1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Paul,
usually those fans need about 1/2 of sec to get into full run at ~3000 RPM. If each cycle takes about 4-5 sec, then it definitely doesn't look like electrical issue. I'd say that there's no enough coolant flow thru radiator to match fan performance.
Referring to the breakdown posted above:
- you may need to check the crank pulley, though I don't think it's your issue since if it's gone then you'll also notice weak power steering assistance. Since you don't mention you steering has become less power-assisted then you crank pulley should be fine
- check the belts and their tension
- flush your system. If it doesn't help then you may need to go deeper and get it cleaned out using plenty of water and some chemical additives (but be careful not to go with too strong ones that will eat your engine and both radiators). Refer to what you see coming off the system when performing that flush. Don't forget to bleed the air out of the system using that nipple on the thermostat housing (it's two-step procedure: let the air get out on a cold engine when pouring a coolant in and after the engine is warmed up and the fan is toggled on at least once shot it down and wait for minute and open the nipple once again until fluid starts coming out; do the warm up mostly at idle speed, but jump to about 2000-2500 RPM for about 10-20 seconds after you notice that radiator has become hot, but before the fan kicks in - refer to what you see happening in the coolant reservoir)
- check the temperature sensor that runs the temperature gauge. Just try another brand new sensor
- it may happen that termo-switch that runs the fan has lost its hysteresis and thus it toggles on and off at another temperatures rather then specified and/or, THAT IS MORE IMPORTANTLY the temperature difference for on/off toggling is too low (e.g. instead of 94/90C on/off temperatures it works with 100/99C - a hysteresis is the difference of levels, in this case it's the temperature difference when it toggles on and off; if the difference is too low [in my example with stock 94/90C and suggested 100/99C it's 4C vs 1C] then one should have an issue quite similar to yours, but so far I haven't heard of termso-switches that go wrong this way). Try another one termo-switch.
Good luck,
Zig
P.S.
when saying xxC (e.g. 90C) I mean to refer to some centigrade degree temperature.
posted by 77.37.1...
, Sun, 13 Jun 2010 14:14:02
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