2005 "Exon Valdez" GPX250 Oil leak

[pengoau]

Got a mechanic out today, looks like oil is getting into the airbox and leaking out thru the hole in the airbox compartment that sits behind the coolant bottle.

He is currently trying to track down where the airbox is getting filled with oil from, as the small hose that connects the engine to the airbox isn't oily at all.

[Damon Z1000]

I was gonna say an engine breather hose?
Just pull i down yourself as Rob says and don't spend money on mechanics per hour until you expend simple possibilities.
You will get on really well around here if you are willing to get your hands dirty. Oh and you have to have a beer whilst doing so, except for Rob who's not interested in beer because it ditracts money from him buying another bike or new parts for a new project
Get into it

[pengoau]

Well for whatever reason oil keeps collecting in the airbox, more than is designed and should be burned off as you ride. So when the bike sits, the oil leaks out the small hole in the airbox that the coolant bottle sits in front. The only breather hoses are one for the fuel tank and one for the coolant bottle, with the theard "hose" being for the airbox that is closed via a cap and metal clip. I undid this and some oil leaked out but not a lot. Even after draining this hose (and since re-capping it) the airbox still leaks a bit of oil. So yeah the airbox is consistantly filling up with more oil than it should.

Its not like there is too much oil in the bike, as it still leaks even when the bike is running quite low on oil. I'm using Motul 5100 10w-50 and I live in SE QLD, I don't know if its coz the oil is not thick enough or its something else more mechanical. I've now run out of 5100 so going to ride it until the oil gets low agai and do an oil change. I'll leat it drain for a few hours to ensure all the oil is out of the bike. Then I'll be refilling it up with Shell Advance SX4 15w-50.

From my research the only explaination is that my seals are gone and oil is being forced up into the airbox thru incorrect compression from the crankcase/engine? Basically if this is the case and my seals are gone in the engine, then its not going to be an easy or cheap fix!

I found this elsewhere on the net about seals wearing:

G'day,

Oil (preferably oil vapour) coming through the breather is due to crankcase pressure ie:the pressure built up due to the pistons rising and falling.
When the compression rings are worn the pressure increases therefore more oil is pumped out through the breather.Some engines have a valve (small ball) located at the breather connection to the cam/rocker cover that traps the oil but allows the pressure (with some oil vapour) to pass.
I would check to see if your engine has a valve as standard and if it is in place and/or get the compression checked or preferably a leak down test ie:Air pressure forced into the cylinder to identify where the leak is coming from.

Cheers.

So there is meant to be a valve in the breather hose, is the breather hose on the GPX the one that connects the airbox to the crankcase and has that metal clip on it? Maybe I'm missing this "valve" in the breather hose? So instead of vapor all the oil is able to be forced up into the airbox? What would a valve in the breather hose look like? Is it something that wears our or can be removed from the breather hose?


Is there any easy way to check if my seals are gone? Or only a mechanic will have the tools to check compression in the bike and confirm if its the seals? I wouldn't be surprised if its the seals as the bike has done over 42,000k's... I've been told this is not a lot but still, I don't know how its been treated previous etc. Tho what would cause the seals to fail? Not changing the oil regularly enough? Over revving the engine? Revving it too hard when its cold?

I also found this elsewhere on the net:

Greetings Bill,

Oil found in the airbox is related to the cranckcase being overfilled with oil.

Blow-by combustion gasses pressurizes the space in the engine crankcase. When oil is overfilled, oil may be forced through the crankcase vent and carried into the airbox via pressure vapor.

This is also common when carbs varnish. Petrol overfills floatbowls flows into carb Venturi's, cylinders, and into crankcase. Petrol saturates oil and causes ccrankcases to overfill.

Thanks for the compliments.

Respectfully,
Mark Shively

If my carby has "varnished" do I just need to add some carby cleaner to the fuel tank and run it thru the bike? A short while ago when I was trying to track down the leak, I noticed a whole bunch of dirt/oily grime around the carby that I've since cleaned off with kero. Since then there hasn't been any more build up of oil around the carby.

Could I do any damage running carby cleaner thru the fuel system now, in an attempt to fix this problem of oil constantly going into the airbox? Or wasnt you have pressure problems in the crankcase is it a bit beyond cheap/simple fixes (e.g. using carby cleaner)?

[robracer]

stay away from the carb cleaner in the fuel.... if the carbs have built up deposits then they will need to be cleaned properly, as far as the oil level being high look at the site glass....if it is between the max & min fill lines then its def not overfilled. Dirty grime around the carb makes no diff its the condition on the inside that could cause you problems. To test the compression you will need a compression tester that you screw into the plug hole & crank the motor to test..... I suggest having the mechanic do it.

[pengoau]

I'm going to drain the oil fully tomorrow and add new oil to it tho not for the recommended amount 1.9L; add about 1.5L and see if the problem occurs. So this should have the bike about 3/4 full.

Took the s shaped breather hose off the crank case and reved the engine a bit and saw oil pushing up out of it, little droplets. So there is definately a compression issue going on there.

Took the fuel tank off and looked in the airbox the foam filter was caked in oil and lots of oil in the airbox.

The oil isn't overfull thats the thing tho, as it would still leak even tho the sight glass had oil only sitting just slightly above the bottom notch.

Also had a look at the s-shaped breather hose and can't tell if there is anything into to obstruct oil but not the vapor. I'll definately be getting a mechanic to do a compression test. Tho with it not blowing smoke and there being a compression problem, does that just mean the compression rings are borked?

[pengoau]

Might just add a oil catch (aka catch can) to the airbox and move the airbox drain hose to the oil catch tank for easy draining of it.

Could live with that for the next 9 months until I replace the bike.

[pengoau]

Drained the oil, slightly over 1L and about 50ml out of the airbox drain hose....

If my compression seals are gone what sort of cost to fix?

[pengoau]

Spoke to a mechanic $1500-$3000 to fix compression seals and no guarentee it'll be fixed too lol what bullshit.

Tho looks like it is a compression seal issue. Time to trade the bike in and upgrade I think!

[mike-s]

Compression seals, i take it you mean piston rings? I would guesstimate about $200 for rings & head gasket plus I would estimate 4 hours in labour (that's usually billed at $85-120/hour depending on the shop) provided that all you need is a cylinder hone and it isn't worn/require a boring out to the next oversize, which would probably add a hundred or a bit more to the costs.

If it's valve related then it's going to cost more because although you don't need to take the barrels off, you need to compress the valve springs, remove the valves, clean any carbon out, replace the oil seals and then re-grind the valve seats and re-assemble the whole thing.

One way to test the compression and determine if its rings or valves is to do a compression test, then put a few ml of oil down the spark plug and do another one. If the compression improves then the problem is with the rings. If it turns out to be no different, then it's a problem with the valves and their sealing ability.

This is exactly the situation i am facing with my 250, 90PSI for both cylinders with no improvement with the oil added, which is good as the rings i put in there are less than 4kkm old, however it means that the valves need to possibly be adjusted, or more likely the valve seals are shot to crap. Next up i have sourced a spare engine and am going to swap the heads & maybe barrels if warranted.

[pengoau]

Got the little plastic bottle I was after, prolly is 25ml at max cap. When I added it to the bike, only about 5ml of oil prolly came out of the hose (so from the airbox) into the bottle.

I got a mechanic to compression test it and he said its fine and he stuffed some gausse into the crankcase breather hose to try and stop all the oil from going into the airbox. It has mostly stopped the airbox from filling but now, since the crankcase breather hose is full of gause where it connects to the crankcase it doesn't seal properly. So now oil leaks out the bottom of that breather hose all over the crankcase . Bloody gpx, really wish I wasn't such a tight ass and went with the VTR250 now, tho hindsight is 20/20!

Tho speaking to someone else who has worked on bike he looked at a diagram of the gpx's gearbox and apparently there is a metal plate that prevents oil from going out that breather hole that the hose connects to. He rekon thats if you can put your finger down the hole then you are missing the plate.. I'm gonna investigate this further and well see if he can link to what he is referring to, so I can go back to my mechanic and see what he rekons..

The GPX is a good little learner bike I just wish it didn't have this oil leak, otherwise it would be perfect!