Thermostat Recommendations
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Junior Member
Joined: Aug 2008
Posts: 58
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From: Ont, Canada
2005 C230K coupe
Thermostat Recommendations
A couple of years back I noticed my car running cold (1.8 Kompressor), especially in the winter. It took a long time to warm up, defrost, etc. I pulled out the thermostat and sure enough it was in bad shape - there was a seal that had come out of place which would allow coolant to bypass, even when the thermostat was closed. A new thermostat fixed the issue right up and I had no complaints about heat.
Fast forward to now... Mostly working from home so the car has been sitting a lot, but when needed it sure is cold again! Even worse than last time around - takes the engine forever to reach temp. So, I'm guessing that the thermostat is a dud again after too short of a lifespan.
I can't recall the brand I used unfortunately. Are there thermostats that anyone has had particularly good or bad luck with? I'd like to put one in and be done with it for a reasonable amount of time.
Thanks!
KP
Fast forward to now... Mostly working from home so the car has been sitting a lot, but when needed it sure is cold again! Even worse than last time around - takes the engine forever to reach temp. So, I'm guessing that the thermostat is a dud again after too short of a lifespan.
I can't recall the brand I used unfortunately. Are there thermostats that anyone has had particularly good or bad luck with? I'd like to put one in and be done with it for a reasonable amount of time.
Thanks!
KP
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Joined: Dec 2003
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From: BC, Canada
2003 C230K Coupe Orion Blue
The OEM for the thermostat is Wahler. The exact same thermostat can be obtained under many different brands (ie the only thing different is the box that the part comes in). Febi and Behr come to mind for example, but other reputable brands will work too because of the aforementioned reason. Sites such as FCP and RMEuropean will carry the correct part. If the part you get turns out to be a Wahler, it will have the brand engraved on it. The new (aftermarket) one I put in was completely identical to the OE one I replaced and cost 1/5 as much. No need to subsidize the fancy dealership coffee machines. 
These thermostats do die every few years. They are designed to fail open so that people don't overheat their engines. Personally I'm on my 3rd one.
Lastly, be sure to replace all the plastic coolant pipes, including the one that holds the thermostat. I'm guessing the seal failed because the plastic has turned to powder. These have all been updated with a different grade of plastic. The original parts are all known to fail.
These thermostats do die every few years. They are designed to fail open so that people don't overheat their engines. Personally I'm on my 3rd one.
Lastly, be sure to replace all the plastic coolant pipes, including the one that holds the thermostat. I'm guessing the seal failed because the plastic has turned to powder. These have all been updated with a different grade of plastic. The original parts are all known to fail.
Last edited by slammer111; Jan 31, 2022 at 02:01 PM.
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From: Richmond, VA Metro Area
2005 C230 Sport Sedan-6 Speed Manual
Thread Starter
Junior Member
Joined: Aug 2008
Posts: 58
Likes: 1
From: Ont, Canada
2005 C230K coupe
Thanks to all for the feedback! I will search out a Wahler masquerading under a cheaper brand!
And about the plastic cooling system parts... They most definitely have a very specific lifespan! I've replaced most of them, minus the long pipe thingy that runs up near the valve cover. I have a new one of those on the shelf and ready to go - probably a good exercise to get it done at the same time as the thermostat. I replaced the water outlet that holds the thermostat in place last time around, hopefully it's still good. The OEM one was still installed back then, and I recall extracting the broken portion(s) out of the block...
And about the plastic cooling system parts... They most definitely have a very specific lifespan! I've replaced most of them, minus the long pipe thingy that runs up near the valve cover. I have a new one of those on the shelf and ready to go - probably a good exercise to get it done at the same time as the thermostat. I replaced the water outlet that holds the thermostat in place last time around, hopefully it's still good. The OEM one was still installed back then, and I recall extracting the broken portion(s) out of the block...
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Joined: Dec 2003
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From: BC, Canada
2003 C230K Coupe Orion Blue
^ The thread I posted above describes how to replace the long pipe you described. Good idea to replace it while replacing the thermostat, since you will need to lower the coolant level to do the job.
Lastly, I would keep a spare nipple around. The thing can break for no reason. I remember mine broke when I placed my hand on the overflow pipe (connecting the pipe you described and the coolant tank) while doing an unrelated repair. PN is also in the thread I posted. Also if you haven't done so, look into replacing the coolant tank. The black plastic on top also turns to powder over time. I remember I could break pieces off the old tank like a cookie. The lid and all hoses and clamps can be reused.
Lastly, I would keep a spare nipple around. The thing can break for no reason. I remember mine broke when I placed my hand on the overflow pipe (connecting the pipe you described and the coolant tank) while doing an unrelated repair. PN is also in the thread I posted. Also if you haven't done so, look into replacing the coolant tank. The black plastic on top also turns to powder over time. I remember I could break pieces off the old tank like a cookie. The lid and all hoses and clamps can be reused.
Last edited by slammer111; Feb 1, 2022 at 07:00 PM.
