Jump to content

Transmission oil breather leak

Recommended Posts

Hey guys, I have an 07 crf250r that started puking oil out of the transmission breather tube after a short ride around the cul de sac and then letting it idle in the garage. I’ve put about three hours on it with the same oil so no recent changes in oil capacity. I’m going to check my crank case breather hose tonight to check and see if there’s a blockage causing excess pressure but I didn’t know if this was a common thing.

  • Like 1

Share this post


Link to post
Share on other sites

Is the engine oil level decreasing?

Best to drain & measure the trans oil to see just how much is in there first.

  • Like 2

Share this post


Link to post
Share on other sites
Is the engine oil level decreasing?

Best to drain & measure the trans oil to see just how much is in there first.

That’s one of the things I’m going to do tonight. Drain and measure both and refill to correct specification.

Share this post


Link to post
Share on other sites

Definitely had too much oil in the trans side. Not much on the engine side. No blockage from the breathers that I could see. Refilled oil and ran it for about 15 mins with a short ride and it still reading on the dipstick and no oil leaking out of the hose. The rate it was leaking the other day I would have expected it to start leaking again by now

Share this post


Link to post
Share on other sites

Yep sounds like a worn main seal causing oil migration. Pretty common.

Plenty of threads on this to read up on.

Share this post


Link to post
Share on other sites

I guess I’ll be replacing all the seals I can with out splitting the cases. Definitely no blockage in my vent hoses or in the valve cover. I put about a half an hour on it today checking the dipstick level periodically and never had a change. I don’t want something just letting lose tho and smoking the engine because I don’t notice a leak while riding

Share this post


Link to post
Share on other sites
15 hours ago, Loganclark73 said:

I guess I’ll be replacing all the seals I can with out splitting the cases. Definitely no blockage in my vent hoses or in the valve cover. I put about a half an hour on it today checking the dipstick level periodically and never had a change. I don’t want something just letting lose tho and smoking the engine because I don’t notice a leak while riding

Did you by chance drop the bike recently?

Share this post


Link to post
Share on other sites
Did you by chance drop the bike recently?

The last ride before I noticed the leak I was trail riding. Last 1/4 mile of trail I over shot the corner laid it over. It wasn’t violent, just didn’t get a good footing in the vegetation before I was too far over to stop myself. Could that have done it?

Share this post


Link to post
Share on other sites
1 minute ago, Loganclark73 said:


The last ride before I noticed the leak I was trail riding. Last 1/4 mile of trail I over shot the corner laid it over. It wasn’t violent, just didn’t get a good footing in the vegetation before I was too far over to stop myself. Could that have done it?

And sorry I should have asked this originally.

Which vent tube was it coming out of?

Was it actually tranny oil and when you say puking was it like an oz or more?

Did you measure tranny oil and fill the tranny side as per spec recently?

Did you drain and measure the tranny oil?

Are you 100% sure engine oil level is not dropping or increasing?

Share this post


Link to post
Share on other sites
And sorry I should have asked this originally.
Which vent tube was it coming out of?
Was it actually tranny oil and when you say puking was it like an oz or more?
Did you measure tranny oil and fill the tranny side as per spec recently?
Did you drain and measure the tranny oil?
Are you 100% sure engine oil level is not dropping or increasing?

It was definitely the trans vent tube coming from the right side of the engine on the lower case.
I had a bout a square foot of oil on the garage floor under the bike.
I had about four hours on the previous oil change so no recent changes.
Trans oil was about 400cc over spec after it already drained out of the vent tube.
I’ve put about a half hour on it since draining and refilling both engine and trans to spec but have not been able to measure a change in engine oil level on the dipstick. It’s stayed consistent through three heat cycles now.

Share this post


Link to post
Share on other sites
1 minute ago, Loganclark73 said:


It was definitely the trans vent tube coming from the right side of the engine on the lower case.
I had a bout a square foot of oil on the garage floor under the bike.
I had about four hours on the previous oil change so no recent changes.
Trans oil was about 400cc over spec after it already drained out of the vent tube.
I’ve put about a half hour on it since draining and refilling both engine and trans to spec but have not been able to measure a change in engine oil level on the dipstick. It’s stayed consistent through three heat cycles now.

I use 780ML on the tranny side so did you by chance over fill it?

If you can post a pic of the vent tube it was coming out of.

I dropped my bike once where it was almost upside down for a few minutes and engine oil vented into the air box and started dripping out. Not sure if this could happen on the tranny side but it MIGHT?

If your not losing engine oil IMO it's sort of a weird tranny oil issue but I am no means an expert.

Share this post


Link to post
Share on other sites
I use 780ML on the tranny side so did you by chance over fill it?
If you can post a pic of the vent tube it was coming out of.
I dropped my bike once where it was almost upside down for a few minutes and engine oil vented into the air box and started dripping out. Not sure if this could happen on the tranny side but it MIGHT?
If your not losing engine oil IMO it's sort of a weird tranny oil issue but I am no means an expert.

Well when I drained the engine and trans the engine side had almost no oil in it. Maybe 100cc.

Share this post


Link to post
Share on other sites
24 minutes ago, Loganclark73 said:


Well when I drained the engine and trans the engine side had almost no oil in it. Maybe 100cc.

Sorry I'll now bow out of this. Good luck and I would be interested to hear how this works out for you dude.

 

Edited by filterx

Share this post


Link to post
Share on other sites

It wasn’t down for long. Maybe ten seconds. And yes it’s engine to tranny side as far as I can tell. I’m gonna keep checking it and probably replace the seals for pm if nothing else.

  • Like 1

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:


  • Similar Content

    • By Kadensmith44
      I’m wanting to powder coat my bike but it’s all new to me. I’ve got a powder coater picked out that I’ve heard is good for what I’m doing. I’m not 100% what kind of sand blaster I need and what kind of media. I have also heard you can’t cook in the oven after you’ve baked your parts is that true?
    • By luke8500
      Hi all, 
      I have a 2004 honda crf250r and it wont start hot at all. The motor was just rebuilt with a new cylinder and piston. The valves were just adjusted. It will start cold in 1 or 2 kicks with choke but as soon as it gets hot it wont start. If you bump start it the motor will just turn over without starting.  sometimes it will start. It runs great until you shut it off.  im thinking its either a fuel issue or an electrical issue. Any help would be greatly appreciated. 
    • By SandSoldier
      Hello! This listing is for my 2007 Honda CRF250R dirt bike. Last winter I spun the rod bearing and just recently finished rebuilding it. Selling to fund new bike. I am currently the second owner.

      Current registration valid until 2020, pink slip in hand.

      Fresh parts:
      -top end kit: Wiseco; forged, moly skirt coated, 12.9:1 comp ratio (new wrist pin, gaskets, etc)
      -cylinder: new OEM
      -bottom end kit: Wiseco; (new bearings, seals, etc)
      -oil pump: new OEM
      -head studs & nuts: new OEM

      -fresh oil and filter
      -all tolerances checked in top end
      -valves adjusted
      -carb adjusted

      Note:
      *rebuild was done by my dad (master tech at CAT) and I (4th year mechanical engineering student)
      *has maybe 15 minutes on new parts, IT HAS NOT BEEN PROPERLY BROKEN IN YET
      *I have email receipts, pics of rebuild, and old parts as proof of rebuild, just ask and I'll show em off

      Other parts:
      -90% tread on front and rear tires
      -excell takasago front wheel
      -custom aluminum skid plate
      -wrap around hand guards
      -spark arrestor
      -kickstand

      Feel free to ask for any more specifics or pictures!

      LOCAL PICK UP ONLY

      Thanks!
    • By Matt Ray
      Okay so the title is a little vague. 
      So it was having trouble idling and even starting when I first bought it about a month ago for $2k. 
      So I did a rough clean of carb, looked up on YouTube, Forums, Etc on how to do it. I only cleaned jets with carb cleaner and sprayed around the float bowl area and such, so not too extensive.
      Did that and I took it out to a park, It would start up right away mostly, few kicks sometimes, but when I got it started, I had to keep the choke on. Right when I was ready to go fast and go up to 3rd and 4th gear I'd switch it off and it would work fine and sound fine and everything, but when I slowed back down and coasted around 1st gear i'd pop it back out again because it sounded like it was going to do. I have some videos if people would like me to link to them.
       
      So after that I decided to take it apart and replace spark plug with OEM NGK R0409B-8, replace main jet from a old 170 to a new 170, replaced pilot jet from a old 40 to a new 42, and kept starter jet the same just made sure that wasn't clogged, ordered a new adjustable fuel screw and used that.
      and it was still having a little bit of problems! I just started up today and the day before today. It would run only with choke on, if i twisted throttle in neutral it sounded pretty good, no gun shot noises or anything, pretty smooth. 
      If I tried to take choke off it would die immediately. So I started it back up again, took around 6 kicks.. So again with choke on it sounded like it was starting to lose power and RPM's would drop so I'd twist throttle a few times and it would stay idling.. then after a small amount of time, start to sound like its about to die again... so I would rev it up again, and repeat..
       
      Fuel line isn't clogged, flows fine.
      I tried fuel screw everywhere between 1 and 2 turns out..
      I checked valve clearances, and I'm no expert but from the videos I watched the slipped underneath intake and exhaust with only minor force.
      So I'm lost.. 
      Maybe float bowl is messed up? Should I just do a COMPLETE carb rebuild from videos I've seen on youtube, like this one -> https://www.youtube.com/watch?v=3AXb9UprT30? Or what? 
       
      It's getting annoying taking it apart all the time, I jsut want it to start up quickly and run well!!
       
      Thank you!
       
      Austin, TX, Elevation 600ft, where I ride its around 900ft
       
       
    • By Bryan Bosch
      WASHINGTON, D.C. – August 16, 2018 – (Motor Sports Newswire) –

       
      Honda Recall Summary:
      Name of product: CRF250R Off-Road Motorcycles Hazard: The clutch outer can break, posing crash and injury hazards. Remedy: Repair Recall date: August 16, 2018 Units: About 3,200
      Consumer Contact: American Honda toll-free at 866-784-1870 from 8:30 a.m. to 4:30 p.m. PT Monday through Friday or online at http://powersports.honda.com/ and click on “Recall Information” at the bottom of the page for more information.
      Honda Recall Details:
      Description: This recall involves all 2018 Model Year CRF250R off-road motorcycles. The recalled motorcycles were sold in a red color. The names “HONDA” and “CRF250R” are printed on the sides of the motorcycle. The model name and model year are printed on a name plate label located at the front right top of the frame, near the steering head.
      Remedy: Consumers should immediately stop using the recalled off-road motorcycles and contact their local authorized Honda Powersports dealer to schedule an appointment for a free repair. Honda is contacting all known purchasers directly.
      Incidents/Injuries: American Honda has received 19 reports of clutch failure, including two that led to engine lock up. No crashes or injuries reported.
      Sold At: Authorized Honda Powersports dealers nationwide from November 2017 through July 2018 for about $8,000.
      Manufacturer(s): American Honda Motor Company Inc., of Torrance, Calif. Manufactured In: Japan Recall number: 18-759 This recall was conducted, voluntarily by the company, under CPSC’s Fast Track Recall process. Fast Track recalls are initiated by firms, who commit to work with CPSC to quickly announce the recall and remedy to protect consumers.
      The U.S. Consumer Product Safety Commission is charged with protecting the public from unreasonable risks of injury or death associated with the use of thousands of types of consumer products under the agency’s jurisdiction. Deaths, injuries, and property damage from consumer product incidents cost the nation more than $1 trillion annually. CPSC is committed to protecting consumers and families from products that pose a fire, electrical, chemical or mechanical hazard. CPSC’s work to help ensure the safety of consumer products – such as toys, cribs, power tools, cigarette lighters and household chemicals -– contributed to a decline in the rate of deaths and injuries associated with consumer products over the past 40 years.
      Federal law bars any person from selling products subject to a publicly-announced voluntary recall by a manufacturer or a mandatory recall ordered by the Commission.
      Source: Consumer Product Safety Commission

×