So my coolant expansion tank developed a leak. So I replaced it but forgot to bring the cap from the old tank. Anyway I thought that I would try filling it up and running it warm anyways.
So I turned on the internal heater and and started her up. Temperature started rising and all seemed fine. As the water was getting hotter the I think that it expanded some with a little overflowing as a result, nothing unexpected.
So getting ready I turned of the inner heater, and after some minute or so water just started overflowing a lot. I turned of the engine to not introduce any more heat.
After a few minutes of cooling down I filled up the tank again. It swallowed about 1.5-2l water, so quite much. Expansion tank takes 1.5l.
Now I'm just wondering if this is a expected behaviour since I din't have a cap. Or does it suggest that I have an air pocket in the system, and need to find some way too bleed it properly?
(It's a Range Rover P38 V8 4.6l)