300tdi - Head Gasket??

OK, I know I posted another thread about my coolant leak but things have taken a significant turn today so wanted a new title.

Fitted new thermostat housing gasket, P-Gasket, new Airtek water pump, new expansion tank and cap. One bolt sheared undoing the power steering pump but we decided three will hold it OK so not unduly worried.

Ran the old girl up, sounded sweet. Got her hot then left her sitting at 2000rpm for about 15 mins. Top hose pressurised rock hard, could see through the new partially transparent expansion tank that the coolant rose about half and inch and was turbulent to say the least - then, low and behold a dribble on the floor which appeared to be from a different spot on the P-Gasket. This dribble only started once the top hose was solid.

To start with, I'm surprised the new cap didn't release some of this pressure but my feeling is just that the P-Gasket was the weakest point and gave in. All bolts were torqued correctly and gaskets smeared with Blue Hylomar.

Anyway, after a cuppa we refilled the system to near brimming and started her up with the expansion tank cap off. Instantly apparent there was a great deal of movement in the water and the water level just climbed and overflowed the tank. The Disco was parked nose uphill and thermostat housing and rad were checked for airlocks but were fine.

It appears there are micro bubbles in the water. I was expecting "proper" bubbles but these are tiny, finer than the ones in a fizzy drink.

At a total loss for any explanation other than head gasket. Obviously will strip down and replace P-Gasket again.

I've been quoted £25 for skim (or £90 if they strip and rebuild the head) and £35 for pressure test. This is the first quote, have two more firms to call locally.

Next question: New head gasket - same thickness as old one (unknown atm) or go for a "no hole" thick one after a skim? Will get an Elring set rather than Bitpart etc. Also, is it worth paying extra for Elring head bolts instead of the cheapies commonly available?

Ally spacer section to engine block face.Had them before with repeated P gasket leaks,turned out ally section not flat.So,clean the block face smooth and flat and replace the ally section (expensive) or get the nice skimmer bloke to go over it while hes doing the head.

Are you filling coolant with air bleeds,heating open,and expansion bottle raised?

Ive never yet had the bloody pressure release cap work.....it always blows a hose or something.

While cranking the engine do you notice a rise and fall in the expansion tank?

I generally fit 3 holers now but its always worth having a good look before cleaning for any sign of anything hitting anything else,that and measuring the piston level with a steel rule and feeler gauge if it looks high or low.

£40 pressure test and skim, bradford engine units.
good blokes, good work.

MEASURE THE PISTON PROTRUSION! if you fitting anything other that a no hole hg!
use a dti, measure each piston 90 degrees round periphery, use the highest measurement!

0.1mm difference in thickness for each hg. you wont see this with the naked eye.

elring or payne hg. (£15 - £30 depending on where you get it)

torque bolts according to rave. ive not used new bolts yet, but thats my choice.

as already said, clean block face, i use oil stone after hg remnants removed. stone evenly and all over.

which pump bolt sheared? if a long one, i'd replace it.

Thanks Shocker and Nrgserv for the replies.

Yes, I'd had heaters blowing on full hot and yes as I revved and idled the engine the coolant would noticeably rise and fall. Front wheels on ramps and parked uphill so encouraging all air to the thermostat bung.

Think I may have been dealt a hand from lady luck today. I spent about an hour constantly releasing pressure at the thermostat and rad bungs and eventually she held her own. No leak from P-Gasket today but since it was breached yesterday I feel like changing it again next week.

Anyway, went for a 10 mile jolly with 3 gallons of water in the back, no problems. Had a saunter up the dual carriageway at 70mph for 15 miles to my local LR dealer to get another P-Gasket (none in stock), no problems. In all done about 60 miles today and she's holding her own. I'm beginning to think I had the great grandfather of the mother of all airlocks. I've never had this amount of trouble bleeding the coolant up but hey ho, better than a head gasket.

Not having another 300tdi next to me to refer to, after a run the top hose is slightly pressured but not solid, heater matrix hoses much less pressure. Hardly a hiss when I took expansion cap off. Loads of hot air and temp rock steady.

I've got to drain it down again as I'm water only atm so have to get some antifreeze in there. Might chuck some rad flush in first.

Any agreement or otherwise to changing the P-gasket again after yesterdays breach even though not leaking today?

Also, looked at my head gasket today and mine is a 3 hole so only the no hole available as a thicker option if skimmed.

Sheared bolt was left hand one of the 4 power steering pump bolts. Seems overkill having 4 anyway so I'm sure 3 is ample.

skimming doesent affect the thickness of gasket as the heads flat already.
a 3 hole will go back on ok.
should be no hiss when cap removed.
doesent matter when filling coolant where heater set to, as matrix flows continously.
keep an eye on p gasket and water levels.
listen while driving for gurgling noises. (air from leaky hg forced round system)
one of first sign of problems is heater blowing cold when set on hot. check this if you hear the gurgling!

Looks like I was being optimistic. Just got home and, as ever recently, checked my top hose.

Quite pressurised but not solid. Loads of pressure in expansion tank and big rush when I took the cap off.

Water level down about half an inch.

All this for about 30 miles of motoring spread over last night and this morning.

Think it's time for a head gasket after all



ps Heater still blowing hot.

Get that head off before you bend it!!

Hi disco magic just read your post and I have the same problem, where are you based? can't seem to find any one who will skim the head they seem to want to sell me a recon head at £500 plus.I have posted a thread on the 300 tdi forum hopefully some one may know some where in birmingham area that may help. thanks

I know a place in bilston if thats any good to ya

Blue Riband Engines (B'ham), Birmingham, , Great Britain, Automotive Cylinder Head Repair, Cylinder Head Repair

googled. first one clicked on. 2 minutes.

and those that seem to want / need help, never put their location on the usercp

Thanks chaps I will look in to it today.