BMW 740I M62 Cooling System Problems |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Posted: 12-November-2007 at 13:31 |
Hi All I am now the proud owner of a 1998 E38 740I with just under 100000miles on the clock ... Will get pics and stats up ASAP, but just wanted to get opinions on a problem that the car has...? When I was driving it back from the dealership, I made sure that the expansion tank was full! The car had no problems on the way home, which was about 40 miles. As I turned into the driveway and was waiting for the gate to open, the engine temp suddenly started rapidly moving towards the 3/4 mark. I quickly got the car inside and heard the aux fan had kicked in. I then parked the car and left it to cool down for about 4 hours. I went back to it and slowly opened the expansion cap. The expansion tank was bone dry and there was a gurgling/hissing sound coming from the bottom. I then went back to it the next morning and was able to add another 1.5 litres of coolant back into it... I replaced the fan clutch and radiator cap on Saturday afternoon as the clutch was def shot!!! I then started driving the car again. It was fine for the whole of Sunday, when I drove about 50 miles, and then it started to act weird while I was driving home. The temp needle would move about 3mm over the centre line and about 30 seconds later, it would move back again to the centre line. It did not do anything while I was sitting at the traffic light though! When I opened the expansion tank cap again this morning, the tank was bone dry again...meaning the car had boiled about 2 litres in 50 miles of driving...no sign of visible coolant leaks in engine bay... The only thing I get is that after I park and smell the front of the car, around the kidney grill area, I can smell hot coolant. I can also hear a weird hissing\cracking\popping sound from the right side of the radiator..which is the opposite side from the expansion tank! The hoses dont seem to be too hard and after about 7-8 hours, they have gone back to their normal size and can be easily squashed... Please tell me that this does not sound like a blown head\headgasket ... I assume the car is getting hot because all the cololant is dissapearing out the radiator...but where to is a mystery??? Any ideas??? PLEASE Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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Rhys
Moderator Group Coffee addict... Joined: 02-February-2003 Location: from the Latin locātiō Status: Offline Points: 10053 |
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Haven't got a hole in the rad have you?
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V reg Rustbucket Merc C220 Cdi estate
J Reg Saab 900i 16v '63 Ford Anglia 105e deluxe R reg Honda PC50 moped.. No BMW as yet... |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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I know this may sound very stupid...but how would I tell as most of the forward facing part of the radiator is covered up? If I remove the radiator, how would I tell where the leak was being as I could not get it pressurised? Is it normal to hear that sort of cracking\popping sound from the V8's cooling system...? Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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Rhys
Moderator Group Coffee addict... Joined: 02-February-2003 Location: from the Latin locātiō Status: Offline Points: 10053 |
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Never really looked at an E38 rad, so didn't know they were covered up etc. Had a rad go on a Citroen van, we put in rad-weld but that didn't work, at least it showed us where the problem was (it was totally knackered lol) Hope it's not much of a problem in the end |
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V reg Rustbucket Merc C220 Cdi estate
J Reg Saab 900i 16v '63 Ford Anglia 105e deluxe R reg Honda PC50 moped.. No BMW as yet... |
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Sporty1
Really Senior Member II Joined: 18-October-2006 Location: Hertfordshire, United Kingdom Status: Offline Points: 2297 |
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Bleed the system thoroughly/completely, check stat operation, any hole in the rad would be obvious as steam or pool of water, especially if it's using 2 litres of water over 50 miles. Congrat's on the 7... hope the problem is not something more sinister........ have you informed the selling dealer of the problems or does it not work like that in SA? |
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Sport Evolution Schwarz #043 |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Hi Guys Thanks for the replies ... So what you are saying is that if the car is loosing that much water from the radiator, I would be able to see it leaking underneath the car while it is parked? I have not seen any steam coming from underneath the bonnet, but I do hear that hissing\crackling sound from one side of the radiator...and the smell of coolant... Is it possible that air in the system would cause problems...like the coolant loss? I can actually see some evidence of a leak at the thermostat, but it looks like it is old coolant. I suppose, based on the cost, I should just replace this part anyway. The car does warm up very quickly and the top hose of the rad is very hot, so I guess it is working...but as I say, based on cost, may aswell try it. Is it worth removing the radiator from the car and giving it a good clean out and flushing...or should I just leave it alone??? Many Thanks BB Edit: How hard is the M62 engine to bleed? Is it anywhere near as fun as an M50??? Edited by BeemaBoy |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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m3tiko
Really Senior Member II Joined: 29-May-2005 Location: Braveheart Country..aka Pai Status: Offline Points: 1483 |
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No expert on this...but suffered this with a fellow boarder on a 728i E38.
Almost identical....mine first displayed check coolant level, checked and running smooth again.Couple of hours later, same again....Took it BM Motors who suggested a "possible computer error"....and that it's probably advisable to flush and bleed the system just to be on safe side. All done as suggested, 20 mins into the drive needle on red once again. At this point, the message changed to now check coolant temperature.....That was enough for me to just park it up and get AA to give it a look over.Lucky me he was an ex bmw-tech or was it lol....some quick tests performed. First of all checked water pump by taking off cap etc...Then removed oil cap and looked for any suspect "mayo look". Nothing shown then....final "watched this", he said...2 minutes later with the engine idle all coolant mixed with specs of oil decided to come spurting out.... HEAD GASKET KAPOOT!!!!! |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Hi Guys The thing is, that the car has never actually overheated or got anywhere near the red zone. I dont notice anything that looks like oil in the coolant and nothing that looks like coolant in the oil. The hoses do seem to be quite hard, but after checking the 525I, they seem about the same. They also start to get soft after about 4 hours of sitting and are very squashable after about 8 hours of sitting, which is about the same as the 7. Now, when the headgasket went on the 525I, the hoses would stay hard no matter what until I undid the expansion tank cap. After this, a lot of air would come whooshing out... There is none of this on the 7... Just a sucking gurgling sound when I take the cap off... The 525I would also be at centre gauge while driving and would then suddenly race towards the red zone... That was a failure between the combustion chamber and the coolant passage...which caused air bubbles in the system which would eventually create an air pocket at the thermostat and cause the car to overheat! Funny thing is that there are no signs of this on the 7...just a major coolant loss... Could a leak in the cooling system cause temperature fluctuations? Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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bmw1066
Really Senior Member II GOOD OLD E23 Joined: 16-January-2005 Location: West Sussex Nr Brighton Status: Offline Points: 1095 |
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sound's like a air lock, have you checked inside for a possable heater matrix. you could also get a block test dun simpol 5 min job to see if the heads gon. Hope she's OK |
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Mark 735 se 1982
RED BARON A E23 is for life not just for x-mas BMW e34 530 v8 Sport kit Spelling always Bad |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Hi All Thanks for the replies... Got some news... Took the car to a friend of mine and got his dad to have a look around the radiator to see if he could see any obvious problems. After about 5 minutes of looking he pointed out a coolant drip at the passanger side of the radiator. With the engine off, it was letting a drip out about every 10 seconds...dripping down onto the sump guard, which is why I did not notice it on the floor after I parked the car... I assume that any leak in the radiator will almost certainly cause a loss in coolant, which I assume wil result in a overheating problem if there is no coolant in the radiator? I am really hoping that this is the cause ...as a radiator is much cheaper than a new head! Do you guys think I should bother getting it repaired or just buy a new one from BMW? I wil get a new thermostat at the same time aswell as the cover and then refilll the system with coolant and then bleed, bleed, bleed to make sure there are no bubbles Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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doogie
Groupie Joined: 02-May-2007 Location: Barrhead Status: Offline Points: 80 |
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Hiya,
Sorry to hear about your troubles! I'm not familiar with the M62 only having had M20 and M30 engined cars. If you want to keep the car for the forseeable future, then a new rad is obviously the right way to go, obviously aftermarket from an ebay dealer or rad specialist is probably a lot cheaper than original, although if you're in Jo'berg according to your location I don't know what your local options will be. For the short term/ quick fix you can either just rattle in a couple of litres before every trip (as long as they're short!) or put in some radweld or similar which may or may not work, but could potentially cause other problems in the cooling system(I don't know if your water pump has a plastic or metal impeller) Have you joined over at www.the7seriesregister.co.uk yet? |
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16 Feet of pure pleasure DB02157, 01/90 E32 730i Calypso Red, single-point StarGas LPG conversion, Mac Mini on board |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Hey doogie There is a 7seriesregister ... I will be there now ...thanks for pointing that out... In terms of the rad...I have heard horror stories about using radweld...so will not be going that route... I have found a local radiator guy that sells BEHR radiators...and he has stock of the E38 ones...so popping by on Friday to pick on up... One worrying thing...I plan to change the rad myself, but after reading stories on removing them from M60 E34s...it sounds quite hard! What is all this business of removing the ATF cooling lines and having to replace the seals on them. They then tell you to check the ATF level afterwards...??? How do you do that on an E38 ...let alone fill it if I have spilled any? Is it possible to do the job without disconneting these lines or am I making something sound difficult when it actualy is not? Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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doogie
Groupie Joined: 02-May-2007 Location: Barrhead Status: Offline Points: 80 |
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Hiya, I don't know about the ATF deal on those engines, but someone on the 7 register will almost certainly have an answer!
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16 Feet of pure pleasure DB02157, 01/90 E32 730i Calypso Red, single-point StarGas LPG conversion, Mac Mini on board |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Well guys, it looks like the radiator... I decided to pull it out the car and you can clearly see that the plastic side of it has split away from the metal fins...which was gushing coolant all over the splash guard...!!! It also appears that the part of the radiator that faces the engine has got small holes all over it...which are evident by little green marks of coolant all over the fins... The most worrying thing is that the radiator is only 3 years old according to the label on it ... Please tell me that a 740I radiator lasts longer that 3 years!!! The guy at the radiator place could not explain what had happened, except that he said I should bring the car in and have the "Circulation" tested??? What would that have to do with a failing radiator? Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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Sporty1
Really Senior Member II Joined: 18-October-2006 Location: Hertfordshire, United Kingdom Status: Offline Points: 2297 |
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Poor circulation of coolant would be down to the water pump....... would it not? Is that a genuine BMW radiator or a 'cheaper' pattern part?
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Sport Evolution Schwarz #043 |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Hey Sporty1 I would have thought that poor circulation is either down to a shot water pump, blocked radiator or a shot stat? But would any of these cause the amount of damage that has happened to my radiator, and if so, what has it done to the engine ? The one that I got out of the car is a Behr, supplied by the radiator specialist that I am going to now (Silverton). By looking at the one that my friend bought from BMW for his 5 Series, they are both Behr...and were roughly the same price...infact BMW was cheaper! Not the case on my 740I though! BMW wants in the range of double what the 5 Series radiator cost my friend...which seems ridiculous...expensive parts for a supposedly expensive car! Will be getting the radiator today and probably putting it in tomorrow evening. Will let you all know the results... Many Thanks BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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bmw1066
Really Senior Member II GOOD OLD E23 Joined: 16-January-2005 Location: West Sussex Nr Brighton Status: Offline Points: 1095 |
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Hope it all goes well
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Mark 735 se 1982
RED BARON A E23 is for life not just for x-mas BMW e34 530 v8 Sport kit Spelling always Bad |
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BeemaBoy
Really Senior Member II Starting a Collection Joined: 25-October-2004 Location: Johannesburg, South Africa Status: Offline Points: 927 |
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Hi guys Thanks bmw1066 for the support... I am happy to report that all did go well... Picked up the new rad on Tuesday and installed in lastnight. Took me about +- 2 hours and I also cleaned the MAF out while I was there. Managed to add about 9 Litres back into the system which sounds ok as I did not drain the block... Started the car with the heaters on full and bled the system. Dont seem to be any more bubbles comeing out the bleed screw and she warmed up very quickly, got to centre mark and did not move...even when revved a few times. Will check when I get home now to make sure that the coolant tank is topped up and then I will go for a spin... There are also no more hissing and cracking sounds coming from the front of the grille...so for now, all looks good ... Thanks for all the great help and advice guys Now, just to fix the staring issue...and then she will be drivable BB |
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87 E30 320I
95 E34 525I Auto, Executive Package, Arctic Silver 98 E38 740I Steptronic, Silver |
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