A question on expansion tank

[azeL_Inc]

i read through the forum and found that ppl mentioning about changing/buying expansion tank, for around rm300.The question is,1. why ppl change their expansion tank? could it be all of theirs damaged? or it s better change to new one (stock is not good or whatsoever)2. Should i change mine? My car juz clocked 18000miles3. I dont really know wgat is expansion tank, is it the same as the 'reserve tank' for the radiator coolant?Thanks in advance.*pardon me if this has been discussed before, feel free to point me to existing thread. tq

 

[jarance]

yes, it is the reserve tank for the radiator. Due to the design, the tank is clipped onto the side of the radiator. Being plastic, they tends to failed due to being exposed to heat.

You will also hear of story of expansion crack and result in rapid loss of coolant and cause your engine to overheat.

18,000 M is relative low. If you need to top up water in the radiator every week, then this is the sign to change rubber hose and the expansion tank cos they will start to fail one after another. So the answer is NO.

 

[affan66]

if you just got the car, better change. Then every 2-3 years, change again. No need to worry about hairline cracks causing coolant loss. Better safe than sorry.

 

[BlueMixWhite]

Yes it will crack, just got mine changed. There will be no warning, when it crack it will just bleed coolant when it is hot.

 

[infinityKL]

just changed mine, failed after 11 years...

 

[hakim_radzuan]

i think the expansion tax shud be change every 4-5 years.

 

[Mouse]

recommend to change every 60,000KM regardless if there is lost of coolant or not, its relatively cheap around 300, so dun take the risk

 

[razman]

frens,

Where to get the expansion tank? mine just failed days ago, very small leak, only visible when hot. Just to share, got it fixed for temporary basis. I had it sealed with 2 ton chemical bonding glue 2days ago. It works handsomely thus far. Perhaps i might only change the tank whenever there is a sign of leaking again. The chemical bonding only costs me RM15.00. Good luck.

 

[B33mEr]

It may work handsomely now but later you might hv to pay an ugly price to fix a broken engine ... better change it soon bro.
Google for bavarian auto or stuggart for bmw parts

 

[mizhan]

other than for reliability and effectiveness reasons, a new expansion tank will also make your engine compartment look nice.. :wink:

 

[infinityKL]

RM225... expansion tank

 

[Hellraiser]

18K mileage is relatively low to think of change. people normally change after 60-80K mileage. it doesn't cost very much and it very much comes under normal maintenance.

 

[Mouse]

frens,

Where to get the expansion tank? mine just failed days ago, very small leak, only visible when hot. Just to share, got it fixed for temporary basis. I had it sealed with 2 ton chemical bonding glue 2days ago. It works handsomely thus far. Perhaps i might only change the tank whenever there is a sign of leaking again. The chemical bonding only costs me RM15.00. Good luck.

y take the risk for a expansion tank that cost less than 300

 

[jarance]

y take the risk for a expansion tank that cost less than 300

Yes sound advise..

Repairing a expansion is not a wise decision. Penny wise Pound foolish.

You may save abit at this moment. A crack in the expansion tank is a sign that the lifespan have been reached. Get it change ASAP.

There might be other hairline crack that is not seen. The expansion tank is known to burst without any prior notice. This will result in rapid loss of engine coolant and will cause your engine to overheat.
Believe me, you dont want to be caught in a situation when you have engine overheating.

 

[astroboy]

The tank can crack because its pressurized and the pressure will shoot to the roof if the thermostat fail to open/jam.

Why can't they design the cooling system's reservoir, away from the radiator and connected after the pressure point, above the radiator cap like a breather concept used by JDMs? :stupid:

Pressure is needed in the system because water cooling will be more efficient under pressurized environment, "takat didih"/boiling point will raise above 100 degrees Celsius depending on the pressure, so water won't boil above 100 degrees. Boiling will cause loss of liquid/loss of cooling efficiency. So very bad for the system. That's why one of the performance part for JDM is the radiator cap that has a higher pressure release latch. That also if your radiator can withstand the pressure, otherwise, bocor everywhere.. Too bad that the earlier batches of BMWs designed their reservoir as part of the pressurized system.

I think E90 reservoir design has improved, at least its not part of the radiator.. I am not sure if the have isolated it from the "pressurized system" though?

What I'm trying to say is one must understand the system, then the problem will be less "scary".. and was the problem an "origin" or is it caused by some other failure which u overlooked, and end up not fixing the root cause. Make sure the Thermostats (few of them) are in good working condition, failing which, your reservoir will "pecah"!...which is a good thing, otherwise, your radiator will "pecah".. that time its not few hundred but few thousand to replace. So you should be "thankful"?!

 

[funfer_fahrer]

I just discovered a simple way to prolong the life of the expansion tank. Make sure the coolant level no more than half in the tank. This will give more room for the coolant to expand and less stress on the tank.

 

[astroboy]

lower coolant will result more air in the pressurized enclose cooling system.. I wonder between gas and fluid, which expand more when heated..

 

[funfer_fahrer]

lower coolant will result more air in the pressurized enclose cooling system.. I wonder between gas and fluid, which expand more when heated..

I changed two radiators (expansion tank) in a year by following the 'standard' coolant level recommendation. Yes, there will be more air trapped but there's a valve for the air to escape. The trapped coolant that's going create more pressure. I don't know about you but it works fine with me. Anything less than 2 radiators a year is a plus for me.

 

[Hellraiser]

are we still discussing this issue? "to buy or not to buy ...that is the question" - william shakespear

 

[jarance]

lower coolant will result more air in the pressurized enclose cooling system.. I wonder between gas and fluid, which expand more when heated..

If the expansion tank is "overfill", it will result in overpressure when the coolant expand due to rise in temperature. Please take note water is not compressible whereas air is.

So it is more likely that coolant will splash out when it heated up. Hence do not overfill the expansion tank and bleed it properly to get rid of air lock.