Temp sensor

[terbear]

I was cruising around town on Sunday, lots of stop and go traffic. All of a sudden my temp warning light comes on, yet the fan was not running. Once I got some air thru the radiator again, it went out.
When I got home, I let it idle in the driveway, and sure enough the light came on again with out the fan starting.
Later I shorted the temp switch that runs the fan at the bottom of the radiator, and the fan began to spin.

Question is: How does on know if the fan is staring to late, or if the temp warning light is coming on prematurely???

I know I should take it to the dealer, but I would have to put my original pipes back on, and, they would probably have to order a part, and leave it there for a few days, I live 90 miles from there.

Any sugestions?? Thanks Terbear

Is there an automotive replacement switch for the fan switch, I would rather spend 20 bucks on my own than bring it to the dealer.

You can just order a new fan switch on-line and the postman will deliver it to your door.

The only way I know to check what temp the fan is coming on is with a thermometer. You can't really stick it in the coolant with the bike running and the gas tank on, so I'd just tape it right to the bottom tank on the radiator, near where the lower hose enters. That should be the hottest spot.

Ummm.. BTW, have you checked your coolant level lately? If it's low it could cause this.

Because there's coolant in the recovery tank does NOT mean there's enough in the rest of the system. You need to lift the tank to check that at the filler cap.

[ells]

Originally Posted by caddmannq

Because there's coolant in the recovery tank does NOT mean there's enough in the rest of the system. You need to lift the tank to check that at the filler cap.

I've been told, by a usually knowledgeable source, that the engine will draw coolant in from the reservoir as it cools down after being shut down, which is also why you can't it fill it at the reservoir after draining the entire system. Do you have a different perspective?

[cactusjack]

I live in one of the hottest places in the country, and I have never had my temp light come on. However, my fan does switch on quite often. My point is, if it's hot enough for the temp light to come on, the fan should have been running already. I'd say the fan switch or relay is defective.

[blowndodge]

Originally Posted by Ells

I've been told, by a usually knowledgeable source, that the engine will draw coolant in from the reservoir as it cools down after being shut down, which is also why you can't it fill it at the reservoir after draining the entire system. Do you have a different perspective?

You are technically correct. If no air is in the system and since it's pressurized it "should" draw coolant from the overflow reservoir as the engine is shut down or cooling down. Doesn't always work that way when there is not enough vacuum in the cooling system because of low levels.

Originally Posted by Blowndodge "Darksider"

You are technically correct. If no air is in the system and since it's pressurized it "should" draw coolant from the overflow reservoir as the engine is shut down or cooling down. Doesn't always work that way when there is not enough vacuum in the cooling system because of low levels.

...Or (more commonly) because there's a tiny leak in the system that allows it to suck in air easier than it can siphon up coolant from the tank. The engine will heat up and blow out coolant until the recovery tank is full, and it stays full, as the system goes empty. Then you wonder why the engine is overheating.

Back when I first met my wife, her car had this problem. The leak was very slow, and hidden in the heater core box, so it dripped out through the A/C condensation weep tube and went un-noticed. After some months the car got low enough on coolant to overheat, and she took it to some crackpot mechanic who changed her fan relay for $50 and sent her down the road. 10 miles later it was boiling over.

The filler cap was rusty and I had to bend the tangs to get it off, but when I did the radiator was empty. The recovery tank was full.

After I found and fixed the leak myself I went back to the bozo that'd worked on her car and asked him, "When somebody comes in with a car overheating, don't you look in the radiator first thing?"

"Yeah," he told me, "But I couldn't get the cap open."

Fu**ing moron couldn't get the cap open, and was too stupid or lazy to pry it off, but knew he could rip some poor woman off for $50 in 5 minutes and just did it without remorse.

It was very difficult not to just bash him with a tire iron.

[cactusjack]

Originally Posted by caddmannq

[quote author=blowndodge board=nomad thread=5444 post=98741 time=1216736419]


...Fu**ing moron couldn't get the cap open, and was too stupid or lazy to pry it off, but knew he could rip some poor woman off for $50 in 5 minutes and just did it without remorse.

It was very difficult not to just bash him with a tire iron.

I'd have used my bare hands I find that's more satisfying than using a tire iron or some other blunt object.

I fried a transmission in my last pickup truck because the clowns at the lube shop didn't have the right tool to remove the plug on the side to check the fluid level (Getrag 5-speed manual in a K1500). It took something like a 19mm hex wrench. I was even paying extra for their 4x4 service package (check both diffs, xfer case, etc). I was going to go back and ream the manager when the guts of my tranny fused together on the shaft from the heat.

Turns out they had noted on the service tickets that the transmission was non-serviceable. I had never noticed it. Instead of them saying "Sir, we don't have the right tool to check your transmission fluid, you may want to check it yourself". I had been assuming they had been checking it and refilling as required. Granted, It was my fault for not reading the tickets but they could have done a little bit more to inform me. In retrospect, it's probably just as well they didn't service it, because they most likely would have filled it with 90W, when it required GM Synchromesh fluid at $24.99/qt. That's probably the real reason they "didn't have the tool". Ooh, I'm so worked up now I need a BEER!

This is why nobody else works on my bike. It keeps me out of the coffin and the big house. I'd be in one or the other by now.

[scion0]

Originally Posted by Blowndodge "Darksider"

You are technically correct. If no air is in the system and since it's pressurized it "should" draw coolant from the overflow reservoir as the engine is shut down or cooling down. Doesn't always work that way when there is not enough vacuum in the cooling system because of low levels.

My coolant level is barely above the "Low" mark when cold. Should I add a bit more? If so, what kind and how much? My fan does seem to come on a lot.

[macmac]

Scion0, if the level is low when the bike is held up straight add more. But then begin the hunt of loose hose clamps and a less than finger tight rad plug... Most of the hose clamps are too loose from the factory, and I have no idea what the whimp is like that installs drain plugs..

Just snug them ALL. If you find a white powder residue that is/was a leak.
..............................

terbear The sencor is likely bad.. If i were you I would pull it, and if you like test it with OHMS mode and a heat source, such as a plumbers torch, because you need it over 212 degrees.

Now don't just flame the part hard on, as it has parts that fire will cook... 'Paint' the flame over the part away from soft parts. It will heat fast enough this way. You might consider making a heat shild from a tin can so you don't cook the test wires..

Inside is a bi-metalic spring, which is probably gone 'open'. I am big into testing bad parts to confirm they are bad parts.

I am not sure what the thread pitch is and or the diameter, so I can't say if there is a automotive part that will fit. You could try to match one from most any foreign car parts store, as these will be most likey to be with in spec. I suspect most of these will be to big to fit.

However the time spent could save a few bucks. And if not buy OEM and install it yourself, and since your at it flush the system and add new coolant anyway.

[dogdoc]

My fan hardly comes on even in TX so i was worrying about it to the point I made an appt at the dealer. I took a 40 mile round trip the day before the appt and lo and behold what came on after the trip was nearly done<<<<< fan. Seems it took a longer trip to heat up the motor I guess. No over heat light ever kicks on either. Just change the coolant and did the flush. Running a K&N filter on the left.

[nomad]

i've never seen my fan running. i have been wondering about this for a while. should i let it idle for a time to see if it comes on? BTW, i've never had a temp light come on either.

I regularly ride stop & go traffic in 100^oF + temps and my fan does come on once in a while. It also sometimes comes on as I park the bike after a hot ride. It rarely comes on on days cooler than 80 ^o. It never stays on long, and my temp light has never come on in 32,000 miles so far.

[scion0]

My fan comes on all the time I think. :-) I need a light that tells me since I do hear it from time to time, but when I park it in the garage, the fan seems to come on often. That is why I thought I may be low on coolant (right at the low line when the bike is straight up). If low, what do I add to it?

I've been using Pro Honda Cool, which is premixed. Just make sure that whatever brand you buy is silicate free. I've been told Prestone is now silicate free, but I've never used it in a bike yet.