Oliver,
There may not be any specs for temps at places other than the sensor
unit for the gauge and the radiator. Temps at other places as measured
by the infrared may or may not be useful--I don't know about that.
Have you confirmed that the infrared gauge is reading correctly?
Are you finding the 220 temp at the radiator top tank?
That infrared tool is just the thing for checking water flow through
the radiator. Testing top-to-bottom, left-to-right should reveal a given
temp horizontally along the top, then the temp falling as you check down
the radiator toward its bottom tank. If you find spots that are
significantly cooler, that likely indiates something plugging a tube or
two.
Back-flushing with clear water will do no harm and may be worth doing
again. Remove the thermostat to do it. Use lots of pressure for this.
Also back flush the heater separately, but be gentle with the
pressure. The heater can hold an amazing amount of silt.
While the 'stat is out, test its opening in a pan of water on your
kitchen stove.
An overly rich antifreeze mix restricts the ability of the mixture to
transfer heat. 50/50 is all you would ever want and a lesser mix may well
give the antifreeze protection you need for your winters.
The heater control valve and the rad cap won't affect the engine temp,
except that the pressure maintained by the rad cap raises the boiling
temp of water. Higher temp difference between rad temp and air temp gives
more efficient cooling, but that's not your situation now.
I suspect that the AC is restricting air flow. Have you always had the
AC?
Is the plastic fan the MGB yellow plastic fan? Some electric add-on
fan?
Have you changed fuel? Changed ignition settings? Replaced water
pump? Checked belt tension? Is that foam rubber filler piece in place
between top of radator and the radiator bulkhead? Licence plate in same
location on bumper?
Bob
On Fri, 8 Sep 2006 22:54:45 -0500 "oliver" <sumton@sbcglobal.net> writes:
> hi, all.
>
> i could use some help.
>
> 73 mgb roadster, radiator recored at a supposedly reputable shop,
> new
> thermostat, plastic fan, dealer add-on air conditioning, new sending
> unit,
> reads same as old sending unit, second gage hooked up reads about
> the same;
> system flushed by running water through it in the last few year or
> so,
> antifreeze/water mixture fairly new, prob 60/40 to 50/50, new heater
> control
> valve and radiator cap.
>
> car runs hot, infrared says about 220 after typical 15 minute drive
> through
> neighborhood; needle about 3/4 on an 80 degree day. have had
> trouble with
> engine running hot for last several months as i've been working
> through
> replacing/testing various items in cooling system.
>
> try removing thermostat? what else to check? could there be a
> blockage
> somewhere and how to tell/find?
>
> thanks!
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