Re: <E30> Cooling system problem

[Mark Holbrook <holbrook@xxxxxxxxxxxx>]

Way back on June 22, I described a cooling problem I was having. 
Several listers sent me private responses and I thanked them
individually (Thanks, again!) but the rest of you, having not heard
anything more about it, probably thought, "Oh, well, there goes yet
another bozo who joined the list just to get some advice and then
disappears.

Well, I'm back to tell you how it turned out.  (And actually I've been
on the list for ages.  The main reason it's been more than a month is
that I have a garage full of motorcycles to use and haven't really
needed the car!).  Anyway ...

Back then I wrote:

> My '89 325i w/ 95K miles overheats.  The temp gauge creeps up to 3/4
> under normal driving (A/C off) in this warm weather, and will go higher
> except that I turn the heater on full blast (directed out the windows,
> of course!), which brings it back down to about 1/2, or slightly higher
> than it sits when everything's "cool" <yuk yuk>
> 
> Got that?
> 
> I replaced the thermostat.  The old one was broken shut.  But there was
> no real change in the overheating problem.
> 
> I replaced the fan clutch after "testing" it with a rolled up newspaper
> when the engine was hot.  I could stop the fan and therefore declared
> the fan clutch dead (95K miles, after all).  After installing a new one,
> I got the same behavior.  Beginning to suspect the radiator at this
> point.
> 
> (Incidently, at the same time I replaced the fan clutch, I had to
> replace the broken auxiliary fan ($330, ouch), but this shouldn't really
> be part of the problem or solution, except for when it gets really hot
> and the sensor kicks it in.)
> 
> Sensors, switches, fuses, and relays check out.  Coolant is new and the
> system is righteously bled each time I fiddle with it.
> 
> So what's left?  The radiator and the water pump, no?  I suspect the
> radiator because of the fan clutch behavior, the fact that the aux fan
> doesn't come on even when the engine is hot (non-circulating coolant not
> hot enough to trigger sensor), the fact that the engine *does* cool down
> when you crank open the heater (indicating that the water pump is likely
> working, pushing coolant through at least the heater core), and the fact
> that there's no noise or leakage coming from the water pump (although it
> also is original).
> 
> So, I'm about the pull the radiator and take it to a shop to be
> flow-tested.  However, I'm not absolutely sure that's the problem.  The
> radiator and hoses all feel plenty hot when the car's running and
> practically no crud has come out of the radiator, nor has the coolant
> ever look cloudy or cruddy.  But I don't wanna do the water pump yet if
> I can help it (I'd rather do it when I get to the next timing belt
> change (due at 120K)).
> 
> Do you think I'm on the right track?
> 
> Is there anything I'm overlooking (like a funky heater control that
> could possibly affect the radiator circulation?)
> 
> Thanks for sitting through this windage.  Any advice will be
> appreciated.

Well, I never took the radiator to a shop 'cause the best/closest guy I
talked with was busy as hell.  Instead, I opted for replacing the water
pump next, the reason(s) being 1) it was cheap ($50 from my local
imported auto parts store), 2) it was about time anyways (95K miles), 3)
it isn't terribly difficult to do, and 4) a new OEM radiator was $275
from my local store and $240 (plus shipping) from Bav Auto (I'm a cheap
bastard!)

Of course, that didn't fix the problem.

Next I tried an off-the-shelf chemical flush (Zerex, "what everyone
uses" according to the mega-parts store guy) and left it in there for
probably 8 hours worth of engine running.

While the stuff that drained out was nicely brown, there was no loose
solid crud and the problem persisted.

Finally, I bit the bullet, but got smart and called Greenfield Imported
Car Parts (consider this a plug for them! http://www.gicp.com)  They
could get me an aftermarket radiator for $188 plus $10 shipping (same
state (Massachusetts), how convenient).  I called on a Thursday.  They
said they could have one by Friday.  It showed up Tuesday.  After
flushing the system with water twice yesterday, I installed it and fresh
coolant this morning (Friday).

Everything works just fine again now.

- -- 
Mark (Holbrook@domain.elided)                    "Back roads. Period."
http://www.net1plus.com/users/holbrook/mark.htm

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