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Discussion Starter · #1 ·
Hi All,
Recently got a first bike which is a new to me 1996 F650 funduro with ~42k km.
At first when I got it I had only been practicing in the indoor car park at low speeds and noticed the temperature needle was around the dotted line but not so much into the red bar section and I thought that it was probably just because while going slowly there wouldn't be much air to cool the radiator, but then when I went on a longer ride ~70km and realized it was hitting very high when it definitely shouldn't be now out in the wind etc.

When I got back and turned off the engine and left the ignition on for around 5-10 minutes while the fan was running until it had cooled somewhat and the fan stopped automatically. While the fan was running I put my hand in front of the radiator where the fan was blowing and the air did not seem particularly hot like I had expected, and neither did the radiator seem very hot either, although I don't know how how it should be in general.

I had a look at the coolant level in the expansion tank and it was within the range, although it was the green type which some people seem to say might not be ideal, but that's hardly causing that. I've ordered some new Motul coolant and oil too for general maintenance which I will probably do soon but obviously want to figure out what is happening and how to fix it and hopefully avoid any damage.

Does anyone knows what might be causing that?
Or what should check to narrow down and hopefullly fix it?

Thanks

Land vehicle Vehicle Plant Mirror Motor vehicle

(also realized the speedo isn't working but found the cable was broken so that should be easy to replace)
 

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There are a few things to check.
Check that the coolant is circulating. The water pumps are known to blow seals and leak. Check the oil to make sure it is not milky or foamy from coolant getting in.
It sounds like you may be safe there if the coolant level is good but make sure the pump is working.
Check that the thermostat is working. You can take it out of the housing and put it in near boiling water, you should be able to see it open.
Make sure that the connectors onto the temperature sender unit are clean and free of corrosion. The wires from the temperature guage need to have a good contact to get a proper reading on the temperature.
If you have a multimeter put it on the OHMS scale ( omega sign) and check the resistanceof the sender unit, when the engine is cold, warm and hot. The readings should be different at each stage.
Last step is to clean the radiator.
But it sounds like dirty terminals on the sender or a thermostat that is not opening fully.
Good luck
Pete
 

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Discussion Starter · #3 ·
There are a few things to check.
Check that the coolant is circulating. The water pumps are known to blow seals and leak. Check the oil to make sure it is not milky or foamy from coolant getting in.
It sounds like you may be safe there if the coolant level is good but make sure the pump is working.
Check that the thermostat is working. You can take it out of the housing and put it in near boiling water, you should be able to see it open.
Make sure that the connectors onto the temperature sender unit are clean and free of corrosion. The wires from the temperature guage need to have a good contact to get a proper reading on the temperature.
If you have a multimeter put it on the OHMS scale ( omega sign) and check the resistanceof the sender unit, when the engine is cold, warm and hot. The readings should be different at each stage.
Last step is to clean the radiator.
But it sounds like dirty terminals on the sender or a thermostat that is not opening fully.
Good luck
Pete
Thanks for the reply
I took off the dash plastic to replace the speedo cable so finally got around to doing it all at once, it turned out to not be as complicated an issue as I had thought (but unfortunately probable worse for the engine - just hope I didn't damage anything the times I did ride it before).
The coolant level in the radiator was way too low, and I don't know why the expansion tank had still been full and hadn't refilled it if the level went down. All the tubes seemed to be working as far as I could see when I had the radiator cap off so possibly there could be something wrong with the cap valves itself but I'll be keeping an eye on the level in the radiator and expansion tank in future.
I should have also checked the thermostat and other parts individually when I already had the coolant drained but once I saw the coolant level that seemed the most urgent issue so I just cleaned the contacts too.
But since refilling properly with coolant although I haven't gone on a long ride yet but just from running for 15 minutes or so in the underground car park it didn't reach the red section that it would have before and when the fan kicks in you can feel the heat being blown out properly how it should be.
Is there anything you would recommend checking or keeping an eye on now that would point to any other issues or damage having been done?
Saving Drinkware Money handling Dollar Money
 

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The easiest one to check is the Weep Hole in the coolant pump.
Under the bottom of the pump there is a small hole. The idea is that if the pump seals fail coolant will leak out and you will see that there is a problem and fix the coolant pump.
There are two seals in the pump, one between the coolant chamber and the engine crankcase ( oil seal) and one other seal that just keeps the coolant in.
They are different.
What you do is put a small metal pin ( such as a flattened paper clip) into the hole. It should go in until it hits the shaft. ( my memory tells me it goes in about 30mm but best to check the manual on that) if the metal pin does not go in very far then that means that the seals have moved and need to be replaced.
If the weep hole is filled with dirt then it won't give the indication it is supposed to.
If you clean the weep hole and fluid leaks when the bike is parked then a pump rebuild is required. (Motorworks have kits with a new impeller and seals).
If there are no leaks and the hole is clear then good.
Keep and eye on the radiator level, and make sure that the radiator cap is sealing properly.
Also check that the hose from the radiator to the overflow tank is in good condition and does not have holes in it.
If the overflow pipe has holes then the coolant will not return to the radiator when the engine cools down.
Good luck
Pete
 
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