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Coolant leak

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TheWizardofOdds
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Re: Coolant leak

Post by TheWizardofOdds on Fri 17 Jun 2016, 4:34 pm

@eternally_troubled wrote:The cheap blue concentrated coolant from halfords plus some distilled/deionised/pure water is fine for the CB500 - you don't need a Honda specific one!

Unless the system is very gunked up you don't really need a flushing agent either - fill the bike with tap water, run it up to temperature, rev it a bit and leave it to cool and then drain, then re-fill with the correct coolant.

Thanks for the advice.  If there isn't much difference between the two I'll get the honda stuff at £19.99, good shout though. 

I'm unsure whether to replace the rad cap right now, as the fan may or may not run. I'll have a think. I had a look again at lings parts and the sealing washer for the coolant drain is £5.20. FFS, for a washer? I think I'll leave it where it is out of principal!
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eternally_troubled
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Re: Coolant leak

Post by eternally_troubled on Tue 21 Jun 2016, 8:39 am

I think the coolant drain washer is a copper washer, so, really, should be replaced - however *any* copper washer will do - you don't have to buy a Honda one! Also (for the bodgers out there) it probably won't leak if you don't replace it and just re-use the old one - just don't complain to be when it does Smile

Anyway, back to your question on the fan earth:

The idea is that the radiator is well grounded to the bike frame and hence the negative pole of the battery. The fan switch connects to the radiator and when it gets hot connects the negative side of the fan to ground (via the radiator) which causes the fan to turn (the other side of the fan is permanently connected to the positive via the fuse you replaced earlier).

Now on old bikes (like all of our CB500s are!) the fan-mountings get corroded and don't conduct as well as they once did - this means that the fan doesn't work (even if the switch is fine).

So, if you have a multimeter you can check the grounding of the radiator - measure the resistance between the radiator body (scrape off a bit of paint to make sure you contact the metal) the negative terminal of the battery and/or the engine. The resistance should be, say, less than 1 ohm.

If it is high-resistance (or not connected at all!) then you need to supply a new ground to the radiator - I did this on my bike by finding a screw on the frame under the tank (I think there was one of the bracket that holds the thermostat), checking that it was low-resistance to the negative battery terminal and running a wire between that screw (I lifted it a bit, wrapped a bit of wire round it and tightened it up again) and one of the radiator mounting screws.
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TheWizardofOdds
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Re: Coolant leak

Post by TheWizardofOdds on Tue 21 Jun 2016, 10:40 pm

Thank you. A very informative and enlightening post, for me! 

Yes, it's a copper washer. I drained the coolant today. 

The rad mounting is very corroded on my bike so could well be an issue. I'll check tomorrow night for rad grounding with the multimeter. 

I was hoping to drain, flush and fill coolant today but got only as far as draining the radiator. I then went to drain the reservoir but was met with a very rusted hose clip ( I forgot, I'd checked it the other day). Sprayed the hell out of it with gt85 and got my heavy duty screwdriver and spanner on it but it is fused with rust. Aaarrrghh! Everywhere I turn with this bike is another issue. 

What now? It's not exactly easy to access either the tank drain hose. I've yanked and twisted the damn clip so much now it probably has to come off. It hasn't budged one bit though. Should I chance leaving it? Not sure how much fluid is in the reservoir, I can't see any. If I flush it there will be water left.
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rob75
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Re: Coolant leak

Post by rob75 on Wed 22 Jun 2016, 4:02 pm

Just my 2 cents, but looking at any part that is really corroded gets me to buy new parts. Especially parts like hose clamps. These cost next to nothing and after a long period loosening them may be problematic (as you experienced!). Just cut of the old one with a pair of wire cutters.

You can measure the resistance between the radiator and the frame (negative pole) from the hexagon part on the fan switch. It's brass and measure from this point to the frame or battery negative plug.

Coolant: use a good quality (pre-mixed or concentrate) suitable for aluminium engines. Anything decent from Castrol, Shell etc. will do. It may be a good idea to rinse the system with water if the previous change was long ago.

These bikes aren't the hardest ones and are straighforward in engineering.

As you were experiencing coolant leaks, it may be a good practice to inspect all hoses and when in doubt loosen them, clean the mating surfaces and refit using new hose clamps.
Rusted bolts and nuts, spray them liberally with a decent penetrating oil (with graphite) and let it soak for some time.

If at any given moment you forgot buying a brass sealing ring, using a blow torch (simple soldering one) can be used to heat the ring until it is red hot and then cool in water. This will revive the ring. This looks like bodging, but it is just good old fashioned mecanics.

Succes,
Rob
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eternally_troubled
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Re: Coolant leak

Post by eternally_troubled on Thu 23 Jun 2016, 9:02 am

@TheWizardofOdds wrote:

What now? It's not exactly easy to access either the tank drain hose. I've yanked and twisted the damn clip so much now it probably has to come off. It hasn't budged one bit though. Should I chance leaving it? Not sure how much fluid is in the reservoir, I can't see any. If I flush it there will be water left.

You should probably replace it as Rob said - it will only come back to get you in the future, but if you haven't got the time or inclination to fix it right now you can drain the coolant reservoir by using a big syringe with a bit of rubber hose on the end to suck out the old coolant. This won't drain it as effectively but it will be fine for now.
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TheWizardofOdds
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Re: Coolant leak

Post by TheWizardofOdds on Thu 23 Jun 2016, 2:06 pm

@rob75 wrote:Just my 2 cents, but looking at any part that is really corroded gets me to buy new parts. Especially parts like hose clamps. These cost next to nothing and after a long period loosening them may be problematic (as you experienced!). Just cut of the old one with a pair of wire cutters.

You can measure the resistance between the radiator and the frame (negative pole) from the hexagon part on the fan switch. It's brass and measure from this point to the frame or battery negative plug.

Coolant: use a good quality (pre-mixed or concentrate) suitable for aluminium engines. Anything decent from Castrol, Shell etc. will do. It may be a good idea to rinse the system with water if the previous change was long ago.

These bikes aren't the hardest ones and are straighforward in engineering.

As you were experiencing coolant leaks, it may be a good practice to inspect all hoses and when in doubt loosen them, clean the mating surfaces and refit using new hose clamps.
Rusted bolts and nuts, spray them liberally with a decent penetrating oil (with graphite) and let it soak for some time.

If at any given moment you forgot buying a brass sealing ring, using a blow torch (simple soldering one) can be used to heat the ring until it is red hot and then cool in water. This will revive the ring. This looks like bodging, but it is just good old fashioned mecanics.

Succes,
Rob

I will ultimately have to replace all, and I mean all, hose clamps. I can't cut it off at the moment as I wouldn't be able to get wire cutters through the clip to get it off. 

The radiator is needing replaced in its entirety, fan and mounting too, I might leave it at the moment though if I can get this together and add it to my monstrous winter maintenance upheaval. I haven't had a chance to check grounding yet but will follow the advice I have received. 

I will replace the sealing washer as for the meantime I have no means to heat the old one sufficiently. 

I have purchased halfords coolant as suggested here as rather negatively I'm not convinced I'll be able to fix this in one go so the coolant may well not last long at all. 

I agree though about using quality products. I've learned the lesson with my cars too , buy cheaply buy twice. Use the good stuff, even for a CB and it will pay off. 

Thanks for your reply and suggestions. I'm surrounded by people who are helpful and knowledgeable on this forum. Cheers.
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TheWizardofOdds
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Re: Coolant leak

Post by TheWizardofOdds on Thu 23 Jun 2016, 2:12 pm

@eternally_troubled wrote:

@TheWizardofOdds wrote:

What now? It's not exactly easy to access either the tank drain hose. I've yanked and twisted the damn clip so much now it probably has to come off. It hasn't budged one bit though. Should I chance leaving it? Not sure how much fluid is in the reservoir, I can't see any. If I flush it there will be water left.



You should probably replace it as Rob said - it will only come back to get you in the future, but if you haven't got the time or inclination to fix it right now you can drain the coolant reservoir by using a big syringe with a bit of rubber hose on the end to suck out the old coolant.  This won't drain it as effectively but it will be fine for now.
I just want my bike back! It's been off the road a week now and I am absolutely disconsolate. And that is why I will probably follow your clever suggestion with the syringe ( a bloody big one) . If I can just get the bike through to October say, I can then begin a proper assessment and plan of my mission to return this bike to looking as if I care about it. 


Thanks for the suggestion. 


I may not get much opportunity to fettle now as I won't be off until the end of the month early July . We'll  see...

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