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Valve seals and smoke ?

9K views 16 replies 10 participants last post by  VRodPete 
#1 ·
I have been having to add a little oil between changes at 6Kmiles for the past few changes.

I did a compression test and leak down test this past winter, everything checked out okay. Quite good as a matter of fact.

I sometimes ride aggressively, drop a gear or two and wind the rpms well up toward the red for a pass, or running higher rpms while pushing the ride in the uphill twisties.

The bike has always blown a puff of black smoke when I do this, but during a recent ride around Vermont a fellow rider said it is more like a trail of smoke rather than a puff. The smoke is black, not blue like we used to see with oil burners. But I wonder does synthetic oil burn blue?

I've been using Mobil 1 for some time now and seem to remember someone (Saddleman?) saying that there were reports of Mobil 1 getting used up more than others. (I did switch to good ole' petroleum based oil (Advance Auto Parts store brand if you want to know ;) ) just to see if it makes a difference.

If it were just a black puff of smoke, I'd attribute it to the KLT's tendency to run a little rich under such conditions, but with the increased smoke, and increased oil consumption I'm wondering about other causes. Another note is that the gas mileage hasn't changed noticably, and is pretty good.

The thing that comes to mind is valve stem seals. Anyone had a problem like this? Has anyone changed out the valve stem seals?
 
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#2 ·
Nah.. Black smoke is the engine running rich... Even at high rpm's and large throttle openings it still runs rich....

Experience on my LT was if you kept it full, It used a little. If you kept it halfway across the site glass it rarely went below that..

John
 
#3 ·
JPSpen said:
Nah.. Black smoke is the engine running rich... Even at high rpm's and large throttle openings it still runs rich....

Experience on my LT was if you kept it full, It used a little. If you kept it halfway across the site glass it rarely went below that..

John
Thanks for the reply.
There is a definite change in oil consumption. Over 78K miles I never had to add between 6K mile oil changes. It now drops below the sight glass and I have to add to bring oil back into view.

I am sure some (all) of the smoke I am putting out is rich fuel mixture, but I am still wondering why the change in oil consumption.

I never really noticed increased oil consumption with the level high in the sight glass. Maybe it does use a little more when filled to the upper level, but I used to go 6K miles without adding any and I did fill to the upper level of the glass. (The crankcase volume on the K doesn't change that much with piston movement, as two pistons come in as two go out. Oil consumption on Airheads can be really noticable if filled to the very top of the dipstick marker, on those bikes both pistons travel in and out at the same time resulting in a big change in crankcase volume which can push oil out the breather. On those bikes when filled to the maximum, the level will seek the middle of the dipstick and then stay there.)

On my KLT presently, the oil doesn't seek a level and then stabilize, rather it disappears from view in the sight glass and I have had to add more the 1/2 quart to bring it into view.

Thanks for your thoughts.
 
#4 ·
Curtis, I have been noticing very similar evidence of usage on my '00 LT also. And she used to go all over the place without ever dropping in the sight glass, but recently I find that it will drop down from the center to out of sight on the center stand. So I find myself carrying a quart along on the long trips. I use Castrol Syntec, and have been from around 20K till now, with over 170K on her.

So I will be interested in the replies to your inquiry as well. Even though there is no drop in performance or mileage, we still would like to know why. I do believe it is just high milage taking its toll. I do tend to ride fast and aggresive quit a bit, so that may be a factor also.

John
CharlieVT said:
Thanks for the reply.
There is a definite change in oil consumption. Over 78K miles I never had to add between 6K mile oil changes. It now drops below the sight glass and I have to add to bring oil back into view.

I am sure some (all) of the smoke I am putting out is rich fuel mixture, but I am still wondering why the change in oil consumption.

I never really noticed increased oil consumption with the level high in the sight glass. Maybe it does use a little more when filled to the upper level, but I used to go 6K miles without adding any and I did fill to the upper level of the glass. (The crankcase volume on the K doesn't change that much with piston movement, as two pistons come in as two go out. Oil consumption on Airheads can be really noticable if filled to the very top of the dipstick marker, on those bikes both pistons travel in and out at the same time resulting in a big change in crankcase volume which can push oil out the breather. On those bikes when filled to the maximum, the level will seek the middle of the dipstick and then stay there.)

On my KLT presently, the oil doesn't seek a level and then stabilize, rather it disappears from view in the sight glass and I have had to add more the 1/2 quart to bring it into view.

Thanks for your thoughts.
 
#5 ·
I've only put around 2K on my '99 but my .02 cents on oil is to get the best quality regular oil you can. I like Castrol or if I can't get that Pennzoil is pretty good stuff. Don't pony up for the synthetics because a good part of what contaminates oil is blow-by and generally the oil's pretty gacked up before you rack up enough miles to significantly cause actual viscosity break down. I've never had an oil related problem between my umpteen cars, trucks and bikes. With oil you definitely get what you pay for and the house brands in the Autoparts chains are none too pure.
 
#6 ·
WheelsNWaves said:
I've only put around 2K on my '99 but my .02 cents on oil is to get the best quality regular oil you can. I like Castrol or if I can't get that Pennzoil is pretty good stuff. Don't pony up for the synthetics because a good part of what contaminates oil is blow-by and generally the oil's pretty gacked up before you rack up enough miles to significantly cause actual viscosity break down. I've never had an oil related problem between my umpteen cars, trucks and bikes. With oil you definitely get what you pay for and the house brands in the Autoparts chains are none too pure.
I included the fact that I bought Advance Auto parts house brand oil 'cause I was trolling.
Got ONE ! :histerica

Popeye uses Olive Oil

Now back to my original post. Has anyone ever replaced the valve stem seals? Has anyone who has changed the seals seen a reduction in oil usage?

The bike isn't leaking. Again, compression and leakdown tests are spot on. Where else could the oil be going?
 
#8 ·
Could be your 02 sensor needs to be changed. That is one of the most common reasons for an engine running rich. Your mileage puts you in the right range if you have never changed it.

Just a guess.

Steve
 
#9 ·
silverlt2002 said:
Could be your 02 sensor needs to be changed. That is one of the most common reasons for an engine running rich. Your mileage puts you in the right range if you have never changed it.

Just a guess.

Steve
I have thought about the O2 sensor. Last check with the GS911 showed no faults, but I imagine the O2 sensor can slowly degrade, resulting in a rich mixture, but not throw any faults to the scanner. My gas mileage is still good.
Even so, I guess I'll add changing out the O2 sensor to my next BMW "inspection".
Thanks for the suggestion.
 
#11 ·
CharlieVT said:
I've been using Mobil 1 for some time now and seem to remember someone (Saddleman?) saying that there were reports of Mobil 1 getting used up more than others.
The oil I was referring to is Mobil Delvac Not Mobil 1. I just switched to Mobil 1 V-Twin oil from the Delvac & I'll keep an eye on the oil level to see if it makes any difference. I have been going thru 1 qt. every 6000 miles with the Delvac.
 
#12 ·
Would the horizontal engine on the LT have the same diagnosis as a vertical V6 or V8 where you run along and a steady RPM, then let off the throttle and engine brake then reaccelerate and watch for blue smoke. At least that is what I remember the procedure was for checking for bad valve stem seals.

Roy
 
#13 ·
bigbear said:
Would the horizontal engine on the LT have the same diagnosis as a vertical V6 or V8 where you run along and a steady RPM, then let off the throttle and engine brake then reaccelerate and watch for blue smoke. At least that is what I remember the procedure was for checking for bad valve stem seals.

Roy
Thanks.
I don't think we're seeing that but will check again using that procedure.
 
#14 ·
CharlieVT said:
I included the fact that I bought Advance Auto parts house brand oil 'cause I was trolling.
Got ONE ! :histerica

Popeye uses Olive Oil

Now back to my original post. Has anyone ever replaced the valve stem seals? Has anyone who has changed the seals seen a reduction in oil usage?

The bike isn't leaking. Again, compression and leakdown tests are spot on. Where else could the oil be going?

Busted! :D

Wear on the valve guides would do it. I had a similar situation with a marine engine. Compression was fine in all cylinders but oil consumption (particularly as rpms were increased) went up at a steady rate. Ended up changing out two valves and several guides where either the guide or the valve stem was worn and oil was seeping past when the valve was open but compression was fine when the valve was seated closed.

Another factor in that particular case was excessive exhaust back pressure (although if that were the case in the brick I think you'd be seeing a significant loss of power, reluctance in starting and possibly even backfiring).
 
#15 ·
WheelsNWaves said:
Busted! :D

Wear on the valve guides would do it. I had a similar situation with a marine engine. Compression was fine in all cylinders but oil consumption (particularly as rpms were increased) went up at a steady rate. Ended up changing out two valves and several guides where either the guide or the valve stem was worn and oil was seeping past when the valve was open but compression was fine when the valve was seated closed.

Another factor in that particular case was excessive exhaust back pressure (although if that were the case in the brick I think you'd be seeing a significant loss of power, reluctance in starting and possibly even backfiring).
Thanks for the reply!
My oil consumption does seem to increase when I am out riding hard at high rpms.
I think I'll put in a new O2 sensor (I know it won't affect oil consumption, but may help with the black smoke issue), and I'm going to check the vent hose carefully. After that, I might just do a top end job, inspect the valve guides and change the seals.
 
#16 ·
CharlieVT said:
I have been having to add a little oil between changes at 6Kmiles for the past few changes.

I did a compression test and leak down test this past winter, everything checked out okay. Quite good as a matter of fact.

I sometimes ride aggressively, drop a gear or two and wind the rpms well up toward the red for a pass, or running higher rpms while pushing the ride in the uphill twisties.

The bike has always blown a puff of black smoke when I do this, but during a recent ride around Vermont a fellow rider said it is more like a trail of smoke rather than a puff. The smoke is black, not blue like we used to see with oil burners. But I wonder does synthetic oil burn blue?

I've been using Mobil 1 for some time now and seem to remember someone (Saddleman?) saying that there were reports of Mobil 1 getting used up more than others. (I did switch to good ole' petroleum based oil (Advance Auto Parts store brand if you want to know ;) ) just to see if it makes a difference.

If it were just a black puff of smoke, I'd attribute it to the KLT's tendency to run a little rich under such conditions, but with the increased smoke, and increased oil consumption I'm wondering about other causes. Another note is that the gas mileage hasn't changed noticably, and is pretty good.

The thing that comes to mind is valve stem seals. Anyone had a problem like this? Has anyone changed out the valve stem seals?
My 2007 also blows black smoke when under full throttle, particularly when the RPM is still below 5,000. I ride with a small group fairly often and several of them have commented on this. It isn't just a puff of smoke, but continuous black smoke until I either let off the throttle or get to fairly high RPM. And the black film that quickly forms around the exhuast outlet is further evidence of this rich condition. I understand wanting to protect the engine, but I think BMW when a little overboard in the full throttle enrichment department.

As to oil consumption, my LT has used oil since it was new. I have broken in most of my past vehicles using the owner's manual technique which generally has one stay at low RPM for the first 1,000 or so miles. After reading a couple of articles about the virtues of breaking in an engine using the "run it like you stole it" approach, I did that on my last two new vehicles: a 2006 Hyundai Sonata and the 2007 LT. The Sonata uses virtually no oil, but the LT requires a half quart between changes at 3,000 miles using BMW branded dino oil. The consumption seems to be getting less as the miles accumulate (almost to 18K now), but it still uses oil. I will like switch to Mobil 1 at the next oil change as I was told it could take 18K miles to fully break-in the Nikasil lined cylinders. I have no idea if that is fact or old wives tale.
 
#17 ·
Voyager said:
My 2007 also blows black smoke when under full throttle, particularly when the RPM is still below 5,000. I ride with a small group fairly often and several of them have commented on this. It isn't just a puff of smoke, but continuous black smoke until I either let off the throttle or get to fairly high RPM. And the black film that quickly forms around the exhuast outlet is further evidence of this rich condition. I understand wanting to protect the engine, but I think BMW when a little overboard in the full throttle enrichment department.

As to oil consumption, my LT has used oil since it was new. I have broken in most of my past vehicles using the owner's manual technique which generally has one stay at low RPM for the first 1,000 or so miles. After reading a couple of articles about the virtues of breaking in an engine using the "run it like you stole it" approach, I did that on my last two new vehicles: a 2006 Hyundai Sonata and the 2007 LT. The Sonata uses virtually no oil, but the LT requires a half quart between changes at 3,000 miles using BMW branded dino oil. The consumption seems to be getting less as the miles accumulate (almost to 18K now), but it still uses oil. I will like switch to Mobil 1 at the next oil change as I was told it could take 18K miles to fully break-in the Nikasil lined cylinders. I have no idea if that is fact or old wives tale.
My experience says that is indeed a fact. In the aircraft world Nikasil cylinders are notorious for using oil for the first 500 hours of service. The V-Rods I own also have them and it took me 4000 miles to stop oil consumption on my '08. I have seen V-Rod cylinders torn down after 15K miles and you can still see the honing crosshatch. The good news is that they pretty much last forever and in my mind a little oil and attention to level until consumption is managed is cheap insurance in the long haul.
 
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