TD5 Overpressure - AGAIN!

Hi All
Lurking these forums for a while and it didn't take me long to figure my TD5 (W reg 2000) had the classic head gasket failure. So taken in and dealt with by the local cyliner head specialist.

For a couple of weeks all is running sweet. Then start to lose water. No pressure in system. Take it back and some hose clips replaced. Leak gone. A week later...

Now as soon as the engine works hard I get the dreaded hoses over pressurised. Even after a cool down taking off the expansion bottle cap just results in loss of coolant!

Take it back again. Thermostat changed, system flushed, pump changed. Same.

So fair-do's he takes off the head again and hot pressure tests (- uses a steam cleaner to heat up!) Head fine. New gasket fitted just in case. Put it all back together and no change

So this is driving the mechanic almost as crazy as me?
Any ideas folks? Are block failures common? Remember when the HG was first done it ran sweet for a couple of weeks - inc some hard working (tows).

Many Thanks!
Rob

I used to find pressure testing heads was a bit pointless unless you had a leak in to the combustion chamber of coolant ie white smoke in the exhaust. The pressure applied during off the vehicle testing is water jacket pressure. The combustion pressure is of a different order and will penetrate even the smallest pinhole or hairline fracture. Trouble is, before spending big money you would like to know for sure. Almost impossible to guarantee unfortunately. You need to use the symptoms and maybe check for combustion bye products in the water. Testing kits are available. If it pressurises before it gets hot then suspect head, gasket or cylinder liner. Once an engine is hot it's a little more difficult to be sure but you should rarely in the UK get to a situation where the water jacket is highly pressurised and you can't remove the cap with a little care.

Sounds like the head is cracked on the inlet side. It's what happened to mine too. I ended up buying a good secondhand head for mine.

has the head been skimmed or checked to see if its flat

It does sound like a cracked head - usually around the exhaust valve seat area causing the exhaust to "vent" particularly under load, into the coolant.

My TD5 used to drive 30 miles or so before over-pressure suddenly caused the coolant to dump itself suddenly and entirely on the road.

During the process of correcting it, I became very aware that some "testers" are much better than others.

Some just really don't know what to look for, how to block the ports on a common rail head or how test a head in hot water

Using a steam cleaner to warm up the head certainly doesn't sound very.......erm.......scientific.

Personally I would get the head back off and get it to a head specialist for testing, checking and if ok refacing.

Thanks for the feedback all.
The head has been skimmed etc and after the initial HG job was done was sweet for a a couple of weeks. There is no gas in the coolant that is detected by a CO tester but then reading this forum suggest this is often the case - also the pressure is so huge that I cant see it can be anything else. So folks so I go recon or the extra mile and get a new one from Turners? Before I do this is there anyway it could be a crack in the block?
Cheers!

silly, but did you change the radiator it could be blocked

ah yes - also tried another radiator. My wallet is trembling already...

So to wrap this one up (which I know from experience will help future browsers with similar problems). 2nd hand warrantied head found by 1st spares web site - £400 with warranty and delivery. + fitting, new gasket etc. Another £400ish - Problem solved. Though not as easy to start in the mornings. Next problem

Could u PM me the link for that site please?.... i'm affraid that i'll be in the same situation soon... though the symptoms have vanished for now after i've replaced the stat but i want to be prepared... cheers

instead of fitting new rad if your unsure feel old one all over surface to see heat is evenly distributed

Hi everyone,although this is my 1st attempt to post ive been on LZ for most of my life it seems owning a 01D2td5. Iwonder if Sierra ferry is still here and if so did the thermostat cure his overpressurising,I have now this problem,also had the dreaded oil pump bolt plus fuel cooler, fuel pressure,windows, locks, sunroof, fuel pump, fuel pipe chafe,compressor,discs,to name a few, most unreliable LR ive owned. Sadly still after advice, head gasket or head,hoping thermostat will cure it,or perhaps a match