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General Category => General Discussion => Topic started by: Bison on September 01, 2023, 12:31:50 PM
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Hi folks
Need help here. The air box on my Le Mans is filling with oil and soaking the bike and back tyre.
I thought I had it fixed when I had the valve guides and heads overhauled, the valve guides were badly worn. I’m way up in the north of Scotland and will take the tank off in the hotel car park tomorrow to have a look. The bike is running beautifully, never better, but a prolonged 60 to 70 mph run and it’s soaked, it did over 200 miles and not a sign of oil, mostly at 60 or below. The oil level was close to minimum so not overfilled. It only did this after over 20k faultless miles. Any ideas?. The ball valve has been replaced, pipes are/were not blocked. Could do with some input please?. Thanks.
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:popcorn:
Rick
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Put in another check ball valve. Seen newer ones stick. Get rid of airbox is another. Then you see it right away.
might check frame for obstructions.
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Agree.....Check your PCV/ check ball valve in your breather. If stuck, the engine will pump oil out the breather.
Tom
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Thanks for the replies folks
I’m heading down after breakfast to take the tank off and have a look.
The oil isn’t just coming out of the breather, it’s everywhere, in the v of the engine, the alternator cover, the front of the frame, even the underneath of the tank!. All will be revealed, hopefully, when the tank comes off.
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Leak in oil line?
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All that oils upfront I would guess oil lines or even the pressure switch. Or maybe valve gasket.
My oil pressure switch/sensor leaked for 3 months before I figured out it was loose on my 850T. I even thought my forks were leaking at one point from that spell.
Good luck.
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IF?....??? the breather valve is clogged, it will over pressurize the block. The oil will then find the easiest way out through seals and the like.
But with your description of "everywhere". You need to look everywhere. Breather hoses, oil lines, oil pressure sender, ect..
Good luck!
Tom
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Check oil feed to heads. Also check the drain from frame to valve covers are clear. Common for them to get gummed up. Then the frame fill s up and oil gets sucked into the air box.
There is a line from air box to frame to create suction to suck fumes back through the intake.
When mine started leaking oil out of the air box it was the drains onto the valve cover
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Ok, so, I removed the main breather pipe, no ball valve, it must be laying around on my bench, not like me to miss things but it seems I did. The big problem was the return pipe that goes through the bell housing was blocked, I took the little pipe off the spigot on the frame and oil , lots of it, well an eggcup full, came out I then blew down the pipe into the crank case, blocked solid, a bit of tying wire and some carb cleaner down the hole and eventually it cleared, I can easily blow down it now.
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Might be time for an oil change and sump clean as well, because that stuff just fell into your sump
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Oh yes, the sump will come off and a filter change too.
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Don't forget to pour fuel in passage holes & blow 80# plus through the discs in pressure valve. Just like book says.
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Soooooo,
Cleaned the whole bike, degreased, fitted the ball valve breather, cleared all the breather pipes, the rubber pipe going to the bottom of the air box was broken at the frame end, a pipe has been placed over it, that I think is where it is leaking, all over the front of the engine then blown back. So, a nice ride today, lovely sunny day, no oil leaking, until I take it above around 3500rpm or so, then yes, you guessed it, pissing oil, my boots, jeans, the whole bike, rear of the front fender, rear tyre, everywhere. My driveway is a mess. Tank off, all pipes are clear, the return back through the bell housing is clear, you can blow through it and hear the oil gurgling, when you remove the small pipe at the frame it seems the frame is full of oil. It seems like it's pumping oil up past the ball valve into the frame and air box, then when it gets to critical when the return can't cope it fills the air box and also leaks out of the pipe at the front of the frame and covers everything below it with oil.
So, next is to fit a ford crankcase breather valve, fix that pipe at the front of the frame, perhaps fit a catch tank to the small pipe at the return
BUT. Why is it happening?. It leaks oil whether the ball valve is fitted or not, the engine is spot on I checked compressions, they are both perfect, valve guides are new, oil level is at minimum. The bike started doing this on a run last year, nothing new had been done, it was running very well, oil level was where it has always been in many thousands of miles, then for no apparent reason it starts throwing oil out. This speaks of a component failure?.
Now, no ball valve fitted but return pipe blocked so leaks oil, fit ball valve, return pipe clear , leaks oil, it all points to the ball valve. But it seems fine, it's only a ball in a tube for goodness sake.
Ford valve ordered!
It doesn't have breathers going to the rocker covers.
Alan.
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Try a leak down test. Always a good way to test mechanical condition for so many parts. My.02
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I took the little pipe off the spigot on the frame and oil , lots of it, well an eggcup full, came out I then blew down the pipe into the crank case, blocked solid, a bit of tying wire and some carb cleaner down the hole and eventually it cleared, I can easily blow down it now.
And herein lies a mystery
The way it works is
Oil returns to sump UNDER the oil, via a long banjo bolt behind clutch
If broken so is higher than oil level it will spew oil as banjo bolt becomes pressurised pushing oil back up return pipe.
Have a look underneath to see what was “ blocked” and is now “clear”
Then
Leakdown test as above, if you’ve broken a ring, slight blow head gasket etc, it’ll show
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You mentioned that you can here the oil gurgling when blowing down the return pipe. That would indicate that the return line is intact to the base of the sump below the oil level in the case as it should be. When you pulled the heads to do the guides were the barrels removed also , ? Perhaps to replace the base gaskets? I suspect the case is being over pressurized by blow by . Perhaps a broken ring or excessive end gaps or piston grove fit. A leak down. test would be a good place to start . Check carefully for leakage thru to the case via the oil fill opening when pressurized.
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Hi folks, thanks for all the answers, here’s what I think may be happening, the ball valve is jamming , so the crankcase can’t vent, the only place it can is back through the return pipe, up into the frame then spills through the pipe at the top of the frame. This would explain why when the pipe got blocked and no ball valve was fitted it blew oil up into the top of the frame, when I cleared the return pipe, still no ball valve fitted, it rode down from Ullapool no problem, 247 miles, no oil leaks, I fit the ball valve and 16 miles later it’s spewing oil!
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How much oil are you putting in? No more than 3 quarts is needed.
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I'm pretty sure I remember the check valve for your breather system when I looked up the parts diagram to see what you have.
My EVT uses the frame as a breather box similar to your bike. I have the large rubber hose, but instead of to the bell housing from the frame, it's just in front of the RH cylinder then to the frame. It does not use a check valve, at least none that I have found.
My return line from the frame, instead of going to the return tube at the bell housing like yours, it goes into the rocker covers. Looks like the early "breathers", but they are oil return lines.
Provided that you can blow through the check valve, rattle and the ball moves freely, AND have it installed the correct direction ( it should be slid into the fitting at the bell housing then the rubber tube slid on the fitting so the air travels out the bell housing fitting then through the valve and then to the frame).
A PCV valve is designed to keep the engine from sucking dirty air back into the engine if I understand them right.
My EVT is sorta a closed system where there is no way to get dirty air. The last venting for the system is in the air box. I think your bike is the same.
So...maybe run it without the check valve permanently? Mt EVT does this, why can't your??
Tom
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Hi Folks,
I got to the bike today. I cleaned all the pipes through, none were blocked, removed the ball valve and fitted a ford Pinto valve at the top of the large diameter pipe where it goes into the upper frame tube. I replaced the end of the pipe which goes to the air box, I think that may have been leaking the oil all over the front of the engine, I then routed the air box drain pipe down by the left footrest and fitted an (empty) salad cream bottle to the frame, the pipe now goes into that, looks very fetching I must say, almost a factory fitment!!!. I'll go for a ride tomorrow keeping an eye on my racy catch bottle.
I didn't remove the barrels when I did the heads, and I just did a compression test both exactly the same at 180PSI with the throttle open. little or no piston rock at any point in the bore when pushed with fingers. It doesn't use oil (just leaks it now) or show even a hint of smoke at any time, never has. I believe the MK3 Le Mans has Nikasil bores so it would seem the flaking problem is negated.
We shall see what happens tomorrow.
I can always remove the crankcase vent valve, that might fix it, but it's not a fix if I can't find the problem. To be clear, I have done many thousands of miles on the bike, and with no warning it started pumping oil, never did it before, and that was with the oil level between halfway and full at every oil change. I've never had to top the oil up between oil changes, and I certainly don't ride the bike hard. There's no reason I can think of that might have resulted in a broken ring, and the bores are spotless, not a scratch.
It's a mystery, as Toyah might say!.
I'll report back.
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Are you absolutely sure that the hose that goes from the air box to the forward most fitting on the frame is clear and air will pass through the frame fitting?
I know you wrote that you just replaced this hose, but again, is the fitting on the frame clear?
If this hose or fitting was clogged, I believe that it would act like the pcv valve was frozen or clogged by not letting air out of the engine. Again, this could cause the oil to get pumped up the oil return line and into the frame. And if there were cracks in any of the hoses to the frame, that could be where the air is getting out and bringing the oil with it.
Just a theory here. If the air box to frame hose and or frame fitting was clogged. I think that with a pcv valve installed correctly. The air and oil mist could fill up the frame and then try to make it's way back to the engine through the big breather hose. With the pcv valve in place, the oil has no where to go except to fill up the hose and leak through any cracks. Without the pcv valve, the oil may be able to flow back down the big hose??
Just a few thoughts, not sure if my theory is correct. Hope maybe it helps a bit,
Tom
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Hi Tom,
Thanks for the reply.
Yep, all hoses clear, and just to make sure I pushed a long zip tie through them. When I had all the hoses off I put my fingers over the two upper frame holes and blew through the return hose, then removed my fingers at different times, blew through no problem, so the frame is all clear too. I then pushed the same zip tie down the crankcase vent hole and that is clear, I wondered if perhaps that was blocked and the oil was coming back up the return pipe, nope, all clear. Blew back through the air box vent pipe, all clear. Seems the only obstruction could be the PCV valve, and that is now replaced. Unless there's rust floating around inside the frame I suppose, and blocking the return sometimes?. I could take the return flexible pipe to the catch tank too, and also one from the return solid pipe, that might give me more information. But one thing at a time, I'll ride it tomorrow and see if the catch tank fills up.
Alan.
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Let us know if the saga continues. Never had that problem with any of the bikes I own and still have. Good luck! :thumb:
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IF?....??? the breather valve is clogged, it will over pressurize the block. The oil will then find the easiest way out through seals and the like.
But with your description of "everywhere". You need to look everywhere. Breather hoses, oil lines, oil pressure sender, ect..
Good luck!
Tom
Question:
What is the breather valve ? what does it do ? where is it located/how does it look ?
Just curious. Thanks.
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Bison, good luck tomorrow!
Tom
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Hi, is the flapper valve in the right way? I.e. (Is it up side down?) Yeah I know it is a stupid question, but my Mk III only has blow by above 6000 RPM and she is old. 200,000ks +.
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Hi Folks,
Well, after a 50 mile ride there is no oil in my makeshift catch tank or, more importantly, all over the bike. I did some fairly spirited riding, and slow stuff, tried it all, so far ok!. So, the only thing I have changed was to swap the ball valve for the Ford Pinto valve, and mount that valve at the other end of the breather pipe.
Tomorrow when it's cooled down I'll remove the tank again and check everything out, I'll remove the return pipe to ensure there's no oil build up in it too. I've ordered a new air filter, and I'll change the oil again, but first I'll do more miles to be sure to be sure.
I'll put a little more oil in to take it midway between high and low on the dipstick, right now it's just above low.
I'm more willing to accept that (hopefully) it was the ball valve that was giving problems. The fault appeared out of the blue, then went away with no ball valve fitted, (I was unlucky when the return pipe got blocked, that threw a spanner into the works), then came back when I refitted it, and now seems to have gone away with the Pinto valve fitted. Large crossing of fingers.
I'll report back.
Alan.