Coolant draining fast out of drain hose? YZ426, not overheating though


25 replies to this topic
  • xnofriendsx

Posted May 17, 2009 - 05:48 PM

#1

I did a search on this but i still need some opinions.

I just starting noticing tons of coolant draining from my drain hose on mile 35 of a 45 mile ride yesterday. I thought my bike was going to overheat so i beelined it back to my truck but my bike never did overheat. The next day (we were camping), i put 3 full large cups of water (no coolant on hand) in the radiator and just tested it out on a 8 mile ride or so. When i stop the bike after a mile or so, it is just pouring out. When i got back to the truck and cooled down, it took about 3-4 full cups of water this time.
It is for sure leaking it all quick. I am not sure how much a full radiator holds, but it seemed to be pretty dry.
My main question is why.
Is it just the cap?
Is it the water pump?
Is it a bigger problem internally like a head gasket or other pressure issue?

The bike is not overheating though at all. It is probably a bit hot, but without totally taking my bike apart, can i do some quick tests with a new radiator cap or other simple inexpensive tests before i take my bike in or rip it apart.

Any help is much appreciated.

  • xnofriendsx

Posted May 17, 2009 - 07:10 PM

#2

I was just thinking that it might be the weep hole. It looks like it is coming out of my drain hose because i have a big skid plate that covers that whole area from water pump to drain hose. When i was riding i was sort of assuming it was the drain hose, but it might just be draining down the skid plate when i lean my bike over to the left to view the drain hose.
Can it come out of the weep hole that fast?

I drained my coolant pretty fast.

  • grayracer513

Posted May 17, 2009 - 07:27 PM

#3

First off, relocate the overflow tube so you can more easily distinguish whether the tube or the escape port (weep hole) is the source.

If the impeller seal fails, you can loose coolant fairly fast, yes. The system holds right around one quart of fluid.

  • yz007f

Posted May 18, 2009 - 11:33 AM

#4

I would pressurize your coolant system, to me it seems like it could be a head gasket problem.

  • TIG88

Posted May 18, 2009 - 11:41 AM

#5

I would pressurize your coolant system, to me it seems like it could be a head gasket problem.


Good advice. I was thinking along these lines too.

How does your oil look?

  • grayracer513

Posted May 18, 2009 - 12:24 PM

#6

I would pressurize your coolant system, to me it seems like it could be a head gasket problem.

It's a possibility, but first we need to see where the coolant is coming from. If it is from the escape port, we have one problem, if from the hose, another.

  • dankman

Posted May 18, 2009 - 01:11 PM

#7

if the leak is coming from the escape port, that means it's a bad impeller seal? - and if that's the case, would it leak as long as the motor is running (as in leak as soon as it starts) and fluid in the system?

  • grayracer513

Posted May 18, 2009 - 02:14 PM

#8

Impeller seals can leak under any of the 4 possible conditions:
  • shut off, no pressure
  • running no pressure
  • shut off, under pressure
  • running, under pressure
...and not the others, or some of the others in any combination, or all of them. Water pumps are funny things like that.

It's also true that the fact that the impeller seal is bad doesn't mean the head gasket isn't blown, too. It might be, or it might not.

  • xnofriendsx

Posted May 18, 2009 - 03:38 PM

#9

Just got off work late today, so i am going to tear into it tonight and report back tomorrow AM on what i find. I need to do an oil change anyways so i will check all the above and see what is going on.
This way i can clean up all the dirt around the area to see if it is coming out the drain hose or somewhere else.
It should be pretty easy to tell once i get it cleaned. I just came off a big ride so it is pretty dirty from the mud and such.

Thanks for the input so far though. I need this thing up and running for a race in early June and for being a 2002 YZ426, this is really my first real issue with it. Crazy how good this bike has been for 7 years.

  • erickdj

Posted May 18, 2009 - 03:41 PM

#10

I was there during the 45 mile ride, to me it looked like it was coming from the overflow hose. just my $.02 I saw the coolant dropping to the ground, the only way it could have flowed that fast from the weep hole is if the seal was completely destroyed.

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  • xnofriendsx

Posted May 20, 2009 - 10:12 AM

#11

OK... well good news, sort of.
I finally got to look at it today (busy lately).
I had drained the water/coolant the other day and today i tore off the skid plate so i could just get a better look at it.
When i poured the 1.2L of water in the radiator, it was already dripping out the bottom somewhere. It turns out that it was the weep hole and i had not even started the bike yet to get it warmed up.
When i started it up, it leaked even faster. At this rate i would say the 1.2L of water would be gone in like an hour or so. It was dripping like 1-2 drops a second when the bike was not running, and almost a steady flow when it was running and warmed up.
So....

It looks like I have to replace the shaft and bearings. I replace both, right?
It is not as simple as remove the water pump cover, huh?
The manual looked as though i need to drain oil, coolant, and remove the crankcase just to get the shaft and bearings out, is this right?
Should i replace anything else while i am in there?
I just bought a new high pressure radiator cap today, a 1.6.

This bike has been running so well i have not had to do any work like that on it so it will be my first time removing that stuff. Oh well, good learning experience.

Any other advise?

Brian

Oh yeah, the oil was not milky and looked like a normal oil change that i do every 150-200 miles or so.

  • grayracer513

Posted May 20, 2009 - 10:49 AM

#12

  • It looks like I have to replace the shaft and bearings. I replace both, right?
  • It is not as simple as remove the water pump cover, huh?
  • The manual looked as though i need to drain oil, coolant, and remove the crankcase just to get the shaft and bearings out, is this right?
  • Should i replace anything else while i am in there?

  • Yes, usually, and both seals. NOTE the direction the seals face as you remove them. They way they go in may appear "backward" at first, but it makes sense when you think what they do and how they work.
  • Nope.
  • That is correct. The impeller may be very tight. Before you ask, it IS a normal, right hand thread.
  • The gaskets. Check the big primary drive gear nut to be sure it's still tight.


  • xnofriendsx

Posted May 20, 2009 - 12:30 PM

#13

Thanks for the info.
I just ordered all the parts. (shaft, two seals, and bearing for $38)
The impeller shaft seemed pretty jacked up as well as the oil seals. It actually smelled like burnt oil so i am guessing they were pretty bad. The bearing seemed OK, but i ordered one cause it is best to replace all of those parts so they get a good seal.

My AMA membership and gift card to BikeBandit.com helped too so hopefully the parts come in soon and i can report back to see if this was the fix.
Hopefully....
Thanks,
Brian

  • xnofriendsx

Posted May 29, 2009 - 04:09 PM

#14

OK, i have some issues.
I got the two seals in, then onto the bearing...
The thing was so hard to get in. I was hitting the outer race and finally got that thing in, but.... the smaller oil seal got pinched and it tore the rubber where the circle spring is.

So i guess i have a few questions.

1. Is there some easier way to get that bearing in?
2. Could that be the wrong oil seal? It seemed a bit thicker than my old used one by just a minimal amount.
3. How did that get pinched since the bearing should have just fit plush against the top of that oil seal?

The only way i can think if it getting pinched is that the oil seal is a bit thicker and when the bearing pushed up against the seal, it pinched the bearing and the circle spring of the oil seal together and got it pinched.
The bearing has to be put in all the way as well as the oil seal.

Any suggestions?

  • erickdj

Posted May 29, 2009 - 06:50 PM

#15

I did that same job on a yz400f last year, but I can't recall if I changed the bearing or not, but I think I did. In any case, by looking at the parts diagram I can tell that the bearing must be put in place before the seals. What I'm trying to say is that if the bearing had been installed first, the seal wouldn't have been there to get pinched/damaged. So is the seal damaged to the point of being useless, or can it still be used?

  • Derrick852

Posted May 29, 2009 - 07:02 PM

#16

I just bought my 01 426 and had the same problem, I changed the NASTY coolant in the bike and replaced it with straight de-ionized water and purple ice, and almost right away, she sprung a leak. Like you I thought it was the hose, but after pulling the skid plate, I saw that it was the weep hole. Its really easy and cheap to fix the seals, and make sure you have a good look at the bearing and shaft. I am not expert on these bikes, but I have alot of wrench time on everything from diesels to dirtbikes. When I posted my water pump problem, a senior member told me that the shaft is also supported by one of the balancer bearings, so another thing for you to check when you tear her apart to fix the beast.

  • Derrick852

Posted May 29, 2009 - 07:04 PM

#17

and the real oil seal is installed prior to the bearing from the backside of the engine case

  • xnofriendsx

Posted May 29, 2009 - 07:51 PM

#18

and the real oil seal is installed prior to the bearing from the backside of the engine case


"real"?

I am replacing both seals, bearing, and shaft. The case is off (obviously)
Bikebandit is actually sending me another seal free (saying its defected, they hooked me up i guess), but i have a race next weekend and am barred if i do this same thing twice. I might just take it in cause i am sure some mechanics have done this plenty of times.

  • xnofriendsx

Posted May 29, 2009 - 08:07 PM

#19

I did that same job on a yz400f last year, but I can't recall if I changed the bearing or not, but I think I did. In any case, by looking at the parts diagram I can tell that the bearing must be put in place before the seals. What I'm trying to say is that if the bearing had been installed first, the seal wouldn't have been there to get pinched/damaged. So is the seal damaged to the point of being useless, or can it still be used?


Erick,
I don't see how you can put the bearing in first?
If you are just looking at the parts diagram, then you aren't seeing that the cover is off and you have to work from both sides of it.
The cover goes in between parts 4 and 5 (both seals).
Part 5 (the smaller SD type seal) has to go on first, then the bearing.

In the manual it says oil seals in first, (Chap 4-56)

  • Derrick852

Posted May 29, 2009 - 08:21 PM

#20

"rear"
duh





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