RE: E30 Overheating -- any advice?

["Chao, Harvey" <harvey.chao@xxxxxxxx>]

In V9 #31, David posted:

> fan clutch to kick in.  If its clogged you can't really clean it out,
> you have to get a new one or a used one that was never clogged.  After
> replacing my radiator, my car has never gone beyond the 1/2 on the
> heat
> guage, that includes running in 95+ degree temps, with the AC on while
> idling.
> 
> 
What is a good way to tell if your radiator is clogged.  I've been
dealing with a stupid overheating problem in my wife's '84 318i and I
wanted to check the radiator, but I don't know how.
=================

When I was having problems with my E28 running warm, I thought I was being
so smart, and used a stem thermometer located at the top right and left
corners of the radiator between the core and fan shroud to measure the
relative temperature of the coolant entering and exiting the core - seemed
to show a good temperature drop so probably the radiator was doing its job
and I proceeded to look elsewhere.  BLAAAATTTT!!!   Wrong.  I eventually
eliminated all reasonable sources and wound up back to the radiator, so I
replaced it and then took the side tank off of the old one.

FULL OF CRUD!  Clearly one of the two POs had neglected the cooling system
at some point.  Since there was a neck on the side tank not removed, I jury
rigged a garden hose and propped the radiator so that the core tubes were
vertical and being fed clear water from the bottom.  I examined the water
flow from the tubes at the "top" of the radiator.  Bottom line was that 2/3
of the tubes were not flowing at all, and that these were the ones in the
center  of the radiator directly in front of the fan.  Thus any cooling was
occurring on the tubes in the top 1/6 and bottom 1/6 of the radiator core.
Since my stem thermometer were in the upper right and left hand corners
where there actually was some flow - - - -.

Probably the only non destructive way to get an indication of radiator flow
is to systematically scan the surface of the radiator core with one of those
remote infrared reading thermometers while the engine is up to temperature
and running.  This SHOULD show  where tubes are clogged by temperature
readings that are cooler than adjacent flowing tubes.

Harvey

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