14 replies to this topic

[gmulvaney]

Strange overheating issue on motorways but not around the doors

BMW One Diesel
2003

I drove from Newcastle to Liverpool at the weekend, was doing 75mph, steady, until after about an hour I noticed the internal heating was no longer blowing out hot air, but cold, and the water temp was in the red, I slowed down to 65mph and the temp went back to normal, after a further 30 minutes, it began to rise again, so I came off the motoway looking for somewhere to pull over, the temp went back to normal and stayed there, (I was expecting that slowing down, changing gears around the doors, stopping and starting would have increased the temp, instead of decreasing it!?!) Anyway, I couldn't find anywhere open to check the coolant, so carried on a bit further on the motorway, again as soon as I did this the temp went up into the red. Eventually I did find services that were open, the coolant level was very low, (this car had just had a service and MOT approx a week ago, and there was no water leaking underneath or from any part of the engine that I could see, there is no white goo under the oil cap, or any issues I could see with the engine, radiator or hoses, etc). After adding around a litre or more of water, I then started travelling again, and for around 40 minutes the car was fine, 75mph ish, but after 45 mins the overheating started again, and whenever I slowed down or brought my revs under 2000rpm, the water temp went back to normal, but then it started to rise a bit again just before entering Liverpool, as soon as I got into the city, and again started changing gears, stopping and starting, the temp went back to normal and stayed there?!?

The next day, I topped up the water, started her up and watched underneath for any leaks, there were none. Nor was there any steam or water coming from the exhaust. The car seemed fine again, the issue is, that when on a motorway for an extened period of time, for some reason the coolant seems to get used up rapidly causing the car to overheat, however slowing down, or even stopping the car cools it down.

Anyone had anything similar or any ideas what this could be? - I don't think head gasket, as I would have thought the temp would stay up and get worse around lower gear changes and stopping and starting, can't see any leaks either, slightly confusing....

All standard parts...

Thanks..

Edited by gmulvaney, 15 March 2011 - 06:05 PM.

[AndyMiniMad.]

Sounds like you have a leak somewhere that only manifests itself at higher revs. ie: motorway driving. maybe some sort of presure related leak!! sorry but I dont really know much about new mini. Maybe someone here might be able to help. but you might be beter off on the BMW mini forum as most of the guys and girls on here drive the clasic mini. Good luck, hope you get it fixed.

[Dan]

Thanks for posting that answer Andy, Gulfclubby your post has been pruned as innappropriate. Please don't send people away before anyone has had a chance to try and help them or without even trying to help yourself, this forum is open to both Mini and MINI owners and many of our members drive both and may indeed be able to help. We have quite a few members who do know about these cars but they don't get a chance to respond or are worried they'll get flamed if they do. The same rules for the technical section apply to MINI threads, if you can't help don't post.

[TopCatCustom]

Unusual for a diesel to have overheating problems, have you checked the radiator and made sure it isn't rammed full of rubbish? A friend got a freelander really cheap the other week because it had overheating problems, he blew all the crud out of the rad and is it fine!

At low speeds your fans may be keeping it cool but at high speeds the engine relies on the radiator much more.

[Carlos W]

I'd speak to the garage who serviced it, see if they can shed any light!

[gmulvaney]

I did take a look at the radiator the next day when it was running stationary, it had a little dint in it possibly from a stone chip, but nothing out of out of the ordinary, no leaks that I could see, but probably need to check further and have it running for an extended period of time, I've heard that some of the BMW mini's can get air pockets and blockages in the coolant system if not drained correctly or maintaned correctly, it might be something like this, gonna have to get a garage to investigate properly I guess.

[Carlos W]

was anything done to the cooling system as part of the service?

And can you hear the fan running when it's hot?

Edited by Carlos W, 15 March 2011 - 06:41 PM.

[gmulvaney]

Don't think the cooling system was touched to any great degree during the service, (they might of changed the coolant at the most) they may have topped it up at least, I'm gonna ring and check, the fan was going mental once it initially reached the red mark, don't think it went off after that, even if the gauge went back to normal, and the car must have a built in safey feature to cool the air down if the engine overheats, hence the cool air coming through the dash even though the vents were set to hot, unless the fan was causing this?

[Gulfclubby]

Thanks for posting that answer Andy, Gulfclubby your post has been pruned as innappropriate. Please don't send people away before anyone has had a chance to try and help them or without even trying to help yourself, this forum is open to both Mini and MINI owners and many of our members drive both and may indeed be able to help. We have quite a few members who do know about these cars but they don't get a chance to respond or are worried they'll get flamed if they do. The same rules for the technical section apply to MINI threads, if you can't help don't post.

Duly noted.

[MiniLuke]

I had a similar thing on a MINI one. The cold air is due to the heater not receiving any warm water from the cooling system, due to air locks as coolant is lost. I think it was the pump leaking on ours. The fans used to go crazy too.

Not sure about the diesel, but the petrol engine has a safety "mode" when the engine is overheating, where it reduces power to protect itself. It was detailed in the handbook i think, worth having a read. Have you noticed any loss of power at all?

We had ours done under warranty, even though it was out of warranty! Good will gesture as I had had so many problems.. two steering columns, a rack and a gearbox under warranty.

[gmulvaney]

I didn't lose any power or notice any loss in power, but I did notice that if the water temp cooled down sufficently the air temp rose again and went back to normal, but then if the water temp went up again, the air temp went cold again, very odd, but thanks for your feedback.

[Gulfclubby]

I didn't lose any power or notice any loss in power, but I did notice that if the water temp cooled down sufficently the air temp rose again and went back to normal, but then if the water temp went up again, the air temp went cold again, very odd, but thanks for your feedback.

Almost sounds as if the thermostat was fitted in the wrong direction, if that's even possible:)

[designermatt]

sounds like head gasket to me, there is a definate way to test for a head gasket leak, by using a head gasket kit to test for the carbon dioxide coming out of the expansion tank, this is because the exhaust gasses in the pitons is going into the water channels through the headgasket.

but for some reason i dont think it will be a h/g though?

because its a modern car maybe

[Scallywag630]

Thanks for posting that answer Andy, Gulfclubby your post has been pruned as innappropriate. Please don't send people away before anyone has had a chance to try and help them or without even trying to help yourself, this forum is open to both Mini and MINI owners and many of our members drive both and may indeed be able to help. We have quite a few members who do know about these cars but they don't get a chance to respond or are worried they'll get flamed if they do. The same rules for the technical section apply to MINI threads, if you can't help don't post.

Sending a bini owner to a more appropriate forum IS the right thing to do...according to the forum rules!!!!

The BMW MINI


TMF is BMW MINI tolerant and posts that are in any way offensive towards owners of BMW MINI's will be removed and the forum member will be warned. Continual disregarding of this will result in further action being taken.

TMF however is focused on the Classic Mini, therefore it is appropriate to direct any technical advice on BMW MINI's to a more relevant forum if you cannot answer the question. Below is a link to MINI2 - an online community dedicated to the BMW MINI

MINI2

[gmulvaney]

I thought I would add some feedback on what has happened and what has been discovered with my mini, firstly it was left down Liverpool for the week with a BMW specialist, they stripped it down and examined the coolant system, initially they advised that they could not find any issues, and they replaced the thermostat, they checked the water pump and the radiator, and filled the coolant back up, then a day later they advised that they had found a tiny hole on the corner of the radiator, and a small amount of coolant could be seen very slowly dripping out, they also advised that they could see tool marks on the radiator and the expansion tank which suggested that someone else had been examining the car for a coolant issue, (not good!) However the good news, is they patched her up to get my home with some radweld and a new radiator is being fitted today, she never overheated on the return journey yesterday, which I guess confirms that the issue is with the radiator and the radweld worked as a temporary measure to get me home. There was no indication that the head gasket was on its way out, thankfully. Fingers crossed this will be the end of it....