Changing coolant

[koenr]

My Dexta ran a little hot this summer, doing work in the hay, and since I topped up the water a few times, I wasn't sure of how frost resistant it was. The coolant could do with a replace anyway - it was in there for a long time and looked brownish.
To my surprise, nothing came out of the back tap. I checked with a little cable if the tap was open, and it was. The cable was covered with greasy, sticky, smudge. No Idea how that got there: leaking head gasket? No white smoke, nothing in the oil. Mixing different types of coolant? It's possible. Any other possibilities?
So I flushed the engine with a mild vinegar solution without result, then let it soak overnight with diluted dishwasher powder, which did something. Finally I let it rinse for an hour with a hose pipe connected to the rear tap. In the beginning, the water just dripped out of the disconnected lower radiator pipe. Loads of rust came out, and after a while the water was clear and running. After disconnecting the hose pipe, it took at least 45 minutes before the tap at the back stopped running. Going to close everything, fill up with new coolant and hope for the best.

[Bensdexta]

Good work but why not finish the job by running the engine for a few minutes with some radiator flush? Then drain and refill with coolant, when the engine has cooled?

[koenr]

I needed the machine up and running and no radiator flush around .
It took 7,5 liters of coolant to fill it up, so I think it should be reasonably clean now.

[pjjms]

It will be interesting to see how much cooler it runs. Clearly there is a lot of rust scale and other sludge built up around the bottom of the liners limiting the ability of the water to cool them.

I took the tap out of mine (bigger hole) and by getting in with a wire was able to dislodge a lot more than just by flushing.

I have another which I took the liners out of and they were 3/4 buried in clay. I assume it had been filled from the creek many times over the years.