radiator problem..

[irdanlz84]

salam n good day,hello fellow sifus...the story goes like this, 3 month back, my "check coolant level" lights appear, then i check the expansion tank, the level was far below "kalt" level, so i topup the water without opening the bleeder nut. After driving about 2-3 days, the car overheat, water steam can be seen gone out from the expansion tank cap, so i assume that either the cap kaput or i did not close the cap properly..Then my brother in law send the car to a radiator shop, what they do is they detached the radiator and check for leakages.. seems everything is ok, so they fill in new coolant and water... They came out with a conclusion that i topup the radiator without opening the bleeder screw.. therefore, the added water somehow cannot join in the system.. and came out thru the expansion tank cap... (the worksyop is not a bmw workshop, but do mainly on radiators)So now radiator flushed, system back to normal..month later the "check coolant level" lights appear again, When i checked the tank, the coolant level is far below "kalt" again...this time I topup the radiator With the bleeder nut opened..The warning light came off only for a day then it went on..When the engine is cold, i check the coolant level...again, the coolant level is far below "kalt" but when i open the bleeder screw, the coolant level rise to "kalt"...Now every day the "Check Coolant level" light appear during start up, and during the engine turned off..And every day i check the coolant level:Expansion tank cap open & Bleeder screw close = coolant Level far below "kalt"Expansion tank cap open & Bleeder screw open = coolant level reach "kalt"During operating temperature, the level cannot be seen, bcos the plastic tank become cloudy already, can't see through it..Is this normal? or my expansion tank kaput? Warning light "Check Coolant Level" still appears... got anything to do with sensors?plus the temperature needle is slightly pass middle mark (very little)..the engine seems running quite fine i guess..so now really pening with this matter and really hope that all the sifus around can help me solve this prob.. thanks a lot =)

 

[Eby]

My mechanic was telling me to be extra careful with opening the radiator cap when the engine overheats as air can get trapped in the cooling system, making it more likely to get overheat the next time. Don't know how true it is but better be safe than sorry.
The last time I encountered overheating, I got the expansion tank and sensor changed.
Never encountered your problem before...... maybe the GURUs can shed some light......:listen:

 

[Crymson]

I'm no sifu but here's what I've experienced so far. Others please correct me if I'm wrong.

plus the temperature needle is slightly pass middle mark (very little)..the engine seems running quite fine i guess..

I too have the same mark. But if you fill up your coolant with filtered water /distilled water this should move the mark to the middle or slightly lower the middle. (I hope you understand). Do a search about coolant in the forum.

What I mean filtered water is if your house is equiped with a filter at the main pipe, your hose water will do.

When topping up your coolant, you should open your expansion tank cap and the bleeder screw. You will need to bleed air out of your radiator. Fill the expansion tank until the level reaches to the marked point and until fluid begins coming out of the bleed screw. At the bleed screw, you should see bubbles coming up. Continue filling until there are no more bubbles coming out. When no more bubbles exit out of the bleed screw, tighten it to 8 Nm (71 in-lb). Now, run the engine until it reaches it's operating temperature. Turn off the engine and let it cool down. Then, top off the coolant in the expansion tank to the appropriate level, if necessary.

At your first topup, make sure your engine have cooled down.

 

[irdanlz84]

i see.. thanks for the responds guys... so the conlusion :

When topup the coolant, bleeder screw open is it?
cos i thought i read somewhere in this forum, someone mentioned that for topup the coolant, no need to open bleeder screw, however during flushing and refill then you open the bleeder screw during the refill.... care to elaborate on this guys?

One more thing, this morning during the engine is cold, i opened the expansion tank cap without opening the bleeder screw (closed), initially the expansion tank is almost empty, however after waiting for a while (2-3 seconds) , Sound of water filling up the expansion tank can be heard, finally the water level reach the "kalt"/ "cold" level... is this normal?

is the coolant level should be around "cold" / "kalt" all the time, during the engine is cold and the cap opened and closed?

Thanks in advance.. =)

 

[LCP]

I thought the coolant level (when the engine is cold before any starting) on the expasion tank is always steady, should not be moving when you open up the cap. I think something is not right, possibly some blockages or trapped air.

 

[LCP]

I don't think there's a need to open the bleeder screw just for topping up the level in the expansion tank, no mention of this in the user manual.

 

[wc9922]

LCP : The owner manual is too simplified.

You have to open the bleed screw to let the air out.

Never overfill the expansion tank. Just above the indicated mark will do. This is for air gap for the hot water to expand. If you fill to the brim, the hot water when engine is running hot will expand and overpressure overpressure the cooling system.

what happens next is coolant going to overflow through your radiator cap! And you think u have overheating. Just at the mark will do.

Next think when you close the radioator cap, tighten to max you can turn, something like jamming it. Unlike japanese cars, the radiator cap has to be tighten quite a bit, not just hand tight.

Don't worry about the water level exactly. around the mark or below slightly should be ok. But if your expansion tank is always nearly empty after a few a days then have to do a pressure test to see where is leaking.

hope this helps.

 

[Alan Teh]

LCP : The owner manual is too simplified.

You have to open the bleed screw to let the air out.

Never overfill the expansion tank. Just above the indicated mark will do. This is for air gap for the hot water to expand. If you fill to the brim, the hot water when engine is running hot will expand and overpressure overpressure the cooling system.

what happens next is coolant going to overflow through your radiator cap! And you think u have overheating. Just at the mark will do.

Next think when you close the radioator cap, tighten to max you can turn, something like jamming it. Unlike japanese cars, the radiator cap has to be tighten quite a bit, not just hand tight.

Don't worry about the water level exactly. around the mark or below slightly should be ok. But if your expansion tank is always nearly empty after a few a days then have to do a pressure test to see where is leaking.

hope this helps.

Totally agree

 

[LCP]

Okay, I re-read the Haynes and Bentley service manuals again, for just topping-up there is no need to open the bleed screw, but if there has been any draining of coolant for some radiator or related cooling system work, then it is a must to open the bleed screw.

I think car manufacturers including BMW would have thought long about this, not everyone who owns a car is technically inclined to be able to do and understand an air bleed procedure, that is why the bleed screw is a recessed screw, not meant for regular usage.

 

[LCP]

Yes, on the levels... just approx on the COLD mark will do, slightly above (maybe 1-2cm or less) or below is okay.

Btw, there is a bypass outlet to let out excessive coolant, not necessary through the cap.

 

[irdanlz84]

I thought the coolant level (when the engine is cold before any starting) on the expasion tank is always steady, should not be moving when you open up the cap. I think something is not right, possibly some blockages or trapped air.

Agree with you bro, i think must be something going wrong with the pressurize mechanism of the system,

So it is confirmed that during the engine cold, the coolant level should maintain at all time, with the radiator cap on, or removed rite?

am going to do pressure test as recommend by bro wc9922...

thanks for the info guys, will update on this prob for the benefit of other forumers.. for the time being, if anybody have any thoughts on this matter, feel free to add :wink:

 

[LCP]

So it is confirmed that during the engine cold, the coolant level should maintain at all time, with the radiator cap on, or removed rite?

Yep, that is also the reason why the expansion tank is made translucent, so you can see the level without having to open up the cap... the plastic on mine has turned very yellow though. So, obviously the level should be steady all the time, no sudden or fast change unless there is a problem.

am going to do pressure test as recommend by bro wc9922...

Go ahead, these are basic tests to determine leaks.

 

[irdanlz84]

update...went to a workshop today, found out that the thermostat cover cracked, need to change the whole set + black hose (rust accumulate badly), also found out the o2 sensor and knock sensor fault also... need to change, then the valve cover gasket already leak... looks like more money will be spend.. haiyoo =(

 

[LCP]

Good, at least it got diagnosed... I think German things have a habit to crack...

And hey, while you are at it, get those silicon radiator hoses, if budget permits and there's one for your car model, they last much much longer, and makes your engine bay looks like one on a race car...

 

[chairoger]

Okay, I re-read the Haynes and Bentley service manuals again, for just topping-up there is no need to open the bleed screw, but if there has been any draining of coolant for some radiator or related cooling system work, then it is a must to open the bleed screw.

I think car manufacturers including BMW would have thought long about this, not everyone who owns a car is technically inclined to be able to do and understand an air bleed procedure, that is why the bleed screw is a recessed screw, not meant for regular usage.

Yup,where got people open the bleed screw just to do a bit of top up one. Got do pressure test on the cooling system? Maybe got leak in one of the hoses or radiator got hairline crack

 

[irdanlz84]

Good, at least it got diagnosed... I think German things have a habit to crack...

And hey, while you are at it, get those silicon radiator hoses, if budget permits and there's one for your car model, they last much much longer, and makes your engine bay looks like one on a race car...

hehe, tight budget ar bro... will stick to the black one.. spent almost 3k at the workshop... done injector cleaning, decarb, change several parts and change the faulty sensors (there are broken to pieces).. the more you open the engine, the more faulty parts that you will find =( .. anyway the car now runs very2 well... smooth~.. anyway thanks a lot to all bros for the help and infos.. :rock:

 

[jarance]

Please do a pressure check on the expansion tank and the cooling system. Most workshop will removed the radiator and connect a handpump with a gauge. The will pump air and pressurise the expansion tank and the cooling system. If there is a leak, the pressure will drop indicating a leak somewhere.
However, based on my experience with an E36, the pressure test does not really can confirmed that there is NO leak in the cooling system. A very clear indication is when you have to top up the radiator expansion tank every week. This is very abnormal. If there is no leak, the level will remain the same whether you overfill or under fill. As long, the water level is within the HIGH and LOW mark, it is OK.

If you fill to HIGH mark and after a days of driving, the water level drop to "Middle", then there is a clear indication that there is a leak.

Leak can be attributted to many things. Some of the thing are:-
1. Expansion Tank (this one very classic)
2. Old rubber hoses (especially after 6 years in service). BTW there are about 6 water hoses.
3. Water jacket in the engine block have hairline crack. This can be caused by engine overheating and adding cool water to the engine when it is very hot. A work of caution is not to add any water for at least 2 hours to prevent engine block from warping.
4. Solenoid valve for hot water to AHU unit faulty or leaking.

As for me, my problem was old hoses. After changing the top up is less frequent. Finally found the solenoid valve was faulty. Did a bypass and now hardly top up at all. The last time I top up was 3 months ago and it is only 2 fingers.

 

[jarance]

btw, the radiator cap is also a pressure relief valve. It will release pressure from the cooling system should you have an warped engine block.

Sometime, a faulty radiator cap will also caused you to lose coolant.

 

[LCP]

Hi jarance... on E36 with expansion tanks integrated to the radiator (M43, M50, M52, not sure about M42 and M40), there is no HIGH or LOW mark, just one mark, the COLD mark. User manual says not to top up above the COLD mark, but I also think it is okay to exceed the COLD mark a little as our ambient temperature is already quite high, therefore there will be less expansion under normal usage (eg. water temperature will go from maybe 25-32C to 95C here, delta of 70C max versus maybe from 5-10C to 95C in Europe, that's a delta of 90C).

Anyway, mine dropped from a bit above the COLD mark to a bit below the COLD mark in one year and two months, and I haven't top up yet... I don't think there's a leak anyway.

 

[LCP]

hehe, tight budget ar bro... will stick to the black one.. spent almost 3k at the workshop... done injector cleaning, decarb, change several parts and change the faulty sensors (there are broken to pieces).. the more you open the engine, the more faulty parts that you will find =( .. anyway the car now runs very2 well... smooth~.. anyway thanks a lot to all bros for the help and infos.. :rock:

Heh heh... for about 5-10% more money that you have spent, you can get the silicon hoses already...