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Oil Burner-Backfire?-Detonation? What gives??

4K views 24 replies 7 participants last post by  herk402 
#1 ·
I'll try and make this long story short, but I want to throw out all details.

Ever since my '03 LT was new I thought that it used a little to much oil but chalked it up to break in period and that it would stop. I rode out to CCR and back and used 2qts in 5000 miles. No other problems.

On the way back from CCR I hit a bird and as it turns out a good portion ended up in the air snorkel and then on in to the filter.

Just got the bike back from it's 24K check (it has 25650 mile on it). A week or so prior to the 24K check I noticed that as I rolled the throttle on from a normal "shift point" weather it was 2-3 or 3-4 that I could hear "pinging" i'll call it. It actually sounded like I was lugging the engine in a gear to high, before anyone says it-- it wasn't lugging, just sounded similar.

It also has a slight noise "light backfire" as you would roll off the throttle from the same "shift point".

The service manager at Milwaukee BMW rode the bike and noticed all the things that I mentioned above. He thought that it might pe slight "pre-detonation". His words not mine.

Just picked the bike up from the 24K service and noticed three thingS:

1. The 2,3 &4 plugs were very fouled with oil.
2. Bird parts were found in the filter
3. Dealer said all the symptoms were gone after the 24K--but on the ride home it was making all the same noises--just not as bad.

Any ideas on whats wrong with my motor????- I want to get a paper trail going with the dealer so I have a strong warranty case when
 
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#2 ·
I've been having much the same symptoms with my bike as you describe.
It was lacking power...lugging badly...pinging horribly...running with black smoke...and backfiring.

My proposed solution may be a bit premature as I've not gotten my bike back together yet to see if have indeed found THE problem.

I found 4 oil fouled plugs. I then pulled the breather box off the throttle bodies and found oil in the top of all the bodies. It looked like it was spraying in there from the ports that are connected to the crankcase breather hose. Next I noticed a lot of oil spray on top of the engine from the 3rd throttle body back to the rear. I then took off the fuel injector rail and the throttle bodies. I found my crankcase breather hose to be SPLIT at the "Y". I think this was somehow causing oil to be drawn out of the crankcase, into the throttle bodies, and down the intake to the plugs. I am assuming with new plugs the bike will run as it should. I didn't try that before tearing the bike down further to find the culpret.

I'd say look under the bike and see if you can find a bunch of oil spray. If you do then you've probably got the split breather hose. Mines not the only one documented on this site.
 
#3 ·
Thanks for the reply Tom...I'll pass that info on to the dealer for them to look at next time under the tupperware. I called them today and told them the bike continues with the problem. They suggested I keep an eye on the oil usage and as it is used see if the symptoms get worse.

Could you see any "oil mist" evidence without plastic removal?
 
#4 ·
Put the bike on the centerstand...get under it and see if the centerstand, skid plate, and lower frame are oiled up. The lower section of my bike is grimmed from the split and ensuing leak. The wind blowing through the bike sprays the oil to the rear and it does get around. I couldn't see the actual root of the problem until I had the bike in "exploded view".

I offered my experience based mainly on your fouled plugs...especially because they were the rearward ones. Plus your symptoms mimick mine exactly.

A question for you. Have you swaped plugs yet? And if so, did the performance improve immediately and dramatically??? It would make me feel better about my eventual outcome if your's did such.

Take care, Tbird
 
#5 ·
Paging Dr. Shealey to the white courtesy phone ...

Hey, David -- your thoughts? Think I'm over-reacting with the following??

herk402 said:
I rode out to CCR and back and used 2qts in 5000 miles. No other problems.
That much oil consumption is *very* unusual on a relatively new engine. I'm on my 3rd LT, and this engine comsumed *teaspoons* of oil over the first 6K -- and that was more than the first two bikes!

I would be very concerned that you have ring/cylinder damage on at least one cylinder. I say this for two reasons.

First, I'm aware of one case reported here of BMWNA replacing a new engine due to excessive oil consumption, IIRC, resulting from a deeply scored cylinder -- so even while extraordinarily rare, such a defect is within the realm of possibilities.

Second, your symptoms suggest huge blow-by compression leakage, pressurizing the crankcase and greatly increasing the amount of oil passed through the breather into the throttle bodies. Whether due to a scored cylinder, broken rings, or broken piston crown (like David Shealey's bike), I suspect at least one cylinder/ring/piston is allowing compression to blow by the rings. Such damage would also be consistent with the unusual noise you reported.

Hate to say it, but if it were me, I wouldn't be satisfied until the head was pulled and someone closely eye-balled the cylinder walls and piston crowns/top rings.
 
#7 ·
Tom--First off I will check the center stand area for grime etc.--I am under the bike cleaning things often & haven't noticed anything.

When I picked up the bike after the 24 K last week it did "seem" to run better, maybe it was because I wanted it to. New plugs were replaced. The following day I went on a 256 mile ride to SW Wisconsin (beautiful color), I checked oil lever prior to departure and it was just below the top of the glass 1/8 inch or so maybe a little less. Checked after the ride and it was a good 3/8 less but still above half. To much oil for such a short ride.

I stated earlier I think that I called Milwaukee BMW today and told them that it still was doing all the same stuff. They called about 2 hrs later and said the regional rep was going to be in on Friday and they wanted him to look at it.

They wanted it for a day or two to do some compression checks etc. (looks like they are thinking like you David).

Do you think I need to put the canister back in before i take it back in? I hate to have the regional rep deny anything based on it being removed. It can't be a contributor to the problem can it?
 
#8 ·
Update

My bike has been in the shop to get treated for the symptoms discribed in my origonal post in this thread. I stopped by the shop today and found out that the compression check were all within spec but the "leak-dawn" check on number 4 failed by 50%. When I left they had approval from the regional rep to remove the head a continue investigating.. Valves..rings...piston or whatever is causing this failed leakdown. Any input from anyone on what you think I might expect?
 
#9 ·
herk402 said:
Any input from anyone on what you think I might expect?
Just a guess: Piston and ring damage, which in turn has scored the cylinder wall.

Because the cylinder cannot be re-bored (the liner surface is a super-hard, super thin, plasma-deposited nickel/silicon/etc. alloy), a complete engine replacement will follow. BMWNA has done this under warranty a number of times -- as much as folks B&M about NA, they do step up to the plate on things like this.

If this is it, it was probably defective from day one, not a result of something you did, and, bottom line, you likely will ride out with a new engine under you!
 
#10 ·
Thanks for the reply Mark,

As I spoke with John at BMW Milwaukee I asked him about that very thing. I asked "if the ring and/or piston are at fault and the cylinder wall has been scored, what happens next?"

John stated that if the cylinder wall was not scored out of limits that it would be honed and new rings and piston installed. Is this a reasonable reply? He even mentioned the name of the shop that they send their machine work out to. You said the cylinder can't be bored...can they be honed?
 
#11 ·
herk402 said:
Thanks for the reply Mark,

As I spoke with John at BMW Milwaukee I asked him about that very thing. I asked "if the ring and/or piston are at fault and the cylinder wall has been scored, what happens next?"

John stated that if the cylinder wall was not scored out of limits that it would be honed and new rings and piston installed. Is this a reasonable reply? He even mentioned the name of the shop that they send their machine work out to. You said the cylinder can't be bored...can they be honed?
If the thin coating has been penetrated, it's a write-off.

If the scratch is minimal, though, it in fact *can* be resurfaced -- but it requires some rather expensive specialized equipment (this ain't a set of honing stones chucked in a drill kind of job :)). In the past, there was literally no one in the U.S. equipped to do it. In the last few years, though, a *few* (very few) independents have made the investment to be able to hone a NiKaSil-coated bore; sounds like your dealer knows of one.

Given the scarcity of experienced shops, the fact that few dealers know where to send one out, and that it may cost BMWNA less under warranty to throw in a new engine than to pay for engine removal, disassembly, ship-out, refinishing, return, reassembly and reinstallation, my stock answer is "they'll probably put a new engine in" :)
 
#13 ·
I got into this one late, see you already have a lot of good info from Mark.

I replaced a set of pistons in my LT due to all four having broken second ring lands from detonation.

Basically, you cannot hone scratches out of the NikaSil coating. It is so thin that almost any scratch is through it and into the aluminum of the engine casting. As Mark said, even if it was so small as to be honeable, you have to have high pressure Diamond honing apparatus to do it.

There is a company that can hone the original coating out, re-coat it, and hone it back to size, but if I remember correctly it is 2-3 hundred bucks per cylinder to do it.

My engine had been running for several thousand miles with 1 inch long pieces of ring land bouncing up and down between the top two rings, but there was NO damage to the cylinder coating. It still looked like new at 100,000 miles. I just put a new set of pistons and rings in, even re-used the original rod and main bearings, as they still measured within factory install tolerances. To my surprise, even the ring gaps were barely at the top of factory install dimensions, not even started into the allowable wear range yet, after 100,000 miles!
 
#14 ·
Good info David, Thanks for more "ammo" without yours and Marks input I wouldn't have known about this "NickaSil" coating. I hope my dealer does. I have no reason to suspect they won't be on the up & up, they have always been true in the past. Again--Knowledge is Power... Thanks guys.
 
#15 ·
herk402 said:
Good info David, Thanks for more "ammo" without yours and Marks input I wouldn't have known about this "NickaSil" coating. I hope my dealer does. I have no reason to suspect they won't be on the up & up, they have always been true in the past. Again--Knowledge is Power... Thanks guys.
I suspect your dealer's being on the level with you. As to knowing about NiKaSil, I have *no* doubt he knows -- BMW started using it in the early '80's airheads, and it was a big selling point -- as well as a bone of contention with the do-it-yourselfers. They were all afraid that BMW was trying to get more money out of them, because you could no longer get over-size pistons/rings, but instead would have to buy a whole new jug when you wanted to do a top-end rebuild.

BMW got the last laugh -- where the earlier airheads often needed at least a ring job and tended to slightly oval out the bores as you approached 100K, the NiKaSil cylinders still looked like brand new well past 100K. Rather than having to spend more to maintain the airheads, the DIY luddites had to (sheepishly) admit that this then-new technology actually eliminated some rather expensive rebuild work, to the *customer's* benefit. Today it's rare to see a NiKaSil airhead jug sold, except to repair accident damage.
 
#17 ·
Update # 2

Dealer called today and said that the cylinder wall was in good shape and that the leak down failed due to the rings not being seated correctly and also the ring gaps not being lined up properly from the start. They will replace the rings etc. and button it up.

Kind of funny---when the gaps are lined up properly, they arent.Anyway..

Does this sound like reosanable reason for the trouble I had and a proper fix?

All is covered under warranty and should have it back by Saturday.
Thanks again fella's..
 
#18 ·
herk402 said:
Does this sound like reosanable reason for the trouble I had and a proper fix?
Yes, it's certainly in the realm of possibilities. At this point, I'd take it and run it normally. You now have it on record that there was an issue. It probably is fixed (nice that I was too pessimistic :)), and even if not, you're covered -- so I'd try to just motor on with it out of my mind.

Oh, and don't baby the motor when you get it back -- there have been more problems caused by failing to work the motor hard enough to seat the rings than problems from hard use.
 
#19 · (Edited)
Ring gaps do not necessarily remain in the orientation in which they were installed, so not sure how he knows that is the case. In theory they do not see rotational forces, but I have certainly seen engines torn down that I know were installed properly only to find the gaps not where they should be.

There are a few things that can cause improper seating of rings. Babying the engine too much during break-in is the most likely. Rings seat MUCH better if run pretty hard (full throttle, high gear, low to medium RPM) for stretches of highway, then run easily long enough to get everything cooled back down, then run hard again. Most people take it TOO easy on the engine right out of the showroom thinking they will hurt it, when the opposite is true.

Also a debatable topic is oils used. Some say synthetic oils used too early can hurt ring seating, but as I said, debatable. Whatever you want to believe here is proven beyond doubt on the Internet! :D :D

Certainly putting "miracle" additives in the oil before broken in can cause problems. For rings to seat properly to the cylinder walls, a lot of combustion pressure to force them out is needed, along with sufficient friction to "wear" the surface in, but not so much heat built up as to glaze the oil film, then you have a problem that can only be solved by a "glaze breaking" hone, but that is not recommended by some experts on NikaSil coatings.

I am not at all surprised that your mechanic found excellent cylinder walls. That is a trademark of the BMW motorcycle engines. BMW had a lot of trouble with NikaSil their cars in the late 80s, blamed it on the high sulfur fuels in the US. Funny, Porsche, Mercedes, and even BMW motorcycles had the same coating, but did not suffer. Of course, it could not possibly have been a process problem at BMW on just the car engines during that time, now could it? :D :D

I would love to know if your mechanic runs any type of glaze breaking hone in the cylinders before putting in the new rings. I have read about 50/50 opinions on any type of honing on NikaSil, curious to have another data point.

I used a "ball" type hone just to clean the surface on mine when I put the new pistons/rings in, but was worried whether this was the right thing to do, read so many things both ways it was a 50/50 shot.
 
#20 ·
When I spoke with John at BMW Milwaukee he did say that they would "recondition by honing the walls" prior to installing the new parts. I guess that would be breaking the glaze.

This whole experience, even if it has cost me two weeks of riding, has given me a better understanding of my bike. Silver lining i guess.
 
#21 ·
I asked the head mechanic at my preferred dealer before I did it, he also said to "run a ball hone through for a couple strokes".

I have also read in a couple places that it is NOT recommended on NikaSil, as the ball hones tend to lower the nickle level, leaving the Silicon Carbide particles "sticking up", which will wear the rings faster. In my studied opinion, I felt the ball hone, which is also Silicone Carbide abrasive, would knock down any silicon carbide particles sticking up. Oh well, I only got 10,000 miles on the rebuilt engine before totaling the bike. :( Was hoping to see how many more miles I could get on it.

I wish I knew the "REAL RIGHT" answer though.
 
#23 ·
mobygrape said:
For what it's worth, on the rare occasions when I re-ring a nicasil bore, I give it a couple of strokes with a ball hone to break any glaze that might be there.
Dang, Paul -- I wish you'd post more often! Your hands-on experience means you probably know more about the K12 than David and me combined! :)
 
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