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K

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Discussion Starter #1
Hey,

I am only getting lukewarm air from my heat. I really need it since it is getting like 20 degrees here in New Jersey. My car doesn't really want to heat up and the temp on the gauge stays at like 50 and about 80 on the highway.

Any suggestions ? Someone told me that it might be some type of monologue valve or whatever it might be called....


thanks for the help in advance.[?][?][?]
 

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2x300D-83
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Hi!

Put a cover in front of the radiator with a hole 4-5" square in the middle. That ...


Hi!

Put a cover in front of the radiator with a hole 4-5" square in the middle. That will help if it´s cold enough to never make the thermo valve open.
 

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83 300TD/97 E320/98 SL500
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Heat comes from the engine coolant- if your engine never reaches temperature, that may be ...

Heat comes from the engine coolant- if your engine never reaches temperature, that may be the problem. However, if the coolant temp is hitting 80 and you still get lukewarm air, you might want to check out the either the circulating pump or the mono valve. The circulating pump is electric, and is located on the passenger side of the engine compartment- on my TD, it's underneath the coolant expansion tank and hydraulic oil resevoir. The mono valve is on the passenger side firewall, up high- my understanding is that this valve is normally open. When you start the car, the solenoid is energized, forcing the valve closed. The valve does wear out with age and can get stuck- rebuild kits are available.
 

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84 300D; 85 380SE
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definitely take a look at your monovalve. there's a
rubber diaphram that tears fairly ea...


definitely take a look at your monovalve. there's a
rubber diaphram that tears fairly easily. it will be
an obvious diagnosis when you pull it out.

the fix is very easy and cheap. if memory serves,
the rebuild (and you only want the insert -- not the
whole monovalve) runs about $30.

the next thing to look at would probably be the
heater circulation pump.
 
K

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i just ordered the monovalve....i think that that might be cause of my problems with the...

i just ordered the monovalve....i think that that might be cause of my problems with the heat... i cannot take driving to work in a hat :)
 

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1985 300D Turbo
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Well, I also had this problem, yet I have been told that it may not be my monovalve. It was pointed out to me that my coolant is not circulation and it is more likely my thermostat that is the problem. To test and see if it is indeed the monovalve, unplug it from the battery, and if there is heat, then you found the problem. Is there any way to somehow temorarily force open the thermostat to get the coolant flowing? I know for sure that it is my thermostat because the collant tank is not bubbling like on my 300sdl and 560sl. Please help.
 

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2021 SL770
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If you're certain it's the thermostat, just replace it -- they're less than $15. If you want to test it, remove it from the vehicle and place it in a pan of water, then bring to a boil to see if it opens.
 
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I found the problem. It was the thermostat after all. I cannot believe how much better the car runs, even sounds a whole lot different. Runs smoother and will probably get more miles per gallon. The heat coming inside is incredible. :) I am so so happy with this car. I bought the thermostat from Strauss Auto for 15 bucks. Took me a whole 10 minutes to do the install myself but it literally changed my car since it would never heat up over 40 celcius. Here are some pics of the old thermostat. This is still the original, I believe.







 
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