[dogwater]

Ive always though that on a Chevy gen 1 that the water interned the rad. thru the top hose then back to the water pump from the bottom hose, am I wrong? I ask because Im using an adjustable fan controler that has the bulb on the end of a small wire,I put it next to the top hose thru the rad. fins.Im thinking it might do a better job if it were next to the bottom hose.I went for a long drive to get it set to turn on the fan at 190 deg. then turn off at 180.It was working fine now 2 weeks later it turns on the fan at 190,runs for a few mins. then turns off, then the water temp.climbs up to 210.Its not consistent.The sm.wire that goes to the bulb is looped next to the rad.Maybe the air comming thru the grill is having an effect on the wire,such as the bulb is hot because its in the fins but the air is cooling the wire.Any ideas.....Am I right about the hoses?

[cdminter59]

The water pump pumps the water thru the radiator thru the bottom hose and back into the engine after it is cooled thru the top hose. Usually that sensor is attached to the radiator on the engine side.

[dogwater]

So I should poke the bulb into the fin pack close to the water inlet (botttom pass.side).I put everything on the driver side behind the head light,I made a box for the fan controler,a bracket to mount the box on,an ran all my wire to that side.I hope the wire going to the bulb is long enough.

[sirron]

How is that working for you? Because as the engine warms up the thermost opens and allows coolant to enter the rad through the upper hose. The hottest coolant is at that point. The water pump pulls the coolest coolant from the bottom on the other side of rad ,enters the engine and the cycle starts over. You'll want the fan senser at the hottest point. The wires have no effect on the fan, the temp is taken from the bulb on the end of the wires. There should of been instructions with the control.
Good luck

[oldbogie]

Originally Posted by dogwater

Ive always though that on a Chevy gen 1 that the water interned the rad. thru the top hose then back to the water pump from the bottom hose, am I wrong? I ask because Im using an adjustable fan controler that has the bulb on the end of a small wire,I put it next to the top hose thru the rad. fins.Im thinking it might do a better job if it were next to the bottom hose.I went for a long drive to get it set to turn on the fan at 190 deg. then turn off at 180.It was working fine now 2 weeks later it turns on the fan at 190,runs for a few mins. then turns off, then the water temp.climbs up to 210.Its not consistent.The sm.wire that goes to the bulb is looped next to the rad.Maybe the air comming thru the grill is having an effect on the wire,such as the bulb is hot because its in the fins but the air is cooling the wire.Any ideas.....Am I right about the hoses?

For the Chevrolet, the hot coolant returns from the upper hose that typically runs between the thermostat housing on the front of the intake manifold to the radiator. For older down-flow radiators that hose will connect to the upper tank for later model cross-flow radiators it will connect to the top of the left (drivers) side tank.

The coolant flows downward in the down flow to be picked up from the cooled bottom tank from the right (passenger) side by the pump; this is always the larger hose. For the cross-flow, hot coolant moves across the core left to right collecting in the cold tank on the right (passenger) side. It is returned to the pump from the bottom of the cold side tank. Again the pump intake hose is the largest of the hoses.

An electric fan needs to be sensitive to the temperature of the hot returning fluid; therefore, the sensor will be placed on the upper hose.

Given that the fan is not needed once road speed gets to about 20-25 mph the sensor should be adjusted to so as not to turn on till the thermostat's rated opening temp is exceeded by about 15 degrees F. Otherwise it just will cycle on to off to on again as the engine temp will probably cruise a window of about 5 to 7 degrees depending upon load changes the engine sees between flat or hilly highway.

Bogie

[dogwater]

There wasn't any instructions as to placement of the bulb other than it had to be in the fin pack.I haven't changed its position yet nor have I put my flex fan away yet either.The problem with the flex fan was it was keeping the engine to cool,only on the hottest days would it get up 190,mostly it ran 160 deg.I didn't have a fan clutch on it.Yes I know that it needed a fan clutch,but I just couldn't see a clutch on a flex fan.I'll just play around with the fan temp.adjustment some more.Thanks for the input.

[oldbogie]

Originally Posted by dogwater

There wasn't any instructions as to placement of the bulb other than it had to be in the fin pack.I haven't changed its position yet nor have I put my flex fan away yet either.The problem with the flex fan was it was keeping the engine to cool,only on the hottest days would it get up 190,mostly it ran 160 deg.I didn't have a fan clutch on it.Yes I know that it needed a fan clutch,but I just couldn't see a clutch on a flex fan.I'll just play around with the fan temp.adjustment some more.Thanks for the input.

The thermostat should contol the temp, the fan should not have anywhere the capability to over run that as the thermostat would just close down to a level or even close to stop circulation untill the coolant temp is high enough to reopen the controlling valve. This type event where the thermostat cannot contol coolant temp is a risk when too many or too large vent holes are drilled into it. A single hole not larger than 1/8th inch should be it or else the leakage around the closed valve is so much that the thermostat may not be able to control the coolant temperature.

If the temp switch for the electric fans is placed in the fin pack, that it should in the upper left side of the radiator for a Chevy which is the hottest place so this provides the earliest signal to the fans about the engine temp. If the radiator configuration is other than OEM Chevy then the sensor should be in the fin pack as close to the coolant return from the engine as possible.

Bogie