Pressurising 300TDI

My 300 TDI seems to be misbehaving, she isnt using any water but as she runs the header tank level goes up slowly (very slowly) and the system pressurises. after about 150 miles the header tank will be up to the neck and water level can be dropped by releasing the air out of the stat housing.
Anyone come across this before? she runs sweet as a nut, no smoke, no oil contamination.... all I can assume is a very slight leak from the cylinder into the waterways, possibly head gasket weep or worst case a hairline crack, I may try n tweak the head down a little with a big torque wrench n see if that helps but otherwise any other ideas out there???

Cheers Steve

Hi Steve,

Is it the correct header tank cap your using? just a thought ive seen folks use the wrong caps before that either release pressure to early or dont release any at all. That would be a cheap thing to just go and check

or just a faulty cap. cheap thing to try either way

^+1

Both the 300tdi's I've owned suffered head gasket failure. The first started off pressurising the header tank while slowly losing coolant despite no obvious leaks. It went on like this for a long time and didn't get any worse. The other one blew spectacularly on the motorway and overheated instantly. It could empty it's entire cooling system through the header tank in about 10 seconds from starting.

Think I may have cured it but time will tell, tweaked the head bolts last night, not the most scientific but definately something astray, 25% of the bolts were solid, 50% allowed at least 60-90 degrees of movement without too much effort and the last 3 or 4 getting towards 180 degrees

Considering they only normally torque to 40 then two twists of 60 degrees something clearly wasnt good...

ran it for an hour this afternoon and then released the bleed on the stat housing and out came water and no air

have I cured it?? time will tell on the run back to lancs on thursday so fingers crossed

Cheers Steve

Keep us posted fingers crossed