Hi,
Bavaria 38 2004 - Volvo D2-40 engine.
Just replaced my coolant hose as it was leaking. After the replacement I am trying to fill it back up with coolant. I understand it is self bleeding to get rid of the trapped air?
I filled up coolant and turn the engine on at idle a few minutes and topped it up a bit but I dont think I have put as much coolant in as it drained.
Any advise on exact procedure to bleed the air? Should I keep the coolant tank cap on or off when the engine on? It feels like it should be left open to allow the coolant get inside the air to stop suction but not sure.
How do I make sure I have managed to put enough coolant? I am worried that there is not enough coolant due to air trapped inside and when I get going engine will overheat and end up damaging.
The regular cap of the expansion tank has an air valve in it to prevent overpressure and vacuum... just keep an eye on the level of the expansion tank, so far you have done it right. There may still be some air in, but usually this will get out during running.
it should self bleed, but you will need to run it up to working temperature to fully open the thermostat and let coolant circulate fully and get any residual air bubbles through the system. just remember to cover the cap with a rag and slowly release any pressure when you take it off, so you don't get a hand/face full of boiling hot water.
we usually run hgv engines up to near temp with the cap off, then top up and take for a test run, let it cool and top up again.