1983 TD heat pump problem - PeachParts Mercedes-Benz Forum

jamesx2 · #1 12-09-2012, 05:46 PM

This is my first post on here and hope someone can help out so My 17 year old Daughter dosent freeze in her 83 Turbo deisle

My Sister gave her the car. We had to drive from New york to Maine to get it and drive back home the same day
Everything else works perfect, Door locks, moon roof, you name it. Shes got 183000 miles on her
The car has the typical heat pump problem . Well maybe not so typical.
Its not getting power to the pump . I checked the fuses and all are good

I do know that iI need a new thermostat. Its running a bit cool

I think operating temp should be 80
When the cars in motion heat comes out but at idle it blows cool.
These are symptoms of a bad pump

Even though there power at the fuse theres no power at the plug. Is there a solenoid or secondary fuse?

jamesx2 · #2 12-10-2012, 08:00 AM

Thanks for moving this into the correct area

MB-Owner-in-ind · #3 12-10-2012, 12:52 PM

It does need a thermostat if this is the typical reading after 20 min of running in non-freezing weather. I assume you have checked the power at the aux. pump plug and found none after it warmed up. The system does have a shut off relay that won't allow the heating system to work until the engine is 125 degrees. I am not sure where it is located on the newer cars but it might be under the dash on the passenger side. That was where I found it in a 1977 280se. I would replace the thermostat, flush the radiator and check for power at the aux pump.

jamesx2 · #4 12-10-2012, 03:11 PM

Quote:

Originally Posted by MB-Owner-in-ind

It does need a thermostat if this is the typical reading after 20 min of running in non-freezing weather. I assume you have checked the power at the aux. pump plug and found none after it warmed up. The system does have a shut off relay that won't allow the heating system to work until the engine is 125 degrees. I am not sure where it is located on the newer cars but it might be under the dash on the passenger side. That was where I found it in a 1977 280se. I would replace the thermostat, flush the radiator and check for power at the aux pump.

This is exactly the answer I was looking for. Thank you very much! The new thermostat is on order from Summit

vstech · #5 12-10-2012, 12:58 PM

some wisely install a 1 amp fuse in the wiring to the pump. check for one. install it if it's not there.
the push button unit sends ground to the pump, if the pump is shot, your PBU could be burned up. it's likely...

jamesx2 · #6 12-11-2012, 05:52 AM

Quote:

Originally Posted by vstech

some wisely install a 1 amp fuse in the wiring to the pump. check for one. install it if it's not there.
the push button unit sends ground to the pump, if the pump is shot, your PBU could be burned up. it's likely...

Do I fuse the black or white wire?

vstech · #7 12-10-2012, 12:59 PM

also, these heat systems have a monovalve on the firewall that directs hot water to the heater core. if it's torn, similar symptoms will present themselves.

jay_bob · #8 12-10-2012, 01:49 PM

Also in case you were not aware, the lit up caution light on the dash is the front brake pad wear detector.

The service manual for this car is available from M-B for free online and explains it all... At
startekinfo.com

jamesx2 · #9 12-10-2012, 03:06 PM

Quote:

Originally Posted by jay_bob

Also in case you were not aware, the lit up caution light on the dash is the front brake pad wear detector.

The service manual for this car is available from M-B for free online and explains it all... At
startekinfo.com

Thanks. The light came on last month and I changed the brakes. I broke one of the sensors and thats probably whats turning on that light.
This was my first time doing Benz brakes. I learned how not to break the sensor on the second set

SD300 · #10 12-10-2012, 05:03 PM

pull the monojet valve, usually thats the culprit, hot water didnt get thru.

the motor pump is there to help out when u sat at traffic light or stop & go too long the engine didnt rev enuf, so hot water dont pass as easily.
or your heater core is clogged too.

the inside heater core is divided on both L & R side, one side could be clogged, one W126 I had I had to plug the middle so water goes from L to R, basically block off the centre.

one of my car had the monojet screen plugged, so i yank her out, and heat was ample.
Even though the valve is OK but slowed down the water passage.

vstech · #11 12-11-2012, 06:46 AM

it doesn't matter.

jamesx2 · #12 12-13-2012, 08:48 PM

Got home from work today and the thermostat was at the front door. I asked my Daughter whae did she have to be at work and she said in 2 hours.
Cool. I have plenty of time to install the thermostat.
The the trouble started,
The housung bolts i just had off gave me a major problem. The top most bolt froze in the threads and snaped off. Out of the 3 this was the best one to snap as the access is easiest by removing the radiator hose.
Now I have to cut it flat. drill and tap the hole.
First I need to get a right angle drill. So thats my plan for the weekend
Heres my other obsession

jay_bob · #13 12-14-2012, 09:32 AM

The bolts holding the water components on the front of the engine are the worst for snapping off. If it was over torqued in the past you are in for a nasty surprise...

Maybe someone on the forum has a spare 617 tstat housing, and they would be willing to help a new member out....or there is always PNP.

jamesx2 · #14 12-14-2012, 10:10 AM

Quote:

Originally Posted by jay_bob

The bolts holding the water components on the front of the engine are the worst for snapping off. If it was over torqued in the past you are in for a nasty surprise...

Maybe someone on the forum has a spare 617 tstat housing, and they would be willing to help a new member out....or there is always PNP.

I was lucky its the top most bolt.
I have a air powered angle drill, tap , new bolt and never seize ready to go. along with a new thermostat and gasket.
If all goes as planned it shouldnt take more then 30 minutes

vstech · #15 12-14-2012, 10:11 AM

Quote:

Originally Posted by jay_bob

The bolts holding the water components on the front of the engine are the worst for snapping off. If it was over torqued in the past you are in for a nasty surprise...

Maybe someone on the forum has a spare 617 tstat housing, and they would be willing to help a new member out....or there is always PNP.

Gee Jay... How would you know this eh?

(that 240 was a fun one wasn't it...)