w123 with no heat??? - PeachParts Mercedes-Benz Forum

Ya Mar · #1 12-11-2010, 10:41 PM

Hello All,

My '85 300D Euro import is suffering from a lack of heat.

The 85' 300TD Wagon has heat working just fine, but the Euro is a 4speed and I prefer driving a standard transmission vehicle during the Vermont winters.

However, a car with no heat is a problem!

The heat coming out of the vents is in keeping with the temp the engine is running at. If I drive in 2nd gear up a mountain and heat up the engine, it will blow hot air, but as soon as the temp drops down to below 80C, the air just becomes mild, with cold air blowing out the two center vents.

Any ideas on what might be going wrong here?

Thanks!

jt20 · #2 12-11-2010, 11:09 PM

your temperature should not be dropping below 80 *C

other than that, does the heat supply correspond with engine RPM?

69shovlhed · #3 12-11-2010, 11:15 PM

feel your heater hoses to make sure they are hot. t-stat must be bad if the temp is dropping below 80°C. if the hoses are good and hot, could be vacuum problem or stuck door in heater box? but i'd still put in a new t-stat 1st.

MBeige · #4 12-12-2010, 12:12 AM

Quote:

Originally Posted by 69shovlhed

feel your heater hoses to make sure they are hot. t-stat must be bad if the temp is dropping below 80°C. if the hoses are good and hot, could be vacuum problem or stuck door in heater box? but i'd still put in a new t-stat 1st.

Or it could have a lower rated thermostat.

my123ca · #5 12-12-2010, 08:42 AM

Quote:

Originally Posted by Ya Mar

If I drive in 2nd gear up a mountain and heat up the engine, it will blow hot air, but as soon as the temp drops down to below 80C, the air just becomes mild, with cold air blowing out the two center vents.

Any ideas on what might be going wrong here?

Thanks!

You shouldnt be getting air in the center vents if you are set in heat mode in US models, im not really familiar with euro models. Could be an ACC problem.

Stevo · #6 12-12-2010, 11:49 AM

X2 on the bad T -stat

kerry · #7 12-12-2010, 01:03 PM

Could also be a failed auxilliary coolant pump. I get pretty decent heat even though the temp gauge is lower than 80. Hence I strongly suspect the pump.

Stevo · #8 12-12-2010, 01:52 PM

Quote:

Originally Posted by kerry

Could also be a failed auxilliary coolant pump. I get pretty decent heat even though the temp gauge is lower than 80. Hence I strongly suspect the pump.

I don't think he has one on a manual euro, not sure tho.

kerry · #9 12-12-2010, 03:54 PM

Quote:

Originally Posted by Stevo

I don't think he has one on a manual euro, not sure tho.

Why would the automatic climate control need one and the manual not? Isn't it designed to solve a problem that both systems would have-low coolant flow at low rpm's?

Stevo · #10 12-12-2010, 06:30 PM

Quote:

Originally Posted by kerry

Why would the automatic climate control need one and the manual not? Isn't it designed to solve a problem that both systems would have-low coolant flow at low rpm's?

Good question, I have never had anything but manual 123s and have never seen an Aux pump. Somebody will know the answer too that. Do manual tranny (euro) 617s have the AUX pump??

Wheres it suppose too be and I'll go have a look

kerry · #11 12-12-2010, 06:37 PM

On my 77 it was right near the servo. I think it's in a similar position on my 85--right front inner fender I think.

Yak · #12 12-12-2010, 06:44 PM

Quote:

Originally Posted by Ya Mar

The heat coming out of the vents is in keeping with the temp the engine is running at. If I drive in 2nd gear up a mountain and heat up the engine, it will blow hot air, but as soon as the temp drops down to below 80C, the air just becomes mild, with cold air blowing out the two center vents.

Any ideas on what might be going wrong here?

Thanks!

It's been a while since I owned a euro W123, but if I recall correctly the center vents were for "fresh" air only and controlled by the lever below them. It's been a while so I could be wrong. What's the owner's manual say?

Stevo · #13 12-12-2010, 07:41 PM

Quote:

Originally Posted by kerry

On my 77 it was right near the servo. I think it's in a similar position on my 85--right front inner fender I think.

My 85 Euro 300TD engine is just like the 85 Euro 240D (both manual trannys) with the exception of one more cylinder and an oil cooler, no aux pump, fan clutch, oil separator or servo, Manual heating and, yes, fresh air only comes out the center vents.

Take a look, I dont think I have any of that stuff.

kerry · #14 12-12-2010, 07:54 PM

So now I'm puzzled. Why no need for the pump on the Euro?

Stevo · #15 12-13-2010, 10:24 AM

Any resolution or new info? I would start with a new OEM T stat and be sure and take notice of the little arrow indicating "up". I haven't had to buy one lately so I'm not sure they all have "arrows' now, so look closely.

Kerry, no aux pump on the Euros might be another example like, why "no oil coolers" on the Euro 240Ds. I really like the idea of "less to break", unless your good at fixing those things, which I'm not.