engine temperature maxing out at 70 C...?
 

even after vigorous driving my cluster only indicates an engine temp of about 150 F. i checked the block with an infrared thermometer, and sure enough, 68 C. on this basis i think the sensor and gauge are working. getting up to temperature i have no questions about, i have just read so many posts about temperatures north of 90 C that this low reading confuses me.

my (W126) radiator fan appears to run nonstop. would a failed viscous clutch have this effect on temperature, or is something else likely to be afoot? do i actually have a problem?

thanks for any tips.

Bad thermostat is a good possibility.

^ Agreed.

thank you, off i go to replace the thermostat.

Be very very careful with the bolts, they have a nasty habit of breaking off with little provocation.

On your second note, a viscous coupled fan always spins but the degree of coupling to the engine varies based on the temperature of the air coming through the radiator.

very good, that was an easy fix. the only hiccup was figuring out that my thermostat housing was original to the chassis, so i had to reuse the old O-ring instead of the brand new gasket with the stub protrusion. i took the opportunity to reroute another heater hose and spill coolant all over my alternator. happy day!

so, now it gets up to 90ish C much more quickly, and i am more happy too. i was incorrectly assuming that the thermostat opening temperature was much lower than it actually is (80 C). thanks folks!

wow KarTek, i see. thank you. then i will assume that it works until i find out otherwise.

do u have a brand and part number off that thermostat? i ordered one for my car ( wont get past 70) but the one sent was not correct ...

hi trudge, i bought it from pelican parts. they have several from different brands, but as far as i can tell, the main difference is whether they have the old or new style of gasket (does the vernet one come with both?). the one i got was wahler brand.