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Discussion Starter · #1 ·
hi people,i was wondering if anyone could help me with my problem.
i was driving along fine when the computer beeped and a message came up saying check water temp or something similar.the temperature gauge was as far up as it could get.
i turned the engine off for a while to let it cool down a bit,it had cooled down about a quarter of the way on the dial.
i started the engine up and the dial went down to the halfway mark.
when i drove off again the temp climbed back up to overheating.
any ideas?
 

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Sounds like a possible airlock-follow this procedure



1.Jack the front of the vehicle up onto stands as high as possible,
2.Turn the ignition on,engine off,heater on fan setting 1 and temperature fully hot,
3.Remove the rad cap/expansion cap,remove the bleed screw from the radiator and IF you have them the bleed screw(s) from the thermostat housing/top hose, return pipe or EGR thermostat.
4.Fill the radiator up and keep pouring till there are no more air bubbles coming out from the bleeds, using a funnel that fits tight in the radiator neck and filling it full of water will help push any troublesome air out, when good you can then install the bleeds and tighten down(don't snap them),ensure the rubber O-rings/seals are still on the screws/on the bleed holes.
5.Suck some water out so it's not full to the brim, replace the cap and then start the car. Run her up and check for heat from the vents when warm and check if over heating still persists. You may have to bleed troublesome cars twice(but rare).
6.If all is good then check the water level again in the morning when cool.

:thumbsup
 

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Discussion Starter · #4 ·
water levels fine,car was at the halfway point on the dials and stayed there,drove it a little bit but nothing major and stayed the same,is it possible the problem(if it was an air lock) cured itself?
 

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You really should bleed the cooling system as there's a good chance there's air in the system, leaving it could mean more over heating problems, :frown.

Once bled, run the car up and check the radiator is getting hot all over and the lower hose is getting hot. When the car is fully up to temperature check the viscous fan doesn't stop easily using a rolled up newspaper, if it stops easy it will need a new viscous fan hub.

Also as the car over heated while driving it would be a good idea to get a block test done just incase http://www.uktools.com/product_info.php?products_id=12508.

Also could you please remember to add the vehicle details in the thread title next time as per forum rules please, they have been done for you this time. It makes it far easier for people looking up help for their own problems or conversions.
 

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Discussion Starter · #10 ·
haha,that was a good one actually.
just dropped it into the local bmw specialist to get a diagnosis(£55 an hour)im thinking some sort of sensor judging by the way it goes up then cools back down once its turned off then on again.
 

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Discussion Starter · #11 ·
right,the fan coupling has stopped working somehow so i'll need a new one of thoses and that has caused the pressure to build up in the pipes which may have caused the head gasket(s) to blow but i will not know until my mechanic gets back monday.in the mean time ive been looking for parts.the bmw specialist has the coupling for around 70 and ive found this gasket online http://cgi.ebay.com/ebaymotors/BMW-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories for $400.does anyone one know if this is the correct gasket and if anyone knows where to find parts cheaper would be helpful.thanks.
 

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The water pump stopping spinning will not under any circumstances I can think of cause a head gasket to blow unless you run out of water and overheat the engine so much that the heads warp. The filler cap has a safety overpressure valve built into it. If that fails plastic parts will break before the head gaskets, including probably the top of the radiator which I think is made of plastic on your car.

Hence I don't think you are going to need a gasket kit, and if you do you will also need the heads to be overhauled or certainly checked.

Before all that, though, you need the cooling system pressure tested (this is simply done using a hand pump and a manometer). Failing fan clutches is a normal problem - they wear out (so don't be tempted to buy a second-hand one). Check the water pump bearing since you are down there anyway.
 

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Discussion Starter · #14 ·
it wasnt the water pump it was the fan coupling at the front of the engine.the guy at the bmw place said that there was enormous pressure built up in the pipe because of the fan not working properly which may cause the gaskets to go(will get a second opinion monday)
 

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So, how high do you think the compression/combustion pressure is compared to water pressure at the temperatures we're talking about? Water pressure will not blow a head gasket (as an isolated factor) - never seen that happen. Other things will break first and release the pressure.
 

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Discussion Starter · #18 ·
yep will do,i think my mechanic does this so ill save some cash and get him to do it.i checked the dipstick and the oil cap and cant see any sign of water in the oil.i only drove it for a few mins twice when it overheated so dont think much if any damage occured.
 

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Discussion Starter · #19 ·
got the car sorted today.changed the fan coupling and hasnt overheated yet after about 10miles so fingers crossed.even though the old coupling seemed fine.(if it happens again i'll assume its the termostat)
so just need the diff flange changed and the car will be mechanically sound.
going to upgrade the brakes aswel.
 
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