Date: 29-03-24  Time: 12:19 pm

Author Topic: Radiator problems...  (Read 4189 times)

Andyb00123

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Radiator problems...
« on: 06 December 2015, 09:54:04 pm »
Hello all, had a problem, changed my engine for a new one, put it all back together filled with all liquids etc and realised the engine was getting very very hot, couldn't think why then I realized the radiator was cold, any idea why? Any bleed screws for coolant etc? Thanks!

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Re: Radiator problems...
« Reply #1 on: 06 December 2015, 10:03:43 pm »
I'd guess your thermostat isn't opening. The coolant gets pumped around the engine until the thermostat warms up and opens and allows it to flow around the rad to cool it down. If the thermostat is stuck closed the rad will stay cold and the engine will overheat. Did your original engine overheat by any chance? Or the coolant is really low but I'm sure you've checked that already.

Andyb00123

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Re: Radiator problems...
« Reply #2 on: 06 December 2015, 10:33:04 pm »
Not sure about old engine, replaced it within the week of getting the bike, only had it around 2 weeks, will check everything over tomorrow to make sure about all levels etc!

darrsi

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Re: Radiator problems...
« Reply #3 on: 06 December 2015, 11:35:27 pm »
Check the coolant level in the expansion tank.


If it's empty you may just have a blocked system. When the fluid can't flow properly it ends up getting boiled and then dumped out of the overflow pipe.
When it all cools down anything left in the expansion tank will get sucked back into the system.


If the expansion tank is empty you will need to use Radflush and clean the whole system properly so it can be descaled.


With a proper air tight system and the liquid moving around freely when the bike cools down the level of fluid in the expansion tank should virtually stay the same.
I may top up a very tiny amount maybe once or twice a year.
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Andyb00123

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Re: Radiator problems...
« Reply #4 on: 07 December 2015, 01:39:39 am »
OK thanks will go over it all tomorrow, what's best way to make sure it's properly bled also? Thanks!

darrsi

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Re: Radiator problems...
« Reply #5 on: 07 December 2015, 06:04:46 am »
OK thanks will go over it all tomorrow, what's best way to make sure it's properly bled also? Thanks!


Fill the expansion tank no more than the upper level, and fill the rest really slowly via the thermostat cap up front, just let it trickle in to avoid bubbles or air pockets.
Once it's filled to the top you can actually start the bike with the thermostat cap off and let the coolant circulate, and in the process hope that any excess air escapes to the top.
Don't give the throttle a massive blip or you'll end up wearing it as the water pump increases the flow.
Just let it tick over and keep an eye on the fluid and see if any bubbles pop up and the level gets lower.
Remember you'll probably only get about 2 minutes of this before the fuel runs out, unless you find a way of keeping the fuel pipe connected, but it's normally enough time anyway.


The main thing is using the Radflush to unclog the coolant engine/radiator channels in the first place though.

What i normally do, especially as the weather right now is a perfect temperature, is leave the Radflush in for a couple of days topped up with clean water, so that the bike heats up and cools down a few times, and the Radflush really gets to circulate and clean the system properly.
Obviously this is not ideal if you do long motorway runs, or if the weather is too hot or too cold, as the coolant/anti freeze covers both ends of the temperature scale, that's why the temperature right now is perfect (i presume you're not in the Scottish highlands and you haven't got snow?)
Once you're done flush it all out with a hose then refill with a decent coolant, i prefer the premixed bike stuff myself, others will mix their own 50/50, but that's just personal choice.
Once it's all done and all working fine again you should literally be able to leave it alone for ages.
Every now and then if the bike's on the centre stand i'll check the expansion tank level but it rarely moves between the lower/upper levels once the bike has cooled down and that means all is good.
If you suddenly see it's empty then either the above procedure needs doing, plus you can also check that any jubilee clips around any water pipes are tightened up correctly, especially around the thermostat area.
A good trick is to wait until dark then use a torch around the appropriate areas and a suspected coolant leak can be seen much easier, as the coolant will shine under torch light.


I'm not ruling out the 'Dudes suggestion of an iffy thermostat either, but from history i've always found them to be quite a reliable part of a bike.


Whether the expansion tank is empty or not will be a huge indication either way.


Don't rule out a knackered water pump either, if the water simply isn't circulating at all then that's another reason for overheating!
While the thermostat cap is off and the engine is running you can VERY GENTLY give a bit of revs and you'll see the fluid move if the pump is functioning okay, just don't give the throttle a full handful.
« Last Edit: 07 December 2015, 07:27:41 am by darrsi »
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Re: Radiator problems...
« Reply #6 on: 07 December 2015, 08:35:29 am »
It could be blocked but I think the fact that it's just the rad that's not heating up points to the thermostat staying shut. The expansion bottle won't tell you what's causing it to overheat just that it is overheating. Once it overheats for any reason it dumps into the overflow. It could be doing that because it's blocked, or it losing pressure because of a leaky hose, a dodgy thermostat cap or I had an o ring fail in the thermostat housing causing it to lose pressure, the thermostat itself could be faulty, it could be low coolant, the fan might not be working, the fan switch might not be working, the pump might not be working. You could even be overheating from a failed head gasket or cracked cylinder letting engine gases into the cooling system. All that will cause it to overheat and dump into the expansion bottle so the empty expansion bottle won't give you any clues which problem you've got. The cold rad though is a clue that the thermostat is stuck closed.

There's a chance that the same problem cooked the previous engine too. It'd be a nightmare if you went to the trouble of replacing a whole engine only for the next one to bake as well over a £10 thermostat! In my opinion don't start it again until you pull the thermostat out and test it. You could give the engine and rad a flush by taking a lower hose and an upper one off and stick a garden hose in and flush it out until the water starts coming out clear.

darrsi

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Re: Radiator problems...
« Reply #7 on: 07 December 2015, 10:53:19 am »
It could be blocked but I think the fact that it's just the rad that's not heating up points to the thermostat staying shut. The expansion bottle won't tell you what's causing it to overheat just that it is overheating. Once it overheats for any reason it dumps into the overflow. It could be doing that because it's blocked, or it losing pressure because of a leaky hose, a dodgy thermostat cap or I had an o ring fail in the thermostat housing causing it to lose pressure, the thermostat itself could be faulty, it could be low coolant, the fan might not be working, the fan switch might not be working, the pump might not be working. You could even be overheating from a failed head gasket or cracked cylinder letting engine gases into the cooling system. All that will cause it to overheat and dump into the expansion bottle so the empty expansion bottle won't give you any clues which problem you've got. The cold rad though is a clue that the thermostat is stuck closed.

There's a chance that the same problem cooked the previous engine too. It'd be a nightmare if you went to the trouble of replacing a whole engine only for the next one to bake as well over a £10 thermostat! In my opinion don't start it again until you pull the thermostat out and test it. You could give the engine and rad a flush by taking a lower hose and an upper one off and stick a garden hose in and flush it out until the water starts coming out clear.

All valid points, but just flushing with a hose doesn't really do anything other than remove loose particles, it's the crud lining the walls that really needs removing, and which causes the narrowing of the circuit, the same as descaling a kettle.
If the thermostats are that cheap then I'd maybe just change it anyway for peace of mind though.

I can't imagine the fan being a main cause, those buggers rarely switch on anyway.
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Re: Radiator problems...
« Reply #8 on: 07 December 2015, 01:22:06 pm »
I wasn't saying he had those other issues I was just giving those other examples of over heating and why the expansion bottle could be empty. Give it a radflush to get it working at 100% but the rad is staying cold so the thermostat must be staying shut and the coolant is bypassing the rad. I'll eat my hat if it's not the thermostat causing the problem :lol

Andyb00123

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Re: Radiator problems...
« Reply #9 on: 07 December 2015, 01:54:44 pm »
OK so been over the bike, reserve coolant empty and low in rad. Checked bike all over and there was a small clamp at bottom of engine on the left that was a little loose that may have been leaking, had the engine running for 5 mins and the top of the rad started to get hot, that's a good sign right? Also topped up all coolant etc

darrsi

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Re: Radiator problems...
« Reply #10 on: 07 December 2015, 03:42:57 pm »
OK so been over the bike, reserve coolant empty and low in rad. Checked bike all over and there was a small clamp at bottom of engine on the left that was a little loose that may have been leaking, had the engine running for 5 mins and the top of the rad started to get hot, that's a good sign right? Also topped up all coolant etc

Have a look later on in the dark with a torch, it will show up any previous leakages much easier.

And can someone pass the Dude his hat.  :rollin :rollin :rollin
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Re: Radiator problems...
« Reply #11 on: 07 December 2015, 04:00:24 pm »
nom nom nom tastes good :lol If I'm eating my hat your drinking that radflush because we were both wrong! Scale in the cooling system yeah right! Badger in it more likely :lol If he was losing pressure from a lose clamp the coolant might have boiled before the thermostat was hot enough to open so that'd explain why the rad stayed cold.

darrsi

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Re: Radiator problems...
« Reply #12 on: 07 December 2015, 04:12:11 pm »
nom nom nom tastes good :lol If I'm eating my hat your drinking that radflush because we were both wrong! Scale in the cooling system yeah right! Badger in it more likely :lol If he was losing pressure from a lose clamp the coolant might have boiled before the thermostat was hot enough to open so that'd explain why the rad stayed cold.

I do believe I did mention checking jubilee clips as well?  :b

I've had 2 bikes with a clogged system before, that's why I'm so familiar with it.
I used to sit at lights watching the bike piss itself out of the overflow pipe, which was embarrassing, and the Radflush sorted both bikes out.

Personally I would still do it anyway as it's an engine he knows little about and there's a good chance it may never have been done before.
You gotta keep your waterworks in good nick.  :D
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Andyb00123

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Re: Radiator problems...
« Reply #13 on: 07 December 2015, 06:21:55 pm »
Will do, I'll pick some up this weekend and get it all out of the way, thanks people!

Bretty

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Re: Radiator problems...
« Reply #14 on: 07 December 2015, 10:19:31 pm »
I reckon the actual problem was that the original poster had been trying to refill his cooling system at the expansion tank and is too embarrassed to admit!...





(that's what I did 3months ago because I'm an idiot and thought that's what the Haynes manual said)
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darrsi

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Re: Radiator problems...
« Reply #15 on: 07 December 2015, 11:17:36 pm »
I reckon the actual problem was that the original poster had been trying to refill his cooling system at the expansion tank and is too embarrassed to admit!...





(that's what I did 3months ago because I'm an idiot and thought that's what the Haynes manual said)

As long as the system was air tight that would theoretically work.
It would get sucked back into the engine when it cooled down.
BUT, the fact it may be empty in the first place would've meant all was not well.
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Bretty

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Re: Radiator problems...
« Reply #16 on: 08 December 2015, 08:35:27 am »
It was empty because he changed the engine. ;-)

Last time I put my engine back in in a bit of a hurry, It was 3am and I was just doing the last few jobs. I tried filling it with coolant through the expansion tank. Glad I double checked everything the next day.
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darrsi

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Re: Radiator problems...
« Reply #17 on: 08 December 2015, 11:04:05 am »
It was empty because he changed the engine. ;-)

Last time I put my engine back in in a bit of a hurry, It was 3am and I was just doing the last few jobs. I tried filling it with coolant through the expansion tank. Glad I double checked everything the next day.

There is always that  :lol
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Andyb00123

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Re: Radiator problems...
« Reply #18 on: 08 December 2015, 12:07:53 pm »
I've got no pride I'd admit it :') I remember putting it in as I remember spilling it from putting too much in and it overflowing everywhere  :'(

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Re: Radiator problems...
« Reply #19 on: 08 December 2015, 02:42:26 pm »
Also I had the engine fitted around 8/9pm :) we definitely did it as I bought a second bottle of coolant and water :P

darrsi

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Re: Radiator problems...
« Reply #20 on: 08 December 2015, 03:43:26 pm »
Also I had the engine fitted around 8/9pm :) we definitely did it as I bought a second bottle of coolant and water :P

It's okay, we believe you.  :lol
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