Just did a 300 mile journey no problem but a day later after 3 miles it shot into the red.

I checked the coolant and the tank was empty.

Filled it up but it only took about 2 litres left it overnight night then topped up another 1 litre.

No leaks any where, checked the engine oil and no sign of mixing.

Drove out and again after a few miles shot into the red.

Left it a while and again coolant tank empty. Topped it up again.

Drove another mile into the red again only this time the coolant was still full then oddly the temp gauge fluctuated and dropped back down to dead centre.

I'm wondering if its an air block. I cant remember should the pipe from the radiator into the engine be hard, Its hard to start then as it cools gets softer or does it sound more like a dodgy pump.

Update. Just took the expansion tank cap off and filled up with the engine on whilst squeezing the pipe. Is it normal for it to start overflowing with the cap off.
It doesnt seem to be over heating now but I have no hot air.

If it's drunk 3Lof water, that must have gone somewhere. You'll need to find the leak. Few things to check (apart from leaky hoses and visible stuff) O ring on cap, water pump<br> If the coolant tank was empty, you'll have to properly bleed the system, not just top it up. Follow RAVE bleeding stuff to the letter, no short cuts!

1. Disconnect radiator bleed hose at the radiator.
2. Blow through hose to clear any residual coolant.
   Reconnect hose.
   CAUTION: If radiator bleed hose is not
   cleared of coolant, air may become
   trapped at top of radiator during refill,
   leading to subsequent engine overheating.
3. Fill expansion tank until coolant is level with
   base of neck.
4. Start engine, continue filling at expansion tank
   until coolant level stabilises at the ’COLD
   LEVEL’ marking.
5. Run the engine until the thermostat opens (top
   hose becomes warm).
6. Stop engine, allow to cool.
7. Check coolant level, top-up as necessary.
8. Refit expansion tank filler cap.

if you have no hot air you have a huge airlock. Air expands far more than coolant (or even water) so the air expands and pushes the water out of the expansion tank.

Ok, I think it was definitely a huge air lock. It probably ran out of coolant , I suspect the Body heater plate has a leak even though I only replaced it last year. I havent done the RAVE bleed yet , it seems to be ok after I topped it up without the expansion cap on and ran the engine. I now have hot air again but I will do a full bleed.

Cheers Gilbertd and Ob.

Still having problems.

I am also a bit confused with the rave bleed guide.

" Fill expansion tank until coolant is level with base of neck" where exactly is the base of the neck? does that mean just below where the filler cap would normally be.

I have only filled it to the cool level as when I turn the engine on without the cap on it then once warm starts to raise over the top of the neck & overflows.

I have also read elsewhere that instead of disconnecting the bleed hose from the radiator to disconnect it from the expansion tank instead and blow down it.

I've only done this once myself, and just recently, although it has been done many times over the years.

I pulled up the reservoir carefully (not to break anything) to raise the water level higher than the heater and top radiator hose (mines a Thor).

Then blew through that damn little pipe (or you can use one of those small compressors).

Filled to the seam of the tank, started the engine and squeezed the top rad hose and also the heater pipes and watched air releasing in the reservoir.. You can see tiny bubbles emerging in the reservoir from that small pipe.

Level went down after a while.

Topped up and then kept an eye on the coolant level over the next few weeks.

I must say I had over thought it as it was very easy.
.
HTH a bit.

In my view point 2 of OB's explanation of Rave to clear the bleeding pipe before filling is because the vertical difference in height of the tank, top of engine and top of radiator is so little that any left coolant in that pipe will distort the flow-through during filling with engine off.
The neck of the tank is just barely above those levels so that's the level to start with. Give it time to flow through the engine before starting.
Last time I popped the tank out of it's bracket to gain some height.
Then, when staring up the level will drop, keep it at cold level untill it rises again (tophose becomes warm, stat opens) and stop the engine to cool down.
Don't wait untill you feel the hose becoming nice hot or when the meter is in the middle, stop the engine earlier.

When cooled down fill up to cold level and tighten cap. (I whish it had, like my old Classic, a pipe over the heads with a bleed plug).

Edit: crosspost with Spiggy!

Did your coolant level start to rise to overflow with the cap off at any point?

Sounds like Im probably running the engine too long then Ferryman.

Ok, Thats better.

Just raised the expansion tank as you both suggested and it completely changed the scenario.

It didn't overflow or even attempt to go above the level this time plus when I disconnected the bleed hose from the radiator it pissed out coolant from the radiator which probably aided the unblocking whereas before nothing came out.

Spoke too soon.

Its seems fine around town back n forth to work at 30mph but anything around 50mph its overheating again.

Would a faulty thermostat cause this maybe

Possible but unlikely, clogged radiator or insufficient flow for some reason is more likely.

The radiator was replaced 18 months ago. I'm now suspecting the water pump.

Grrrrrr.

Its not the water pump.

Guess the next thing to change is the thermostat .

It only overheats above 2k rpm

I have a horrible feeling it might be a head gasket.
Even though there is no sign of water/oil mix. Just reading that if the HG has gone the exhaust gas will cause pressure back up into the expansion tank.
The strange thing I'm getting is that even with the cap off the expansion tank will overflow with the engine on meaning I guess its flowing from the radiator to the tank but not flowing from the tank to the engine. Surely it cant still be an air blockage.

Try a sniffer test. That'll tell you if you have exhaust gases in your coolant. <br>
Have you been all the way around your cooling and heating pipes and rads with an infrared thermometer with engine up to temp, following the flow diagram in RAVE?

Still sounds like an air lock to me. If it was head gasket it would pressurise no matter what revs it was doing, it just might take slightly longer at lower revs.

I hope you're right Gilbertd but I'm doing it by the Rave so dont know how else to shift it especially as Ive just drained it to fit the pump.

I dont have an IF thermometer OB but I will add that to my tool list

I'm with Gilbertd on this, thinking you still have an air lock/ blockage hence going around it with an IR thermometer like this <br>
http://www.ebay.co.uk/itm/New-Handheld-Temperature-Gun-Digital-LCD-Thermometer-Laser-IR-Infrared-UK-Seller-/201576010004?hash=item2eeeddd114:g:YigAAOSw1DtXKIHJ <br>
They can take bloody ages to bleed

Worth a bash at that price OB, cheers.