Sorry, I am slow on this one (was admitted to ER and spend 14 hrs there due
to my heart pulse at 160 for an hour).
Did you check the temperature switch in the engine? I had this problem in
my 190E which runs high even though I did flush the system, changed the
radiator cap, change the thermostat. It was the switch that fails to run
when it is at around 90.
Good luck.
K.S.
----- Original Message -----
From: "LWB250" <lwb...@yahoo.com>
To: "Mercedes Discussion List" <mercedes@okiebenz.com>
Sent: Saturday, April 25, 2009 4:48 PM
Subject: Re: [MBZ] 87 MBZ 420 SEL High temp
My former 82 300SD ran hot when I first got it, but only at speeds above
about 30-40 mph. If you got out on the highway it would run up in the 90s
(C) and just sit there. Drop down to a lower speed and the temp dropped
down to the expected 87C.
1.) Cleaned the radiator. That is, removed it and pressure washed the
core. It was nasty. No joy.
2.) Replaced the thermostat. Rumors abound of Behr thermostats being
grossly inconsistent. Not this time.
3.) Made sure the little bypass line was working. Yup, clean as a
whistle.
4.) Replace water pump - the pump that came off was a NAPA pump. Oh, boy,
this has GOT to be it. Nope.
5.) Take radiator out and have the guy that did all of our industrial
engine radiators take a look at it. Bingo.
At some point in time, the PO ran the evil green stuff in it, and long
enough that it got exhausted and a great deal of the chemicals dropped out
of solution. So much so to the point that it clogged the center tubes of
the core. Interestingly enough, when he rodded the core out, only a
circular portion of the radiator tubes were clogged, that is, the very
center of the core where air flow (fan hub) was at the lowest.
So, the reason it would work fine at lower speeds was because I had plenty
of surface area to dump the heat. At high speeds when I needed all of the
radiator surface to dump engine heat to ambient air, I didn't have it.
Therefore, the excess heat remained in the cooling system and the
temperature of the system increased.
I got into the habit of taking every radiator out of my MBs after that
point and having them professionally cleaned. It's an easy job and
relatively cheap (used to be well under $100.)
Dan
--- On Sat, 4/25/09, Luther <benz-n-h...@gulseth.net> wrote:
From: Luther <benz-n-h...@gulseth.net>
Subject: Re: [MBZ] 87 MBZ 420 SEL High temp
To: "Mercedes Discussion List" <mercedes@okiebenz.com>
Date: Saturday, April 25, 2009, 2:25 PM
My SDL is in that same shape....
Luther
OK Don wrote:
> Every time I've had an engine runnig hot, a new
radiator cured it. Cleaning
> the old one has only made minor differences. Seems
that every car I've
> gotten that has had green coolant has needed a new
radiator.
>
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