How do I drain coolant?

Jared

Well-known member
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101
Location
Arlington, WA
#1
So I recently bought a used EX, and had noticed that while charging the water pump didn’t sound the same as my EXR and after riding there was some white foam on the left side of the frame about an inch back from the battery badge. Water pump whirrs at too high a pitch, then gurgles and slows down. I checked the coolant level and found none visible with cap removed. I snaked about 9 inches of zip tie down the hose that goes to the fill port (end of zip tie at 3rd bend in hose) and was able to find some coolant to look at. Looks like water with the slightest tint of green color. I added about 10oz of regular green antifreeze and turned the key on. The water pump whirr was too high pitched at first then you could hear it prime and slow down, but now there is a lot of foam at the fill port and I want to replace the coolant. Is there a drain somewhere?

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Jared

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101
Location
Arlington, WA
#3
The drain is at the bottom of the RBH. It likes to spurt out quick. Also top tip when reloading coolant. Go through the key cycling three times in a row to activate the pump cavitation to allow for the coolant to properly drain into the coolant system (Use a funnel/graduated cylinder)

View attachment 3975
Thanks a million, I would have never guessed that to be the coolant drain. Thank you 😀
 

snydes

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Pennsylvania
#5
@Jared , just FYI the coolant will foam if the level isn't proper. You can also get a stubborn air bubble that doesn't work itself out easily. I've found that riding the bike a bit helps work them out. Once you have foam though you will have to let it sit a little while and then recheck your level. Hopefully that helps.
 

OneLapper

"You don't *really* need the water pump...."
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Connecticut
#6
@Jared , just FYI the coolant will foam if the level isn't proper. You can also get a stubborn air bubble that doesn't work itself out easily. I've found that riding the bike a bit helps work them out. Once you have foam though you will have to let it sit a little while and then recheck your level. Hopefully that helps.
Bingo

The foaming is from low level. Very common if the drain plug up top has not been blocked off. Coolant will leak when the bike is on it's side if it's not plugged.

Somewhere on the forum it was reported that Alta pressure tested the coolant system and verified is was safe to block off the drain tube. Since then, I've had no aeration issues with the coolant.
 

Rashid510

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South San Francisco, CA
#7
Bingo

The foaming is from low level. Very common if the drain plug up top has not been blocked off. Coolant will leak when the bike is on it's side if it's not plugged.

Somewhere on the forum it was reported that Alta pressure tested the coolant system and verified is was safe to block off the drain tube. Since then, I've had no aeration issues with the coolant.
The last revision of the coolant hose eliminated that drain tube. So yes it can be plugged.
 

Motophyllic

Well-known member
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199
Location
NY
#10
Ok, thanks.
When I turn the key on, the pump and headlight/taillights run for 15 minutes and then shut down. Does the 3 cycles do something different? Sorry if I should know this!!
 

effinsiok

New member
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4
Location
PNW
#13
The last revision of the coolant hose eliminated that drain tube. So yes it can be plugged.
Do you know what plugs to use for the drain and overflow holes when trying to close up an early MX? It looks like the overflow could use a barbed plug of some size, and the drain is maybe a 1/8" NPT?
 

snydes

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Pennsylvania
#16
Had to make a McMaster order for some other things so I threw two of the above mentioned plugs in on the order. If just plugging the tube, definitely go with the .170” OD. Can’t say for sure if that size will work when removing the brass barb at the filler tube though. E76D8E56-8745-46DB-B7BC-EFDC7D6AA69F.jpeg 4E6CDB91-044C-4C89-93C2-AEC5103E4BD2.jpeg
 

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