V40 More Coolant Problems

[gazzaon]

Hi folks.

Background...

I have a 64 reg V40 D2 1.6 with around 110k miles.

For ages (over a year) I have had cooling system issues.

All started when I randomly got a low coolant warning with no other symptoms. Unsuspectingly opened the header tank (level was a smidge below minimum) when the engine was stone cold, and didn't expect it to surge the tank, causing a big rush of coolant which overflowed then settled back down again.

I topped it back up and sealed it up and never really thought any more about it.

Immediately after filling it though, I have been going through various stages of faultiness from cold heater, overheating for brief periods then cooling right back down to centre line again within 4-5 seconds, sometimes full overheating showing on dash (up to max temp) for longer periods, and low coolant messages, still with the same level problem, undo the cap and the water comes back up.

Never any engine management lights, never any water in oil or evidence of gases in the header tank although I have not properly tested for that yet.

I have bled it and bled it and bled it manually via the thermostat housing screw, I can't find any other bleed points, but itis acting like there is a big air pocket in the system, but nothing seems to fix it.

My latest attempt was to purchase a Laser vacuum filler/purge kit and tried to use it this week. That has only made the car worse, overheats badly now, almost constantly having to stop and let it cool down but then it can go for 15-20 mins with no issue.

However.

Expecting to have around 10L of coolant draining I got a large bucket and disconnected the lower rad hose. Only around 3 litres came out, despite trying various things to coax more water out. That seems extremely low, but would obviously expect some components to retain water and not just come out by gravity. (heater matrix, maybe egr cooler amongst other things)

But. The vacuum pump pulled a good vacuum, but never yet pulled out any water. The system refilled by vacuum by slightly more than I removed, but I am going to have to re-do this.

Anyone any bright ideas on how to completely drain/purge this system, or am I on a loser. Expert opinions would be helpful.

I am basically trying to eliminate the "air in the system" theory before deciding to bin the car with what sounds like it may be the dreaded cracked block issue.

Been a great car but recently it has been steadily ticking all the V40 fault boxes (coil springs, interior mirror, turbo hose splitting, coolant problems etc etc)

Cheers folks. Sorry for the ramble.