moose Posted September 1, 2009 Share Posted September 1, 2009 Morning all, I have picked up a 96 300tdi disco cheap as it had failed an MOT on rotten sills, just done that and noticed the exhaust gasket was blowing so new one in a and when took it for a drive all good... but. I checked the coolant level and it was low (def was ok when i picked up the truck in the first place), so filled it up and ran the engine. In the header tank i get a very small amount of white foam, after stopping the engine and putting my ear over the tank its like listening to a class of fizzy pop So iam think its a head gasket? but do i need a new head? as its a unknown history (well to me) and i guess it might have been cooked at some point any signs that might tell this? If i get it skimmed will they be able to tell me if its warped etc... thanks for any input.. Quote Link to comment Share on other sites More sharing options...
saltyoldseadog Posted September 1, 2009 Share Posted September 1, 2009 I have just had what sounds like exactly the same problem with my 200 TDi. When Mark Knight (KVMS) removed the head he told me it twisted up like the Forth Bridge but it skimmed up okay. All is now well and she runs like a sewing machine. We also had to have the valves reground and two had been leaking and were carboned up so needed new tips but after fifteen years it seems a very little problem compared to what might have gone wrong. And compared to some of the problems correspondents report on this site! Good luck with it. George Quote Link to comment Share on other sites More sharing options...
matt bristol Posted September 1, 2009 Share Posted September 1, 2009 If it is the head then its not that big a job, I followed the instructions/guide from the tech section and it took me about an hour and a half to remove the old head, and only a few hours to clean and refit the replacement one. all the problems since then have been of my own making! Quote Link to comment Share on other sites More sharing options...
moose Posted September 2, 2009 Author Share Posted September 2, 2009 thanks for the replies.. nope your right not a big job, and just spoken to my local machine shop and they can skim and pressure test the the head for me (as i was thinking about just replacing the gasket). Quote Link to comment Share on other sites More sharing options...
plasticbadger Posted September 2, 2009 Share Posted September 2, 2009 Hey Moose, hope that disco was darn cheap! Anyway, definatey worth the skim and pressure test and also re-lapping the valves before re-assembly. There's nothing worse than going to all that work and find that you've got no compression, or blow out the new gasket in 500 miles (I've had both ) Quote Link to comment Share on other sites More sharing options...
Thys Posted September 2, 2009 Share Posted September 2, 2009 Hey Moose, hope that disco was darn cheap! Anyway, definitely worth the skim and pressure test and also re-lapping the valves before re-assembly. There's nothing worse than going to all that work and find that you've got no compression, or blow out the new gasket in 500 miles (I've had both ) You may remember my 300Tdi's cylinder head saga in March/April 2008. One big lesson learned was that the pressure testing of the Tdi's head is not done the same way a petrol engine's head. Mine's head "passed" the pressure test, only to discover after removing the "passed" head twice, that the pressure test procedure was incorrect, the head was cracked. I bought a new head, and that was the end of my problems. The correct pressure test procedure? This is what a reputable Cylinder Head Specialist told me: Once the head's water channels are heated with water circulating at a temperature of 120ºC (I don't know how they do it, as water boils at 100ºC at sea level), the water temperature must be maintained through out the pressure test. The applied pressure, 8 Bar if I am correct, must stay constant for at least 24 to 48 hours. If the head fails the pressure test, it is wise to replace the head, as opposed to "stitch" the crack. Quote Link to comment Share on other sites More sharing options...
DiscoStu Posted September 2, 2009 Share Posted September 2, 2009 Its all down to pressure. Water can reach temperatures higher than 100 degrees without changing state if the pressure is high enough. I'm probably wrong, but dredging the recess of memeroy I think its described as "An inverse relationship between temperature and pressure" and it may even be Charles' or perhaps Henry's law. I cant be bothered googling to confirm... Stu. Quote Link to comment Share on other sites More sharing options...
moose Posted September 2, 2009 Author Share Posted September 2, 2009 Hey Moose, hope that disco was darn cheap! PB if it carries on prob not cheep enough but after this engine work it will still be a sub 500 quid motor. all for do it once do it right approach.. esp due to the trans European towing mileage it will see next summer Thys I had heard that about the 300 heads thanks for the... "heads up" .. don't fancy getting a new one just yet tho... Quote Link to comment Share on other sites More sharing options...
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