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  #1  
Old 01-14-2015, 10:44 AM
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Testing for pluggage in 1985 300D heater core

I've got the car in that is kicking my butt in regards to making the heater work ( A/C blows cold. Anyway, I've got a known good monovalve installed and even with the wire at the monovalve disconnected it still blows cold whether I am at idle or driving down the interstate. My next step is going to be to disconnect the hoses at the firewall and see if I can blow through the heater core. Any other things to consider while in there. tia

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  #2  
Old 01-14-2015, 11:03 AM
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disconnect the hose to the top of the mono valve and pump back towards the fire wall.

disconnect the hose on the back of the head so that if there is anything in there it will flush out there instead of into the engine or radiator.
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  #3  
Old 01-14-2015, 11:25 AM
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Is the heater core hard to get at on the w123? Just curious cause I know someone who has one that might be leaking.
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  #4  
Old 01-14-2015, 01:18 PM
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Lol, I don't even want to have to think about replacing heater core. Not necessarily as much a pia as time consuming.
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  #5  
Old 01-14-2015, 11:27 PM
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Quote:
Originally Posted by biopete View Post
Is the heater core hard to get at on the w123? Just curious cause I know someone who has one that might be leaking.
Well....you will have to remove the Dash, and Iam pretty sure you will have to remove the Heat/AC control box assy.

I have removed about 5 of these in the PNP yards, and it is a bit of work to do. The heater Core sits vertically facing the radio part of the dash panel. On the Firewall (eng side) you will see the 3 pipes the heater hoses connect to. These pipes are bolted to the Heater Core. So it isn`t something you can easily lift out. Plus you will have to discharge the AC Freon if there is any.

The Heat/AC control box assy. is three pieces with side clips that hold the case together, you have the AC Evaporator, Blower Motor, Heater Core, and vac lines etc...

As mentioned by Engatwork, time consuming.


I wish this was as easy and the one I just replaced on my 86 Ford F-250.
2 heater hoses on the Eng. side, drop the knee panel on pass side. and there she is looking at you. Easy R&R.

Charlie
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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

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  #6  
Old 01-15-2015, 05:05 AM
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Hmm

Quote:
Originally Posted by engatwork View Post
I've got the car in that is kicking my butt in regards to making the heater work ( A/C blows cold. Anyway, I've got a known good monovalve installed and even with the wire at the monovalve disconnected it still blows cold whether I am at idle or driving down the interstate. My next step is going to be to disconnect the hoses at the firewall and see if I can blow through the heater core. Any other things to consider while in there. tia
I will try to call this afternoon.

.
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HV-A/C Climate Control.
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  #7  
Old 01-15-2015, 06:55 AM
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Quote:
Originally Posted by charmalu View Post
Well....you will have to remove the Dash, and Iam pretty sure you will have to remove the Heat/AC control box assy.

I have removed about 5 of these in the PNP yards, and it is a bit of work to do. The heater Core sits vertically facing the radio part of the dash panel. On the Firewall (eng side) you will see the 3 pipes the heater hoses connect to. These pipes are bolted to the Heater Core. So it isn`t something you can easily lift out. Plus you will have to discharge the AC Freon if there is any.

The Heat/AC control box assy. is three pieces with side clips that hold the case together, you have the AC Evaporator, Blower Motor, Heater Core, and vac lines etc...

As mentioned by Engatwork, time consuming.


I wish this was as easy and the one I just replaced on my 86 Ford F-250.
2 heater hoses on the Eng. side, drop the knee panel on pass side. and there she is looking at you. Easy R&R.

Charlie
I've heard rumours of people removing the heater unit with the dash in place - getting at it from the passenger footwell...

...don't know if that was also with AC - if I remember correctly it wouldn't have been too hard to do that with my Euro non AC unit.

Still I'd be looking at the valves that open or close the flow first. (Again never seen an AC unit so I don't know how that works - my 300D has two little white plastic taps with cables that go into the cockpit - all very simple)
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Don't leave that there - I'll take it to bits!
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  #8  
Old 01-15-2015, 07:48 AM
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Have you checked your auxillary water pump to see if 12 volts makes it pump and its not plugged?
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  #9  
Old 01-15-2015, 08:20 AM
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Have verified that all your vacuum pods are working? I had a issue in my 126 where the cold air from deforst would blow at same time as heat .
After replacing the pods including the main flap all air comes out where it is supposed to.

Just a thought.
greazzer2b
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  #10  
Old 01-15-2015, 10:42 AM
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Quote:
Originally Posted by charmalu View Post
Well....you will have to remove the Dash, and Iam pretty sure you will have to remove the Heat/AC control box assy.

I have removed about 5 of these in the PNP yards, and it is a bit of work to do. The heater Core sits vertically facing the radio part of the dash panel. On the Firewall (eng side) you will see the 3 pipes the heater hoses connect to. These pipes are bolted to the Heater Core. So it isn`t something you can easily lift out. Plus you will have to discharge the AC Freon if there is any.

The Heat/AC control box assy. is three pieces with side clips that hold the case together, you have the AC Evaporator, Blower Motor, Heater Core, and vac lines etc...

As mentioned by Engatwork, time consuming.


I wish this was as easy and the one I just replaced on my 86 Ford F-250.
2 heater hoses on the Eng. side, drop the knee panel on pass side. and there she is looking at you. Easy R&R.

Charlie
Thats what i thought looking at it. The last heater core i did was a geo prism 15 years ago. It was a 30 minute job and 20.00 part. I think i'd have to take a sawzall to the dash or firewall if this ever happens to my car. lol. That would be more fun.
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  #11  
Old 01-15-2015, 12:14 PM
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Quote:
Originally Posted by Stretch View Post
I've heard rumours of people removing the heater unit with the dash in place - getting at it from the passenger footwell...

...don't know if that was also with AC - if I remember correctly it wouldn't have been too hard to do that with my Euro non AC unit.

Still I'd be looking at the valves that open or close the flow first. (Again never seen an AC unit so I don't know how that works - my 300D has two little white plastic taps with cables that go into the cockpit - all very simple)

Here is a couple pictures of the unit.


Here is the heater box out, and one the driveway.



You can see the 3 aluminum pipes at the top of the picture, the core is behind the center vent opening.
That center panel needs to come off as I remember, so maybe the whole box does not need to be removed from the vehicle. Remove it and the core may be able to lift out.

And the heater Core.




I borrowed these form a couple other threads.

Also daw_two has a good set of pictures:

How To Disassemble A W123 Manual Airbox Photos by daw_two | Photobucket

Charlie
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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Last edited by charmalu; 01-15-2015 at 12:26 PM.
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  #12  
Old 01-16-2015, 04:13 AM
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working to hard

Quote:
Originally Posted by engatwork View Post
I've got the car in that is kicking my butt in regards to making the heater work ( A/C blows cold. Anyway, I've got a known good monovalve installed and even with the wire at the monovalve disconnected it still blows cold whether I am at idle or driving down the interstate. My next step is going to be to disconnect the hoses at the firewall and see if I can blow through the heater core. Any other things to consider while in there. tia
Disconnect the heater hoses.
Reverse flow through the heater core, full volume with a garden hose.

To clear the air vanes.
Blast two full cans of scrubbing bubbles through the air ducts.
Flush the duct work / heater box with massive volumes of water.
YES, the floor pan will flood, be prepared.

.
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Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

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  #13  
Old 01-16-2015, 07:51 AM
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Quote:
Disconnect the heater hoses.
Reverse flow through the heater core, full volume with a garden hose.
On list to do this today.
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  #14  
Old 01-18-2015, 08:14 AM
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Thank goodness the heater core is fine.

I'll be dog gone. Something is going on at the other end of the engine. Upper radiator hose is hot and lower is cold so I will be getting into engine cooling system sometime today.
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  #15  
Old 01-18-2015, 09:21 AM
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Quote:
Originally Posted by engatwork View Post
I'll be dog gone. Something is going on at the other end of the engine. Upper radiator hose is hot and lower is cold so I will be getting into engine cooling system sometime today.
But upper hot lower cool (progressively on radiator) is normal. Laws of physics.

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