Coolant leak

[Converted Steve]

Have a problem that developed a couple of weeks ago, I have a water/coolant leak right at the front of the engine bay; water/coolant is accumulating on the tray at the front of the engine bay. I’m 99% certain that the leak is from either the expansion tank or one of the joints around it.

I’ve looked on euro car parts and they have the expansion tank on discount at £56

http://www.eurocarparts.com/ecp/c/B...8fc72f12f51024d5e8ad14cc79292304e34c56&000125

Several questions I wonder if I can get answered:

How easy is it to fit a new expansion tank?

Do the seals or ‘O’ rings for the joints come as part of the expansion tank?

 

[csm180]

Sounds like your coolant expansion tank. I watched my independent mechanic fit mine after they had replaced the old one for a new BMW oem part. Unfortunately the bottom push in figment hadn't been seated in correctly. This meant when it got to full temp and full pressure it leaked. I would not tackle it myself and he has to try repeated attempts before it connected correctly. I hope this helps. I believe the o rings were part of the tank but that was from a dealer not euro car parts.

 

[Converted Steve]

Sounds like your coolant expansion tank. I watched my independent mechanic fit mine after they had replaced the old one for a new BMW oem part. Unfortunately the bottom push in figment hadn't been seated in correctly. This meant when it got to full temp and full pressure it leaked. I would not tackle it myself and he has to try repeated attempts before it connected correctly. I hope this helps. I believe the o rings were part of the tank but that was from a dealer not euro car parts.

Thanks for your comment 'csm180' i've decided I can't be arsed and haven't really got the time at the moment to do it myself, so am booking it into the local dealer tomorrow

 

[RussellP]

I had exactly the same problem but traced mine to the coolant temp sensor located in the hose, the o ring had deteriorated....

 

[Converted Steve]

I had exactly the same problem but traced mine to the coolant temp sensor located in the hose, the o ring had deteriorated....

Strange you should say that, today I thoroughly dried everything off, the engine under tray, bottom of expansion tank etc, dove car about 3 miles to Torquay lifted bonnet a small pool of coolant had dripped onto engine under tray, I felt up under the expansion tank and it felt like the leak was coming from the part that fits in the bottom of the tank, the expansion tank itself seemed dry.

As it happens someone recommended an Independent BMW Specialist in Torquay today, he takes his 3 series M sport their and says they do a good job so I’m going to ring them first thing in the morning and take the Z over, should be a tad cheaper than the main dealer.

 

[GreyZed]

The expansion tank fits to a 'mounting plate' which is in all honesty a sh1tty design idea as it just introduces additional joints and potential points of failure. If you are going to replace your expansion tank I suggest you also replace the mounting plate at the same time. It is actually very difficult to get the expansion tank out without damaging the mounting plate anyway unless you have a pit or a ramp to give you really good access to apply pressure carefully and in the right direction. The plastic BMW used for these parts goes seriously brittle over time. :thumbsdown:

I have just done this job and I replaced my expansion tank, mounting plate and top hose to be sure as it wasn't possible to identify exactly where the leak was coming from (I could just just see occasional dry residue never any wet areas). BMW use bespoke O ring push fit joints with them nasty wire clips instead of good old fashioned jubilee clips so they can be a nightmare to part and and re-fit (again plastic bits go really brittle).

I did the whole job from the top with the car on the ground so it is do-able as a DIY but I did not enjoy it and it was not easy (and I'm saying this as a relatively accomplished DIY mechanic having built a kit car in the past and done plenty of engine swaps/clutches/prop shafts/CV joints etc. etc.). I started this job thinking 2 hours max including flush and coolant swap but it took twice that! The bottom hose on the other side of the rad was an absolute bitch to get off and even worse to get back on (wish I'd picked up a new one of these too!).

So in summary my advice is pay someone else to do this unless you are confident in your ability. :wink:

 

[GreyZed]

I had exactly the same problem but traced mine to the coolant temp sensor located in the hose, the o ring had deteriorated....

That's on the other side of the engine bay away from the expansion tank.

 

[Converted Steve]

Thanks GreyZed

I would say I am a fairly competent and confident with any vehicle repairs normally, but new to BMW, this is my first one.

I think after reading what you have said its confirmed my decision to take it into an Independent BMW Specialist, I’m doing a 300 + trip to see the family in the Midlands next Saturday and don’t want to have a problem on route and although I’ve got loads of flexi and holiday to take I’m just to busy at work at the moment to have a day off to do it.

Thanks for your advice

 

[GreyZed]

All O rings come pre-fitted to the expansion tank/mounting plate/hose unions btw :wink:

 

[Converted Steve]

Well picked the Zed up 20 minutes ago, turns out it was the expansion tank had a small crack in it at the bottom, under pressure coolant seeped out.

Had new expansion tank fitted, system flushed out and refilled with the correct coolant total cost including parts £177, so I’m well pleased. Labour was £60 so it really wasn’t worth doing myself.

Highly recommend the garage, Five Ways Garage, Independent BMW Specialist, Teignmouth Road, Torquay, Brian the owner is a really nice, friendly, honest and very knowledgeable guy, he will certainly get my business in future

 

[GreyZed]

Well picked the Zed up 20 minutes ago, turns out it was the expansion tank had a small crack in it at the bottom, under pressure coolant seeped out.

Had new expansion tank fitted, system flushed out and refilled with the correct coolant total cost including parts £177, so I’m well pleased. Labour was £60 so it really wasn’t worth doing myself.

Highly recommend the garage, Five Ways Garage, Independent BMW Specialist, Teignmouth Road, Torquay, Brian is a really nice, friendly, honest and very knowledgeable guy, he will certainly get my business in future

Tip top! You did the right thing for the sake of 60 quid! I would have happily paid that for someone to do mine (though I do like getting my hands dirty now and again). Couldn't see any cracks in my old expansion tank but the dried coolant residue on the underside of the bonnet is gone and my coolant level is now static.

Btw if anyone is interested BMW told me that they use the same blue coolant in ALL BMW cars apart from one or two diesel engine versions (one was a Mini). They replace it every 4 years again they said this applies to all cars.

 

[Converted Steve]

Well picked the Zed up 20 minutes ago, turns out it was the expansion tank had a small crack in it at the bottom, under pressure coolant seeped out.

Had new expansion tank fitted, system flushed out and refilled with the correct coolant total cost including parts £177, so I’m well pleased. Labour was £60 so it really wasn’t worth doing myself.

Highly recommend the garage, Five Ways Garage, Independent BMW Specialist, Teignmouth Road, Torquay, Brian is a really nice, friendly, honest and very knowledgeable guy, he will certainly get my business in future

Tip top! You did the right thing for the sake of 60 quid! I would have happily paid that for someone to do mine (though I do like getting my hands dirty now and again). Couldn't see any cracks in my old expansion tank but the dried coolant residue on the underside of the bonnet is gone and my coolant level is now static.

Btw if anyone is interested BMW told me that they use the same blue coolant in ALL BMW cars apart from one or two diesel engine versions (one was a Mini). They replace it every 4 years again they said this applies to all cars.

Yeah the crack in mine was really hairline, looked more like a scratch but water was seeping through it.

Like you I like doing most things myself but like you say for the sake of £60 it just isn’t worth it, also its to bloody cold at the moment, don’t know about you but I feel less inclined to work on my car during the winter unless its something that saves me big money or its got to be done

 

[Shamrock20]

I had this problem and it was fixed with a new expansion tank. The original was a faulty product and cracked but out of warranty. The replacement is an improved type of plastic and works very good. It is easy to replace.

 

[GreyZed]

I had this problem and it was fixed with a new expansion tank. The original was a faulty product and cracked but out of warranty. The replacement is an improved type of plastic and works very good. It is easy to replace.

Sounds like you have had yours replaced with a non OEM alternative part as the BMW ones are identical to factory fit (dark brown plastic). As expansion tank swaps go the Zed is far from 'very easy' imo as you have to remove the front cover and the fan just to see the bloody thing!

I was tempted to go non OEM for my tank as the more conventional opaque white plastic of the aftermarkets does look less brittle but I was concerned about getting a pukka fit on the hoses and clips so went genuine BMW.