Re: cooling system problem

["Russ Maki" <rinard@xxxxxxxxxx>]

Mark,
Sure sounds like the radiator. The fact that the overheating can be
controlled suggests partial blockage to me. Bet it cools down a little when
you wind it out.

BTW, I just did a little 95K (actually, 100k) work on my own E30 -- new
shocks/struts all around, shock mounts, control arm bushings, driveshaft
flex disk. All were worn out except the shocks/struts. Also changed the
driveshaft center bearing (may not have needed it) and muffler, which was
the original after 13 years of driving.

I dunno if you've done any of the above...I'm just suggesting that it may be
time to start looking for wear at these points.

HTH,
Russ

> Date: Thu, 22 Jun 2000 09:18:44 -0400
> From: Mark Holbrook <holbrook@domain.elided>
> Subject: <E30> Cooling system problem
>
> 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.
>
> - --
> Mark (Holbrook@domain.elided)                    "Back roads. Period."
> http://www.net1plus.com/users/holbrook/mark.htm

------------------------------

End of bmw-digest V9 #1504
**************************