DAN82SED Posted September 18, 2011 Share Posted September 18, 2011 i think my cooling system is holding to much pressure. the hose pictured started with a small leak from the plastic middle piece before shearing of. the engine was barly upto normal temperature when it happend! the part that separated was brand new (only done about 100miles) At the same time i replaced the hose i also fitted a new cap to my allisport header tank because it was leaking coolent through it. my concern is the fit of the cap on the thread of the header tank because the new one still leaked, so i tightened it as hard as i could by hand, and then this happened! any ideas guys??? Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 18, 2011 Author Share Posted September 18, 2011 forgot to attach picture Quote Link to comment Share on other sites More sharing options...
Litch Posted September 18, 2011 Share Posted September 18, 2011 Obvious answer is that the system is over-pressurising and when you effectivly sealed the header tank the next leakest link in the chain broke. I have to admit that I can't see over-tightening the cap would stop the pressure-relief working (looks like a standard cap, was it?) but I guess it must have hence the failure of the pipe. You will have to find out what is causing the over-pressurisation. Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 18, 2011 Author Share Posted September 18, 2011 thanks litch, the cap was a standard cap but it doesnt seam to fit to the alli tank as well as it would to the standard plastic. what would you recommend checking? all i can think is head gasket! Quote Link to comment Share on other sites More sharing options...
Litch Posted September 19, 2011 Share Posted September 19, 2011 I use a standard cap on my identical Allisport tank and that seals perfectly, if yours has been leaking (rather than venting excess pressure) I would try a new cap. I think you will probably have to assume head gasket, i'm no expert but are there any other symptoms? Why did you replace the hose and had there been any problems prior to that? Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 19, 2011 Author Share Posted September 19, 2011 the cap is a new one (changed the same time as the hose) but i wasn't able to see if it still leaked before the hose came in half. the reason for changing it in the first place was it was scuffed quite badly by the fan and started leaking (the fan shroud isnt fitted) i got a glimmer of hope that it is just a faltly hose because i returned it today and got a new one, the guy said im not the first one hes seen it happen to (im the thrid). im going to fit it and run the engine without the fan so i can check for blowing around gasket other issue i had, might be related, is the oil warning light sometimes comes on when engine is up to temerature, but only on idle. i have changed oil which seemed to sort that but came on again the day before the hose blew Quote Link to comment Share on other sites More sharing options...
Mutz Posted September 20, 2011 Share Posted September 20, 2011 The 300tdi i have had the same symptoms of the oil light flickering on although the oil was at the correct level, when it had a gauge connected it was found to have very little oil pressure on tick over or even at low revs. Suggest you check the oil pressure. the fault with mine was a cam bearing had worn and moved.. Surely if you start the engine from cold with out the header tank cap on if the gasket has gone and you are getting pressure from the cylinders the water will blow out, i have had this on other vehicles. HTH Graham Quote Link to comment Share on other sites More sharing options...
Tanuki Posted September 20, 2011 Share Posted September 20, 2011 Run the engine up from cold with the cap removed - if there's any significant bubbling in the expansion bottle you have a head-gasket issue. If there's no bubbling, check that the pressure-relief in the pressure-cap is working. If you don't provide a path for coolant-expansion pressure to be relieved as the engine warms up, something's gonna burst! In practice, I can drive my TD5 for 350 miles up the M5/M6 in summer while towing a 3-ton trailer with the expansion-tank pressure cap completely missing (ahem! who forgot to re-fit it?) and not lose any coolant at all. --Tanuki. "Badgers - always part of the problem, never part of the answer" Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 20, 2011 Author Share Posted September 20, 2011 cheers graham, think you're right. i replaced the hose today and bleed the system, ran the engine with the cap off and no sign of blowing. i also removed the fan to check around the head and found no evidence of leaks (other than rocker cover) so fingers crossed it was just a duff hose! with regards oil pressure, the oil light has only been doing its flicking thing once since the oil change, and ive now discovered that the sump was dripping. it has been about 2 months since checking the oil was on max and it had dopped to about 1/3 the distance between min and max. any ideas how low the oil needs to be before the warning light comes on? also, how big a job was the cam bearing? Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 20, 2011 Author Share Posted September 20, 2011 cheer tanuki, might sound like a stupid question, but how can you tell if the cap is working? im pretty new to this mechanics lark Quote Link to comment Share on other sites More sharing options...
cackshifter Posted September 20, 2011 Share Posted September 20, 2011 If your oil light is flickering, yes, if you have a gauge test the pressure, but I have had this twice and both times it has been a duff oil pressure switch, a quick cheap fix. Assuming you are using engine oil 5W/40 -15W/40 and not 30 (that would do it) Nigel Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted September 20, 2011 Share Posted September 20, 2011 If the oil light comes on whilst you're driving, it's usually too late to prevent damage, so check levels regularly. Mo Quote Link to comment Share on other sites More sharing options...
Mutz Posted September 20, 2011 Share Posted September 20, 2011 with regards oil pressure, the oil light has only been doing its flicking thing once since the oil change, and ive now discovered that the sump was dripping. it has been about 2 months since checking the oil was on max and it had dopped to about 1/3 the distance between min and max. any ideas how low the oil needs to be before the warning light comes on? also, how big a job was the cam bearing? I bought the 90 off a friend who had a quote for doing all the work to repair the cam bearing (the single bearing is about £4 ) Its a BIG job, engine out and complete strip down to the bare block before the engineers would do it, and obviously a rebuild once done. They quoted between £1700-£2000. Hence i got my 90 really cheap, i did it myself apart from having the new cam bearings put in and honed, and cost was about £600, but i did replace all the bearings, bolts etc at the same time. I have an oil gauge fitted in place of the clock now as its far more accurate than waiting for a little light to come on to tell me its too late!!! Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 20, 2011 Author Share Posted September 20, 2011 If your oil light is flickering, yes, if you have a gauge test the pressure, but I have had this twice and both times it has been a duff oil pressure switch, a quick cheap fix. Assuming you are using engine oil 5W/40 -15W/40 and not 30 (that would do it) Nigel cheers nigel, ill pick up a new switch and try it tomorrow. i was told to use 15w/40 due to millage being 167,000 If the oil light comes on whilst you're driving, it's usually too late to prevent damage, so check levels regularly. Mo will do mo, i did have a drip from the sump but i was alarmed when i checked the level after only a couple of months I bought the 90 off a friend who had a quote for doing all the work to repair the cam bearing (the single bearing is about £4 ) Its a BIG job, engine out and complete strip down to the bare block before the engineers would do it, and obviously a rebuild once done. They quoted between £1700-£2000. Hence i got my 90 really cheap, i did it myself apart from having the new cam bearings put in and honed, and cost was about £600, but i did replace all the bearings, bolts etc at the same time. I have an oil gauge fitted in place of the clock now as its far more accurate than waiting for a little light to come on to tell me its too late!!! cheers mutz, had read that it could relate to bottom end trouble, but really hoping it isnt! sounds way to complicated for me, if that is the case, will be looking at getting a good secondhand engine rather than fix it. the idea of tackling the head gasket was duanting enough Quote Link to comment Share on other sites More sharing options...
cackshifter Posted September 20, 2011 Share Posted September 20, 2011 cheers nigel, ill pick up a new switch and try it tomorrow. i was told to use 15w/40 due to millage being 167,000 When it's hot it's the 40 bit that counts. When it's cold the 5 or 15 counts. 40 is what it is designed for at about 90 deg. That's way thinner than 5 or 15 at zero. I have a 300tdi with 163k running very well on 5w/40. The oil pressure light goes out very quickly when cold. I have tried 15/40 and on frosty mornings it took an age to get pressure up ; it had to go. If you think it needs thicker oil because of wear you'll need to look at say a 10w/50. However if you truly aren't getting much pressure, the turbo and pistons will suffer eventually (no cooling flow etc) , so best to check with a gauge if poss. I think the switch thread is M10 x1 Nigel Quote Link to comment Share on other sites More sharing options...
DAN82SED Posted September 20, 2011 Author Share Posted September 20, 2011 cheers nigel, i didnt know what the difference between the oils were. think i might have been mis guided with 15w/40 . the issue i have is when the engine is up to tempurature, when cold, on start up the light goes straight out. will change the sender, and if it is still happening, it will be purchasing some 10w/50 i have been checking out pressure guages on tinternet, dont like the price, but might have to be done Quote Link to comment Share on other sites More sharing options...
Mutz Posted September 20, 2011 Share Posted September 20, 2011 Yes i wish i had gone down that route with another engine Quote Link to comment Share on other sites More sharing options...
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