I have a 95 scrambler that I bought not to long ago The red temp light came on and i noticed the fan was not running, so I drained all the coolant, washed out the radiator and installed a new electric fan on a switch. so after running for ten minutes the light comes on. the coolant is full and a minute after you turn it off you can put your finger in the coolant. I know that the coolant will not cool that quick. what tells that light to come on? is it overheating somewhere else, I changed all the other fluids with the correct weight and ounces. I may just have to unplug it so I don't have to look at it.

Eric

 

Temp sensor on top of head on 400L, on left side of cylinder on 500 4-stroke. Fan sensor sound like problem on radiator if gets hot and no fan. 2 lead sensor behind radiator cap on 400 2-stroke engines, at bottom of radiator on 500 4 strokes. Or could be faulty temp sensor (shorting out) Coolant not hot you say? Is coolant circulating steady? Did you bleed air from system? Lot of questions I know,but said you replaced fan motor, bad?did you check old fan with 12 volts direct?

 

I am having fan trouble too. I replaced my fan a few months ago and now when my fan hits water it cuts off and the hot light comes on and I just keep going and it will soon start back up and back to normal? I have cut the machine and started it back and all was fine. My connections all seem to be okay. I did order that fan from the fan man and I kept the straight fin blades on the fan and I am now begining to think that it pulls so much air that when it hits water it is too hard on it and cuts itself off. I might pull the fan and put the curved blades back on and give it a try.

 

if the coolant isnt hot at all but the engine is, sounds like there no cirulating. check to make sure water pump or thermostat is working. is therm. stuck closed it might do it as well. just a thought.

 

I pretty sure that the system is cycling. I did loosen the bleed nut/ screw and let any bubbles out. Is there a thermostat and a pump on a 400? i thought the 400 had an impeller in the case?

 

Now that I know its 400L,Yes impeller internal,check also good connection on temp indicator sensor on head. NO themostat. Coolant enters waterpump inlet,circulates through cylinder and out top hose on head back to radiator. Most problems I've had on 350-400 engines are early fan motors with vent tube that allowed water in and shorted out (replacement fan motors are ventless) and fan temp sensors(behind radiator cap) that would short out because they are at top of radiator and if coolant level allowed to drop sensor was not in coolant flow! One reason why sensors are at bottom now,with exception of 325-330 oil cooled with thermister at top. Recheck bleed screw on head,make sure good flow of coolant with no air. Jump between the two wires on radiator sensor to see if fan operates. If fan comes on then wiring ok,run until hot if no fan then radiator sensor suspect. Hope this helps. Also check c/balacer fluid for seal leakage(milky color). No coolant smell from exhaust?(Head gasket leak)

 

fan was shot I tested it with a twelve volt supply. replaced it with a ten inch fan from oreilly auto parts. you said that the sending unit os on top of the head, what does it look like. how do you test to see if it works.

 

Sending sensor right behind bleed screw,at back of head has one wire connection,check for bad connector/bare wire. Not noted to go out very often, wiring problems usually most of my encounters. Did you jump wires at radiator sensor to see if fan works?

 

I finally got a chance to get a good look at the scrambler. I pulled the pipe off and when I did that antifreeze came out of the pipe and the exhaust. I guess that I found the most likely answer to my problem, the head gasket is shot. I pulled the head gasket and the thin piece of metal was all warped and twisted. Anyone else think that this was causing the problem? I guess it will be a couple of days until I know, as usual the local dealer does not keep the part on hand and I had to order it.

 

I had a 95 and the temp light was coming on and the fan was running. It ended up being piston slap and blew up a short time later. May not be your problem, just my two cents.