Jump to content
Sign in to follow this  

yz 250 coolant leak

Recommended Posts

Ok guys new here

and new to MX bikes

i picked up a 2000 yz 250 last summer, guy owed me money

I got the bike, had it looked at by local shop

said all was well

good compression,no leaks ran very well and srtong

replaced plug, and oil, air filter, and coolant fluid.

rode bike about 20 times, before winter

stored bike with gas drained, and changed oil before storing

dug bike out yesterday

filled with fresh gas, installed new plug, check coolant level, basic pre ride stuf

bike fied up on second kick, blew a little blue 2 stroke smoke for a few seconds, and then seemed fine

took bike on a ride( old logging roads and coal bank hills)

10 min.s into it, I stopped to take a small break at the top of a hill i just climbed.

and noticed i was leaking coolant out the overfill line, as I reved the bike.

shut it down, waited a little for it to cool off.

then checked the coolant levels, they were low.

road the bike back nice and easy(only about a mile or so)

let it cool down

added more coolant, check the plug(was looking good0

started the bike up, and as it got warm and I reved the bike again it would flow out the over flow tube.

shut it down

decided to change the oil to see if i was getting any fluid in it

seemed just fine, replaced with new oil

I have no visable gasket leaks.

any ideas on what going on?

my budget is tight, as just lost a job after 22 yrs, so I am hoping its something simple so I can get it fixed

thanks

Share this post


Link to post
Share on other sites

I would drain the radiators pull the drain plug at the water pump put a jug or container under the water pump put a garden hose in the filler and run water thru it to flush the system after it sitting for a while you could have a buildup blocking something i.e. Hose water pump impeller etc. Causing it to get hot and belch out the overflow

Share this post


Link to post
Share on other sites

If it is blowing coolent out the overflow when you rev it I would guess head gasket (orings) is bad. Is there white smoke coming fron exhaust? Does exhaust have a sweet/antifreeze smell? Just pull the head and check the orings for a crack or pinch. Its a cheap fix and all you need is a torque wrench and the orings. If you dont have the manual ,I recommend that as your 1st purchase, or download one . Somewhere there is a free site, just search these forums for the site ,Im sure it will be easy to find.

Share this post


Link to post
Share on other sites

thanks guiys

no it has no swet smelling smoke or white smoke

just a hint of 2 stroke

I have never taken a bike apart at all, and right now no real place to do it

the bike will be going to a shop for this repair

any idea on cost to have the ehad gasket replaced at an average place?

thanks

Share this post


Link to post
Share on other sites

Well they will probably charge you an hour labor + parts. An hour labor could be $60 - $100. It only takes about 15 minutes to change that gasket assuming thats what the problem is. If you can change the spark plug you can do it. Remove those 6 bolts around the spark plug, the bolt on the bracket to the frame, pull the head off and replace the o-rings. Clean any carbon off the head, make sure its not warped or damaged and reverse the process. Tighten the bolts in a criss cross pattern and your done.

Share this post


Link to post
Share on other sites

Before you go dumping your bike at a shop for a simple repair, make sure you know what the problem is.

How much coolant did you loose? Where was the coolant level in relation to the fins in the radiator? In my bike the coolant level is just barely above the top of the fins.

If the bike was fine and was not burning coolant before the winter, the head o-rings did not pinch themselves from sitting. They may deteriorate, but that seems far fetched and may depend on the conditions the bike was stored in.

Ride the bike a little longer while constantly checking the fluid level. Zip tie an old water bottle to the frame and insert the radiator drain into a hole drilled through the cap. This is so you can keep an eye on the amount you are loosing without waiting for the bike to cool down. If the bottle fills up, you have a problem. If it only fills slightly, the cooling system is above capacity and as pressure builds, the excess is ejected.

Share this post


Link to post
Share on other sites

Ok guy thanks for all the imput

I forgot to mention, that I had a shop install a new chain and both sprockets before i put it away, would have done it myself , but couldn't get the front sprocket bolt loose, no matter what I tried, even with a small impact gun I had at hand.

any way, I didn't think nothing about this, as I just figured it was done right

WELL, after giving the bike a close inspection on a stand, I found that my case saver(works connection) I am guessing made of aluminum, well, the sprocket thats on the bike now is either thicker, or they do not have the bolt on all the way

my case saver is rubbing very very bad on the bolt, so much so that after my short ride, it chewed up about an 1/8 of it so it sits flush with the sprocket bolt

now the bike rolled freely, thus I didn't notice it I guess

but I now think that maybe why my bike was running hotter, as it was having a load right at the front sproket.

I also changed the coolant today, new prestone50/50

after replacing it, while running it with the cap off, it bubble's a lot,but I think this is normal

yes/no??

I didn't take it out for a ride, but did let it het hot and ran in on the stand for a few minutes(1st,2nd and 3rd gears)

and didn't have any issues

could the case saver rubbing been the problem/

thanks again

Share this post


Link to post
Share on other sites

OH, and I was planning on taking the bike to ashop to have a flywheel weight added to this bike, so while its there I am going to have them MAYBE fiix this issue if its still there>

Share this post


Link to post
Share on other sites

Don't know about the case saver. GMO has some good points and tips. I don't think a lot of bubbles is normal, there should not be any air in the cooling system. Maybe after a coolant change as the air is pushed out but not on an ongoing basis. One of the signs of a blown head gasket is loss of coolant due to exhaust escaping into the cooling system and pushing it out, this would cause bubbles.

If you were doing the work yourself replacing the head gasket o-rings would be a cheap diagnostic, just to rule it out thing. I'd follow GMO's advice and play with it some more before spending the money. If your coolant levels out just above the fins and no more escapes your probably golden. Just be careful, there are no warning lights and bad things happen to aluminum engines that overheat.

Share this post


Link to post
Share on other sites

here are a few pictures of it after i added the washers to get clearance

you can see how the nut's face is worn clean, and the metal build up on the case saver

568.jpg

568.jpg

Share this post


Link to post
Share on other sites

The case saver did not have any effect on the cooling of the engine. It may have put a slightly higher load, but nothing near the mechanical abilities of the engine and cooling system.

Share this post


Link to post
Share on other sites

bubbles in the cooling system is head gasket leak buddy or hopefully not but could be cracked head

Share this post


Link to post
Share on other sites

no more bubble in radiator

that case caser was pressing a ton on the front sprocket nut, and I am guessing it caused the bike to run a bunch hotter, thus the overheating issue

ran the bike several times since the fix on the the nut/case saver

and not once did it get hot to the point of anything coming out the overfill, like it did before, or while idiling

so!

I do plan a top end rebuild as soon money allows

so, will see the seals then if they are /were good or bad

or sooner if the bike overheat again!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By Lone Danger
      Ok so I'm looking for opinions from those who have been on yz125s and 150 exc/xcw's and maybe the ktm 200's exc/xcw's. You gotta be out there.
      Here's the deal...I'm 5'7" 165lbs. A couple years back I was looking for a small bike for my wife to learn on and for me to play around with and race. Could only afford one bike. I got a '09 ktm 105 sx. Once I got it sprung for my weight it was great. I have been top five consistently in my local harescrambles B class, believe it or not. Ya, you were not the only ones shocked. And did pretty good in the local mx races as well, junior class up here in Canada. Lack of power was sometimes an issue but I learned to deal with it and just scream, scream, scream!
      However my wife is a complete beginner and she is scared of it. I have since moved her to a 4 stroke.
      Just got a mint '01 yz15 mid summer. Like less than 200 hrs! I have absolutely loved it on the mx track. Suspension is perfect and I love the extra power. I had planned to set it up for woods/mx with a suspension revalve. However, did a harescramble race a month ago that was really technical. Granted I have not done anything to the suspension minus clickers, had too much psi in the tires (13 front and 15 rear) (yes I know that's wonkey, I only had time to get a heavy duty tube in the front and had a stock tube in back. Less psi in the back would have been instant pinch flat because its so rocky) and it was running rich. I had to scream the thing to keep it running and even changed a plug mid race. Well I'm sure you can guess but it was the worst experience I have ever had on a motorcycle. The more open sections I passed a lot of people but the tech sections required way more effort than I liked and the suspension beat the hell out of me!!! Like my knees, wrists, and shoulders were just done. (I was out there for three hours).
      So keep in mind that I just came off a 105sx with suspension mods (set up for woods/mx). I have no problem slipping clutch and shifting precisely, yatta yatta. (I don't think the 105 would have done well here either due to even less power, however...) I've been second guessing fixing this 125 up for woods ever since I rode a friends '09 ktm 250xcw. I rode it on a local mx track. The power was just so effortless and I was absolutely floored by how the suspension worked. I never thought that I could hit the woops that hard and clear every jump on the track on an xcw and feel THAT good! It felt a lot heavier though, and I think the price tag on these things are going to be a stretch.
      So here's my question. I want the lightness of a 125, but want to be able to race both woods and mx. How does a 150 exc/xcw ENGINE compare to an mx 125 engine? I love the 125 engine, but more low end would be usefull in tech areas. But if there is not a huge difference, I will probably just revalve the yz for woods and go tubless, etc. The 150exc's are so expensive and I hardly ever even see one for sale unless its brand new. I don't want the weight of a 200/250/300. I barely touch the ground on a 125....so it has to at least be light. Is it worth waiting for a 150 engine? Thanks guys.
       
       
    • By doolan
      Hi guys I have a 2018 yz250 looking at changing springs front and rear I'm 200 pound ride b class moto.
      Having problems choosing spring weights using the calculators as mx tech say I need .45 fork springs and 5.2 rear but racetech say .48kg forks and 5.8kg rear.
      What are other bigger guys
    • By YamahaYz1
      Hey TT, I know there's endless topics on YZ250/ two stroke tuning in general but I have not been able to find one that helps me get my 09 YZ250 set up for my riding style and where I ride so I'm here asking for help. I got this bike around 1.5 years ago and have not known how to set it up properly. I know no one can give me a perfect set up but I'd like a good starting setup to work from and tweak to perfection. Throughout this time I've had this bike, its always been covering the bottom of the entire silencer and dripping all over the swing arm and rims with oil. Also, the joint between silencer and expansion pipe has oil around it too but I've heard I have to close the gap a little to squeeze the silencer a little tighter and stop the leakage there. I don't have too much experience messing with carbs but I've messed around with previous two strokes and tuned them a little better. I change the oil on my bike after 15-20 hours on it and clean and oil the air filter after almost every ride. The sparkplugs never last me more than a few months but recently have been lasting me no more than a few weeks. With the excess oil from the pipe and spark plug fouling you can see why I need to set my bike up to stop this. 
      The bike:
      Completely stock with V-Force 3 Reeds and a FMF Shorty silencer. 
      Usually running around 32:1 premix with 91 pump fuel because I prefer to keep it well lubricated instead of running rich.
      Riding:
      I ride enduro in Ontario, Canada. So mostly single track and some fire roads but nothing close to MX and not a lot of time wide open. Therefore, probably mostly 1/4-1/2 or 1/4-3/4 throttle range.
      Where I ride:
      Usually 0-500' above sea level. With temperatures ranging from around 15-35 degrees Celsius (55-95 Fahrenheit).
       
      If anyone can give me a setup to go from, that would be very much appreciated. Even multiple set ups for different temperature ranges or any suggestions would be much appreciated. Thanks and sorry for the long read, I just didn't want to leave anything out. Ask any questions if you have any, too.
    • By Goon Rides
      Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.


×