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Discussion Starter #1
Has your radiator failed with a leak at the upper right (throttle) side similar to the attached picture? If so, reply here.

I have a theroy that the root cause of this common(?) failure the way the horn is mounted. It's possible that the horn mount is causing stress on the tab that is welded to the top of the radiator. The horn is fairly heavy, and the leverage advantage is about 12/1. I think that is enough to cause stress on the tab.

I've removed my horn, and substituted a flanged bushing around the screw. I have screw that is used on the left side on order, and will use that when it arrives. Meanwhile, I'm going to make an alternative mounting bracket that doesn't involve the expensive radiator.
 

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Has your radiator failed with a leak at the upper right (throttle) side similar to the attached picture? If so, reply here.

I have a theroy that the root cause of this common(?) failure the way the horn is mounted. It's possible that the horn mount is causing stress on the tab that is welded to the top of the radiator. The horn is fairly heavy, and the leverage advantage is about 12/1. I think that is enough to cause stress on the tab.

I've removed my horn, and substituted a flanged bushing around the screw. I have screw that is used on the left side on order, and will use that when it arrives. Meanwhile, I'm going to make an alternative mounting bracket that doesn't involve the expensive radiator.
I don't have the knowledge to help your theory.

Yes, my radiator failed exactly there. So did the replacement. I had a custom rad made and it works just fine without failure. It's important to note that while I had a blown head gasket that certainly exacerbated the problem, I complained to the idiots at the dealer that it smelled like burning coolant even before the major symptoms of a busted gasket surfaced.

The idiots claimed it was probably just oil from the road, and shrugged when I mentioned that it rains a lot on Seattle so the oil gets washed away pretty regularly. The idiots are no longer a KTM dealer. Good riddance.

Sent from my XT1710-02 using Tapatalk
 

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I didn't have a rad leakage to help you with your threory.
Though I stepped in to just wonder, how come so stupid people are hired by the dealers?
Damn, they make more harm than anything else...
 

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Has your radiator failed with a leak at the upper right (throttle) side similar to the attached picture? If so, reply here.

I have a theroy that the root cause of this common(?) failure the way the horn is mounted. It's possible that the horn mount is causing stress on the tab that is welded to the top of the radiator. The horn is fairly heavy, and the leverage advantage is about 12/1. I think that is enough to cause stress on the tab.

I've removed my horn, and substituted a flanged bushing around the screw. I have screw that is used on the left side on order, and will use that when it arrives. Meanwhile, I'm going to make an alternative mounting bracket that doesn't involve the expensive radiator.
It's certainly something vibration-related that is causing that, and I imagine that something like a horn vibrating on the same fixing point as the radiator could possibly cause that. How many miles did it take before the damage happened?
 

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My theory

I didn't have a rad leakage to help you with your threory.
Though I stepped in to just wonder, how come so stupid people are hired by the dealers?
Damn, they make more harm than anything else...
I have a simple theory as to why service departments are sometimes full of idiots. Very simple actually. A lot of these idiots interview well to get a position and perform poorly and cause lots of damage and grief to unsuspecting customers bikes before they are found incompetent and tolerated or terminated and sent to apply for work at another dealership. And the process begins again with a trail of poor work and pissed off customers at another dealership or shop. No easy soloution here only a bit of advice to the lucky bastard that finds a good service shop or tech. Treat them well and support them with your business. Don’t cheap out on him by shopping internet sites for stuff he sells. Help the guy out by supporting and promoting his shop. Hopefully his shop prospers and you keep a good tech in business so you and other riders have a good shop to service your machine.
 

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Discussion Starter #6 (Edited)
It's certainly something vibration-related that is causing that, and I imagine that something like a horn vibrating on the same fixing point as the radiator could possibly cause that. How many miles did it take before the damage happened?
16,200 miles before my rad' failure.

WRT crappy service at bike shops... I don't think it's any different at car dealerships. They all suck in almost all cases. I can count on one hand the number of problem-free visits to automotive shops.

I have some horror-stories of off the charts incompetence and dishonesty. I had a wheel fall off my truck after a bearing replacement. I didn't even make it home. The mechanic forgot to put a cotter pin in. A Honda dealership left my bike in the rain with the carbs off. Rusted the valves in place, and bent half of the valves when they started it. Then they claimed it was like that when I brought it in. A Chevy dealer pulled a head and surfaced it to fix a coolant leak. In the process, they dropped the intake and dented two runners. Dismissed it an unimportant. Oh, and the leak was caused by a lose hose clamp on a heater hose. A friend found that and fixed it in 30 seconds.

Unless it's warranty work, or I simply can't do what is required, I will do service work myself rather than risk another moron encounter.
 

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Has your radiator failed with a leak at the upper right (throttle) side similar to the attached picture? If so, reply here.

I have a theroy that the root cause of this common(?) failure the way the horn is mounted. It's possible that the horn mount is causing stress on the tab that is welded to the top of the radiator. The horn is fairly heavy, and the leverage advantage is about 12/1. I think that is enough to cause stress on the tab.

I've removed my horn, and substituted a flanged bushing around the screw. I have screw that is used on the left side on order, and will use that when it arrives. Meanwhile, I'm going to make an alternative mounting bracket that doesn't involve the expensive radiator.
I've had 2 radiators go there, the first one the mounting bolt was missing for a while til I spotted it so I thought that was the cause. The second one split after a harsh landing from a wheelie. p.s. I wheelie my bike all the time and I'm sure this doesn't help
I've also considered the horn mounting and I think you're right in that it makes the problem worse.
I'll look into remounting it

Sent from my TA-1033 using Tapatalk
 

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I have a classic car (Lancia Beta Spider/Zagato) and it went in for a noisy water pump and came out with a wrecked engine (multiple piston/valve contacts) because the idiot doing the work thought it might need a new cam belt and forgot to tighten up the idler pulley. The cam belt was only 2000 miles old. I knew something was off when I saw him removing the crank pulley nut (not necessary for the job) with a hammer and cold chisel.
 

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Discussion Starter #10
I've had 2 radiators go there, the first one the mounting bolt was missing for a while til I spotted it so I thought that was the cause. The second one split after a harsh landing from a wheelie. p.s. I wheelie my bike all the time and I'm sure this doesn't help
I've also considered the horn mounting and I think you're right in that it makes the problem worse.
I'll look into remounting it

Sent from my TA-1033 using Tapatalk
I wheelie a lot too. Hmmmm....

Speaking of wheelies... After installing the new rad' my 690 runs MUCH better. Super easy to power wheelie in second gear now. I know.... This sound like BS, but the difference is profound.

The only differences are:

1) New radiator
2) Refill with a 50/50 mix of Dexcool & distilled
3) Horn delete (-6.3 Oz)
4) Top oil
5) Repeated idle to hot and shut off to chase air from the cooling system (ask if you want to know why)

I'm guessing #5 is the answer. In any case, I love this bike more than ever. Wheelie for safety!

Anyway, I'm looking at the two smaller screws that hold the black plastic fairing thingy as a mounting point for the horn. I'll post pics of the mount when done.
 

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I have a classic car (Lancia Beta Spider/Zagato) and it went in for a noisy water pump and came out with a wrecked engine (multiple piston/valve contacts) because the idiot doing the work thought it might need a new cam belt and forgot to tighten up the idler pulley. The cam belt was only 2000 miles old. I knew something was off when I saw him removing the crank pulley nut (not necessary for the job) with a hammer and cold chisel.
I'd cut a bitch

Sent from my XT1710-02 using Tapatalk
 

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Silent voice of reason

As a mechanic and machinist for many years, and having made my share of mistakes along the way I always try to understand and defend service folks that make mistakes, as we all do in our various occupations. But I just can’t tolerate hack mechanics butchering up fine machinery of any kind. It just flat freaks me out. It made me really nuts as a shop owner when I observed this butchery and had to be the poor bastard that got his head chewed off by pissed off customer and had to make the job right at my expense and possibly lose a customer in the bargain. I don’t have an easy answer either....I just wanted to weigh in again and bitch some more:grin2:
 

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The real answer

I intended originally to post a radiator problem theory I wanted to share and got caught up in a bitch fest rant. The radiator problems observed here as observed by you fellows is probably exactly as observed by @Mario Landavoz
It would seem this observation is correct as the stationary mounting probably does not allow even thermal expansion of radiator and causes a stress riser on area where the expansion is transmitted to. You will see a lot of automotive radiators mounted on vertical posts at the bottom and retained with movable insulator brackets on top to allow even expansion of the radiator. A motorcycle radiator will grow with heat and if this thermal growth is limited it will cause distortion on a weaker or less supported area as shown in common failure area. There may be some benefit from enlarging mounting hole also and using oversize mounting grommet to fasten radiator and relocating horn to eliminate additional mechanical stress as previously suggested
 

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Discussion Starter #15
Fabricating an alternative mount for the horn to isolate it from the radiator was my goal this morning. After hours of dicking around with templates and stainless I decided to go with the stock mount, and a supplementary brace. This is what I came up with:
 

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I wasn't sure if this would help but a generic handguard mounting clamp may help your horn mounting. Large bore is 3/4 minimum ID and will open to 1" with 8mm bolt on end at right angle. Left over part was purchased from magic racing products and is their cheapie off road handguard kit.
 

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Discussion Starter #17 (Edited)
I kinna like that idea. Thanks Augie.

BTW, say hi to Doggie Daddy for me. It's been a long time, but as a kid I used to dig Quick-Draw and Huckleberry, and the rest of the HB crew.
 

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tell yas what i would try.
remove the coolant, ram a rubber glove in the bottom pipe of the radiator.
in the top pipe fit your family vacuum.
the goal is to open the air bleed system on the handle so the vacuum is just enough. borrow a smoke from someone and smoke it up next to the radiator cracks
when you find them, make up some 2 part heat resistant filler and depending on the viscosity crank the vacuum suction so the viscosity sucks into the crack a little .
cut out any fins that get in your way.
 

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wasted youth

ah yes. regards sent to doggie daddy every night in my prayers. you date yourself by the cartoons you recognize when they appear 50 and 60 years later. that is exactly where my handle came from. my father coined that nickname for me as a boy and i cherished it always as it was the only one he used for me without a curse word in it. i inherited a sense of humor and humility from my dad, i reminded him of little auggie doggie once during one of dads epic failures and he was amused by my sense of optimism and encouragement during his fail he coined that nickname for me as i reminded him of the cartoon character that kept a positive outlook at his dads fail. i think our world is a better place from the cartoon influence we learned. i found comfort growing up watching Wil E Coyote crash,burn and fail when i saw i was in good company with my many failures as a boy.....beep beep
 
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Keith Jamieson
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