View Full Version : Burning oil and leak down test on the Shed
Fallout
08-01-13, 01:35 PM
Ok, so the 'shed' as it is referred to by the GMers (GSXR750 K1 28,000m apparently) likes to use oil at a staggering rate. Let's say after a hard 100 mile round trip, it goes from F to halfway down the window. I also get some smoke sometimes at high RPM. I'm not fussed. I'm enjoying having this bike as a learning tool for maintenance, so I'm prepared to learn about replacing rings if necessary. Bring it on!!
I bought a universal compression tester a few months back, suitable for cars and bikes. Of course, it didn't fit the gixxer, so that was a waste of cash. Now I've just read up about leak down tests and basically finding out where the air is escaping, so I reckon I should give that a go.
My basic understanding is:
For each cylinder:
- Get the piston to TDC.
- Lock engine (in gear, rear brake on)
- Attach tester and fire in 100psi of lovely air
- I should be able to read a leakage %age from the gauge, with upto 10% generally being acceptable
- I should be able to listen to exhaust, valves etc. to determine where the air is leaking through and then book a week of my life and several hundreds of my lovely pounds to fixing it
My questions are:
- Does anyone recommend any particular gauges or tools, or have a better cheaper method? I don't really fancy going on ebay and buying posh testing gear I may never use again, or doesn't fit the bike.
- How do I determine if a piston is a TDC? Will I be able to see it through the spark plug hole? I assume I get it there by leaving the bike in gear and turning the rear wheel?
- I'm not 100% clued up on valve adjustments, so not sure how they impact the testing. If air comes out the exhaust, is this definitely rings, or could it be exhaust valves? Should I be doing valve adjustments before I perform this test?
- Critically, I've heard I can just replace the rings which is relatively cheap (plus a few gaskets), but I'm guessing when I open it all up I'll need to be able to determine if I have more pressing problems. i.e. cylinder reboring and new pistons. Don't have the experience to make the call on that one. Anything obvious to look for, or can rings generally be replaced by themselves unless there're serious issues?
Sorry for all the questions. Figured I might as well ask them all now so I'm mot clued up. :) Cheers for any advice.
Surely if air comes out the exhaust it's nothing to do with the ring? Happy to be wrong. Air from the exhaust would indicate a poor valve seal for whatever reason. Worn rings would allow air to escape into the crankcase?
yorkie_chris
08-01-13, 01:42 PM
Bear in mind the 10% is completely arbitrary based on the flow restriction of the tool. Often with cheap tools it's good to check against a known good motor to get a baseline.
I can't remember exactly but do your spark plugs start with a C like the SV? If so then you need a 10mm thread fitting.
Unless the air goes from the crankcase through another worn ring and out an open exhaust valve in another cyl.. Though I havent worked on a big 4t engine yet, only my smaller bikes back in the day. So my advice on rings wont be that good, but I changed them my 125s and once needed an oversize piston.
yorkie_chris
08-01-13, 01:52 PM
- I'm not 100% clued up on valve adjustments, so not sure how they impact the testing. If air comes out the exhaust, is this definitely rings, or could it be exhaust valves? Should I be doing valve adjustments before I perform this test?
You need to make sure there is #some# valve clearance otherwise they won't seal.
You've got an oil problem, this means oil is either getting into the cylinder, intake tract or exhaust tract.
By looking to see when the smoke comes out you can get an idea. Ride it and find out what conditions of throttle, revs, overrun/acceleration etc make it smoke. Then pull it in bits slightly and see if there is oil in the headers/exhaust tracts, can you see it on the plugs, can you see it on the back of the intake valves... etc. Which cylinders it is affecting.
Fallout
08-01-13, 02:34 PM
Surely if air comes out the exhaust it's nothing to do with the ring? Happy to be wrong. Air from the exhaust would indicate a poor valve seal for whatever reason. Worn rings would allow air to escape into the crankcase?
You need to make sure there is #some# valve clearance otherwise they won't seal.
You've got an oil problem, this means oil is either getting into the cylinder, intake tract or exhaust tract.
By looking to see when the smoke comes out you can get an idea. Ride it and find out what conditions of throttle, revs, overrun/acceleration etc make it smoke. Then pull it in bits slightly and see if there is oil in the headers/exhaust tracts, can you see it on the plugs, can you see it on the back of the intake valves... etc. Which cylinders it is affecting.
It really doesn't smoke noticeably to me. On a number of occasions I've stonked past someone at over 10k rpm only to ask them later if they saw any smoke and got a 'no' as the answer. I can't see it in my mirrors. The only time I've ever seen smoke out on the ride was once when we were at lights and I gave it a rev and covered everyone behind me in a cloud of lovely smoke. We may have been going fast before (hence high RPMs) ... I think we were, but it was months ago.
When I start it up it starts fine and idles fine, and smokes a bit, but it's hard to tell in this weather if that's due to the temperature or chuffing out old oil. It's white by the looks of things, so assuming cold weather water vapour. Within 30 seconds it's warm and not smoking and idle is closed. So really despite it going through oil like a mofo, there aren't any obvious visible symptoms apart from a few mentions by people of smoke at high RPM.
Also there's no leaking around the engine or into the fairing belly.
The only other thing I can remember is some oil residue on the valves which the airbox sits on when I was changing the plugs over when I first got it, and some oil around the air box area, but about the same time I discovered a pipe wasn't connected. It looked like it ran from the crankcase up to the airbox, so assuming it was responsible for the oily residue.
As you can tell I know a bit but not enough about all this stuff to make clear judgements, nor are there any massively obvious symptoms which suggest where the oil is going.
It sounds like from what you guys are saying that really I should learn more about valve clearances and all that shananigans first. I've never adjusted a valve so that's probably the place to start then. Sound fair?
Cheers for your help.
That pipe was I'm assuming was the crankcase breather. Is the airbox excessively oily? I have heard of air being forced past the worn piston rings during the compression stroke thus pressuring the crankcase. Then oil and air out of the crankcase breather into the airbox or indeed where the pipe is hanging. This also puts fuel into your oil which isnt good for the engine. Just speculating though.
yorkie_chris
08-01-13, 02:58 PM
Petrol doesn't hang about long in the oil in that sort of dose, it's bloody hot in there tha nos.
But yes it can make it oily if that happens.
It sounds like from what you guys are saying that really I should learn more about valve clearances and all that shananigans first. I've never adjusted a valve so that's probably the place to start then. Sound fair?
Cheers for your help.
You should probably at least learn about timing a motor up and stuff before contemplating pulling the head off.
Not a bad engine to learn on though a bit harder than an SV.
If it smokes badly when giving some beans after overrun then that can say rings or intake valve seals.
Start with basics, what do the plugs look like?
Fallout
08-01-13, 03:26 PM
When I took the old ones out when I got the bike (had it about 6 months) the plugs looked ok. I have no idea when the previous owner last changed them. Could've been weeks, could've been years (very little history). Did I mention this bike was a bargain? :) It looked like standard wear though, no obvious fouling or anything. When I bought the 'universal' compression tester that didn't fit I took the new plugs out and they looked good too. Can't remember if I took all of them out though. It was several months ago. I'll have another look and see how they're doing.
Apart from that oily residue around the airbox where that breather pipe wasn't connected, I can't think of any other obvious symptoms. It starts and runs totally fine. I might say the oil was darker than I'd expect it to be on the last change. I reckon I'd done about 2k miles tops since the last change and it was dark and well used, though no signs of metal filings or anything. Nothing on the magnetic sump plug either. I'd probably put a whole litre of new oil in over that time span to compensate for leakage.
Last oil change was only 200 miles or so ago, so new oil and filter hasn't made any difference (semi synthetic castol).
It has a slight 'burble' at idle. Like up down, up down, up down very fast, but I've noticed other gixxers making this noise, so think it's a characteristic of the IL4. But perhaps a symptom of something else?
Can't think of anything else to tell you. I fixed a leaking alternator cover a few weeks ago. New gasket has sorted that. Can't see it being the problem. I spend quite a lot of time arsing around with the fairing off, including a very thorough ACF50ing before xmas, so would expect to have noticed any additional leaks anywhere.
yorkie_chris
08-01-13, 03:41 PM
Oil always looks black, sometimes on really new motors it still looks a bit gold.
No oil on plugs suggests either it's only doing it when there's enough heat to burn all the crap off, or it's coming out of the exhaust valve stem seals. Pull the pipes off and have a look if there's a lot of crap in them
Fallout
08-01-13, 03:53 PM
My SV engine was mint. Red Motul went it, I changed it far to frequently and dark red motul came out. When I do an oil change and dark black stuff comes out I feel like I've waited too long. I know changing it sooner is ****ing money down the drain though changing red oil. 2k is a good service interval, black oil or not. :)
Cheers for the suggestions. I'll get the plugs out tonight and see what shape they're in, then attempt to check for exhaust valve leakage. Do you mean pull off the exhaust down pipe?
yorkie_chris
08-01-13, 03:56 PM
Yes pull downpipes off head and see what they look like. They're always a bit sooty but if one is leaking you will see difference. If it looks like the powervalve off a 350LC then there's your issue.
Fallout
08-01-13, 04:12 PM
Cool. Cheers for your time mate. I'll stick some photos of what I find in this thread when I have a look tonight. Might help with diagnosis and help anyone else who may be drinking oil. If the exhaust valves are the culprit and it's not ring related, is that something that can be adjusted or a replacement part job?
yorkie_chris
08-01-13, 04:15 PM
Replacement seals, quite involved as it involves removing valves and springs from the head.
Fallout
08-01-13, 04:31 PM
Ar$e. Ok, thanks mate. Will report back with my findings.
yorkie_chris
08-01-13, 04:34 PM
No harder than rings really. They're both a c**t and it might be worth overhauling the lot while you're in there.
Fallout
08-01-13, 04:36 PM
I'd be up for as much as my pocket and patience would allow. Do you mean new rings, and new valve seals? What else would you stick in that overhaul? I suppose that includes a new head gasket. Anything else? Might browse wemoto, fleabay and various other places to see what it'd all cost me.
Fallout
08-01-13, 07:13 PM
Haven't got to the down pipes yet. I had a curry calling my name. Plugs look ok though. Obviously the flash brings up all those minor imperfections you don't normally notice. This is after 2-3k miles approx:
http://forums.sv650.org/attachment.php?attachmentid=12002&stc=1&d=1357672157
Airbox was clean apart from this oozy skank where the crankcase breather hose thing connects to it. There is a wire mesh wool thing in there I assume acting as a filter to stop this skank getting into the airbox. I assume this is all normal.
http://forums.sv650.org/attachment.php?attachmentid=12001&stc=1&d=1357672143
Only other thing is spark plugs were a bit loose. The thread for them is quite ropey. I can get them in, but there are tight spots as they go in, so I try to avoid over tightening to make things worse. They were properly seated, just not in tight. Can't imagine that causing any problems though.
I'll get to the downpipes tomorrow.
I'm almost at the point I'll have to admit the me and Spank take a bit of Fallout's oil out with a pipette each time he slopes off for a fag break on ride-outs then squirt it under Bordteas bike. But I think I can hang out just a bit longer.
yorkie_chris
08-01-13, 07:51 PM
You know you should use an anti-galling lube on the plug threads, copper slip or moly paste works well.
If the threads are a bit gritty this really helps, if they've been graunched by overtightening in the past, it won't hurt.
Are those little black flecks on the plug ceramic?
That crap in airbox is normal.
Fallout
08-01-13, 09:08 PM
You know you should use an anti-galling lube on the plug threads, copper slip or moly paste works well.
If the threads are a bit gritty this really helps, if they've been graunched by overtightening in the past, it won't hurt.
Are those little black flecks on the plug ceramic?
That crap in airbox is normal.
I'll pick up some copper grease. Not used an anti-seize compound on plugs before. Sounds like a good idea. :)
Not sure what the black flecks are. They're not easy to see without the benefit of a zoom and cam pic. I'll have a look tomorrow when I'm ripping off the down pipe and see if they're bits or staining. If they're 'bits' what would they most likely be? I'm guessing nothing from below the piston.
Thanks for your help mate.
Dave-the-rave
08-01-13, 09:27 PM
http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/viewall.html
Looking at one of the spark plugs its dirtier than the rest. Do you remember which ones came from which cylinder?
Fallout
08-01-13, 09:58 PM
The pic isn't very useful other than an overall impression. It's taken with a flash so the ones in the centre have more fidelity and the left one, which looks clean, is just slightly out of focus. I compared them all and they looked very similar. Any difference is quite marginal. I'll have another look tomorrow though as I put them all back in the same cylinders.
Fallout
08-01-13, 10:07 PM
@Dave - That's a good thorough link. Good find. :)
Sir Trev
09-01-13, 09:31 AM
Is anyone else expecting a thread about breaking a stud while taking off exhaust later on today?
Fallout
09-01-13, 10:43 AM
I'm not, because I'm not doing that today. Just attached the Drift to point at the exhaust. Going out for a smoke diagnostic video session in a few minutes instead. :)
yorkie_chris
09-01-13, 10:53 AM
Oooh fancy, you mean there is a modern way to not try and give a GSXR 11 full throttle in top while peering backwards? You lot don't know you're born!!
Fallout
09-01-13, 11:39 AM
There is a modern way, and let's just say the velcro supplied with the modern way was not sufficient to keep said modern way attached to the bike. Good job I tied it to one of the luggage bracket things as an after thought. Should have some footage of smoke trails before it falls off.
Interestingly, now I'm actually paying attention to smoke on start up .... there is a sheeeet load of it.
yorkie_chris
09-01-13, 11:40 AM
If it is white it's probably just water vapour which is perfectly normal
Owenski
09-01-13, 11:57 AM
Do you ride in the rain/wash your bike with a hose...with out an exhaust bung?
yorkie_chris
09-01-13, 12:02 PM
Riding in the rain with an exhaust bung may not turn out to be 100% successful
Owenski
09-01-13, 12:21 PM
pretty sure i fired the drz up a couple of times with the bung in to try and fire it across the garden, it more or less just flopped out... WE NEED MORE POWER!
Fallout
09-01-13, 12:24 PM
Don't spend a lot of time riding in the rain, and the bike doesn't ever see a hose. I'm careful to not dribble in it's exit pipe.
Re: start up smoke. Always assumed it was water vapour. Trouble is now I'm looking for a problem. Probably is fine. There's no noticeable smell of excessive oil or anything, unlike my Mondeo which reeks of diesel when you start it up.
Checked video and I warmed the bike up to about 70-80c cruising about for a few minutes. Then did some up to 10-11K RPM hard accelerations followed by decelerations. No smoke ever. Unfortunately I then overtook a tractor and the road got bumpy and then the camera said goodbye shortly afterwards. Not a lowside, I promise.
Not much to see on this vid. Just adding for reference. If you notice the piece of wheel missing from my rim, I didn't hit a curb or anything. Happened somewhere along an innocuous uneventful 15 minute ride last weekend. Apparently my rims are made of plastic. Another Shed mystery.
MNN2VuJnQvA
Not very exciting. The whole start up bit last over 3 minutes. Yawn yawn yawn.
Did you have to up back and get the camera or did you attach it to the bike as a safety measure??
That is a fair bit of smog.. But none at decel/revs. That says to me that perhaps oil is getting into the combustion cycle at rest. But I cant think how. If it was seeping past the rings with the engine off it would suck up oil running without a doubt. If you were to leave it an hour and start it up, would the smoke return as it has gone at around 2 minutes?
Fallout
09-01-13, 12:58 PM
Did you have to up back and get the camera or did you attach it to the bike as a safety measure??
Attached it as an afterthought with some garden twine I found lying around. Glad I did. The velcro that comes with the Drift is utter junk! But I really like that view though, so will try and figure out a better way to attach it.
That is a fair bit of smog.. But none at decel/revs. That says to me that perhaps oil is getting into the combustion cycle at rest. But I cant think how. If it was seeping past the rings with the engine off it would suck up oil running without a doubt. If you were to leave it an hour and start it up, would the smoke return as it has gone at around 2 minutes?
I've been following Sid's thoughts on valve stem seals and did some more googling today. If that smog is more than vapour (which is does look like), that's consistent with failing valve stem seals as they leak residue oil into the cylinder as they cool down.
Also a key symptom is oil collecting in the cylinder at idle after deceleration. I did test this on the ride but lost the camera. Could've just turned my head and looked back but trusted the camera. :rolleyes: That's consistent with the one time I have seen smog though which was after a high speed run, followed by a long wait at road work lights, followed by my revving the engine and covering everyone behind me in exhaust skank. :thumleft:
The good news is, from what I've read, leaking valve seals doesn't do much harm to the engine, so I've not been slowly destroying it. I'll just carry on burning oil at a biblical rate until I get it sorted.
That makes a lot of sense reading into it, seems it's pretty common on many engines. No harm done eh!
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