Weird overheating issue, intermittent

[tntmo]

My 2005 Tiger has been overheating over the last few months. Before I had the issue, the radiator had a leak and I had it repaired at a local shop.  Shortly after that, the bike overheated on my commute home from work.  It got hot and started pissing coolant from the reservoir on the dash.  I researched the issue and ordered a new radiator cap, since most posts said it was the main culprit.

The bike worked fine for about a week, then randomly overheated the same way.  This time, I propped the tank up and tried my best to bleed the system of air.  I ran it in my driveway for about 40 minutes, cracking open the bleed port randomly as it warmed up. 

The bike has gone through about three tanks of gas, maybe 600 miles.  Today on a nice back country ride it overheated again.  Nothing unusual, just riding it and it got hot and started pissing coolant all over my jacket and helmet.  It got just into the red.  I shut it down for about ten minutes.  Since I was about 25 miles from home I started it again and started riding it home.  I got almost up to the red, and twice went into the red but didn't feel hot.  It pissed coolant two more times.  When I got it home, it dumped some out from the overflow. 

I added some coolant to the overflow tank, and let it idle.  It never got into the red, but got hotter than usual. 

Recap:  Bike overheats.  I have changed the cap and bled the system of air.  It works fine for a while, then out of the blue it overheats and blows coolant from the overflow tank.  What's my next step?  Thermostat?

[Bixxer Bob]

Although I don't know whether the conditions for a random boil up were the same as conditions where the fan is needed, I'd check the fan is working first.  After that change the thermostat.  And find out how your rad was "fixed".  Was it fixed because of stone damage or was it rotten?  It could be it's partially blocked, but do the easy stuff first.

[Chris Canning]

All of the above and if you re-filled the coolant in under 15 minutes ie put some in let it settle etc than it was too quick I have never had to bleed mine.

[daveb]

same as above, however where is your coolant level at cold. I keep mine at the lower mark

[NortonCharlie]

Check that the hoses to the overflow tank are not reversed.  Does it pull coolant out of the reservoir when it cools down?  If it is pissing coolant it should end up on the ground by the back tire not up by the tank.  Possibly a pinched hose for the overflow

[tntmo]

I suppose the best idea would be to get a new radiator.  Ouch they are expensive!  The repair guy said it was getting thin, so it may be rotted a bit and getting plugged?  Always go to the last thing that failed and work from there.   

My bike has 80,000+ miles so I can understand the radiator getting a bit flimsy.  The fan is working fine, comes on as the bike gets past halfway on the temp gauge.  The hoses to the overflow are routed correct and I blew threw them to make sure they aren't clogged. I will double check to make sure they aren't kinked.   

I found a used radiator on Ebay, it's from a 99 Tiger.  Does anyone know if they are the same for the 2005? 

[NortonCharlie]

If the thing is pissing coolant from around the overflow tank something is either hooked up wrong or a drain hose is pinched or plugged.  Replacing the radiator will not fix that problem. 

[tntmo]

I will double check the drain lines.  It also was pissing coolant from the overflow behind the engine, so that line is clear.  I will pull the fairing off today and re-check everything.

I just find it odd that it is intermittent.  It works fine for a few days or weeks, then happens randomly.  I rode it to work today and it ran cool all the way until traffic outside the base, where it got to about half on the gauge and the fan came on.  Didn't leak coolant anywhere and the overflow tank is half full. 

If the thing is pissing coolant from around the overflow tank something is either hooked up wrong or a drain hose is pinched or plugged.  Replacing the radiator will not fix that problem.

[daveb]

what about the thermostat, is that knackered. simple to check once you have remove the thermostat from the bike.

do you have automotive radiator specialists near you, if you think its the Radiator before you splash the cash it might be worth them having a look.

This is one a few miles from home, too far for you but this is the type of place I mean.
http://www.rickettsradiators.co.uk/Radiators.html

[tntmo]

I haven't tested the thermostat yet, might be next on the list.  The place that repaired my radiator does all the stuff like the place in your link.  He said it's getting thin and because of that was difficult to repair.  It probably needs to be replaced, but not sure if it's causing my issues. 

what about the thermostat, is that knackered. simple to check once you have remove the thermostat from the bike.

do you have automotive radiator specialists near you, if you think its the Radiator before you splash the cash it might be worth them having a look.

This is one a few miles from home, too far for you but this is the type of place I mean.
http://www.rickettsradiators.co.uk/Radiators.html

[tntmo]

Just got home from work.  It was running fine, temp gauge was on the lower 1/3 of the gauge until about a mile from home.  Then it slowly climbed up to just below the red and started spitting coolant from the dash area and a bit of steam.  I could see coolant bubbling into the overflow tank.  I got it home, it was still on the high side of the gauge and coolant was coming out of the overflow behind the engine and some steam from the dash area.   Coolant on the right side of the tank as well. 

(https://flic.kr/p/mD3vSn)

(https://flic.kr/p/mD34nR)

(https://flic.kr/p/mD4Guy)

So since I was experiencing the issue at home, I kept it running and started to pull the fairing off.  This is what I found.

(https://flic.kr/p/mD4Hn5)

The upper hose fitting is cracked.  This is where the steam and water appears to be coming from.  I guess I'll order one up and see what happens.   

[Bixxer Bob]

Remember, easy stuff first.  Sort that out, then check the thermostat, it's the next cheapest thing.  Don't blow money on a rad till you have to.

[tntmo]

I checked the routing of the hose from the thermostat housing to the overflow tank.  It may have been slightly pinched, not sure. 

I'm going to try to find an elbow at Home Depot to replace the cracked one. 

[NortonCharlie]

That cracked fitting could cause all of your symptoms.   Fluid would run to the tank when expanded then suck air when it cools and tries to replenish  the tank.  This gives you bigger air bubbles in the tank, less efficient cooling, thermostats get flukey when they are not submerged.   Your coolant system turns into a balloon then when it gets hot it blows a lot of air instead of a little coolant.  I know a few have gone to the hardware store to source an elbow that will work.  I do believe you have found the culprit.

[tntmo]

I incorrectly said it was the upper hose fitting that was cracked.  It's the lower one, which is the one going to the overflow hose that is cracked.