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I have been experiencing a situation with my W221. The heat will work fine at all stages. I will shut the car off briefly, upon the next start there is no heat, just cold air. On occasion, the heat will come back on after a while. The rest of the time I have to shut the car off and restart it. There are no messages, no codes etc... Could this be a thermostat or heat valve control issue?
I have been experiencing a situation with my W221. The heat will work fine at all stages. I will shut the car off briefly, upon the next start there is no heat, just cold air. On occasion, the heat will come back on after a while. The rest of the time I have to shut the car off and restart it. There are no messages, no codes etc... Could this be a thermostat or heat valve control issue?
this is no doubt a failing thermostat..its on its way out, but not quite there yet. i had the same issue go on for 3-4 months with no CEL. i live in staten island too btw lol
this is no doubt a failing thermostat..its on its way out, but not quite there yet. i had the same issue go on for 3-4 months with no CEL. i live in staten island too btw lol
unfortunately, no. I did not..but I don’t think it’s a terribly difficult job, and a thermostat for this car is relatively cheap. Also the location of the thermostat is ideal as it’s front and center on the engine.
unfortunately, no. I did not..but I don’t think it’s a terribly difficult job, and a thermostat for this car is relatively cheap. Also the location of the thermostat is ideal as it’s front and center on the engine.
Agreed on this and I do DIY. The thermostat is the first thing to come off when replacing the water pump, oil filter housing, etc. It's pretty straightforward and right at the front of the engine ( assuming S550?).
Agreed on this and I do DIY. The thermostat is the first thing to come off when replacing the water pump, oil filter housing, etc. It's pretty straightforward and right at the front of the engine ( assuming S550?).
i have a CL550 4matic which shares the M273 engine with the w221 s550's..i noticed you said that the thermostat comes off when replacing the water pump? i havent had my water pump fail on me yet but i am getting up there in miles and age and would much rather do this myself(i see water pumps are also relatively cheap for these cars). are you sure this is necessary?..now im sure the radiator fan/shroud has to come off..and info on how difficult this is?
Last edited by COUPCONNOISSEUR; Mar 6, 2019 at 03:01 PM.
i have a CL550 4matic which shares the M273 engine with the w221 s550's..i noticed you said that the thermostat comes off when replacing the water pump? i havent had my water pump fail on me yet but i am getting up there in miles and age and would much rather do this myself(i see water pumps are also relatively cheap for these cars). are you sure this is necessary?..now im sure the radiator fan/shroud has to come off..and info on how difficult this is?
That's what I recall from doing it, but it has been a year at this point. Let me see if I can dig up the WIS procedures I used when I get home tonight. I don't believe that it directly interferes with water pump removal, just makes it less of a PITA.
As for performance thermostats ... I'm a little on the 'I can't do better than $1B of German Engineering' camp. Meaning the motor is really well built to start, so I just try to keep it running as close as possible to 382hp and 391 torques.
Ok just checked ... the thermostat can stay on, however removing it makes the job easier as some of the bolts for the water pump are below it. Having trouble printing to PDF at the moment, fortunately Konigstiger has already provided everything you need in this post!
AND, this is just one of those cases where if you follow the directions and do the tighening sequence by the book, you will avoid any leaks. I've done 4 of these pumps between M112/113 and M272/M273, the first one taught me everything I needed to know!
The engine thermostat is likely not the problem. The heater control valve (under wiper motor) is more likely. Search it here.
In addition, were there an engine thermostat problem ...
1. You'd likely see it in the dashboard temperature gauge reading
2. You'd likely have a check engine light.
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