Overheating Again

[shercoman2k8]

Right guys, what the hell is it with this bike? I'm sure it's determined to drive me to the mental instution and nowhere else!

Started off after the bike was sat for a bit, in the garage. Two or three days possibly, with temperatures dropping to about -10 at night. I took it for a spin, and it was spitting a bit of coolant out, not much, and the fan did cycle... But it did continue to spit, for the whole ride. Didn't think much of it, just thought possibly there was a loose connection somewhere. Shoved her back into the garage, stripped her down, sorted all the wires, waterproofed them, and sprayed silicone on the connections.

Started the bike up on the paddock stand, took a long time to warm up, but when it did... It continued to spit coolant, but again, the fan cycled. Stopped the bike, put her back away. Started her up again on the stand the next day, let her warm up, revved it a few times, and then the idle went really slow and lumpy, had to turn the tickover right up for it to even run. Lack of power and dribbling coolant out of the overflow.

So, clearly overheating and the fan didnt come on. I've tested the fan directly off a 9 volt battery, it spun fine. Off a 12 volt battery, spun fine. So, the fan works fine. Bypass the stat, works fine. So it isnt the regulator.

Maybe there was a loose connection again? Ran it all up, and the fan cycled as normal... odd.

With the help of a member on the forum it's been narrowed down to the following;

Rad Cap - Loose connection on the stat, causing the fan to not cycle properly. The coolant spits when it runs at the correct temperature anyway... So is the cap releasing coolant before it should?

Thermostat - Dodgy stat, only sending current occasionaly. This would explain the occasional overheating, the occasional spitting, and the occasional normal running. When it sends at correct times, and wrong times. Maybe it's sending at the wrong temperature?

Cylinder head o-rings - More than possible? Sat for a while, in cold weather, o-rings possibly went hard in the cold, and when I fitted the titanium frontpipe and high compression insert the extra pressure's caused them to go finally? This allowing pressure into the cooling system = inneficient cooling and the constant spitting of coolant. And if extra pressure is getting in, the impeller wont be circulating as it should, right?

Then the extra compression with the new insert and pipe. The cold weather causing it to run lean and the ignition advance on the paxau causing all that little more heat, and it cant cope?

Running decent fuel, 80:1 fully synthetic and 98octane fuel.

Cooling system is standard, apart from silicone hoses.

Any more ideas?

Give me your thoughts guys, before I go and strip it down... Any ways to identify if the o-rings really have gone?

Thanks, and a nice big beer in advance.

Jamie

[ham2]

Speaking as Cope's witchdoctor apprentice ,I would go for the easy-peasy stuff first..replace the rad cap,then... let us know so we can rule that out

[shercoman2k8]

Speaking as Cope's witchdoctor apprentice ,I would go for the easy-peasy stuff first..replace the rad cap,then... let us know so we can rule that out

Yeah, got a rad cap here, off my 06. Would try everything else off that, but the stats buggered on it. Fan was on all the time on that, even with the fan not bypassed. Bit late to go start it up now, so will change that and test tommorow afternoon.

Until I get round to doing that, keep imput coming.

Cheers Ham!

[ishy]

I have seen the nut break free from the impeller so it doesn't spin thus doesnt circulate the coolant

[chewy]

I had an "invisible"; crack in the head of a gasser once .......was similar symptoms...i.e pressure in the coolant system.. took ages to find it it really was invisible but the heat & pressure in there at Xthousand times a minute!!!!!!!!!!!!!!!

[tonybroad]

one cause could be head gasket - if it's blowing and blowing into the water chamber it over-pressurises your cooling system and so spits water out, as soon as enough water has gone to stop proper circulation it overheats/fan kicks in

put your overflow hose (or fit one) and immerse into a clear bottle with some water in it (a coke bottle is fine) - it will emit regular bubbles from the tube if your head is blowing into the cooling system but get engine warm

worth a try

tony

[rockyrider]

Hi 2k8, I tend to agree with chewy. It sounds like compression building up in the cooling system. It may not be a crack, but possibly a cylinder head gasket or seal. I'm not sure yet if these have thermostats! Another possibility stuck causing pressure to rise. The main thing is, Don't Panic. Keep checking the forum.

[shercoman2k8]

I have seen the nut break free from the impeller so it doesn't spin thus doesnt circulate the coolant

I had an "invisible"; crack in the head of a gasser once .......was similar symptoms...i.e pressure in the coolant system.. took ages to find it it really was invisible but the heat & pressure in there at Xthousand times a minute!!!!!!!!!!!!!!!

Hi 2k8, I tend to agree with chewy. It sounds like compression building up in the cooling system. It may not be a crack, but possibly a cylinder head gasket or seal. I'm not sure yet if these have thermostats! Another possibility stuck causing pressure to rise. The main thing is, Don't Panic. Keep checking the forum.

Impeller could be a possibility. Will check that last as its an expensive one if I remember correctly. Did water pump seals ages ago.

Chewy & Rockyrider;

Crack in the head, will check if and when I do the o-rings. Could be quite possible as a lot of snow got around the head when I went for a ride just before christmas, dropped bike and landed in deep snow, head was cooled pretty much instantly.

Going to check the o-rings in the head if rad cap doesnt do it, will wire the fan to be on constantly and check for pressurisation. Got a spare head here also. But will need new one, maybe oppurtunity to go high compression.

Thanks guys.

[totalshell]

rad or pipe work 'airlocked' so not allowing water to fully circulate so water is at different temps in the system.. fan may or may not run stat will seem to be working water may be spat out of rad cap/overflow. drain down run water through the system via a hose pipe and then fill VERY slowly measuring the amount you put in and comparing to mfr's spec.

[rockyrider]

Impeller could be a possibility. Will check that last as its an expensive one if I remember correctly. Did water pump seals ages ago.

Chewy & Rockyrider;

Crack in the head, will check if and when I do the o-rings. Could be quite possible as a lot of snow got around the head when I went for a ride just before christmas, dropped bike and landed in deep snow, head was cooled pretty much instantly.

Going to check the o-rings in the head if rad cap doesnt do it, will wire the fan to be on constantly and check for pressurisation. Got a spare head here also. But will need new one, maybe oppurtunity to go high compression.

Thanks guys.

Okay 2k8 man, let's get serious for a moment. I do not want to overshadow any one elses advice. Tony mentioned a good point by looking for air bubbles in the cooling system. This is a good sign of compression leaking into the coolant, but impellers can cavitate causing air bubbles, it's important to tell the difference. Shellman also mentioned filling to mfg's specks to be sure you have the proper amount to begin with. With cracks in the head, they are usually minute, and often not seen with the human eye, as often they only open when the engine warms up enough to make them expand. There is a process called magnaflux, which can be perfomed by a machine shop. Some times a little history of how or when this began is helpful. You mentioned falling over in the snow, I doubt this would have any effect as hot engines plow through water all the time. Keep in mind your engine may NOT have a serious problem, sometimes it just takes a little time to

diagnose it properly. remember, don't panic. Also, did it have enough anti freeze content in it to begin with? This of course could crack a head or cylinder overnight by freezing.

Edited January 7, 2010 by rockyrider

[zippy]

O-ring in the head gone bad..........my 2 cents.

Start storing bike in house, temperature controlled environment your bike will thank you................other humans in the house will hate you.

But hey fair trade as far as I'm concerned.

[shercoman2k8]

Okay 2k8 man, let's get serious for a moment. I do not want to overshadow any one elses advice. Tony mentioned a good point by looking for air bubbles in the cooling system. This is a good sign of compression leaking into the coolant, but impellers can cavitate causing air bubbles, it's important to tell the difference. Shellman also mentioned filling to mfg's specks to be sure you have the proper amount to begin with. With cracks in the head, they are usually minute, and often not seen with the human eye, as often they only open when the engine warms up enough to make them expand. There is a process called magnaflux, which can be perfomed by a machine shop. Some times a little history of how or when this began is helpful. You mentioned falling over in the snow, I doubt this would have any effect as hot engines plow through water all the time. Keep in mind your engine may NOT have a serious problem, sometimes it just takes a little time to

diagnose it properly. remember, don't panic. Also, did it have enough anti freeze content in it to begin with? This of course could crack a head or cylinder overnight by freezing.

Yes, air bubbles and locks in the cooling system is a good place to begin, and has been checked, system flushed right through and filled slowly, allowing air to escape back up the funnel as coolant went in, then gave all the pipes a quick squeeze as reccomded with the silicone pipes. I didn't just brush past this advice, I took it in and will try it, just wasnt anything to discuss about it so didn't get a mention. But thanks tony!

Cracks in the head are hopefully going to be my last place to look if im honest with you. As it's the most expensive part of the whole job... and if I sort everything else out, and it does turn out to be this, it's all just gonna last a bit longer. I'm not saying it's not the head, i'm just saying i'll check all the cheaper parts, and parts I have to hand first.

History - Bike was sat in garage, average temperature of around 5 degrees C when it was put away in the garage. I then went away for a few days, so the bike didn't get ran everyday as it usually does. Come back to find an average daytime temperature of around -5 degrees C, with temperatures dropping to -15 at nights. I ran it, and it spat a little bit of coolant out, as the fan didnt cycle, but that turned out to be a loose connection, sorted with silicone spray and new spade connectors, sorted.. Didn't do it again that day, and fan cycled seemingly normally. Fitted titanium frontpipe and compression insert on christmas day, the day after I sorted the connections. I started the bike up that day, fan cycled on once or twice, seemingly not as often as normal, but I put that down to cold weather, and then she spat a few more mls of coolant out. I filled the rad up to the bottom of the neck the other night, ran it, it spat out a load more, obviously setting it's own levels. Stopped, and the fan cycled.

Went to run it again day before yesterday, and the thing ran right up, overheated, sprayed a lot of coolant out without me realising, and then I killed the engine. It seems to cut the engine of its own accord when it gets too hot to run, so no damage done I wouldnt of thought. Reason behind me testing and finding out before I run it again.

Coolant is an antifreeze coolant, rated down to -30 degrees C, and the radiator was full when issues started, and has been flushed and filled again since.

If I wired the fan on permanantly, and ran it... No coolant lost, and no overheating, this means that there's no pressurisation of the coolant, and that its circulating fine? Basically saying that the issue is the stat?

If I then unwire the fan, so the job is down to the the thermostat, and again it overheats, and sprays coolant. With the fan cycling, or not cycling, it's the stat at fault?

If the fan is on permanantly, and it sprays coolant, yet doesnt overheat, the coolant is circulating, but under pressure?

If the fan is on permanantly, and it doesn't spray coolant, yet seems to overheat, the coolant is not circulating, not allowing heat to get to the radiator?

Stat at fault, new stat, report back?

Under pressure, head gasket and o-rings, report back? Still faulty, try different head?

Not under pressure, but not circulating, check impeller and flush system and report back?

O-ring in the head gone bad..........my 2 cents.

Start storing bike in house, temperature controlled environment your bike will thank you................other humans in the house will hate you.

But hey fair trade as far as I'm concerned.

What I was thinking. At a tenner to do the job, i'd be willing to try this without troubleshooting, but i'd prefer to narrow it down to all the different areas before I go wasting money, incase I need a new head, or stat instead.

Oh, I should be so lucky!

[copemech]

Ok, first thoughts here, get to basics! You do need a good thermo switch! You can run the bike with the rad fully filled and cap off to ck for any iminant bubbles due to a leaky head seal. Fluid circulation(or lack of it) should be evident yet may be easier to see if the level was just above the cores to start. Then top it off and let it do its thing while watching. Continuous bubbles are not wanted. The level may vary a bit with the fan cycling, yet I would not expect much due to the low volume of the system. I would think that without excess engine load the thermo should be able to maintain temps at the setpoint of around 95-98C without cap or pressure. Not sure if you can get a thermo probe into it the ck against the switch for accuracy in the cycling of fan.

MC

Edited January 8, 2010 by copemech

[rockyrider]

2k8 man, here is an easy one. If the stat is in doubt, remove it and run the bike filled with fluid as normal.see what happens,no harm can come of this.

[trialsnutterman]

2k8 man, here is an easy one. If the stat is in doubt, remove it and run the bike filled with fluid as normal.see what happens,no harm can come of this.

The thermostat is not like a car one which diverts flow from the radiator, it is just a temperature switch to turn the fan on at a set temperature.

I suggest you buy a new stat as you say your 06 bike one is broken so you need one anyway, swap the cap off your other bike, if that doesn't do it replace the head orings.

Oh and check the impeller as ishy said, it is only 3 bolts to check, it is easier to check than the head orings