Still sounds like the aux pump to me. Increased air flow (fan on high) with the same trickle of hot water through the heater core will result in air that doesn't get warmed up as much...

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

Place a one amp in line fuse to the Aux water pump, this will blow and same your CCU. It could also save your car from a more disasterous fire.

Nothing like an electrical fire under the dash. Look up the thread "I lost it all".

I picked up an inline fuse from West marine that is water tight.

There are a lot of threads on this up grade.

Charlie

__________________
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

Charlie,

I can see the aux pump clearly. ( i removed the air cleaner canister) Should I hear the pump running when the key is on? Right now I hear nothing. If it should run with the key on, how do I know it's the pump and not something else, say a fuse or relay?? How much antifreeze will I lose if I disconnect the hose?

If it isn't running it is probably siezed up. As I understand it there is no fuse in its supply line from the factory. That's why people recommend installing one.

If you want to take it out, keep the radiator cap on and have a short piece of pipe the right size handy. Loosen both clamps and make sure the hoses are not stuck on the pump. Then you should be able to remove the pump and replace it with the short piece of pipe pretty quickly without loosing too much coolant. You could also clamp the hose on each side of the pump between small blocks of wood using vise grips and then you wouldn't loose any.

I expect that with a siezed pump, replacing it with a piece of pipe will actually improve flow to the heater core and you'll get more heat. Not as much as with a working pump, but more than with a siezed pump blocking the flow.

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

You can validate if the aux pump is seized by removing the plastic cap that covers the motor spindle, place the sharp end of your pocketknife against the shaft, you'll feel if it's rotating, or not. If it's not, check motor voltage at the connector. If you have to replace the pump, occassionally remove the little button cover to the shaft, as mentioned before, and dribble some ATF onto the bearing. Replace cap. I put a small qty of cotton in there, soak it with ATF, and renew it once a year.

'77 300D

I have NEVER had good heat in the SDL and am wondering if removing all the over engineered valves and pump and just letting the coolant run free from the engine would be worth the trouble? I replaced the valve and pump a few years back and now think i need a hotter t-stat now that i am living in a colder climate. When i park it after using it and come back after a short time, i get a short blast of hot air and then cool again! IT never mattered much in AZ but its been in the 20s here in NM at night and matters more.
I did this convert to a beemer once with an inline valve for summer driving and it worked fine.

__________________
[B]AlanT
BELEN NM


93 dodge cummins truck~old reliable
01 Volvo AWD XC70 Turbo Wagon
74 450 SE on the way out!
Recent: 1972 Toronado 56k on the clock!

IF it plugs in, lights up, makes noise,
I'M ON IT!

If you want your A/C to work in the summer, I would leave the complex plumbing - otherwise you will have a hot heater core all year.
Actually , the circuit is more complicated than that and I don't recall the circuit completely - I would not do it.
You have 4 connections on the monovalve (one for heated windshield) - 3 on the heater core - IIRC . Just bypassing the heated windshield as I did was complicated enough. You would have to replace or block off the hose to the head that has the windshield heater line built in - a - mess..
I don't recall the circuit well enough to even know that you would get heat.
EDIT- I don't think you will get heat for some time until the thermostat opens and that is the purpose of the aux. water pump - pumping water from the head until the engine/ head temp. is high enough for water to circulate without the aux. pump.

__________________
1986 300SDL 201K Daily Driver
1984 300D In Progress
1989 240GL 196K Swedish Brick
1984 300SD -- Sold 289K
------------------------------

I've determined that I in fact DO NOT have power at the connector. Any ideas as to what may be the cause?? (I ran a wire from the battery diectly to the aux pump plug and I can hear the pump working, so I know the pump is not frozen)

Theres a swich somwhere behind the glove box that supplies that pump with power when below about 53 degrees. Im not sure where it is located though.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg