The hot lamp switch is probably defective

 

Thanks, I will check it out.

 

Hi, if the over-temp lamp lights up, but the fan doesn't turn on, could a defective hot lamp switch actually be the issue or is there something else at play here?

 

how could it be the hot lamp switch thats defective if it is already turning on a lamp? there must be a second switch somewhere that is not kicking in, my magnum has one on the top backside of the rad that runs the fan maybe check that? the switch on the engine tells the lamp to turn on, the fan needs to kick in preemptively before that over temp light comes on take the rad switch out and put in a pot of boiling water and test it with a multimeter for continuity then figure out at what temp does it close the circuit (turn on) is the water pump circulating enough coolant? make sure no air pocket is trapped in the lines.

 

Yes, that switch on the rad is problematic. I put in a manual switch on 3 of the 4 of mine.

 

Thanks for taking the time to post your thoughts Magnadude and Snowchaser, I have replaced the radiator sensor with a new one and symptoms didn't change. Would an air pocket keep the radiator sensor from detecting the over temp situation and not engage the fan?

 

The sensor in the radiator has to be immersed in coolant, so air in the radiator tank would prevent the fan from turning on and the coolant will boil a short time after the hot lamp comes on. That's why a coolant recovery tank is provided - air is purged from the radiator as the coolant head and expands and as the coolant cools, coolant is drawn from the recovery tank back to the radiator.

 

The other thing that could be happening is your hot lamp switch might be turning on too early and the fan switch isn't near temp but I wouldn't risk running it if that light is on could overheat the engine and cause significant damage heads warp or gasket failure, Piston ring damage and such

 

Never seen an aluminum head warp in 40 years - seen plenty of damaged heads from overheating, but never a warped one - usually damage to the valve seats, guides, seals and bearings, but never warped from overheating. Warp damage usually occurs from over torquing, torquing in an uneven sequence or not torquing in an adequate number of stages.

 

Regardless of it being aluminum it's still not good warp damage or not.

 

My thing is electrical not so much the engine but I have enough damaged tractors in my yard from overheating and warped heads to know it's not a good idea to risk it. Nothing against your 50+ years exp latebird.

 

It's just that aluminum does not have the impurities of cast iron that promotes warping from uneven heating. I have seen hundreds of warped cast iron heads both overhead valve and flat head engines. I have seen a lifetime of damaged aluminum heads, but never one warped from overheating. It's one of the properties that makes aluminum a better choice for cylinder blocks and heads. Someday (and they are currently working on it) they might be making engines from ceramic or composite materials, but they have a lot problems to overcome and they are making headway. By the time my unborn great grand kids are old enough to drive the internal combustion engine may be a museum piece - just a reminder of past technology.

 

Latebird.


I'm just on cautious side cause let's face it I'm wayyy younger and it's something younger generations normally lack. I'm only 31 and my mechanic skills are self taught with farm equipment mostly but I appreciate your pointing out that aluminum heads don't warp really. I learned something new .

 

I'm 70, grew up on a farm, graduated college with a degree in electronics, was messing with motorcycles from about age 14 - learned about DC generators, point ignitions, side valve (flat head) engines working on tractors and other farm equipment (older brother was a trained journeyman mechanic and taught me) - I've learned some, forgot a lot and while I still learn, I am not thirsty for knowledge. I do think it's important for some old accepted methods be rejected and replaced with updated methods.

Example: Will a battery go bad if set on concrete? No - it may actually make a battery last longer, but the battery has to be maintained while not in use. A battery 'decays' when not being used. A warm battery decays faster than a cold battery. Concrete is generally cooler than the air around it. If you place a battery on concrete it will help keep the battery cool slowing the decay, but the battery still need to be charged at about a 750ma rate until a full charge is achieved at least every 30 days. The old 'setting a battery on concrete' myth was a fact when battery cases were made of hard rubber - today's batteries with plastic cases do not suffer from the micro-cracking of the hard rubber cases of yesteryear's batteries. The old hard rubber cased battery would discharge faster on concrete than today's batteries and any battery that is allowed to discharge and is not recharged regularly will go bad. Technology has turned a fact into a myth.

 

Hi All, thanks again for your input. I'm not sure I'm thinking this through correct, but, I was double checking the system the other day and left the radiator cap off as I left my machine idle until the over temp light came on. One thing I noticed was that the radiator did not seem to be circulating like it should, saw the fluid rise a little bit after it started getting hot, but really no noticeable circulation. I'm wondering if the thermostat might cause the issue if it is stuck closed. I was thinking if it is stuck, the radiator wouldn't get the hot fluid to cool down, so the radiator sensor wouldn't close and the fan wouldn't turn on. In the meantime, the the sensor on the engine is going to get hot because there wouldn't be no cooling which would then turn on the hot lamp. I ordered a thermostat on line and it looks like I won't get it for a few days. I'll be sure to update after I install it. Thanks.

 

Some

Some of these machines need the water pump primed to work and I'm not sure how to go about that but it could also be the pump itself.

 

If you want to see coolant flow, you have to lower the coolant level to just above the core tubes so when the engine is running the flow can be observed - if the coolant is up to the filler neck, you might see some discrete movement of the coolant level as the engine is revved, but that's all.

I don't question if a thermostat is stuck closed - I remove it and test it - if it passes the test, I reinstall it.

As far as 'priming the water pump'? I have never yet seen one that needed 'primed' - I don't know about that claim, but I would like to know which make & model it is in case I ever encounter it.

Anybody else ever seen a liquid cooled engine that needed the water pump primed? Maybe certain marine engines?

 

Just remember someone else who had a similar problem and it needed priming, they might of confused it with a oil pump as for model I haven't a clue never seen it.

 

Hey, knowledge is power and if it's out there I want to know - I may not remember it later, but it will come to me if I ever encounter one. I'm not saying it doesn't exist, I've just never run into it. I remember having to prime the old pitcher well pump when I was a kid. It's hell to have to have water to get water, but if the leather seals in the pump dried out, it took water to swell and lubricate them to enable the pump. I may not need to prime a water pump around here, but if I am in a depressed part of the world and need to prime a pump, I still know how.