Leaking radiator - VT750CD

I went out to start the bike this morning and saw about a table-spoon full
of green stuff on the ground under the radiator.

I haven't ridden since Monday afternoon, and the level in the bottle is
still within acceptable range, so I don't think it is just leaking out the
bottom.

An odd thing occured on Monday. I was out riding and stopped at a store.
When I went to leave, I started the bike and heard a loud pop or crack
sound, almost like a backfire (but quieter), come from the front end. I
thought it was very strange, but couldn't think of what it could be.

Could that have been something with the radiator? What could have broken
that would relate to starting the bike? If I had an idea about that, I'd
know where to start looking for the problem.

Otherwise I guess I'll just have to take the whole thing apart and track it
down.

I have no problem with the idea of doing this or other work myself, but
since I've never done any of this before, it's still a little bit daunting.

Thanks for any tips in advance!
Richard

03 VT750CD

 

It might be a leaking overflow drain hose, or the gasket on the
radiator cap might leak. Hopefully the radiator itself isn't leaking.
Aluminum radiators can be repaired by heliarc welding done by a skilled
welder.

Check your radiator mount brackets. It's possible that one broke off
from improper installation. The radiator is supposed to be mounted in
rubber shock absorbing grommets with steel bushings inside the grommets
to keep you from compressing the grommets when you tighten the mounting
bolts.

Otherwise, inspect all the emissions control stuff and check the
exhaust pipe flanges and bolts for tightness.

I suppose your Honda is out of warranty by now :-(

 

It might be a leaking overflow drain hose, or the gasket on the
radiator cap might leak. Hopefully the radiator itself isn't leaking.
Aluminum radiators can be repaired by heliarc welding done by a skilled
welder.

Check your radiator mount brackets. It's possible that one broke off
from improper installation. The radiator is supposed to be mounted in
rubber shock absorbing grommets with steel bushings inside the grommets
to keep you from compressing the grommets when you tighten the mounting
bolts.

Otherwise, inspect all the emissions control stuff and check the
exhaust pipe flanges and bolts for tightness.

I suppose your Honda is out of warranty by now :-(

 

Maybe this will help. There was also coolant puddled inside of the external
case, on the lower left edge, naturally because of the way it sits on the
sidestand, I suppose. See
http://i20.photobucket.com/albums/b202/grichardk/Graphic1.jpg

When I was tracking down a hose-clamp issue, I did find that neither of the
two rubber grommets or bushings at the bottom were correctly in place. One
was squished into it's hole, half of it erroded away. It looked like from
friction. The other wasn't even seated. It was just stuck between the
radiator and that outer grill mentioned above. I managed to fit them both in
place. That was a few weeks ago.

Yeah, it is.

Another thing:

I rode it to work anyway. I don't know if that was foolish, but nothing
occured on the way in. I just went out and checked. There's nothing on the
gound, or in that area in the graphic. The level is still within limits.

I had ridden it kind of hard the last time. I'd forgotten the key (again),
but caught it before the light went out, though it wouldn't start. I let it
stand about forty minutes, then it started right up, so I took it out at
high speed on the highway about 25-30 miles to get the battery charged. Then
parked it.

Richard
03 VT750CD

 

Besides the worst possibility (that the radiator itself leaks) you
might have a coolant leak around the lower radiator hose or around that
sensor or thermoswitch in the lower corner of the radiator.

And the waterpump, wherever it is, may have a leaky seal. The seal
cavity will have a witness hole so you can see the leakage before the
seal fails and you get coolant in the crankcase oil. If the witness
hole leaks and the coolant can follow the frame rail or the lower
coolant hose to the area where you saw it collecting, that might
explain the presence of green liquid where you found it...

OTOH, if it's blue green and really smelly, maybe a chunk of lavatory
ice fell off an airliner and landed on your motorbike ;-)