Oil leak 1985 suzuki 250

[Mhatayas]

Hey guys, long time. I've since gotten a 1987 lt-f4wd.

Problem is, tried bleeding the brakes and I think something went wrong, the brakes were just starting to engage and then the lever just went limp. The fluid is leaking out of the bottom of the hub ! 

 

Also, blue smoke , maybe needs rings changed? 

Hey guys, long time. I've since gotten a 1987 lt-f4wd.

Problem is, tried bleeding the brakes and I think something went wrong, the brakes were just starting to engage and then the lever just went limp. The fluid is leaking out of the bottom of the hub ! 

 

Also, blue smoke , maybe needs rings changed? 

Hey guys, long time. I've since gotten a 1987 lt-f4wd.

Problem is, tried bleeding the brakes and I think something went wrong, the brakes were just starting to engage and then the lever just went limp. The fluid is leaking out of the bottom of the hub ! 

 

Also, blue smoke , maybe needs rings changed? 

Hey guys, long time. I've since gotten a 1987 lt-f4wd.

Problem is, tried bleeding the brakes and I think something went wrong, the brakes were just starting to engage and then the lever just went limp. The fluid is leaking out of the bottom of the hub ! 

 

Also, blue smoke , maybe needs rings changed? 

Hey guys, long time. I've since gotten a 1987 lt-f4wd.

Problem is, tried bleeding the brakes and I think something went wrong, the brakes were just starting to engage and then the lever just went limp. The fluid is leaking out of the bottom of the hub ! 

 

Also, blue smoke , maybe needs rings changed? 

What would cause this to happen, my quad brake fluid leaks from the bottom of the hub after trying to bleed them ?

[Mech]

A blown seal in a brake cylinder probably.

[Gwbarm]

Also brake lines swellup with age and get weak when you put pressure on them they blow out you may also check the bleeder and make sure its sealing correctly.

Blue smoke could be rings or valve guide seals, if its more prominant when you first start it up its valve guide seals if it is fairly constant it could be rings or flooding although flooding is more of a darker smoke and not so blue.

[Mech]

They also have a steel brake pipe between top and bottom cylinders I think, and they might have rusted. It looks like it's coming from inside the drum though, so that would be seals.

If the bike's been sitting the smoke might get better after a few runs so I'd ignore that for a while.. Oil's cheap.. haha.  If it is smoking a lot then Gw's pretty much right about the circumstances...  If it blows a cloud of smoke at startup, especially cold start, it'll be valves, smoke under load, rings. It could be a combination of both, but it's best to do rings and valve grind and seals at the same time anyway.

[Mhatayas]

I owe it to you guys, ever since I started on this forum,  you two have been giving me high quality answers each time. Thank you guys. 

 

Are you guys familiar with these bikes by the way ? I have a huge soft spot for the old Suzukis . 

 

Any recommendations of parts to buy to fix this issue? I think it may be valves and rings.  Also today while riding,  I got a funny squeaking noise from the head like a mouse with every stroke , and seems like lots of vibration in there. 

 

Think I should get a top end rebuild kit? 

 

Also, one last question for now. Lately when riding,  seems like it's hesitating in higher gears at higher speeds , can feel the quad "sputtering" instead of staying consistent, it's annoying when your driving down a road and it starts sputtering i can feel the quad hesitating , almost like it wants to fling me forward then cuts in again 

[Mech]

I've been fixing LTs since they were first made, and I've owned three. I live on very steep land and the low low is brilliant.

An air leak, either at the inlet manifold, or on the exhaust at the head, or even a blown head gasket, can make that squeaking noise you mention.. So can a seizing piston or head. You undo a certain head nut to check the oils getting to the cam.

The spluttering could be water in the fuel, or an electrical problem. I'd try it at different speeds and loads (going up then down long slopes), and throttle openings, and slowly figure whether it was directly connected to revs, load, or throttle position..

[Mhatayas]

8 hours ago, Mech said:

I've been fixing LTs since they were first made, and I've owned three. I live on very steep land and the low low is brilliant.

An air leak, either at the inlet manifold, or on the exhaust at the head, or even a blown head gasket, can make that squeaking noise you mention.. So can a seizing piston or head. You undo a certain head nut to check the oils getting to the cam.

The spluttering could be water in the fuel, or an electrical problem. I'd try it at different speeds and loads (going up then down long slopes), and throttle openings, and slowly figure whether it was directly connected to revs, load, or throttle 

Great information,  I will be sure to try at various speeds and rpms/throttle positions . Yes the super low is great, I actually towed my friend with the same quad back home in that gear a couple days ago. Had to use diff lock up a hill, plus there was a light scant of snow! But made it up that rocky hilly trail!

[Mech]

The idea with the test riding is to figure if it's a load (mid revs /steep hill between 1/4 and full throttle openings), or certain revs (any throttle or load), or the jet it's using at the time it starts missing ( any load or revs but at a certain throttle range. If it's always the same throttle setting then It's going to be a blocked jet. If it's load that does it then probably spark-plug, lead or coil. And if it's always at the same revs no matter the load or throttle, then it's some electrical component failing. Going up then down a slope means you can have certain revs or throttle settings with or without load on the engine.

If you suspect a failing electrical component then it's a good idea to turn the headlights on. The voltage regulators(or wiring) can make them miss bad/buck as you seem to be describing. Good idea to try the headlight anyway probably to se if it makes a difference.

[Mhatayas]

So, I've since taken it for a few more rides, headlight doesn't seem to make a difference, 

when engaging throttle it runs smoother, but when disengaging or hovering throttle at a constant rpm, it bucks, no matter what gear its in.

Also , I should note, i have a carborator from one of the newer quadrunners in it, not the old slider carb. shouldnt make a difference through since the setups are pretty much the same.

 

i know at first it was running fine, no bucking, the throttle or carb was sticking a bit though and revving high, that issue has since subsided, and now it wont idle after  run, wants to cut out abruptly. im going to try adjusting the idle screw firstly to see if that makes a difference. 

[Mech]

"when engaging throttle it runs smoother, but when disengaging or hovering throttle at a constant rpm, it bucks, no matter what gear its in.".

Ok. Good observation. Sounds like a carb problem (or problems). The no idle after a run is probably going to be something that an adjustment of the idle will cure, and it may even help with the stuttering.. Another simple thing to try now would be to change the slide needle position in it's clip and flex and inspect the rubber diaphgram. That can be done in place. Then if that doesn't fix it I think I'd pull the carb off, clean it and check all the jets are clean and what size they are etc, set the float height carefully to a height appropriate for that bike. Carbs for some bikes sit at an angle and others sit flat, and the same carb can be used for both situations, but they have their float heights set different to suit the angle.

[Mhatayas]

On 12/25/2024 at 3:29 PM, Mech said:

"when engaging throttle it runs smoother, but when disengaging or hovering throttle at a constant rpm, it bucks, no matter what gear its in.".

Ok. Good observation. Sounds like a carb problem (or problems). The no idle after a run is probably going to be something that an adjustment of the idle will cure, and it may even help with the stuttering.. Another simple thing to try now would be to change the slide needle position in it's clip and flex and inspect the rubber diaphgram. That can be done in place. Then if that doesn't fix it I think I'd pull the carb off, clean it and check all the jets are clean and what size they are etc, set the float height carefully to a height appropriate for that bike. Carbs for some bikes sit at an angle and others sit flat, and the same carb can be used for both situations, but they have their float heights set different to suit the angle.

So, I figured out the problem, it was an oil fouled plug. I pulled off the plug and it was just saturated in black. Oil and even looked chunky and sticky. I ended up just using one from another ATV instead of cleaning it .

With that being said , I now have the bike parked until I can fix it up. I ordered a set of rings (company called tp) from eBay today, and also valve seals. I'm gonna order a head gasket as well when I get the chance next week. 

 

This should at least cure the smoke problem, I'll also check if valves need adjustments when I pull the head off. 

 

 

 

So here's something funny though, battery is fully charged, and it was -5°c today, wouldn't start no matter how much choke or how long I pressed the start button.

 

I hook my battery charger to the battery and put it to 20amps and crank it over it eventually catches and starts. A few weeks ago when got the bike up and running first of all , it would start effortlessly. Just press the button without using the choke. 

 

Do you think this may be to do with the cold weather?  I'm not sure what is going on here, but I don't like it . 

 

 

[Mech]

A spark plug missing only under low load is a new one to me.. for a carb engine anyway. EFI does that, but never found that with a carb engine.

You should do the valve seals when doing the work.

If they have sat for a few days and evaporated the fuel out of the carb, then the fuel pump sometimes takes a while to pump fuel through, especially if the engine has low vacuum.

[Mhatayas]

13 minutes ago, Mech said:

A spark plug missing only under low load is a new one to me.. for a carb engine anyway. EFI does that, but never found that with a carb engine.

You should do the valve seals when doing the work.

If they have sat for a few days and evaporated the fuel out of the carb, then the fuel pump sometimes takes a while to pump fuel through, especially if the engine has low vacuum.

That's what I'll do next , check the vacuum line for any leaks . I also tried using the throttle adjustment screw, it worked good idling while running, but seems my throttle is a bit sticky or something, it would remain revving for a bit after throttling sometimes. I got this excerpt from the Suzuki manual:

 

"If the plug exhibits a black insu lator tip. a damp 
and oily film over the firing end and a carbon layer 
over the entire nose, it is oil fouled. An oil fouled 
plug can be cleaned, but it is better to replace it"

 

(The gap was also bridged with this substance on mine. )

 

 

I also read that an d7ea is hotter than a d8ea plug , which means if using engine at high rpms and temps, to use a colder plug , looks like I will switch to a d8ea from here on. My 4valve lt250ef has this plug 

[Mech]

A colder plug will oil up easier..

[Gwbarm]

I think you have 2 things going on here you have worn rings and top end and you are running a diaphram carb that wasnt designed for the engine, but should work if everything else is in top notch condition. The plug should not get that oily that fast unless your rings are practiclly non existant which would lead me to did you check the compression, if the compression is low that would cause hard starting when cold plus the battery is weakened from the cold and does not spin the engine fast enough to start. Fairly guttsy putting 20 amps in to that small battery but is it worked that great. 

[Mhatayas]

Folks, I've since took the cylinder head off another 2wd quadrunner I have, that ran without smoking before I took it apart. Upon inspection, the rings and piston looked great on the 4wd. 

 

Today, I was in the process of putting  the cylinder head from the 2wd on, but I'm slightly stuck on getting the timing chain alignment correct. 

 

The part I'm stuck on , is the finding and lining up the "T" mark. 

I crank it over ever so slowly with the pull cord paying close attention waiting for the T and the little line to show up. But upon doing that , multiple times all I see are round depressions, plus the rotor always brings oil back up making it hard to see.

For reference, my quad is an 87. 

 

Would it be easier if I tried to shine some light down the spark plug hole and crank it till I see the piston at TDC (top dead center) or even shoving a wire down there and feeling it to TDC ? 

 Or would I be better off draining the oil and using a paper towel to soak up the bit on the rotor and try it by lining up the marks ?

[Mech]

Ok, well, the oil shouldn't be up to the flywheel. That might be why you are having smoking problems. You should check the oil isn't full of fuel.. They do that if the fuel tap is playing up. Other than that, check your oil filling procedure.

And.. I always take the pull start cover off and turn the crank with the drum that's in there.

[Mhatayas]

1 hour ago, Mech said:

Ok, well, the oil shouldn't be up to the flywheel. That might be why you are having smoking problems. You should check the oil isn't full of fuel.. They do that if the fuel tap is playing up. Other than that, check your oil filling procedure.

And.. I always take the pull start cover off and turn the crank with the drum that's in there.

What do you mean by fuel tap playing up ? The petcock at a certain position? 

As for the oil, I filled it up between the marks on the sight glass, let it run , filled it up to marks again, then once it stayed between the marks I left it . I haven't checked it over the last month or so , but I will tomorrow. It was smoking before that though.

I should have clarified, I used a tissue stuffed into the sight hole for the timing mark and cranked over to clean off the residue, but after every rotation it seems to be picking up oil again on the bottom half of rotation. I'll get a pan and drain it tomorrow and re add it to spec after I'm done. 

 

Do I have to take off the starter and crank the nut to do that ? I know it suggests that in the manual, I got it going slow enough each revolution from slowly pulling the pull cord, it's just the oil made me unable to see the mark

 

 

I seen some guys on a quadrunner group in Facebook got a nibbi pe30 carb and low psi electric fuel pump, I have these two items ordered for my quadrunner, no vacuum this way , apparently they are really good carbs and work very well in that setup.

[Mech]

If the fuel tap doesn't shut off, for whatever reason, then the fuel can get into the oil.

If oil gets onto the crank throws, that's the webs or counterweights that make up the crank, then it flicks so much oil up the bore that rings can't control it and engines smoke. If the flywheel is getting oil on it I'll bet the crank throws do too.

If you want to lower the oil level while you are looking for the timing mark you could just lift one side slightly and the oil will run away.

If you look at a parts diagram you will see there's a big drum in behind the pull start, and that, can be turned by hand or with a screwdriver through it. There's no oil behind that cover and it's a good idea to take it off and check if it's dirty in there, and to move those small bolts.. The cover has a paper gasket, but some of them used to have a dimple in the steel to let water out anyway..They hardly need sealing.

[Mhatayas]

15 hours ago, Mech said:

If the fuel tap doesn't shut off, for whatever reason, then the fuel can get into the oil.

If oil gets onto the crank throws, that's the webs or counterweights that make up the crank, then it flicks so much oil up the bore that rings can't control it and engines smoke. If the flywheel is getting oil on it I'll bet the crank throws do too.

If you want to lower the oil level while you are looking for the timing mark you could just lift one side slightly and the oil will run away.

If you look at a parts diagram you will see there's a big drum in behind the pull start, and that, can be turned by hand or with a screwdriver through it. There's no oil behind that cover and it's a good idea to take it off and check if it's dirty in there, and to move those small bolts.. The cover has a paper gasket, but some of them used to have a dimple in the steel to let water out anyway..They hardly need sealing.

So I got it all put back together! It was running good for a few mins, then started smoking again... 

 

I looked at the oil sight glass, and appears there is no oil in the sight glass! 

 

I'm thinking it just might be what you mentioned Mech, oil getting spat up through the crank shaft. 

 

What are my next steps? Its good I was at least able to rule that out. 

 

Should I drain all the oil and re add it ? 

 

When I got the bike I didn't drain the oil just added some. 

Is there a way the oil is seeping in there where it shouldn't be? 

 

 

[Mhatayas]

So I tilted the bike 45° on its right side, and started it up for a few mins, no blue smoke , just a bit of exhaust smoke. When I put it back on the flat it started smoking blue shortly after. 

[Mech]

I'd suspect that when you think you are seeing low/no oil in the sight glass, you're actually looking at clean oil that's right above the sight glass. Regardless of what the oil level was or is, if fuel gets into the oil it raises it's level, and, when you start them up they evaporate that fuel fairly fast once the engine starts getting warm, and that evaporated fuel gets into the cylinder and makes the bike run rich.

Having the oil level too high splashes it up the bore as I say, and that's probably why your bike stopped smoking when you tilted it over.. (good test by the way..)..

You need to check the operation of the fuel tap, and perhaps the float level needle and seat operation.

I've got the fuel out of bikes just by letting them idle till they got fully warmed up.. Done it a few times with varying amounts of fuel in the oil and it's always worked and doesn't seem to have had any detrimental effect on the engine. If you load the engine with the runny oil though it might damage the bearings.

[Mhatayas]

4 hours ago, Mech said:

I'd suspect that when you think you are seeing low/no oil in the sight glass, you're actually looking at clean oil that's right above the sight glass. Regardless of what the oil level was or is, if fuel gets into the oil it raises it's level, and, when you start them up they evaporate that fuel fairly fast once the engine starts getting warm, and that evaporated fuel gets into the cylinder and makes the bike run rich.

Having the oil level too high splashes it up the bore as I say, and that's probably why your bike stopped smoking when you tilted it over.. (good test by the way..)..

You need to check the operation of the fuel tap, and perhaps the float level needle and seat operation.

I've got the fuel out of bikes just by letting them idle till they got fully warmed up.. Done it a few times with varying amounts of fuel in the oil and it's always worked and doesn't seem to have had any detrimental effect on the engine. If you load the engine with the runny oil though it might damage the bearings.

When tilted on its side, i looked into the sight glass and seen black oil. I am pretty certain there is no fuel getting in there. 

So you mentioned i shouldn't see oil in the crankshaft area like i did when trying to find the timing mark? i looked at the parts diagram and there is some o rings and the such on the end of the crankshaft. do you think one of these could be worn away and letting oil in where its not supposed to? 

 

another thing to mention, i didnt change over the piston or rings or cylinder head because it all looked good, though there was only crosshatch on the bottom portion, there was some straight lines where the piston strokes. 

 

I already got it half apart again and im going to switch over piston and cylinder from the bike that didn't smoke, just to be sure. the rings looked great on the original though... compression was good, 110 psi.. 

there are also other various o rings and seals amongst the crankcase and oil sump and clutch etc.. 

 

do you think one of those could be a culprit? i haven't seen any cases elsewhere of that though, from research.

 

tommorow im gonna try to switch to the other pistons and rings, and cylinder etc, if that doesent work, then i will go ahead and assume its something else

Edited January 11, 2025 by Mhatayas

[Mech]

Inside of the side cases there is oil, and the generator and timing marks are in there where there oil is, but generally speaking they design things so the crank throws and flywheel don't get in the oil, they'd make too much oil mist and breathers wouldn't be able to separate the oil out fast enough, and as I've said, it wrecks the ring's seal.

[Mhatayas]

Mech, is it possible some of the breather hoses not being hooked up would cause it to burn oil? or not so much?

 

the only other possible thing i can see, is the crankshaft oil seal itself (see #17 on this parts diagram) , unless some other O ring or something

https://www.suzukipartshouse.com/oemparts/a/suz/50d0b06af870022c2c53619a/crankshaft

This article seems like it could be the same as whats happening to me .

https://atvconnection.com/forums/kids-quads/201438-suzuki-lt50-question-2.html

I believe i may have found the issue , hopefully. Just read the comments below and its happened to other folks as well

 

[Gwbarm]

Breather hoses not being hooked up will not cause it to burn oil, you may see smoke coming out of the hoses from ring blow by , a bad oil seal would cause more  oil to get into the rotor and stator as you described earlier. Its an 85 im sure all the seals are getting pretty brittle especially if it has sat up for a while.  

[Mhatayas]

4 hours ago, Gwbarm said:

Breather hoses not being hooked up will not cause it to burn oil, you may see smoke coming out of the hoses from ring blow by , a bad oil seal would cause more  oil to get into the rotor and stator as you described earlier. Its an 85 im sure all the seals are getting pretty brittle especially if it has sat up for a while.  

Looks like the oil seal is just beneath the magneto, not as big of a job as I expected. Gonna have to order a new one, though! 

[Mech]

That oil seal #17 is too keep oil in the crankcase and out of the pull start cover. That's not your problem. The LT50 they were talking about is a two-stroke.

Blocked breather hoses could make it smoke, but disconnected hoses won't make it smoke.

You leaned it over on it's side and the smoke went away, you set it down flat and the smoke started again..  There's too much oil in the sump.

[Mhatayas]

1 hour ago, Mech said:

That oil seal #17 is too keep oil in the crankcase and out of the pull start cover. That's not your problem. The LT50 they were talking about is a two-stroke.

Blocked breather hoses could make it smoke, but disconnected hoses won't make it smoke.

You leaned it over on it's side and the smoke went away, you set it down flat and the smoke started again..  There's too much oil in the sump.

I drained the oil, only about a litre came out, i then let it run for a minuite or so, no smoke. I added 3 litres when i added the oil to it in the first place, but it burnt off all that oil (~2l) in just about a tank of gas! i only rode it for a few hours in total.

what do you think i should do next? add oil and see what happens? or add some sorta cleaner in there and let it run for a bit before adding oil. 

do you think there is an o ring or something letting oil go in where its not supposed to? what about #10 on that same diagram?

before i even drained the oil, it wasnt even visible in the sight glass! 

I need to get a new oil filter before anything though! thing is toast

Edited January 13, 2025 by Mhatayas

[Mhatayas]

What about the oil pump? would that have any effect on it i wonder, maybe something is clogged? would the oil pump be a component that would just stop working properly?