Quick overheating when sitting in traffic
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 0
2003 ML500
Quick overheating when sitting in traffic
Hi all,
I recently did a flush and changed out the radiator fluid (Zerex G-05) in my 2003 ML500 because it seemed to be having overheating issues and the overflow tank was leaking.
The fluid was pretty filthy so it obviously needed it. Unfortunately, it didn't cure my overheating issues.
Normally the car operates in the 90-100 degree range once it's warmed up. However, if I hit any extreme stop and go traffic it will creep up above 100 and then rapidly climb towards the 120 range. The only remedy seems to be to pull over and wait for a few minutes, or to try a route where I can make sure to get more air flow.
Needless to say, I'm not enjoying driving at certain parts of the day here in the San Francisco Bay Area, which has stop and go quite often.
One other thing I found odd. The overflow tank level never seems to deviate from the Cool level. Even when the car is very warm according to the gage, it seems glued to Cool. I would expect it would be down towards the Hot level, or else why have two different levels?
Any ideas on what else it could be? I did not replace the thermostat, thinking that was used to measure Temps, rather than regulate them.
I recently did a flush and changed out the radiator fluid (Zerex G-05) in my 2003 ML500 because it seemed to be having overheating issues and the overflow tank was leaking.
The fluid was pretty filthy so it obviously needed it. Unfortunately, it didn't cure my overheating issues.
Normally the car operates in the 90-100 degree range once it's warmed up. However, if I hit any extreme stop and go traffic it will creep up above 100 and then rapidly climb towards the 120 range. The only remedy seems to be to pull over and wait for a few minutes, or to try a route where I can make sure to get more air flow.
Needless to say, I'm not enjoying driving at certain parts of the day here in the San Francisco Bay Area, which has stop and go quite often.
One other thing I found odd. The overflow tank level never seems to deviate from the Cool level. Even when the car is very warm according to the gage, it seems glued to Cool. I would expect it would be down towards the Hot level, or else why have two different levels?
Any ideas on what else it could be? I did not replace the thermostat, thinking that was used to measure Temps, rather than regulate them.
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 0
2003 ML500
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 37
Likes: 0
2003 ML500
Had some more cooling issues, and finally took it to a shop for diagnostics. He's 95% sure the cooling fan is history. They want $1425 for parts+labor.
At this point, I feel confident in pulling the fan and doing the work myself (I've had the fan out when I replaced the radiator and then later the water pump). But, trying to find an aftermarket replacement today seems to be a lot harder than I remembered it being a couple years ago when I considered doing it. Right now, the least expensive one I can find online is a VDO brand for $707, from AZ Autohaus.
There are several companies that have one replacements with the part number 1635000393. But, when I do the "Check vehicle fitment" it tells me it doesn't fit the 2003 ML500, and only the ML55. Yet, this IS the same part number written on the fan in my ML500. What am I missing? They didn't actually make two different parts with the same part number, did they?
Any suggestions on where I might find something less pricey?
At this point, I feel confident in pulling the fan and doing the work myself (I've had the fan out when I replaced the radiator and then later the water pump). But, trying to find an aftermarket replacement today seems to be a lot harder than I remembered it being a couple years ago when I considered doing it. Right now, the least expensive one I can find online is a VDO brand for $707, from AZ Autohaus.
There are several companies that have one replacements with the part number 1635000393. But, when I do the "Check vehicle fitment" it tells me it doesn't fit the 2003 ML500, and only the ML55. Yet, this IS the same part number written on the fan in my ML500. What am I missing? They didn't actually make two different parts with the same part number, did they?
Any suggestions on where I might find something less pricey?
Last edited by robertjm; Oct 5, 2021 at 06:51 PM.
