View Full Version : Expansion Tank Problem? Leaking
I have been trying to chase down a coolant leak problem and noticed that there is a drip coming down what appears to be a plastic flange under the expansion tank. Could the tank be cracked? Is there an easy way to check this? Could this be the reason that the coolant level light comes on when the engine is stopped and then reappears only to disappear when you start driving. Any help would be appreciated.
Chris
95 530i, 1975 C-172 M
Espen
02-10-2006, 08:12 AM
I have the same problem, a small drip from the expansiontank... I just bought this car and havent had time to check this out yet.
Let me know if you find it out.
Dave M
02-10-2006, 08:49 AM
Try a search if you haven't. The M50 rads are known to leak at the bottom end of the expansion tank. If you can get your hands on a pressure tester (or bring it to your indy), try checking it under pressure while cold.
Been a while, but I recall aan O-ring in the M50 rad that like to leak. It maybe a matter ofreplacing the expansion tank only, not a tough job.
Dave M
thanks for the reply dave. it is an m60 with the expansion tank mounted on the firewall. i have searched and searched and found alot about overheating but nothing on how to troubleshoot a leak like this.
I have also read about the lower radiator hose needing to be warm. Well the top hose is hot, the bottom is cold but when i run my hand along the face of the radiator it is consistant in its heat distribution.
Chris
Alexlind123
02-10-2006, 09:11 AM
My expansion tank is mounted to the firewall, like yours. It has had a leak for awhile (was going to order one the other day from bmw but they were out of the other part i needed and shipping is free over $50) but it doesnt leak once its down past a certain level. Its really odd though, the cooling system works flawlessly nevertheless.
same here. i believe the smell i get is from the fluid dripping onto the bell housing. But the cooling system is running one tick over center. i have a new fan clutch coming today and will install it over the weekend. i was thinking of making one without the clutch(i own a machine shop) because they seem to be a weak link in this system. i definately do not want to run when anything is leaking.
Chris
calmloki
02-10-2006, 10:47 AM
My '83 533i expansion tank - mounted away from the radiator - split just above the seam joining the upper and lower parts together. Tricky to spot until it was filled above the split and I checked while it was hot and under pressure. Wiping the wet spot with a rag and seeing where it got wet first told the tale. Patching didn't fix it, replacing did.
Tom Walrod
mystical_wings
02-10-2006, 11:55 AM
same here. i believe the smell i get is from the fluid dripping onto the bell housing. But the cooling system is running one tick over center. i have a new fan clutch coming today and will install it over the weekend. i was thinking of making one without the clutch(i own a machine shop) because they seem to be a weak link in this system. i definately do not want to run when anything is leaking.
Chris
DO NOT REMOVE CLUTCH.I did that before on a 300zx and paid the price.The clutch is there so the fan isnt always ,if ever spinning top speed .removing the clutch will strain your engine and severely lessen engine power.Trust me its not a good Idea.
got a new tank from the stealer. will install and advise.
chris
95 530i, 1975 C172m
Your radiator is different than mine (525i) In mine the expansion tank is built into the end of the radiator. It developed a leak in the gasket between the expansion tank and the radiator end.
Kalevera
02-11-2006, 12:13 AM
Do a search. The firewall mounted expansion tank and the coolant hose associated with it are known to fail at the neck.
best, whit
632 Regal
02-11-2006, 01:06 AM
WTF your a chick and noticed this? you should talk to my G-F (Regals slut) she needs some companionship. AND you noticed this??? wow.
DO NOT REMOVE CLUTCH.I did that before on a 300zx and paid the price.The clutch is there so the fan isnt always ,if ever spinning top speed .removing the clutch will strain your engine and severely lessen engine power.Trust me its not a good Idea.
Cambridge
02-11-2006, 11:41 AM
I, too, have the firewall mounted expansion tank. I could actually see it drip now and then from where the hose connected with the tank. I would try all sorts of things to stop the leak (e.g. pushing the hose on the neck further, additional tightening of the clamp, etc.)
As it turns out, there is a metal insert inside the plastic pipe that the hose slides over. The plastic pipe had developed an irregular hairline fracture that followed the circumference of the pipe. So although the plastic pipe didn't fall off the expansion tank (it being held in place by the metal insert) there was no way it could be stopped from slow leaking through the fracture.
Although I briefly considered repairing the fracture, it seemed that the rest of the plastic was also becomming brittle. I replaced the expansion tank and the problem went away. :)
Jeff N.
02-11-2006, 12:11 PM
On the 535 / M30, the tank is two part with a horizontal seam. The seam will will fail leading to an insidiously difficult leak to locate. Only will leak under pressure, slowly and runs down the back of the firewall where it's most difficult to spot.
Do a search. The firewall mounted expansion tank and the coolant hose associated with it are known to fail at the neck.
best, whit
GS535i
02-11-2006, 12:38 PM
On the 535 / M30, the tank is two part with a horizontal seam. The seam will will fail leading to an insidiously difficult leak to locate. Only will leak under pressure, slowly and runs down the back of the firewall where it's most difficult to spot.
My 535i leaked in the fashion Jeff described: the system would pass a pressure test when cold .... but failed when hot. Evidently, the plastic weld would only open under heat/pressure, making it difficult to find - replacement is the only way.
well i replaced the tank and no more problems. The fan doesnt come on low so bma is sending new microfilter, gaskets, coolant level sensor and some other parts. Now its onto the vac leaks, i found some leaks around the front of the intake manifold. suprisingly not in the rear. I think that poor air flow is causing the clutch not to lock up so i need to fiuge out how best to clean it.
Hold on now, are you still overheating? What fan(s) are you referring to? When you say it won't come on low, are you referring to heater fan, aux. fan, or fan clutch? I am getting confused about which fans are an issue here, you talk about the fan clutch and then you mention BMA sending you a microfilter (which could relate to air flow with your HVAC fan). When you mention the fan not coming on "low", this could relate to the two speed auxillary fan in front of the radiator? Aux fan comes on low when you have the AC turned on or if the coolant temp is significantly over 1/2 on the temp dial. The fan clutch typically blows a significant amount of air under the hood after the engine is fully warmed up, or just when starting off, with a cold engine.
What am I missing?
sorry for the confusion.
the fan which is not coming on is the aux fan mounted to the radiator.
microfilter was just a replacement
the fan clutch on the engine is still not completely locking up and i think it has to do with the air flow thru the radiator.
not overheating but it is 1/2 needle past center. it usually resides at center exactly.
your not missing anything i am confusing the issue.
Sorry.
Ok, so are you still overheating? If not, that aux. fan will probably not come on, unless you press the AC button and your AC was working fine before. Are you in warm or cold climate? Not sure how the wiring works on that one, but I think there is a ballast resistor that some have had to replace to get low speed back on the aux. fan. Others may know more on that one.
The fan clutch may not be locking up cuz it is either fried (is there much oily dirty residue on that area?, if so, it could've lost it's fluid), or temp conditions didn't get hot enough to cause it to lock up. Sometimes this can be coolant flow related with either a bad thermostat or block/restricted radiator.
If you're only one needle width past 1/2 mark, and it is steady now, might not be enough to worry about.
the fan doesnt come on with the a/c so its the resistor. i wired it hot and it comes on high only .
the temp is right around 30 here in tennessee
i replaced the clutch 2 times within 1 week thinking it was a bad one.
i think its a flow issue with the radiator. I was thinking about having it flow tested.
Powered by vBulletin® Version 4.2.3 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.