Fan not working and overheating after 5 minutes!

[weewazza17]

Hi guys, having stripped the bike and cleaned as much as I could, I've rebuilt the whole thing and now it seems as though the fan refuses to work and the bike overheats after about 5 minutes. I did drain the radiator on the clean and have refilled it with coolant. There may be air in the system but I'm unsure of how to get rid of it. I've tried bleed ing from the water pump whilst leaving the radiator cap off and the coolant filler open to see if that would help but to no avail. Any help you can shed on this would be greatly appreciated. I'm stuck on my 125 til this is solved

Cheers guys!

[djez]

You said fan is not working.

Temp should be good if your running but will quikly overheat at traffic condition without the fan.

to troubleshoot provided that youve already done the bleeding.

1- check the thermostat
2- check the fan if the motor is still ok,
3- check water pump.
 
I experienced rebuilding the radiator fan by cleaning up/resoldering  the carbon brush  of the fan but will certainly need replacement soon.

Cheers

[Daveontheedge]

Check your fuses.

[91cb-1]

To check your fan is not broken try bypassing the thermostat to have the fan on all the time

[weewazza17]

I've checked the fan against the frame of the bike and it will motor over with power so it seems to be working? I think the next part to check will be the thermostat. Now just how would I go about that, having never done it before myself?

[xstreamcanadian]

excuse me for budding in, but the thermostat is only going to determine water flow, i think. you want to check the heat activated fan switch. check the connection at this switch as well. i  could be wrong and this switch may only run the temp gauge? I am assuming that it is what trips the fan on. I could be wrong, anyone?

[Kai Ju]

The fan switch will only activate the fan if it's immersed in hot enough coolant.
Either you have no coolant in the system or it's not moving.
Check and see if the radiator gets hot. If so, does it get hot evenly ?
If it gets hot you have coolant, if it gets hot evenly the coolant is flowing but your gauge is lying.
If it gets hot on the inlet side only you have coolant but it's not moving.
If it's not moving check your thermostat and/or your water pump.

[weewazza17]

Hello again, I have checked the thermostat but was unsure as to what a damaged one looks like. It seems completely fine to me. I ran the bike for about 10 minutes to get it up to temp. It now seems as though the coolant is not running around the radiator as both the main pipes and the radiator itself are still cool. I take it this means there is a problem with the water pump?

[Kai Ju]

Did you run it with the thermostat installed ?
Since you're obviously draining and refilling your cooling system you might as well check the pump impellor.
Make sure it's solidly connected to the engine and rotates when you crank the engine over.
If it does, run the bike without the thermostat and see what happens.

[clarkdw]

Hello again, I have checked the thermostat but was unsure as to what a damaged one looks like. It seems completely fine to me. I ran the bike for about 10 minutes to get it up to temp. It now seems as though the coolant is not running around the radiator as both the main pipes and the radiator itself are still cool. I take it this means there is a problem with the water pump?

Check the thermostat by putting it in a pot of water and heat it on the stove. It should open at well below boiling point of water. May be marked on it at what temp if you have a thermometer to compare with. No circulation could be due to an air pocket in the pump or the thermostat (if it is in) not opening. Problem with the pump would be pretty far down my list of probables. The CB-1 is famous for being a bi&ch to bleed the cooling system of air. Keep your reservoir full and heat it up several times so that it expands and contracts drawing in the reservoir coolant each cooling cycle.

[weewazza17]

What a night I had yesterday. Well I've stripped the bike almost entirely to source this problem. The water pump seems to be in perfect working order. I cranked it over and it was rotating fine as well as having coolant in it to drain. The pipe coming from it to the radiator had coolant in it also so no blockages there. The reservoir is also free of blockages. What a bitch that was to get at. I'm beginning to think that this may all have just been an error on my part. When I refilled the system, I filled from the reservoir and not the radiator which may have been the cause of all the problems. As for the thermostat what will it look like once it has opened, having never seen this before. Cheers again guys!

[clarkdw]

You will see the valve portion of it move and open up the passage thru which the coolant flows. There is a spring holding the valve disc closed till it gets hot. The disc will then be moved by the expansion of a wax pellet in the stem on the opposite side from the spring. 

Filling most of the system needs to be done thru the rad cap. The last portion and bleeding the last bit of air out must be done thru the reservoir thru expansion and contraction. Theory says that there should be absolutely no air in the engine and that can only be accomplished by leaving the rad cap on.

[weewazza17]

Well, it is finally fixed. I think the problem was filling the coolant through the reservoir and not the radiator cap. School boy error and a lesson learned I would say. But I've learnt a lot about the bike from this weeks endeavors. Cheers for you help guys. Nice to know people will help out when ya need it! Next project is the final part of my respray.

[91cb-1]

Well, it is finally fixed. I think the problem was filling the coolant through the reservoir and not the radiator cap. School boy error and a lesson learned I would say. But I've learnt a lot about the bike from this weeks endeavors. Cheers for you help guys. Nice to know people will help out when ya need it! Next project is the final part of my respray.

You doin the respray yourself or gettin someone to do it for you? i admire anyone who can do a good spray job by themselves, i did an alright job on my rear cowl but it was a bitch

[weewazza17]

Doin it myself I've done the front cowl and it looks really nice. I'll get a pic on here in a bit. I've done the tail and for some reason it just would not come up so it's gona be a case of stripping it back again and tryin it over. I thought I had it nailed but the shine just isnt showing Then its on to the fuel tank which will be epic considering it took 3 hours just to fully sand down the tail. It has been taking about a week a piece to get finished. sand spray sand spray sand spray and repeat lol. Its all going to be burgundy with black pinstriping and then the rest of the bike will be decked out in chrome and silver. Kinda want it to look properly retro.