Thread: 1996 Discovery 1 300 tdi manual - Header Tank Pressurising

Originally Posted by willowthehat

Hi Guys,

Got a slight issue with my 1996 Discovery 1 300 tdi manual Header Tank Pressurising.

Its been doing this for a little while, nothing too serious just a few stains on the outside of the tank after driving more than say 5 k's. Its not overheating (yet) and seems to run fine. When I open the rad cap (with my hand wrapped in a towel) after a drive the pressure release does not seem excessive.

Yesterday I replaced the radiator, thermostat, coolant and did a flush but still the problem persists. To bleed the cooling system I first filled the rad then to the thermostat housing, then the header tank before starting the car and running with the heater on while opening both bleed/ fill valves to allow any air out of the system. Checked again this morning and the coolant level is perfect and the heater still blows hot once car is warmed up so I'm guessing no air locks.

Oh and I've fitted a new rad cap and the Viscous Fan Clutch is 2 years and 10000kms old.

I feel like this is pointing to a new head gasket but thought I should throw it out there to see whether there's anything I've missed.

Cheers

Sam

Yep sounding like it .
The HG is a straight forward jobbie on a 300 , Dont be scared just do it

As rangie posts, it is probably the head gasket.

It is best to do it sooner rather than later when it may cost you a head as well.

Quite straightforward and plenty of posts on here to describe it all - ultimate cleanliness required for long life of your new head gasket - just remember to check the flatness of the deck, lube the head bolt threads and apply NO sealers on the composite gasket.

All the best

Originally Posted by rangieman

Yep sounding like it .
The HG is a straight forward jobbie on a 300 , Dont be scared just do it

Thanks Chris,

Thought it might be but wanted to get any other ideas first before removing the head.

Yes I've done two before so I know whats involved - not a bad little job.

Sam