164 coolant temp

[Karl Maxon <KLMAXON@xxxxxxxxxxxxxxxx>]

Alfisti - its time to weigh in on the 164 coolant temp thread.  Per the
'91-'93 manual, section 07-3:  The thermostat opens when the coolant
temperature reaches about 87C (188F).  The warning lamp turns on when
the coolant temperature increases above 115C (239F).  Elsewhere in the
manual a description is given about the rad. fan whereby the low speed
kicks in at 196F, and the high speed kicks in at 212F. When the air
cond. is on the low speed fan is on all the time.

Now, in addition to the above, the system is pressurized at approx.
15lbs.  Per Redline Oil data the boil point of plain water at 15psi is
approx. 220F, and for 50/50 glycol/water it's approx. 245.  100% glycol
is approx 260, all at 15psi.

The 164 header tank is prone to leaking/splitting at the large seam
around the middle, and the header tank cap can get gummed up or fail.  I
just replaced both.  $25 total from the dealer.  

Note that in very hot temps that upon engine shut-off the coolant may
boil-over without the 15 psi, since the boil-point of the coolant may be
too low without the pressure.  This is the condition I was
experiencing.  First I replaced the header tank because I noted the
seepage, and then tested the cap and noted it did not hold any pressure
at all.  Replaced both and the engine runs consistently around 190-210
in 100 degree outside ambient temp (consistent with the manual temps
noted above). The coolant level now only rises and falls approx. 1/2-3/4
inch between stone cold and super hot compared to large fluctuations
before I replaced the header tank and cap.

Regarding sealants - several people recommended Edelbrock Gasgacinch,
which I used when I replaced the water pump a few weeks ago.  Worked
great.  

I would suggest sending an e-mail to Redline:  Redline@domain.elided 
and ask for them to send you a brochure/test data pamphlet for their
WaterWetter.  There's a good discussion regarding boiling points, heat
transfer, etc.  

Anyway, I submit that operating temps for the 164 that are between the
amounts specified by Alfa above are A-OK, and everything is operating as
designed.  I'm personally thrown off everytime I jump from my Spider,
where temp is approx. 180, and get into the 164 and see the temp gauge
climb what looks like WAY past that 175 mark to its "normal" operating
range.

Happy motoring - Karl Maxon
'72 Spider
'91 164L

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