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coolant leak - can you help with advice?

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shitthebed
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coolant leak - can you help with advice?

Post by shitthebed on Mon 27 Apr 2015, 9:50 pm

Hi, Ive got a problem with the coolant system on my cb500. 

In a nutshell: I passed my test in march this year. I shortly after bought a '96 CB500. All in all nice bike in decent condition for the year. Sailed through an MOT with no advisories - appears well maintained and looked after. 

On the way back from London last weekend I opened it up on the M11 and was cruising at some fast speeds. This was the first time the bike had (under my ownership) been cruising at motorway speeds for an extended duration. The speeds I was doing are well within the capability of the bike, and It didnt seem like i was overworking the bike, the thermostat showed a slight increase in engine temp but again, nothing whoch caused me concern. When I got home, as soon as I shut off the engine i noticed a lot of steam coming from the engine block. When I looked down it was evident that the coolant had pissed all over my boots and the engine. I had actually checked the coolant level before I left london and all of the coolant was gone. 

I havent yet taken the tank off to inspect all the hoses, however stain marks on the frame suggest the leak is coming from the radiator. The visible hoses and jubilee clips appear to be in good condition. I attach some links to photos which illustrate this. Having refilled the coolant and run again, I could not detect any obvious leak, but I did see some liquid coolant forming a drip at the point where the bottom of the rad connects to the frame. 

I would appreciate advice relating to A) probable causes, B) likely solutions 

My gut feeling (not being so mechanically minded, but fairly hands on) is that I will have to replace the radiator. I have a haynes manual - is this a difficult task? Also any ideas on how much I may expect to pay a breaker for a good condition second hand rad? 

Also would you fit a rad guard and what is the easiest way to test the operation of the fan? 

OK, verbal over! a lot of questions I know, but I am keen to get back on the road quickly! 

Thanks, Stu. 

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HomeBrew
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Re: coolant leak - can you help with advice?

Post by HomeBrew on Mon 27 Apr 2015, 10:31 pm

I don't know how to be 100% sure the radiator needs replacing, but I had similar symptoms and i did replace it which solved the problem. But It could be the cap or something else even head gasket- maybe someone more experienced could advise here. 

I used a fluorescent dye and UV light to locate the leak at a hose clamp-but there was nothing wrong with it and it was done up hard. The old rad created so much pressure it forced out anyway.
The radiator fins get clogged up which reduced airflow and the tubes get corroded inside which blocks coolant flow. Replacing it is an easy task, no problem. 
 
If I was going to replace the radiator personally I would get a brand new one, any 2nd hand one is a gamble and could be old and corroded inside. If you plan on keeping the bike for a while it makes sense. 

I would fit the standard rad guard and get a fenda extenda to keep mud off the rad.

To test the fan you just let it get hot and 3/4 up the temp gauge the fan should come on. Obviously put some coolant in affraid
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shitthebed
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Re: coolant leak - can you help with advice?

Post by shitthebed on Mon 27 Apr 2015, 10:37 pm

Thanks for this, good to get someone elses opinion. accidentally thumbs down'd the reply...sorry! 

yeah planning on keeping the bike for a while so I may go down the route of replacing the rad. 

Stu

sullivj
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Re: coolant leak - can you help with advice?

Post by sullivj on Mon 27 Apr 2015, 10:46 pm

Replace to coolant and let the bike idle for 20 mins - that should kick the fan in.

I expect the rad has failed. You should be able to spot a leak. 

It's not hard to replace it, and refilling the coolant isn't hard either as long as you follow Haynes.
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jchesshyre
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Re: coolant leak - can you help with advice?

Post by jchesshyre on Mon 27 Apr 2015, 11:24 pm

What he said. Follow Haynes carefully and don't worry!

If it is the radiator, which it sounds like it is, changing it does involve taking the fan and mounting off the old one and putting it on the new one. The bolts holding it on to the rad will almost definitely be tough to undo, and it doesn't take much muscle on them before the metal mounting tabs start bending. Squirt them with WD40 or something beforehand and let it soak for a bit. And make sure you make a note or take a picture of where everything went. Spin the fan once you've put it on to check it doesn't rub the radiator - the slight bending of the fan mounting that will probably have happened during its removal might need un-bending :-)

You'll also need to take the rubber bushes out of the old rad and put them in the new one. Again, WD40 is useful for this.

Also, be patient removing the hoses from the radiator. I find grasping them firmly in my fist and twisting them, at various distances from where they join, does the trick. You won't tear them, I don't think...

Whilst (or rather after) you're doing all this it might be worth giving the cooling system a flush - see Haynes.


Last edited by jchesshyre on Mon 27 Apr 2015, 11:32 pm; edited 2 times in total
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jerryfudd
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Re: coolant leak - can you help with advice?

Post by jerryfudd on Mon 27 Apr 2015, 11:28 pm

don't have anything more useful to add than anyone else but I do have a full set of coolant hoses spare if it becomes necessary.

btw nice username.... ShockedLaughing
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jchesshyre
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Re: coolant leak - can you help with advice?

Post by jchesshyre on Mon 27 Apr 2015, 11:37 pm

By the way, don't get cheap unbranded radiators off eBay - false economy. Delkevic ones are good. The Honda ones are £300...

Also, first do what sullivj suggests and run the bike until the fan kicks in a few times. You should spot the leak. When you do, post some pictures!
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wornsprokets
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Re: coolant leak - can you help with advice?

Post by wornsprokets on Tue 28 Apr 2015, 7:15 am

My rad was dripping on lhs bottom where it meet the hose it was pin holes there, these radiators seem to be very soft and not up to much. I changed rad for second hand one and changed the coolant no probs so far but am going to get fender extender to keep crap getting thrown from front wheel onto new rad. Changing coolant was no probs and had no leaks so far
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eternally_troubled
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Re: coolant leak - can you help with advice?

Post by eternally_troubled on Tue 28 Apr 2015, 12:50 pm

I've had a very similar problem to you in the past:  came back from a ride and realised that the coolant was all over my boots and not in the bike!

It was also my radiator that was leaking - I got a new one from Delkevic, here is the link:

http://www.delkevic.co.uk/?section=shop&product_category=cooling_system_e2b0v&sub_category=radiators_ro8hn&product=honda_radiators&variant=cb500_radiator

they are currently 126 quid including postage.

If you can't manage 126 quid then you can probably get a second hand one from ebay or you local breakers (where are you?  if you were coming home up the M11 you might be near me, which means you might be near-ish Ely Motorcycle Spares).

If you're *really* skint and you can lay your hands on an epoxy putty (like milliput - http://www.milliput.com/index.html) then you might well be able to 'bodge up' the hole in your radiator once you've found where it is and cleaned up the area. I can't vouch for how long this kind of repair would last, but it would be better than doing nothing...

Before you do any of this I would refill the bike, run it up to temperature and see where it starts leaking.  If you haven't already got or downloaded the Haynes manual then I would suggest doing that too...

As for causes:  old age, corrosion, stone damage (that's just the radiator!), perished hoses, rusted clips etc  and other things to do with oldish vehicles (remember your CB will be 20 next year!).
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jerryfudd
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Re: coolant leak - can you help with advice?

Post by jerryfudd on Tue 28 Apr 2015, 1:21 pm

.....or sneak round to sullivj's and relieve him of the brand new OE Honda one he has sitting on his 'spares' shelf Laughing
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teamster1975
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Re: coolant leak - can you help with advice?

Post by teamster1975 on Tue 28 Apr 2015, 2:11 pm

When you drop the coolant look for any signs of rad-weld or similar; it clogs the expansion pipe which runs from the filler neck to the expansion bottle, horrible muck.
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shitthebed
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thanks for the advice

Post by shitthebed on Tue 05 May 2015, 10:13 pm

thanks for the responses. i am pretty sure i know where it is coming from. i will take this radiator off and pressurise it. if it leaks i guess ill be paying 120 for a new radiator! you may well see me cruising down the a11 in the next few weeks! 

stu
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eternally_troubled
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Re: coolant leak - can you help with advice?

Post by eternally_troubled on Wed 06 May 2015, 1:54 pm

Good luck, tell us how it goes!

sullivj
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Re: coolant leak - can you help with advice?

Post by sullivj on Wed 06 May 2015, 8:15 pm

jerryfudd wrote:.....or sneak round to sullivj's and relieve him of the brand new OE Honda one he has sitting on his 'spares' shelf Laughing

How is that helpful? Rolling Eyes

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