Coolant issue Relay 2.2

[Willpo99]

Wonder if anyone can shed some light on a coolant issue I’m having with my relay.
It drives fine, doesn’t overheat according to the temp gauge but the coolant level is all over the place.
Bit of history.. engine was recently rebuilt due to suspected head gasket but in fact it turned out to be egr cooler. Took forever to get running properly but eventually (apparently) sorted.
I thought initially it was air in system causing the coolant level to go up and down but would have thought that would have worked out by now(?)
System is occasionally over pressurising and blowing out through the cap, level drops to below min, I fill up to just under max all seems fine then out of the blue it drops again. Top up again then find after a drive that the level is way above the max.
Drove 100 miles las week in the hot weather with no issues, did same journey this week, coolant level dropped below min and signs that it blew out from the cap. No bubbles in the expansion tank when ticking over, no smoke from exhaust but it does look like the top radiator hose is not getting hot.
Any suggestions would be helpful.

[Peter.N.]

Sadly sounds as though the gasket is still leaking or there is a crack in the head. Normally if there is a leak coolant will be expelled under hard acceleration or load which can cause loss of coolant or not depending on how hard the car was driven on that particular journey.

I has a CX Dtr estate many years ago which I drove quite a few miles gently with no problem, when I had got used to it I pushed it hard up a steep hill, all the warning lights came on and there was water all over the place, refilled drove gently - no problem. Turned out mine had a porous block and I had to change the gasket every 15k miles which amounted to 10 or more replacements while I had the car, it was such an amazing car to drive I forgave it that and the head gasket was very easy to change - not like now.

You may find that if you leave the filler cap loose so the pressure can escape it may be OK, I ran an XM for several years like that, it does reduce the boiling point though so you can't thrash it.

Peter

[Willpo99]

ah balls... not what i wanted to hear but have to say the head was pressure tested and skimmed and the block x-rayed too for the rebuild. Only driven 600 miles since then. Its not overheating, just building up too much pressure.
I started it up earlier and left running with the coolant tank cap off. The tank slowly but surely filled up almost to the top. Again, no bubbles or odd smells. The coolant looked like it was very slowly dribbling in from the smallest pipe on the top at the rear of the tank. Nor sure where this comes from. Any ideas?

[Montecarlopaul]

Hi. Did you get to the bottom of the problem, I've got exactly the same problem with my 2012 relay. Thanks