switch on car. 1,5 h working engine and all ok”
- “Hi, mechanic opened radiator.It seems that radiator is blocked”