e34 Coolant Leak

[Vanguard]

I'm looking at buying my uncle's '94 530i (M60) with 98K miles on it. I've been driving it for the past couple of weeks and noticed that it seems to be leaking coolant intermittently. I'm pretty comfortable with the car otherwise, but want to make sure this gets addresses. The coolant leak seems to be coming from the middle to the back of the motor. Up front around the waterpump and radiator hoses seem dry.

Any suggestions at what to look for?

[genphreak]

I've never worked on the V8, but mine has the same overflow tank. Oftentimes as the car gets older this needs to be reaplced as the main connection to the radiator (the one underneath the tank) cracks (usually due to someone over-tightening the connection. Of course a dealer would never do such a thing (well it might be less likely) but many mechanics seem to over-tighten the hose clamps that hold down the rubber coolant hoses over plastic necks. These I imagine are people that learned how to fix radiators on cars with metal components- where one could tighten it up so much the hose rubber would be compounded to death. In the case of most BMWs, the necks crack either during tightening or a subsequent heating/cooling cycle. A brand new tank costs somehting like $60 and is easy to install. Be extra careful not to break the brittle 'pisser' line that feeds from just udner the cap, the other hose there is the overflow line which leaks excess coolant out to under the fender on the passenger side. The cap might be faulty (there was a recall on these I think even on your car). But it might be a coolant hose also, there is one on the back of the motor which I think is notorious and dificult. If the car is new to you I would be changing all the coolant hoses and making sure the connections are smooth, clean, not over-tightened and properly sealed. Do a coolant flush at the same time (make absolutely sure you use Original BMW coolant). It will cost a few hundred bucks to do it all (doing the water pump and thermostat is sensible also) but on an old BMW believe me you want this kind of insurance, it will save you from overheating which can cost thousands as the head gaskets are specilaised jobs that often require much labour and other parts.
http://i96.photobucket.com/albums/l164/genphreak/Radiator-TopConBroken.jpg

All the hoses are wear items anyway. Doing all this is one go would give you reliability with which you can enjoy one of the best cars ever put on the road ;) Nick

[genphreak]

If you can't find the leak in the engine compartment it might be the heater core within the cabin itself. The fan blower blows air through it to warm the cabin when you turn up the cabin thermostats. The cores are plumbed with o-ringed pipe seals, many find the o-rings perish/leak but replace the heater core also as it is in the middle of the dash and can be the source of the leak itself as they can corrode from the inside out (especially if the coolant has not been changed every 2 years or is one of the many incorrect types).

The core is a pretty big job to get to and replace. But its $150 odd for a new core, add some pipes perhaps so still a sub $200 job... If leaking
you can notice a smell of coolant through the fan blower (esepcially if heating), or the leak tray will spill coolant under the car, or it can spray out once the engine is warm and send up soaking the carpet in the cabin.

Best to find the source of the leak I guess :) Nick

[Vanguard]

There's no smell of coolant in the cabin. So I hope I'm safe on the heater core. I guess I need to get under the reservoir tank and check it. It looks pretty grungy and it's hard to tell the coolant level from the outside.

[Vanguard]

http://www.realoem.com/bmw/diagrams/c/k/4.png

It looks like its number 10. But I can't find the part listed at pelicanparts or bav auto. Is this a dealer only part?


http://www.universal5.com/gallery/main.php/d/80-1/DSC01663.JPG

Top portion of the hose.

http://www.universal5.com/gallery/main.php/d/76-1/DSC01670.JPG

If you look in the upper middle just to the left on this one, you can see the white residue on the hose.

[632 Regal]

BMAparts had all the hoses.
http://www.realoem.com/bmw/diagrams/c/k/4.png

It looks like its number 10. But I can't find the part listed at pelicanparts or bav auto. Is this a dealer only part?


http://www.universal5.com/gallery/main.php/d/80-1/DSC01663.JPG

Top portion of the hose.

http://www.universal5.com/gallery/main.php/d/76-1/DSC01670.JPG

If you look in the upper middle just to the left on this one, you can see the white residue on the hose.

[Vanguard]

It was the three way hose. Local foreign auto parts place had the hose, a new expansion tank and cap. Fixed it right up.

[CharlesAFerg]

It was the three way hose. Local foreign auto parts place had the hose, a new expansion tank and cap. Fixed it right up.

My car not only smells of coolant, my windows get horrendously fogged and streaky, it evaporates into my car lol.