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Dumping coolant and overheating

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Rundas
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Dumping coolant and overheating

Post by Rundas on Sat 14 Jun 2014 - 13:39

Hey there, 

I have been riding my CB 500 from 2001 for 2 year know and it worked just fine up until last Christmas were I broke my oil carter trying to change my oil. I went to the mechanic to get it fixed and also asked him to replace my worn airbox, replace my rotten stock exhaust for an Takkoni exhaust (without a rejet to my knowledge), and to remove the 25 KW restrictions.

After about one month of driving around 3 of my O rings in the coolant system stopped sealing. It also started to dump coolant though the overflow hose. So I got it fixed at the same mechanic and he also replaced the thermostatic switch with one that made the fan come on at a lower temperature.

After I got home I noticed that the bike was still dumping coolant. So I brought it back to the mechanic for a head gasket replacement because he told me I needed one (later realizing that I didn't need one. Foolish of me to listen could have saved me a lot of money Sad). They also pressure tested it and it was fine.

After this it was still dumping coolant and the fan wouldn't come on. So went back again and the time he fixed it for free fiddling around with the hoses. After about 20 minutes of riding the gauge went up into the red and it started to dump coolant again. 

4th time at the mechanic they replaced the radiator cap. This also had no effect. 

After all this I decided to work on it myself. So far I have replaced:
- The cap AGAIN with a secondhand tested one.
- The thermostat (tested the new one in a bowl of boiling water).
- Cleaned the system with radiator cleaner and  drained/filled it. The coolant that came out looked clean.
- Drained and filled it again but this time pressing all the hoses.

If I let it idle it warms up slowly till about half way on the gauge and then the fan kicks in. It keeps cool and it doesn't dump the coolant. However after about 20 minutes of riding the gauge just goes up and the coolant leaves via the overflow hose and the won't kick in. Also filled it up with distilled water and that came boiling out of the reservoir and the overflow hose making a steaming hot mess of things. 

I am unsure of what it could be but I have some suspicions:
- The engine is running to lean because the carbs haven't been rejetted.
- There is a small rip in my left intake manifold rubber on the part where it connects to my carb, but not where the mixture goes through.
- There might still be an airlock somewhere.

I would really appreciate any input you guys can give me on this problem. Maybe I have been going at this wrong...

sullivj
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Re: Dumping coolant and overheating

Post by sullivj on Sat 14 Jun 2014 - 15:10

Are all of the overflow hoses unblocked? There was a guy on the CBF forum that went through a similar pain and ended up tracing it to a blocked overflow pipe.
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Rundas
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Re: Dumping coolant and overheating

Post by Rundas on Sat 14 Jun 2014 - 15:37

We think they are, as we could blow trough them.
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glen.wilson1@gmx.com
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Re: Dumping coolant and overheating

Post by glen.wilson1@gmx.com on Sat 14 Jun 2014 - 16:17

I had a similar issue and could blow down mine. When you pull the pipe of the coolent tank from underneath does it drain because mine didn't.  So it couldn't suck it up if the radiator needed it. Turned out I could blow down but some crap floating around the coolent bottle kept settling back over where the pipe connects to the bottle. I got the crap out and never had an issue since. Up till then mine kept dumping coolent after a run too.
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Rundas
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Re: Dumping coolant and overheating

Post by Rundas on Sat 14 Jun 2014 - 22:34

We cleaned the reservoir but it had no effect. 

We filled the coolant and afterwards ran the engine without the RAD cap to get the air out. This gave an interesting to say the least (video below). Judging from the video below my friend tells me it could be that the mechanics made a mistake while putting the head gasket on? 

Air bubbles just kept coming out while we were sure the bike had been filled up with coolant.

If this is the case I am going to be really sad Sad

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eternally_troubled
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Re: Dumping coolant and overheating

Post by eternally_troubled on Sun 15 Jun 2014 - 10:03

The video was interesting.  If the head-gasket isn't working properly and you have a pressure -> coolant leak  I would have thought that the compression test would have given low readings.

I've never tried to run my bike with the cap off the cooling system, so I can't say what a 'good' bike does.

The air coming out could have just been from air trapped in the system - how long did you run it for?

When you refilled the system, did you make sure the overflow tank had coolant before you started the engine?  It shouldn't be able to suck air in that way, but it is best to make sure.

Good luck in finding the answer.
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Rundas
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Re: Dumping coolant and overheating

Post by Rundas on Sun 15 Jun 2014 - 11:05

I don't think they tested the compression. What I do know is that they tested the cooling system for leaks by pressure testing it. 

We left the bike running for like a half hour and the bubbles just kept coming out. Ans yes the overflow tank was filled to the correct level maybe even a bit higher...

We even ran it with the radiator cap on and hanged a see through bottle on the hose which would normally go to the reservoir. We saw air coming out the system and the bottle filled up quite fast.
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cb500motorfiets
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Re: Dumping coolant and overheating

Post by cb500motorfiets on Sun 13 Jul 2014 - 17:59

I do have the same issues as well, , last time I did flush again the system, and replaced a few other hoses... so far almost all hoses are replaced (one is still pending as that's the one feeding the coolant into the engine coolant pockets, and the clamp is difficult to reach)  the radiator cap is replaced,so far i replaced the waterpump and thermostat, I''ve flushed the system several times, I have done a compression test on both cilinders (10 and 11 bars) so that might possible rule out the head gasket. Also none of the hoses is blocked, neither the one going to the expansion tank, as once the motor is cooled off, the tank is empty.
Oil is clean, but still i suspect pressure is escaping from somewhere in the engine entering the cooling system which causes intermittent coolant dump and overheating after one hour driving or so..
For now i use the bike only for short distances, and put an extra bottle of water with me in case it overheats again when planning for anything beyond 30 kilometers or so..

I would really appriciate a permanent fix  Rolling Eyes  so if someone ran into this weird problem and fixed it, it would be great!
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cb500motorfiets
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Re: Dumping coolant and overheating

Post by cb500motorfiets on Sun 13 Jul 2014 - 18:26

From the original question:

"were I broke my oil carter trying to change my oil" This brings to my mind something odd...I do suddenly recall something strange on my bike too....as there's one thing I also did notice on my oil carter, and not sure if it's just a bit grease/oil..as it looks to be wet on the outside..so my question is if any coolant passes close by the oil carter? ...as if it's coolant...would that be a strange place for leakage ?

That leaves me to think that the problem might have started when replacing the oil carter on your bike? But might be very wrong here.. scratch
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Tricky.
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Re: Dumping coolant and overheating

Post by Tricky. on Sun 13 Jul 2014 - 20:13

i had the same sort of problem, i checked/changed everything (including the head gasket) and in the end found it was the radiator partially blocked, water flowed through, but not fast enough.
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cb500motorfiets
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Re: Dumping coolant and overheating

Post by cb500motorfiets on Mon 14 Jul 2014 - 18:01

Hello Tricky,

How did you found out that the radiator was partially blocking ? Btw the test as shown on the video might be an interesting one, as I tested it also without a radiator cap..a few times...but never with a funnel....

Cheers
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Tricky.
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Re: Dumping coolant and overheating

Post by Tricky. on Tue 15 Jul 2014 - 19:42

i found out it was the rad after changing everything: coolant tank, rad cap, all the pipes, thermostat out, thermostat housing, head gasket, all one at a time . . . . . then lastly . . . . . swapped the rad, bingo.
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HomeBrew
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Re: Dumping coolant and overheating

Post by HomeBrew on Tue 15 Jul 2014 - 19:52

So a blocked rad is causing this? What was wrong with it? I have coolant coming out of the radiator hose that connects to thermostat housing, just about to replace the rad. I was thinking it may just be the hose but it seems fine and the clip is tight.
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Tricky.
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Re: Dumping coolant and overheating

Post by Tricky. on Tue 15 Jul 2014 - 20:38

dont know what is causing your problem, that was just the problem with mine. water still flowed through it, just not fast enough, i flushed it through with a hose pipe and it looked fine, wasnt till i swapped it with another one that the problem was cured.
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HomeBrew
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Re: Dumping coolant and overheating

Post by HomeBrew on Tue 15 Jul 2014 - 20:42

Cheers I'll see if a new rad fixes it Smile
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HomeBrew
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Re: Dumping coolant and overheating

Post by HomeBrew on Wed 16 Jul 2014 - 11:16

2014-07-16
Just fitted a new Delkavic rad and refilled it, it hasn't leaked yet but I will take it for a run to double check, I've been revving, letting it idle for 15 minutes with the bike stationary and the temp gauge hasn't moved above the solid cold section. So that is good, though it means I can't test the fan, might have to block off the rad to test that, though it worked before.

Maybe Delkavic could do us a club discount, they said on the phone said he could do CB500 headers and a radiator for £250 delivered but I cant afford headers right now.


Have just blocked off radiator and revved, got the bike hot and the fan came on, no coolant leaking out so seems the new rad worked! 

 Very Happy
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eternally_troubled
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Re: Dumping coolant and overheating

Post by eternally_troubled on Wed 16 Jul 2014 - 13:24

It is certainly possible for the radiator to get blocked - the water passages are not *that* big. I would have thought that a few good flushes with rad flush would have cured it if sludge was doing the blocking. If it was something harder like calcium-salt deposits from hard water then it might not...
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Dext37
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Re: Dumping coolant and overheating

Post by Dext37 on Sun 20 Jul 2014 - 21:55

Right. Hello, I am new here, a bi g fan of CB500 and a 2003 S owner.

I think my bike is an ex-training bike and bought it for £650 with 44,000 miles on the clock.

I am having terrible coolant issues. I cannot run the bike for more than 35 mins when the temp goes mental and coolant dumps everywhere.

I have put a new termo switch on, a new thermostat (official David Silver spares Honda one) coolant flush a few times and still she spits after 35 mins. I am tempted to take thermostat out for the summer and put it back in for October.

Kinda at the point where I am reaching the end of my tether, I don't want the head gasket to go bang and end with a very crocked CB5.

I'm looking at a radiator cap to see what that will do.

Any thoughts/suggestions welcome and appreciated in advance.
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HomeBrew
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Re: Dumping coolant and overheating

Post by HomeBrew on Sun 20 Jul 2014 - 22:23

Where is the coolant spilling out? There are several threads here on overheating atm, some have had blocked overflow pipes and gunk in the overflow bottle, my radiator was blocked and a new one has helped massively. You want to make sure the rad fins are clear of mud and bugs also. 

I don't know much about coolant systems but why take the thermostat out if it is working? Does the radiator get hot at both ends?
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Dext37
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Re: Dumping coolant and overheating

Post by Dext37 on Mon 21 Jul 2014 - 11:08

HomeBrew wrote:Where is the coolant spilling out? There are several threads here on overheating atm, some have had blocked overflow pipes and gunk in the overflow bottle, my radiator was blocked and a new one has helped massively. You want to make sure the rad fins are clear of mud and bugs also. 

I don't know much about coolant systems but why take the thermostat out if it is working? Does the radiator get hot at both ends?

The coolant is dumping from overflow pipes.

Radiator is coolish (you can leave your hand on it) and the coolant hose is boiling hot. You can hear it bubbling and burbling too.

Fan is working thought, I can hear it cut in sometimes.

Dex.
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eternally_troubled
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Re: Dumping coolant and overheating

Post by eternally_troubled on Mon 21 Jul 2014 - 12:42

Sounds like the thermostat is knackered: if you have an old pan you don't use for food any more and a thermometer that goes to 100ish degrees then you can test the thermostat (see the Haynes manual for details).

Having said all of that, leaving it out will tell you if it is causing the problem. The symptoms you describe could also be a blocked radiator...


Best of luck!
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Dext37
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Re: Dumping coolant and overheating

Post by Dext37 on Mon 21 Jul 2014 - 12:57

I have fitted a brand new thermostat from David Silver Honda (official parts) as stated previously, it still hasn't done the trick.

I might look deeper at the radiator.
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teamster1975
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Re: Dumping coolant and overheating

Post by teamster1975 on Mon 21 Jul 2014 - 14:18

Get a sniff test done on the coolant to eliminate the HG; been in the same boat myself and I swapped everything before putting in a spare engine I had which cured it.
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kev44
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Re: Dumping coolant and overheating

Post by kev44 on Mon 21 Jul 2014 - 18:35

hi I got my cb5 august 2013, the coolant pump had been removed by the owner because it was damaged.he lost interest and sold me the bike cheap,he said it was in good running order prior to pump removal. I fitted a second hand pump, filled with coolant and it started fine, after about 20 mins steam and water started comeing out, the rad was cool to touch, my first thought was its air locked, I took off the rad cap, put a bottle of fuel on the fuel line and started the bike, you could see the air bubbling in the rad top,and the coolant level was dropping, so I slowly added coolant to it until the air stop'd bubbling and level stayed constant. put it all back together, and its been fine ever since.
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Stooby2
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Re: Dumping coolant and overheating

Post by Stooby2 on Thu 24 Jul 2014 - 20:23

Dext, read the post above yours. I've been reading up on this and other forums and I'd put money on your radiator being blocked. It seems to me they are almost a service item after about 10 years old. I recently bought a 2003, CB500S and it was getting very warm on the ride back, fan coming on almost all the time.

The external state of the radiator wasn't good, blocked and bent fins, crud everywhere. I did a full Holts flush with it on, took the rad off, ran clean water through the block for 5 mins and then fitted a new radiator. In this hot weather, commuting into central Londom, it stays nicely below halfway on the temp gauge.

I think you need to bite the bullet and fit a new rad. I'd recommend doing the flush first as you don't want to fill the new rad with crud from the block.

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