Pressure from coolant cap when cold

[doddicus]

ok...here goes.
Had Head Gasket done last summer on my 2003 1.8 turbo (K-series)...replaced PRT thermostat last month as wasn't getting any heat from blowers.....flushed cooling system with hosepipe (Checked all areas that water runs through even the engine).....but now i seem to be losing water from somewhere but cant find out where (not drastic amounts)...but when the car is cold from standing overnight there is pressure released when i unscrew the coolant cap.
Am really frustrated and dont know what to do....can anybody advise
Many thanks

[chris75]

The "pressure when cold" effect is usually a symptom of head gasket failure , I'm afraid . You wouldn't be the first one to have had a bad job done on a K-series head . I would get a compression test done to look for any serious differences between the 4 cylinders as a next step .
When a head gasket is replaced on these , issues arise due to liner heights , which type of gasket is fitted , skimmed or not skimmed , and porosity . Are you seeing any steam from the exhaust or a mayo- like deposit on the oil cap or dipstick ?

[Doc Evil]

First check your fan works
start engine press demist and go round to front of car to see/hear fan
next bleed the system correctly as per MGR spec
once that is done if pressure still present the following morning I'm afraid it's highly likely that the head gasket has failed
As Chris has stated people install the wrong gasket in relation to the liner height or the head may have porosity around the fire rings if it still has pressure after bleeding then a compression test is the next step
Doc

[doddicus]

not sounding very good to me then...might be best to get shut...just got 12 months MOT on it too

[Doc Evil]

not sounding very good to me then...might be best to get shut...just got 12 months MOT on it too

Do the checks first maybe just full of airlocks

If it is head gasket it only takes a day day and you can get parts from £15 DMGRS does budget gaskets which are fine to use and if done correctly will give many years of reliable service

Doc

[doddicus]

the head was skimmed and a multi layer gasket used...the guy did say it had been skimmed before.

[doddicus]

how about a bottle of STEEL SEAL....been told its very good

[Doc Evil]

You can skim the head a couple of times if needed but I find people skim habitually rather than test and measure first it only needs skimming if it's warped and to be honest if it's that warped it will be annealed so it's useless, you can pick up a good head from a Rover 25 for £30 and just swap the cams
If you have fire ring indentation you can fit a head saver shims that will counteract this and give a poor head a new lease of life
DO NOT PUT ANY ADDITIVES IN THE ENGINE they will block up the heater matrix and radiator core, been there done that bought the t shirt and spent ages flushing the muck out
Do your checks I specified and report back we can guide you through the correct procedure to sorting this out, if you're not handy with the spanners there are traders near you who will do the job at a reasonable price properly and you will have a great car with the best engine Rover made IMO
Doc

[chris75]

not sounding very good to me then...might be best to get shut...just got 12 months MOT on it too

That's a big step ! At least do the compression test ; it only requires removing the 4 spark plugs , takes very little time and even at a garage should cost very little :}
What about the other checks and symptoms that have been suggested ?
There is a thread running now about Steel Seal ......http://www.the75andztclub.co.uk/forum/showthread.php?t=210724&highlight=steel+seal

[SD1too]

...replaced PRT thermostat last month as wasn't getting any heat from blowers....
Carl,

First of all, lack of heat from the heater has nothing to do with the PRT. It's usually due to air in the cooling system or a blocked matrix.

After replacing the PRT, did you bleed the cooling system according to the MG Rover method here (http://www.the75andztclub.co.uk/forum/showpost.php?p=1533509&postcount=12)? If you didn't, do that now.

Next check that your radiator fan runs continuously when the engine is started from cold with the windscreen demist button pressed.

When the engine is at normal tempersture after a run, feel the bottom radiator hose: is it hot or cold?

Once you've carried out those basic checks you can move on to the more detailed fault finding described, if that proves to be necessary.

Simon