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93 300E 2.8, 79 450 SLC
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539 Posts
Discussion Starter · #1 ·
I am debugging the occasion die-on-stop problem in my 79 450 SLC. I want to clean the idle control valve but I couldn't find it. I have searched the forum but they were talking about the electronic idle control unit, not the idle control valve. My Chilton manual didn't mention it either. Can anyone show me where it is? See photo. is it close to the idle adjustment screw?

Thanks in advance.

 

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500SLC #2624. Black on Black.
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5,120 Posts
Correct me if I'm wrong (and I may be) but i don't think your 450 has an idle control valve.
 

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'09 E350 4-matic sport, '83 240D 4-speed (sold), '77/'78 450SLC (junked), '81 500SLC (junked)
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845 Posts
I don't think you have one either...
 

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93 300E 2.8, 79 450 SLC
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539 Posts
Discussion Starter · #5 ·
Thanks guys. That explains why I couldn't find the ICV.

A follow up question: how does the 79 450sl/slc control the idle speed without an ICV? Only by the idle adjustment screw?
 

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1980 450SL & 1988 560SL
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1,667 Posts
You have a thermo valve near the adjustment screw that adjust the amount of air with the temp of the engine and the WUR also plays a big part in the cold starts. It changes the fuel / air ratio as the engine heats up.
 

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93 300E 2.8, 79 450 SLC
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539 Posts
Discussion Starter · #7 ·
Are you referring to this part (auxiliary air valve?) Just want to be sure. Thanks.

Auto part Flange Metal
 

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You have a thermo valve near the adjustment screw that adjust the amount of air with the temp of the engine and the WUR also plays a big part in the cold starts. It changes the fuel / air ratio as the engine heats up.
Hi, i was wondering what is the "WUR", because i have problem with idle when the engine is cold, and might be cause by the fuel/air mixture.
Thanks and have a nice day all
 

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'79 450SL, '04 CLK200 convertible; former A124, W210, A209.
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3,220 Posts
Welcome to the forum Nikolai, greetings from Mikolaj 😁 WUR stands for warm up regulator and as you pointed out it's responsible for managing fuel pressure. Now, there might be a couple of other factors at play here so proceed with caution.
 

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Welcome to the forum Nikolai, greetings from Mikolaj 😁 WUR stands for warm up regulator and as you pointed out it's responsible for managing fuel pressure. Now, there might be a couple of other factors at play here so proceed with caution.
Thanks for the fast reply, i will check it as soon as the weather goes warmer, because now it is really freezing cold outside🥶
 

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'79 450SL, '04 CLK200 convertible; former A124, W210, A209.
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I hear ya, I know the feeling - subzero is not friendly temperature to be working on an engine. 🥴
 
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