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Discussion Starter #1 (Edited)
hotter engine operating temperatures

lately the temperature gauge has been showing a reading which is generally 5 deg C hotter than usual when cruising through the city.
for example if sitting at traffic lights the gauge will read up to 93-95 deg c (on a long incline it has crept up to 100 deg C) before dropping down to about 85-90 deg C.
(the ambient temperature is warmer (about 25 deg C) since we are approaching summer)
is this normal?


note:
-while bleeding the system some small bubbles and steam? were seen to escape from the filler neck
-temp steady at 82-85 deg C at highway speeds
-water pump seems to be ok
-thermostat seems to open fully at 96 (coolant seen to gush from top hose into radiator)
-coolant/oil emulsion not evident under oil cap or on dipstick
 

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Discussion Starter #3 (Edited)
thanks italiansedanman.....
radiator has a fairly new core...will check alternator belt
...forgot to mention that head gasket was replaced recently...
...however a small amount of coolant was still being lost...(a mechanic suggested it is possibly seeping through the bottom of the liners and recommended using 'stop leak' in the coolant...
this seem to remedy the problem and the temperatures were fine...

would it be possible that blow-by gasses are making their way into the coolant between the base of liner and the o-ring?
 

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there should be no blow by gas getting thru the orings at the bottom of the liners, it would be getting thru the head gasket tho, that is where the pressure is. has the head been retorqued after the gasket was instaled?
cliff
 

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Discussion Starter #5 (Edited)
there should be no blow by gas getting thru the orings at the bottom of the liners, it would be getting thru the head gasket tho, that is where the pressure is. has the head been retorqued after the gasket was instaled?
cliff
thanks for your comments cliff ...
the head was retorqued at just over 800km from initial installation ... (it has only been ~5000 km since head gasket installation)
i am going to check the thermostat again (with regards to warmer temeratures) to make sure that it is fully opening..
regards
 

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My '76 Spider runs really hot, and was even hotter during the Detroit AROC Convention time trials. I retorqued the head, and used a gadget sold here to check for combustion gasses in the coolant. This can be purchased from auto parts stores, and is a simple vacuum pump that draws air from the top of the radiator through a reagent liquid that changes color if combustion gas is present. Cost around US$30.00.

My test was negative, even after seeing 250 degrees F on the guage (!)


lately the temperature gauge has been showing a reading which is generally 5 deg C hotter than usual when cruising through the city.
for example if sitting at traffic lights the gauge will read up to 93-95 deg c (on a long incline it has crept up to 100 deg C) before dropping down to about 85-90 deg C.
(the ambient temperature is warmer (about 25 deg C) since we are approaching summer)
is this normal?


note:
-while bleeding the system some small bubbles and steam? were seen to escape from the filler neck
-temp steady at 82-85 deg C at highway speeds
-water pump seems to be ok
-thermostat seems to open fully at 96 (coolant seen to gush from top hose into radiator)
-coolant/oil emulsion not evident under oil cap or on dipstick

(thankyou to Mr T for his thread on same subject...i am also watching that with interest)
 

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Discussion Starter #8 (Edited)
cooling system normal again

the cooling system has return to normal temperatures...
italiansedanman was right to suspect the radiator...
i had also read somewhere on the digest not to alter the air flow to the radiator as this could cause the operating temperatures to rise by up to 10 deg C...
a little while ago (winter) i had replaced the centre (broken) grill with a plastic mesh (160mm x 260mm) to prevent large foreign objects damaging the grill (edit: not thinking it would make much difference to the alr flow) ...
the effects of this was not realised until the ambient temperatures began to rise...
this was enough to prevent effective heat transfer across the radiator and lead to a warmer running engine (especially at freeway speeds - no fan)...(edit: lesson learnt)
thanks to all who responded
 
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