OK, I recently replaced my rad, t-stat & housing,water pump, and all the hoses on the front of the engine. I bled it out and made sure my coolant level was good, this was a few weeks ago. Tonight I hop in the car and get the warning, so I check it out and sure enough the coolant is a little low. I can see no obvious signs of leakage around the pump or hoses ect. Anyone had a similar experience? any idea where the coolant may have gone? Other places to look for seepage? I can't really take a closer look tonight as it is raining like hell and don't have a dry place to park it.

i had the same problem with my 01 540. Replaced radiator, hoses,etc..etc...over $1,300 job and once in a while the check cooland light will come on again. I just put water until the little thing from the reservior pops up about 1 inch and back to normal. I took it back to the repair place, they measured the pressure and was it ok, and no leaks so i guess just needs a lot of liquid......

Last December I had to replace the radiator, overflow, and hoses on my 2000 ($1,300 – bye bye bonus). As of now, I have to top off the coolant once a week. I took it into my mechanic a couple of weeks ago and he finally found the leak! Apparently, the leak is from hoses located at the back of the engine on the passenger side (both rubber and metal). I'm taking the car in tomorrow for the repairs. Thank God, my mechanic only charges me for parts at his cost with no labor. It will take 2 days to fix.

OK, I recently replaced my rad, t-stat & housing,water pump, and all the hoses on the front of the engine. I bled it out and made sure my coolant level was good, this was a few weeks ago. Tonight I hop in the car and get the warning, so I check it out and sure enough the coolant is a little low. I can see no obvious signs of leakage around the pump or hoses ect. Anyone had a similar experience? any idea where the coolant may have gone? Other places to look for seepage? I can't really take a closer look tonight as it is raining like hell and don't have a dry place to park it.
Do you smell burnt coolant?

If you seen no signs of leakage around the hoses or on the ground, but smell burnt coolant, then it could a blown valley pan gasket, as the leak is burnt off on the hot manifold before it reaches the ground.

Think of the cooling system as just that - a system. You replaced several parts of the system with new and stronger parts, causing further stress on the other parts of the system you didn't replace (and prone to failure), such as the valley pan gasket.

I have same issue. 1999 540i. I replaced rad, hoses, expansion tank and water pump. After a week low coolant light came on. Replaced about 200ml. then three weeks later same thing. Had it checked for leaks and also hydrocarbon check for cylinder head gasket but this was negative.

My service guy says that no system is totally sealed, there is maybe some air pockets still settling from the rad change and so on and if the cylinder head gasket is ok then don't worry.


Even with that advice i still worry!

Do you smell burnt coolant?

If you seen no signs of leakage around the hoses or on the ground, but smell burnt coolant, then it could a blown valley pan gasket, as the leak is burnt off on the hot manifold before it reaches the ground.

Think of the cooling system as just that - a system. You replaced several parts of the system with new and stronger parts, causing further stress on the other parts of the system you didn't replace (and prone to failure), such as the valley pan gasket.

I have never smelled the burnt coolant that you mentioned however, I did see puddles on the ground that started off small and got bigger over time. Like I mentioned before by the time I turned it in (last night) I was adding coolant once a week. I don't know a lot about cars so maybe I'm not understanding everything that you've mentioned. I do know that I noticed the leak since last year and nobody believed me since they couldn't find it. there is no missing it now.

BTW - I have a clunking noise (sounds like a rock bouncing around) every time I hit bad pot holes (all over NJ). When my car is on the lift nothing can be found. I've had the shocks replaced thinking that it would help. Nothing. Any idea what I should check next? The noise seems to be located on the drivers side near the left fender.

Gotta run!

I have never smelled the burnt coolant that you mentioned however, I did see puddles on the ground that started off small and got bigger over time. Like I mentioned before by the time I turned it in (last night) I was adding coolant once a week. I don't know a lot about cars so maybe I'm not understanding everything that you've mentioned. I do know that I noticed the leak since last year and nobody believed me since they couldn't find it. there is no missing it now.

BTW - I have a clunking noise (sounds like a rock bouncing around) every time I hit bad pot holes (all over NJ). When my car is on the lift nothing can be found. I've had the shocks replaced thinking that it would help. Nothing. Any idea what I should check next? The noise seems to be located on the drivers side near the left fender.

Gotta run!

sound like strut mounts to me.