I am having repetitive failures of new, OEM block heaters installed on
my M617 diesel engine (W123 300D).

My latest theory is that there must be metal in the water jacket of
the block (I may be "all wet" on this) or something else that is
shorting out these heating units.

Anyone have any thoughts on this, and/or any ideas on how to verify or
"flush" the block?

Thanks in advance for any info.

"randallbrink (AT) mac (DOT) com" <randallbrink (AT) gmail (DOT) com> wrote

Remove the block heater and inspect it and the block. I've installed a
number of Benz heaters and it is a simple task once the original bung is
removed from the block.

On Oct 11, 11:42*pm, "Chas Hurst" <hur... (AT) comcrap (DOT) not> wrote:
I have inspected both failed heaters and there is no outward sign of
failure.

What is the resistance in those dead heaters?

On Oct 12, 10:19*am, "Tiger" <tiger0... (AT) hotmail (DOT) com> wrote:
I do not get a reading with the ohm meter terminal-to-terminal on the
one I have removed from the engine.

randallbrink schrieb:
Since you have blown up your radiator too, I suspect the reason might be
that you left too much air in the block while filling coolant and the
block heater had been glowing in air instead of water.

--

Roland Franzius

On Oct 12, 11:39*am, Roland Franzius <roland.franz... (AT) uos (DOT) de> wrote:
Actually, the radiator was not the problem, but simply a loose hose
clamp, which allowed coolant to leak from the radiator. It looked
worse than it actually was. Therefore, I do not think that a
sufficient volume of coolant leaked out to dry up the block. When I
replaced the coolant, I only put about 2-3 quarts back in before it
was full, and I am assuming that that came from the radiator and not
the block. I could be wrong about this, but even if that were the
case, it still does not explain going through two new block heaters in
two days.

randallbrink schrieb:
If you open the notch for the heater in a lower part of the block there
will be no water left except in radiator and heater.

Filling water from the radiator side does not work so fast because the
thermostat on top of the block is closed below 89 C. There is a little
hole only to blow out damp and air. If you heat up the electric heater
in such a situation it will probably glow and burn the heaters wire.

Are you sure you replaced all the 6 liter of coolant? Have you run the
motor up to 80 centigrades until the thermostat is open and the
encapsulated air had blown off before using the heater element?

--

Roland Franzius

On Oct 13, 2:19*am, Roland Franzius <roland.franz... (AT) uos (DOT) de> wrote:
I am not sure this was done, and will inquire of the shop as to their
method of replacing the fluid at the time of the block heater
replacement, so as to ensure that this does not happen yet again.

However, I am skeptical of this as a cause, as I had driven the car
some distance from the shop to my home before plugging it in, and the
heater element worked fine for one night, in both instances. The drive
home should have allowed the block to circulate fully and eliminate
any air.

The coolant reservoir is the highest point of the engine bay... so keeping
the fluid level in the resevoir guarantees that the engine block will have
enough coolant. Look at the level of the reservoir compared to the radiator
to the engine head... you get the idea how high the fluid really have to be.

3 quart is practically half of the coolant capacity. It takes only 6 quarts
to refill the radiator/engine after R&R the radiator and not all of it goes
to the radiator.

There got to be some kind of warranty on the engine block heater from the
dealer... inquire to get free heater replacement.