Leo109
22nd February 2009, 09:23 AM
Hi All,
No, not a strike against WMDs (Weapons of Much Deception??) - but against our 300Tdi's head gasket.
Being in the company of, and close proximity to, the Southern Hemisphere's Leading Exponent of the Land Rover Arts (just ask him, he'll tell you so himself!), it seemed like an ideal opportunity to carry out this task in a well-equipped workshop and with expert advice on hand, rather than wait for it to 'go', possibly in a far more remote area. Our 'Daphne' Discovery has 270,000 km on it (not the 360K km as mentioned by JC recently) and 300 to 350K km seems to be a common failure range for the said gasket.
So under the tutelage of The Master, I stripped the top end and removed the head to reveal a gasket showing (in the expert opinion of The Master) definite signs of terminal wear and eventual failure. I'll leave it to others to discuss the relevance and seriousness of these 'signs' from the attached photos.
I was very pleased to see the quite clean piston crowns and valves/head surfaces, with no sign of excessive combustion temperatures despite this engine having been well 'fuelled-up' for the last 180,000 km and having done many, many tens of thousands of kms towing up to 2.3T, in ambients up to and over 46 C. [Also, in recent weeks it's been running slightly advanced injection timing and, for a few days, unlimited boost pressures (i.e. wastegate diaphragm disconnected) up to 22.5 psi - all in the cause of R&D!] Also very welcome was the sight of all that lovely cross-hatching on the bores after this many kms.
While the head was getting a 0.006" 'clean-up', I took the injectors to a local injection specialist (Authorized Bosch Service Agent). While initially skeptical about the worth of testing them at this age, he then invited me into his pump room and confirmed that, while there was a bit of spread in the first stage cracking pressures (between 170 and nearly 180 bar), all the spray patterns were still uniform and quite acceptable. He said he'd be happy to put them back into an engine, so I did.
The engine was re-assembled according to The Master's instructions for care and cleanliness and the clean, oiled head bolts torqued to 40Nm plus two sequences of 60 degree tightening using JC's very simple but foolproof technique. (Well, nearly foolproof. I know nothing is 'foolproof' against sufficiently talented fools but I managed to get it done OK.)
Next day thoroughly flushed the cooling system and refilled it with fresh coolant and demin water and did an oil/filter change, to remove any foreign matter from both systems.
Chatting to my ex-mechanic brother-in-law in FNQ yesterday, he was aghast that we'd not done a valve grind/valves guides and seals while the head was off but JC didn't mention this, so I assume these are normally quite OK on Tdis of this age. I'll have to get his opinion on this next week.
Hope this is of interest to other 300Tdi owners.
Ian
No, not a strike against WMDs (Weapons of Much Deception??) - but against our 300Tdi's head gasket.
Being in the company of, and close proximity to, the Southern Hemisphere's Leading Exponent of the Land Rover Arts (just ask him, he'll tell you so himself!), it seemed like an ideal opportunity to carry out this task in a well-equipped workshop and with expert advice on hand, rather than wait for it to 'go', possibly in a far more remote area. Our 'Daphne' Discovery has 270,000 km on it (not the 360K km as mentioned by JC recently) and 300 to 350K km seems to be a common failure range for the said gasket.
So under the tutelage of The Master, I stripped the top end and removed the head to reveal a gasket showing (in the expert opinion of The Master) definite signs of terminal wear and eventual failure. I'll leave it to others to discuss the relevance and seriousness of these 'signs' from the attached photos.
I was very pleased to see the quite clean piston crowns and valves/head surfaces, with no sign of excessive combustion temperatures despite this engine having been well 'fuelled-up' for the last 180,000 km and having done many, many tens of thousands of kms towing up to 2.3T, in ambients up to and over 46 C. [Also, in recent weeks it's been running slightly advanced injection timing and, for a few days, unlimited boost pressures (i.e. wastegate diaphragm disconnected) up to 22.5 psi - all in the cause of R&D!] Also very welcome was the sight of all that lovely cross-hatching on the bores after this many kms.
While the head was getting a 0.006" 'clean-up', I took the injectors to a local injection specialist (Authorized Bosch Service Agent). While initially skeptical about the worth of testing them at this age, he then invited me into his pump room and confirmed that, while there was a bit of spread in the first stage cracking pressures (between 170 and nearly 180 bar), all the spray patterns were still uniform and quite acceptable. He said he'd be happy to put them back into an engine, so I did.
The engine was re-assembled according to The Master's instructions for care and cleanliness and the clean, oiled head bolts torqued to 40Nm plus two sequences of 60 degree tightening using JC's very simple but foolproof technique. (Well, nearly foolproof. I know nothing is 'foolproof' against sufficiently talented fools but I managed to get it done OK.)
Next day thoroughly flushed the cooling system and refilled it with fresh coolant and demin water and did an oil/filter change, to remove any foreign matter from both systems.
Chatting to my ex-mechanic brother-in-law in FNQ yesterday, he was aghast that we'd not done a valve grind/valves guides and seals while the head was off but JC didn't mention this, so I assume these are normally quite OK on Tdis of this age. I'll have to get his opinion on this next week.
Hope this is of interest to other 300Tdi owners.
Ian