yes I did the citric acid flush. The system has been flushed twice with citric acid, and before that just with water. I believe that if it were just a build up issue, it would be improved by the citric flush. I will keep you all informed as to the results.
Chuck
84 300sd
--- In diesel_mercedes@yahoogroups.com, audiolaw@... wrote:
>
> Chuck,
>
> Was it last week or the week before that you were worrying about over
> heating, and a bunch of folks said: DO A CITRIC ACID FLUSH.
>
> Then you came back with the water pump concern.
>
> Did you do the citric acid flush? If not, then changing the water
> pump, or the radiator may very well NOT solve your problem. If the coolant
> isn't able to fully flush through the block because of schmutz build up, that
> issue is going to remain for all time.
>
> Flushing the system can be messy and time consuming. But it is WAY
> cheaper than throwing new parts, and the mechanic's time involved at the
> problem.
>
> Tom
>
>
>
> In a message dated 7/9/2012 1:13:29 P.M. Pacific Daylight Time,
> jcrcpa@... writes:
>
>
>
>
>
>
> Thanks Mark, this explanation fits with all the facts of my overheating
> car. I think I will have the mechanic replace the water pump, and then if
> necessary, replace the radiator.
>
> Chuck
> 84300sd
>
> --- In _diesel_mercedes@yahoogroups.com_
> (mailto:diesel_mercedes@yahoogroups.com) , "Mark in Lakewood, CO" <beeser750@> wrote:
> >
> > Hmm.... Just because a water pump is turning and not leaking doesn't
> necessarily mean it's good. The first diesel I ever drove was a '74 240D that
> belonged to a friend of mine in Arcardia, CA. When I came out to visit him,
> and asked him why he wasn't driving the 'Benz, he said it kept running too
> hot. He'd replaced the thermostat, had the radiator rodded out, and
> flushed the block. Still, it ran hot. I noticed a small leak coming from the
> water pump area, though not from the weep hole, so, I removed the water pump,
> and found that the aluminum pump housing had so much internal corrosion,
> that the machined part that the pump impeller rides up against (not quite
> touching, but, almost) was completely gone. The pump wasn 't pushing the
> coolant around, but merely stirring it in the housing. In fact, the corrosion had
> made the housing wall so thin there was a pinhole leak. Pump itself was
> fine, but we replaced the housing, and the hot running was gone.
> >
> >
> >
> > (This was a Southern California car, and the corrosion was the result of
> too many years of previous owners not using any sort of
> anti-freeze/anti-corrosion in the cooling system. Just water.... I've since encountered
> former SoCal cars in which the pump impeller was completely rusted away, too!)
> >
> >
> > As to the thermostats: It must be pointed out that Mercedes thermostats
> are double-acting; that is, not only does the thermostat allow and block
> coolant flow through the radiator, but it also blocks/opens flow through the
> by-pass hose at the bottom of the thermostat housing. Looking at the
> thermostat one will notice a lower disc BELOW and mounted on the same shaft as
> the main part of the assembly. When the thermostat opens, this lower disc
> closes off the bypass circuit. Running a Mercedes engine without a thermostat
> will have the coolant directionless, not knowing whether it should go
> through the radiator, or the bypass. So, taking the pass of least resistance, it
> will go through the bypass hose. Running a Mercedes engine without a
> thermostat creates a condition where it is just as likely to over heat as running
> the engine with a thermostat that is stuck closed.
> >
> >
> > Mark in Lakewood, CO
> > ----- Original Message -----
> > From: "n61cm" <jim@>
> > To: "diesel mercedes" <_diesel_mercedes@yahoogroups.com_
> (mailto:diesel_mercedes@yahoogroups.com) >
> > Sent: Sunday, July 8, 2012 8:27:59 AM
> > Subject: [diesel_mercedes] Re: water pump w126
> >
> >
> >
> >
> >
> >
> > I'd say as a general rule, you leave the water pump alone until it
> starts leaking. If it has a belt connected to it and it's turning and not
> leaking, it's pumping. If you've taken the thermostat out and you're still
> overheating, you probably need a new radiator. Heating and cooling a radiator
> bends the vanes where they are attached to the tubes over and over like
> bending a coat hanger back and forth...eventually they break loose, and that
> leads to loss of cooling power. They can also get clogged up inside. If you
> have a radiator shop nearby they might be able to "boil it out" and repair it
> for you, but it's hard for them to compete against overseas labor, so you
> might find that a new radiator is your best option.
> >
> > While you have it off, you might want to clean out the cooling channels
> inside the block.
> >
> > Could be something else, but that's my guess.
> >
> > Jim
> >
>
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