Strange: Coolant leaking after 24 Hours

[JAY_KL]

Hi Dear UDM members & Sifu's, I have a strange problem, after each drive the coolant is leaking 2 ~ 3 litters after parking the car for 24 hours, yes only after 24 hours i have taken my UDM to 2 different spealist one in KL & Penang, both have checked...& there is no drop in preasure test, jack the car and waited like 6 hours and there is not even a single drop, did service the entire cooling system, i have change expansion tank, water pump, termostat, all the hoses, i cannot visible see any leaking, only in the morning when i get to my car i can see a trail of coolant leak and i need to top up my coolant as the dip stick is low. pls help i'am getting out of idea :stupid:

 

[jarance]

May I know why you have to wait for six hour to check for leak?

Care to explain the procedure done by the workshop?

btw, how many rubber and plastic hoses were changed?

 

[JAY_KL]

Hi Bro Jarance,
May I know why you have to wait for six hour to check for leak?
Well i need to wait 6 hours to check the leak because there is no leak when the engine is running ( as there is no drop in preasure test and took out the under carraige cover also cannot see any leak from below) only experience it after i park my car, normally i take my car after 2 days or so i can see a trail of coolant leak.
Care to explain the procedure done by the workshop?
Both workshop did preasure check as usual and did bleeding and change the coolant, flush the entire coolant system, thats all, during this we cannot see any single coolant drop! i'am so lost ...

btw, how many rubber and plastic hoses were changed?
my ex mechanic showed me a change rubber hose under the engine ( Y- Shape)

 

[jarance]

Y-shape hose? What is your engine spec?

 

[JAY_KL]

Mine is E46 328i

 

[jarance]

I cant seem to find a Y-hose for your model.


BMW parts catalog

 

[jarance]

OK found it. see item on the top right. as you see from the two diagram there are many hoses to be change and not just 1 or 2 hoses.


BMW parts catalog

 

[JAY_KL]

Bro. sorry bout the Y-hose, can't really remember the shape of the hose ( but remember him changing 2 or 3 of the hose's as shown in your diagram) the mech told me to leave the car for 2 days to change the hose as its inside the engine, i'am just curious..why does it leak only after 24 hours or so and not during drive? does it actually accumulate somewhere ....

 

[jarance]

based on my experience, mechanics tend to change hose #1,3 & 5 because they are easily accessible.
They tend to skip hose #6 and 8 because it is a major job to change them. Major job because they have to remove the air intake manifold, fuel rail, firewall cover, etc etc to get to the hoses.

I also have change the 3 hoses as you have mention but the leak still persist until I find the leak from the hose # 6 and 8.

and yes, there was no leak when the cooling system was pressure test with a air pump.

I found a a way to check the leak. First is to fill the radiator to the brim. close the cap and start the engine.
Once the engine is warm up, rev the engine speed to above 3000 to 4000 rpm for about 3 minutes. what you trying to do is simulate a running condition. Stop the engine and check for water droplet. Trace the droplet to the source and you will find the leak.

remember to drain the excess water after the test.

 

[JAY_KL]

Oic, Thanks bro Jarance, i shall DIY your method and get back to you guys on the update...

 

[snchin]

Side track a bit. What should be the correct coolant level? I always fill it to the brim and close the expansion tank.

 

[jarance]

you should fill it when the orange stick just start to float out of the expansion tank mouth.

The air pocket is required for the expansion of water/coolant when it get hot.

 

[beemerback]

I wish to add what happened to my car (E53)...

Over the last few months the water level in my car has been dropping mysteriously without any visible signs. Every week I had to top up about 400-500ml of water and this was not cool. It was a situation of "been there done that" and every hose has been checked and not so good ones replaced, including the expansion tank. But still no cure.

Left with no choice and my need for an answer, the replies given to me included "BMW engines and our climate are hot and will cause evaporation and need to top up water every now and then, water could be seeping into the engine, burnt gasket, overhaul and etc to name a few....

Finally last week, the culprit surfaced......the miniature puncture at the radiator (see picture)

The hole has gotten worst and was visible now. Cant really blame the mech guys.....none of them was attached to CSI before and never worked with a microscope.

 

[JAY_KL]

Hi guys tried this as (bro Jarance) suggested "close the cap and start the engine.
Once the engine is warm up, rev the engine speed to above 3000 to 4000 rpm for about 3 minutes. what you trying to do is simulate a running condition. Stop the engine and check for water droplet. Trace the droplet to the source and you will find the leak."

I found out not even a single leak below the floor, check most of the pipe that i can see and also look from bottom. Like always after 24 hrs that is today there is a trail of coolant leak. ooops

 

[jarance]

If there is coolant leak after 24 hours, then it is easy to trace the leak.

Remove the air filter casing and look for sign of white stain around the radiator, hoses and under the air intake manifold.

Take note that water when evaporate due heat will leave a stain mark. However, the stain can be misleading as it could be due to water overflowing and during bleeding. I usually would remove the air filter box and wipe clean all the white stain mark and take a lot pictures. By using this method, I would be able to tell where the new leak is by comparing the pictures.

 

[pussy]

easy, i use a dye for checking for leak... very easy to spot... night much better with a torch light

 

[snchin]

you should fill it when the orange stick just start to float out of the expansion tank mouth.

The air pocket is required for the expansion of water/coolant when it get hot.

bro...mine is E36. I dont see any float in my expansion tank. how ah?

 

[jarance]

bro...mine is E36. I dont see any float in my expansion tank. how ah?

No, E36 expansion tank does not have a float. you just need to fill it up to the mark as shown below.

 

[snchin]

Bro Jarance,

Ok. Noted. All these while have been doing it wrongly. Damn

Bro Jay,

Your problem still not solved?

 

[JAY_KL]

well i'have checked with my night vision glass well all the hose has no leak, also the radioator, but i can see area below hose #6 & #8 above the water pump there is presents of the coolant, i can see it quite clear as my coolant is red in colour,but actually i cant really see the water is driping from wher..