davyd8899 Posted December 29, 2011 Share Posted December 29, 2011 Hi all, right this is doing my head in!! I have a 300tdi that appears to overheat, the symptoms are feezing cold air from the heater with the temp guage through the roof, then a blast of hot air and the temp guage drops like a stone to normal. :wacko: Then after a while, the temp guage slowly climbs to red hot again and the heater slowly goes from luke warm air to freezing cold again. On removal of the header tank cap, with the temp guage red hot, it releases the pressure and the guage goes back to normal, what water comes out is warm/hot but not boiling, so the engine isnt overheating as such, more a massive build up of pressure. so far i have changed the following :- Head gasket (with head skim, new bolts etc) Radiator (new) Top and bottom Rad Hoses (new) Header Tank (2nd hand from a scrapyard, would a bit of plastic make a difference??!!) Thermostat. I have flushed the coolant system through a number of times with a hose to elliminate air locks, if its running low on water, the heater blows cold all the time but the temp guage stays normal!! Am now at a loss to know what to try next so any ideas/help/info would be greatley recieved!! Thanking you all in advance!! Quote Link to comment Share on other sites More sharing options...
BogMonster Posted December 30, 2011 Share Posted December 30, 2011 So what prompted all this - did something blow and overheat the engine in the first place? Generally there's a story behind these things. What's (almost certainly) happening is that the engine is pressurising the cooling system from the cylinders. You've covered most of the obvious possibilities already - head gasket being the prime culprit - so the remaining ones that I can think of will be nasty things like cracked cylinder head or even a cracked block If you take the head off you may see a "washed" cylinder (piston / head will be v v clean not like normal) which may give a clue. Quote Link to comment Share on other sites More sharing options...
fozsug Posted December 31, 2011 Share Posted December 31, 2011 I had this on one and it turned out to be a blocked three way valve http://www.lrseries.com/shop/product/listing/9555/PCH117840-EXPANSION-TANK-BLEED-HOSE.html?search=esr2348&page=1. As BogMonster mention above i have also had a cracked block on No 4 cylinder giving symtoms you deascribe Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted December 31, 2011 Author Share Posted December 31, 2011 So what prompted all this - did something blow and overheat the engine in the first place? Generally there's a story behind these things. The radiator let go on a long run which in turn blew the head gasket, since replacing the gasket, and having the head skimmed and pressure tested etc, this is when it all started. when the gasket let go the engine didnt overheat as i noticed it in time. I had this on one and it turned out to be a blocked three way valve http://www.lrseries....=esr2348&page=1. Is it possible to by pass the valve as its only a 1 way valve ie :- it only lets water pass through it in one direction? Quote Link to comment Share on other sites More sharing options...
BogMonster Posted December 31, 2011 Share Posted December 31, 2011 Ah, the plot thickens... sorry but if it blew the head gasket then it overheated. The gauge might not have said it did, but there must have been at least some local overheating if the gasket went. I think you've probably got a hairline crack in either the head or the block which might stand a 15psi compression test on the cooling system but is letting the much higher cylinder pressures through. The other possibility is that whoever did the skim of the head didn't do a good job of it and it's not sealing on the gasket. The head is the most likely as it's alloy so tends to warp / crack much easier than the cast iron block. The only thing I'm not clear on is if you also changed the header tank cap (which is the pressure relief valve) when you changed the tank. I don't think it will make any difference, but it's worth ruling out if you haven't already. May be wrong - and worth checking out the valve (which is actually called an "ejector pump" though no idea why!) - though I have never seen that particular problem, usually they just go pop and dump all the coolant on the road which sometimes requires a new engine. Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted January 1, 2012 Author Share Posted January 1, 2012 Well the plot thickens as you say!! Took the core plug out the top of the thermostat housing, revved the engine and water started bubbling up though it, so your right, there is exhaust gases presuring the cooling system, kinda new that really, was hoping someone would come up with a magic wand idea but already knew the eventual outcome!! So today the head comes back off, i have heard some awful reports about the company who machined the head the previous time for me, so kinda hoping they messed the skim up and theres no cracks in it!! will keep you updated, thanks for the advice, now, 1 final question.......... do i need to change the head bolts as its only a matter of weeks since i last did the gasket, on some websites is says the head bolts can be used upto 4 times, however, i am a firm believer of "change the head bolts every time"? Quote Link to comment Share on other sites More sharing options...
peterdon Posted January 1, 2012 Share Posted January 1, 2012 The bolts are stretch bolts so should be replaced, particularly with the problems you've had. I'm with you on the change every time. Quote Link to comment Share on other sites More sharing options...
bushwhacker Posted January 1, 2012 Share Posted January 1, 2012 Hi there When you have the head off get a flat sheet of glass a new 12 inch metal ruler and check for warping yourself, use a magnifing glass to inspect for cracks. The bolts are about £30 get a new set, you may need another new head gasket? Give the water pump a good inspection. Its pretty sickening to get work done and it not be up to a good standard for that reason I use this forum to very good use with any of my repairs. If you have any idea about how to do the job you will be ok with the help from the guys on here. Thanks to all for help and info I have had. Mark Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted January 1, 2012 Author Share Posted January 1, 2012 yes was going to change the gasket as a matter of course, now realise i've been a bit foolish, read on the internet regarding a gasket change and then went ahead and did it, have done gaskets in the past on other vehicles so thought i had the information i needed to accomplish the job, however since joining this forum the info i had was totally duff!!! so will be using this forum for all my repairs in the future!! so sorry in advance for being a right pain in the a**e,but could someone please tell me the following torque setting for the head bolts, have read 3 different settings so far!! the tightening pattern :- been told to start with the centre bolts and work outwards thats pretty much what i need to know, have sourced a reconditioned head in case the 1 i have is buggered, comes with a guarantee so should be ok. still hoping the guys that did mine first time round messed it up though!! thank you to all for your help and happy new year to all!! Quote Link to comment Share on other sites More sharing options...
bushwhacker Posted January 1, 2012 Share Posted January 1, 2012 Torque setting and sequence for the bolts I got from a Haynes (they also need to be taken through degrees also). I think they will be on here somewhere have a trawl. If you are sure about the recon/head it might be an idea to put it on? Get the old one checked when it suits. I printed off any topics I thought would be useful. Keep them in a ploypocket for the future. Mark Quote Link to comment Share on other sites More sharing options...
BogMonster Posted January 2, 2012 Share Posted January 2, 2012 Download the proper workshop manual (from www.landroverresource.com is one place) and use the settings in that and the tightening sequence is in the manual too - you need a good torque wrench and an angle gauge for a Tdi head. I haven't looked but I'm pretty sure Les has a how-to in the Technical Archive forum and his articles are the best you will find. Just to clear up one point above, you will DEFINITELY need a new head gasket! IIRC the bolts are re-usable up to 3 times but you could change them anyway to rule that out 100% - if you are having problems then I always go for better safe than sorry! Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted January 2, 2012 Share Posted January 2, 2012 The bolts are stretch bolts so should be replaced, particularly with the problems you've had. I'm with you on the change every time. Tdi head bolts are NOT 'stretch' bolts. They can be used 5 times. TD5 head bolts ARE 'stretch' bolts (you can feel it as you tighten them when they reach their elastic limit) and must be replaced each time. Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted January 2, 2012 Author Share Posted January 2, 2012 ok, heads off, cant see any visable cracks on the block or the head, after spending a good 3 hrs inspecting with a magnifing glass!! however, sat the head on a pane of glass, and its certainly not sitting right, only talking about 1 thou out, if that, need the magnifing glass to actually see its not sitting right, but something is defo amiss!! so will be refitting after taking it somewhere else to be machined, as for the cowboys that skimmed it the first time they will be getting a strongly worded letter. will defo be using new head bolts, new gasket, water pump will be fully inspected, and hopefully that will be drama over!! have found the relevent info for the torque settings and tightening sequance, will be buying an angle guage next weekend (back to work for me tomorrow ) so hopefully greenlaning again next sunday!! thanks to all for the info, hope to be of service to other people on this forum if i can be and happy new year to all!! :i-m_so_happy: Quote Link to comment Share on other sites More sharing options...
peterdon Posted January 3, 2012 Share Posted January 3, 2012 Tdi head bolts are NOT 'stretch' bolts. They can be used 5 times. TD5 head bolts ARE 'stretch' bolts (you can feel it as you tighten them when they reach their elastic limit) and must be replaced each time. My apologies, I was under the impression (wrongly) that they had changed spec before TD5 Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted January 5, 2012 Share Posted January 5, 2012 Nothing to apologise about But it does seem to be a common misapprehension. Some say that as the bolts are pretty cheap it is better to change them anyway .... On the other hand, the bolts in my engine are original so may be higher quality than the ****part or Bearmach replacements so I will re-use them when I do my motor (301 000 kms and still going ) You can't tell what steel a bolt is made from by looking at it and so much stuff is made from shoddy metal in India and China nowadays. Quote Link to comment Share on other sites More sharing options...
dc89 Posted January 22, 2012 Share Posted January 22, 2012 hi got the same problem with my landrover discovery 300tdi at the min, can you explain how to check it with the core plug out, is that the black plug at the top of the thermostat housing could the thermostat also the reason why it would do this. Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted January 25, 2012 Author Share Posted January 25, 2012 core plug in the top of te thermo housing, remove and rev, if its bubbling you got a blown head gasket or worse sorry!!! Quote Link to comment Share on other sites More sharing options...
davyd8899 Posted January 26, 2012 Author Share Posted January 26, 2012 just a thought, is it overheating in general or on a long run/under pressure/ high speed? (well high speed for a land rover anyway!!!) if thats the case it might be worth getting the rad checked as well they get blocked, some of the fins corrode and drop off etc. Quote Link to comment Share on other sites More sharing options...
siammike Posted January 30, 2012 Share Posted January 30, 2012 Hi just spent months with over heating and back pressure problems on a 3.9 EFI V8, it turned out that the bolt we had used in an emergency to lock the viscous coupling had sheared and the fan was freewheeling, so the sleepless nights with worries over head and slipping sleeves seems to be over. Here in Northern Thailand we can easily get up in 30-35 digs. Real solution must be twin Kenlows. Quote Link to comment Share on other sites More sharing options...
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