YZ426F 2002 Coolant question


14 replies to this topic
  • Rotem_46

Posted April 01, 2009 - 02:38 PM

#1

Hi,
This is my first post here so Hello everybody !!
I'm pretty new to dirt bikes, all my life I had sports bike and last year I decided it was time to sell my precious CBR954RR and get an MX bike in the shape of the 2002 Yamaha YZ426F. I have it for a year now and I only ride Enduro/Trails but I have a problem since day 1 and was wondering if its normal...My bike seem to lose coolant everytime I take it out, I usually fill the radiator all the way up with antifreeze but I noticed that everytime we rest the bike is wet as the water are coming out of the relief hose (the one where the cap is) I checked all the hoses and there are no leaks. Is it normal that after every ride I have to fill the radiator again? My father told me it may be a damaged cap but I can't just buy one as it cost here in Israel something like $80 !!! Also, I read that there are some 1.6 caps out there but I'm afraid it will damage my engine as the original state 1.1...
Any thoughts??
Thanks guys !!

  • grayracer513

Posted April 01, 2009 - 03:05 PM

#2

If you fill it all the way up, and the coolant expands when it gets hot, what do you suppose will happen?

Under normal conditions, If the radiator is full, and the bike is run at normal temps for any length of time, the coolant level will return to just above the tubes in the radiator core once it has cooled down. That is normal.

You should also know that the bike does not like to idle at a standstill for more than half a minute or so, and may boil over if it is subjected to strenuous work at very low speeds. That's also normal.

But, if you think the cap is weak, try one for a 1989-90 Toyota Corolla. They should be available in either 1.1 or 1.6 bar ratings, and will be much cheaper than the OEM cap.

  • Rotem_46

Posted April 01, 2009 - 03:41 PM

#3

hey,
Thanks for your answer man !!
Look, when I said that the bike lose the coolant I ment its way under the tubes in the radiator core !! I mean, last friday I forgot to check the level and after an hour riding I suddenly remembered so I've emptied my water from my Camelback into the radiator (about 0.700L was in there) and it didn't get over the tubes !!

  • grayracer513

Posted April 01, 2009 - 06:20 PM

#4

You may have more than a weak cap. Below the water pump, facing straight down, there is a small (3-5mm) hole. This is the escape hole for coolant that leaks past the water pump. See if it looses coolant from this area. If so, you need to replace your water pump impeller shaft, bearing and seals.

If that's not it, you may have a more serious problem, like a leaking head gasket.

  • Rotem_46

Posted April 03, 2009 - 07:31 AM

#5

You're the man grayracer513 !!
I've just returned from the track and saw that the bike has a massive leak, I've turned the engine off and checked the water pump and the little hole was leaking, I've started the bike again and when I rev it the leaking became stronger...So now I'm facing a new water pump ??
Thanks man!!

  • grayracer513

Posted April 03, 2009 - 08:29 AM

#6

Yep. You will need to remove the right side engine cover, and replace the two seals, the bearing, and most likely, the shaft, if it has any sort of wear in it from the coolant seal.

  • Rotem_46

Posted April 03, 2009 - 12:28 PM

#7

Is it possible that my problem is only the seals ? I mean without having to change the shaft and the impeller ? Also, How do I know if I have to replace the impeller and/or shaft? I'm not a mechanic and I don't know what to look for once the water pump cover is off. I mean, How can I tell if the impeller or the shaft are still ok or need to be replaced ?
BTW, Do I have to remove the engine side cover in order to change the water pump parts or Does removing the water pump cover is enough?
Thanks a lot for your help man, I really appreciate it.

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  • grayracer513

Posted April 03, 2009 - 02:24 PM

#8

The impeller won't need replacement unless it is visibly broken.

The shaft will probably have a significant groove worn into it by the coolant seal. If it's enough to feel with a fingernail, buy a new one.

  • gbalias

Posted April 03, 2009 - 04:41 PM

#9

i just did this repair on my supermoto bike. should be less than $75-100 in parts, and about a 40 minute job.

  • Rotem_46

Posted April 04, 2009 - 12:17 AM

#10

i just did this repair on my supermoto bike. should be less than $75-100 in parts, and about a 40 minute job.


Thanks for your answers and your help guys but I live in Israel and they are killing us here with prices for MX bike as they are not legal in Israel. For example, a radiator cap cost $85 !! original exhaust header cost $300, fork caps cost $400 each !!! I guess you get the point...my 2002 YZ426F, which I bought last year, cost me $5500...I'm so happy I paid attention in English lessons so now I can communicate and buy stuff from the US...Anyway, do you know any internet stores that ship overseas that I can buy these part from?
Thanks!!!
If it is not to much trouble, I could really use the parts numbers so I could know what to buy exactly so if you can help me a little bit more it would be great !!! here's a link to Yamahas parts catalog...http://www.yamaha-mo...parts/home.aspx
Thanks.

  • Rotem_46

Posted April 04, 2009 - 01:54 AM

#11

The impeller won't need replacement unless it is visibly broken.

The shaft will probably have a significant groove worn into it by the coolant seal. If it's enough to feel with a fingernail, buy a new one.


Do I have to remove the engine side cover in order to change the water pump parts or Does removing the water pump cover is enough?
Thanks a lot for your help man, I really appreciate it.

  • grayracer513

Posted April 04, 2009 - 06:53 AM

#12

You have to remove the cover.

Need a manual?

http://www.yamaha-mo...ice/manuals.jsp

  • Rotem_46

Posted April 04, 2009 - 04:01 PM

#13

Thanks a lot grayracer513, I have a few more things on my mind though...Does it means that I will have to change the oil? I think that the YZ426F uses the engine oil for both engine and transmition...does it? So if I'm opening the side cover I will have to drain the oil first then do all the work that has to be done, then close everything up and fill oil again..right? Now, How much oil goes in my bike (in liters)? I'm sorry for my ignorant but I don't know anything about engines amd mechanics...
One more thing that not related to this subject, I'm thinking of selling my bike for a newer one and I'm torn between the CRF and the YZF, I'm aiming for a 2006 or if I can efford it, a 2007 model, any thoughts? Do you know whats the different between the 2006 and the 2007 YZ450F? I'm asking you because you seem to know A LOT about these bikes...
Thanks a million bro!!!

  • grayracer513

Posted April 04, 2009 - 08:45 PM

#14

So if I'm opening the side cover I will have to drain the oil first then do all the work that has to be done, then close everything up and fill oil again..right? Now, How much oil goes in my bike (in liters)? I'm sorry for my ignorant but I don't know anything about engines amd mechanics...

Yes, and 1.1L. All that is in the manual.

If you have no experience at all, you should perhaps have it done professionally.

  • Rotem_46

Posted April 05, 2009 - 12:43 AM

#15

Well, maybe I will, I have a friend whos a mechanic so he'll probably will do it for me...
Now, regarding the other thing I asked you:
One more thing that not related to this subject, I'm thinking of selling my bike for a newer one and I'm torn between the CRF and the YZF, I'm aiming for a 2006 or if I can efford it, a 2007 model, any thoughts? Do you know whats the different between the 2006 and the 2007 YZ450F? I'm asking you because you seem to know A LOT about these bikes...
Thanks a million bro!!!

Any thoughts ??





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