Boiling up still
 

I took the car for a 30 odd mile drive yesterday morning. It ran really well but when I got home and popped the bonnet the expansion tank had risen to the top ( usually about an inch in it) and was bubbling and I could hear the coolant boiling in the main header tank as well. Water temp gauge in car reads normal, fans work.

Its booked in to SMD on 8th August for a service and Brent is going to check hoses etc, BUT I really want to bring it up to Barcombe on 29th but not sure if I should be driving it while its getting this hot.

I am thinking It may be air in the system, how do I bleed it??

Alternatively could be thermostat? or a small split somewhere? or, of course head gasket but hoping not!!!

Any idea's would be appreciated.

Hmm my knowledge is limited but I'll try to help :).

Does the bottom hose get hot too? Any idea or receipts as to when the thermostat was last done?

I think the only way to bleed the system is take the cap off the header tank from cold, start it up and let it run all the air bubbles out.

As to the HG, have you checked usual things like blows hot air from vents? Checked if theres no gunk in oil and coolant is clean?

I'm sure someone will tell me what I've said is wrong lol.

Also have you checked the condition of the rad? May be damaged or blocked therefore not cooling.

I had the same issue, thought it was HG but swapped the rad cap, all is good! Cap was not keeping the system pressurised enough and allowing coolant to boil.

I switched the cap a couple of weeks ago. The heater blows hot air, no wet carpets and the oil cap is clean. The coolant in the expansion tank is also clean.

Whats about bottom hose? That can be a sign that the thermostat is stuck shut...
And checked the rad?

Check & clean all the electrical connections in the system too......

If the fans cut in its not normally a blockage

Ah okay. Learn something new every day.

Take it for a drive without any boost and see if it still does it, if not then drive on boost, if it does then I would say HG

Ok, I took the rad cap off, put heater on full, hot and screen and just left it ticking over with the occasional throttle blip.

When it was first started there where bubbles/air in the header tank, after about 5 mins this settled down and the only time i got bubbles was if i blipped the throttle. Sat like this for about 20 mins until eventually the level rose and started pushing water out of the top of the header tank when I then switched off.

Temp gauge read normal (just under half way)

Fans didn't cut in at all - even after 20/25 mins. I saw them working about 4 weeks ago but maybe it didn't get hot enough this time to activate them?.

Top rad hose very hot, bottom stone cold. (just checked again and its warm?)

Just been out to Newhaven, so about a 10 mile round trip, bit of bubbling in the expansion and top and bottom hoses now hot.

Think I'll just take it easy in it and see what Brent thinks on 8th.

Maybe you have a sticky thermostat. it's under the housing where the bottom rad hose attaches.
In the big scheme of things, it's cheap to change so may be worth doing anyway just to eliminate it

Yeah it's not hard to change. Unless it could of been an air lock if you say the bottom hose is now hot after you got the air lock out?

BRENT mate thats your answer you know it makes sense

Yep Sim, its booked in for a service, MOT etc on 8th august. I was just trying to sort this out before the meet on Saturday. Oddly it seems a bit better after what I did this morning.

I think it may be air tho, I gave the bottom pipe a squeeze tonight with the rad cap off and a huge gulp of air came out.

hope you get it sorted mate let me know if you need a lift in the truck or anything lol