Leaking coolant from hole in top of radiator

[NotVeryCreative16]

My coolant has been boiling up out of this small hole in the top of the radiator. The engine does not overheat until the coolant level is low. It was only a little at first and I noticed it at the end of the first day of a 3 day trip so I just added coolant at the end of each day but it has gotten much worse. I limped it home which was a 2 hour drive and noticed the coolant just boiling over and pouring out of the hole in the top of the radiator by the radiator cap. Does anyone know what could be causing this? Thanks in advance.

[NotVeryCreative16]

Okay, I was wrong. This hole is where coolant was leaking from at the end of my 2 hour drive yesterday. I just dropped the radiator guard to get a better look and it is actually squirting from the very top of the front of the radiator, underneath the hole. There doesn’t appear to be any damage to the radiator though so this is confusing.

[bwringer]

Well, uh, there shouldn't be a hole there. But I can't see a hole in that photo. Just an arrow pointing to an area of black pixels.

I can't imagine how a radiator would get a hole there and not anywhere else. Or maybe it's leaking from the crimp between the end caps and the core.

And is your radiator cap on all the way?

 

Anyway, Myler's is pretty much the only place in the US that will repair motorcycle radiators.

https://www.motorcycleradiators.com/

They're fast, cost-effective, and do great work. But you have to ship your radiator to Utah.

 

Or, a new radiator from Yamaha ain't too terribly outrageous; I'm seeing $220 for a 2015 FJ-09 radiator (by the way, exactly what motorcycle are we discussing here, and are you in the US...?) If my radiator developed a hole, I'd probably go ahead and replace it, since you'd probably be in for at least half that with a Myler's repair.

On my Suzuki V-Strom, a new radiator was around $700... so, yeah, I had it repaired by Myler's.

I have to say, Yamaha's almost humane parts pricing has been something of a pleasant surprise compared to Suzuki and Kawasaki.

[Buggy Nate]

It could just be a faulty cap and pooling there too. I’d be topping up giving it a good clean and run it up to temperature a few times. You may have to inspect it with a small mirror.

[1moreroad]

Back in the 1990s, I had a Saturn with a coolant leak (this is relevant because they had aluminum radiators).  The shop added a bright green additive that let them trace it back to a slightly distorted radiator cap.  New cap fixed the problem.

Since Yamaha uses some of the same parts across different models, there was a metal Kia radiator cap that worked in place of the plastic cap on my WR250X.  If it's the cap, do some Googling and you might find a more robust cap.

[KrustyKush]

Probably the cap, but even new rads can leak at solder joints. Either way there isn’t much mystery and it is an easy fix. I wouldn’t bother with a repair, if it is the rad body itself and not the cap. A new rad is relatively inexpensive, while anything “repaired” by our typically under-qualified techs will leave you with a nagging fear. 

[nhchris]

Occam’s razor indicates a cap replacement is in order.

(that cap looks tired)

Edited April 26, 2022 by nhchris

[PhotoAl]

Nope, got it all wrong!  Bike is toast, only reasonable fix is a new T 9 GT.  Plus they come with a new radiator cap 🙂