Heater problem have searched still need help

Morning I have a problem with the heater on my p38 in that I started the car this morning and there is no heat coming from the heater the inlet pipe to the heater matrix is hot the outlet not so I am assuming there is a blockage or is there another possible problem also can the car be driven temp guage is showing normal. One other thing after she had been running for about 20 mins there was a bit of pressure in the top hose from the rad released the pressure and none since - anyone any ideas other than a thicker coat ta

blend motor /blocked heater matrix or head gasket/liner

yeah guess its more likely to be heater matrix there is no book symbol and the aircon works also temp is constant both sides engine has only done 30k and put new hoses and rad etc when I did that - is it pos to blow through the heater matrix or is it a take out and replace job?

One other thing after she had been running for about 20 mins there was a bit of pressure in the top hose from the rad released the pressure and none since


Sounds like an air-lock, with the engine warm, the rad hoses should be 'hard' ( up to pressure) try running the engine with the rad-cap off for half-hour, blipping it now & again, top up with coolant whilst its running, any air in the system will be pumped around & expelled via the open header tank, we used to 'do' this years ago on large truck diesels, no need to bleed the system, it does it itself!!
As for the hot-side, cold-side heater pipes, i'm not sure on the RR, but is there a water-valve somewhere to control the temp? If so, could it be stuck closed or not working?
Alternatively, an air-lock in the heater matrix, would prevent through flow, see above!!
On some engines I've rebuilt, then filling to the top, rev the thing up high for a few seconds, the coolant completely 'disapears' into the galleries, after which I could get many more litres in.
Of course coolant-loss can be external or internal leaks (head-gasket, water pump etc.) or even a weak pressure relief valve spring on the rad-cap, try a replacement cap, it may be that simple!

Gents thanks for the tips I tokk the inlet and outlet hoses off the heater matrix and back flushed with a hose and mains pressure - it was bloody freezing then reconnected and refilled and ran it for 20 mins with cap off - bingo whatever it was its all working fine once again thanks

Does anone know if that would be safe to do on a 20 yr old RRC?

I dont want to burst it!

Dont want to say yes but if you put the hose in the outlet to reverse flush you can control the pressure by how much you open the tap so should be ok if you go carefully

ater presure should be around 2 bar, just limit the tap at first, if its free running then up the pressure.

Thanks guys, I will also wait till A. the feckin thing is runing again and B. its warmer out incase I break something lol.