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Cylinder head and piston removal

14K views 86 replies 21 participants last post by  jzeiler 
#1 ·
My 2000 is on the lift with "tupperware" removed for BMW "Inspection" at approx 95K miles.

She's been using oil beyond what I find acceptable, having to add oil every day on long rides or every couple of days of short rides.

I did a compression test and cylinder leak-down test a while ago, everything normal.
I suspect a cracked piston land so have decided to do a visual inspection of the pistons.

History: No visible oil leaks. It does smoke more on start up than it used to. Friends riding behind me have commented on smokey exhaust but it isn't that severe because I can't see it in the rear view mirrors. I have ridden hard over the years, two up, pacing some of the sport bikes in the hills, so the engine has been hammered pretty hard; basically getting all she has to give it terms of rpm's to the redline. I did have my air temp sensor unplugged for the hot weather hesitation issue for a few years but always ran premium gasoline. I plugged the sensor back in and left it that way since I'm not troubled with really hot weather very often. Other than that, there is no significant history to the engine that I can think of.

I'm no stranger to engines but will be venturing into the LT where I have not been before, so hope to get input and suggestions from my pals Saddleman and jzeiler or others with experience when questions come up.

I'll try to remember to take some pics so I can post and share a little of what I learn.

I have both Clymers and the BMW Service Manual; I'm used to the BMW Manual so I'll use that unless I get confused by it and then I'll check with Clymer.

This is what I expect to be doing tomorrow: sequence according to the Service Manual: 1)remove radiatiors, 2) remove exhaust, 3) remove fuel rail, 4) remove throttle butterfly rail with air silencer, 5) remove timing case cover, 6) remove timing chain.

Questions right now: Should I zip tie the cam chain to the cam sprockets when removing the cam chain? Will that make reinstallation easier and reduce the risk that I'll get the valve timing wrong, or will that just increase the hassle?

Should I do a "preemptive" change of the O2 sensor?

I've done valve jobs on small engines, and lapped the valves on a couple of Airheads, but I think I'll send the K1200LT head out for a professional going through. Any idea who to send it to? I'm wondering if valve guides or seals are a bit worn.

Any suggestions of things to look out for from those who have "been there, done that"?

Thanks in advance.

My posts are often verbose, so full credit to those who wade through them. :)
 
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#43 ·
Curtis, I am curious about these exhaust valves, it would be good to get some information back from the machine shop as to the material and technology used in the valves. Reason being, BMW states lapping or valve replacement, which may mean the valves are nitrided, which typically can be as thin as 0.0005" and a light lapping does not adversely affect that coating, whereas re-grinding will. Also, regarding the valve seat geometry on the exhaust side, is the information available regarding seat width, angle etc ? I think cylinder heads on these engines are typically very good in this area, as not too much is written about problems.
 
#44 ·
Dennis, good questions. :thumb:

Stopped by my local BMW shop and talked about grinding my exhaust valves. They have a local machine shop that they work with. Apparently, they do grind the valves on K bike engines.

Here's a cut n' paste from AJ Cycle's website:

"AJ Cycles Services
Full Service BMW & MOTO GUZZI dealer. Certified Master mechanic with 38 years motorcycle experience.
Parts and Sales personnel with 48 years motorcycle experience.
We have excellent machine shop services which include: Welding (Fin Replacement, Crack Repair in Cylinder Heads, or General Repairs), Boring, Valve guide and Valve seat replacement.Vacuum Testing. Valve Jobs
If it needs to be machined, we can do it all with state of the art equipment."

So at this point, my head and valves are going to the machinist for his evaluation and comments. We shall see what he recommends/does.
Also of note is the official BMW Service Manual states that if the valve seat is ground, new valves should be ground in. Hmmm....what does that mean?

Also, the gent (Alan) at the BMW shop repeated something DShealey posted above, which was that lapping was an "outdated" procedure.
When I said the BMW Service Manual mentioned lapping, the gent at the BMW shop questioned me: "Are you sure that BMW says that?". So I went back and looked; actually the BMW Service Manual does not mention lapping. BMW simply states three things regarding servicing the valves:
1) "Machine the valve seat with turning tool BMW No. 00 3 530.",
2) "When remachining, the correct width of the valve seat must always be maintained.",
3) and "NOTE: If the valve seat has been machined, install and grind in new valve."

The Clymer manual has a more extensive section on valves and does discuss lapping. But then Clymer could just be adding generic, general info on customary valve procedures which are not really BMW specific.
 
#52 ·
Hi Dave,
Got your msg. Thanks for checking on valves. The head is presently at my local BMW shop, or maybe already at their machinist's shop. I probably won't hear anything 'till after the holidays.

DanM kindly offered me valves out of a spare used head that he has. If the machine shop says mine can't be ground, I'll consider taking Dan up on his offer. If those valves look good, I would install 'em and check the seat seal. Maybe lap them lightly.

Nice to have options. Thanks, will be curious to find out what you learn.

Merry Christmas, Happy New Year!
 
#53 ·
The Exhaust valves are smaller than the Intake valves & the fact that they are $40 more each than the Intake valves tells me they are made of a different material or have been through a different heat treat process. They could also be sodium filled.
 
#55 ·
SITREP

Just got head and valves back from AJ Cycles.

Reassembly begins. I probably should have just taken the whole assembled head to them in the first place, but then I'd be missing all the satisfaction of going through it myself...

Valves were seated and vacuum checked. Only the exhaust valves were ground as they were pitted, the intake valves were all okay.





 

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#58 ·
It's been a long time since I've done work like that. From the look of the exhaust valve after grinding it looks like from the margin they didn't have to remove much to clean up the valve face surface. :thumb:
 
#59 ·
I got a PM from fpmlt asking what I thought the causes of my oil use was now that I have had a chance to inspect things.

That prompted me to compare my one of my old valve stem seals to a new one.

The ID of the old seal is about 1mm larger than the new one. Also the rib that is visible on the new seal seems to be absent on the old one.

It looks to me like pretty seriously worn seal; whaddya tink?

 

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#67 ·
This latest post brings up a question (If I may):
Given a valve spring compressor like David Shealey has showed in post 9 of this thread, do you think the valve-seals could be changed without removing the head from the engine-block ?
http://www.bmwlt.com/forums/k1200lt/116985-cylinder-head-piston-removal.html#post1154777
Obviously, each piston would be positioned at TDC when appropriate to keep valves from falling down.

I have removed the cylinder-head before (leaking head-gasket) but never had to change valve-seals and your post got me thinking in this direction...
 
#61 ·
Popeye likes Olive Oil....

Most of the time I used Mobil 1, that is after I got to 20K+ miles.

One of my theories: The bike never used oil for the longest time; it wasn't until 70 or 80k miles or so that I started to having to add oil between changes. I used to be amazed that the bike would go 6000 miles and not need any oil. I used to ride pretty aggressively, two up, passing on uphill grades, rpms to the red line time after time. I routinely pushed the motor like a race engine.

One day at the end of a day long ride of that kind of riding, I discovered the oil level was below the sight glass. Ever since that day, it had been progressively using more oil. I suspect things just got too hot and lubrication at the seals wasn't good and the seals got "cooked".

Whaddya tink of that theory?
 
#63 ·
That sounds very plausible to me. I asked about the synthetic since it swells rubber parts more than regular oil. It could (maybe, not saying it did) swell the seals just enough to get that deterioration started and the carbon particles did them in from there. I can tell you that in overhead valve motors the valve seals are a common source of excessive oil use. Your take on it sounds like the most logical scenario to me.
 
#66 ·
I asked about the synthetic since it swells rubber parts more than regular oil.
I always thought it was the other way around, that regular oil will swell the seals and that synthetic will not. Also on older vehicles, switching to synthetic caused oil leaks as the synthetic oil finds the smallest opening in gaskets.
I blame the synthetic oil on my rear main seal that went out on my LT, causing it to get brittle, hard, and falling apart. With regular oil, it may have kept the seal pliable and not leak.
Just my $.02!
 
#64 ·
You should check for good cross hatching on the cylinder walls. If they looked glazed run a lapping stone through them. With horizontal engines that don't have rider rings on the pistons, do tend to wear the bottom cylinder walls. I dont think the stem seals are the 100% of the problem. Check ring gaps in cylinders before completing rebuild. Place ring gaps away from the cylinder base when rebuilding. They do rotate a little but will not do a full 360 degrees. Check actual stem diameter and check for ovality in guides. Lap seats and valves before final assembly. Been rebuilding engines for forty years now so I know a little about them. Dino or synthetic won't make a difference. Lack of regular changing will however. Don't be shy with rebuilt engine neither run it in hard. Modern made parts are better machined than there earlier counterparts. Some engines need to get full load immediately on first start up or glazing begins straight away. Cummings diesels are the worst for this. So no long periods at idle. Good luck with your project. Last word use Lubriplate when building motor on all bearing surfaces, this will hold off any wear until oil pressure is up.
 
#65 ·
The Nikasil coating on the aluminum bores does not "glaze" like cast iron bores do. The cylinders are aluminum with a thin plating of nickle with microscopic silicon carbide crystals embedded in it. The cross hatching you see is done BEFORE plating, so you cannot add cross hatching later. Factory honing is done with DIAMOND hones, only to make sure the surface is flat, no material to speak of is removed. You can run a ball type hone through the cylinder quickly to 'clean' the surface, but do not try to remove anything measurable off the surface. The silicon carbide crystals in the coating are harder than the honing stone, and you will end up removing a little nickle between them making them stick up. That will cause ring and piston wear.

They did a vacuum check on the valves, no leaks, so lapping is not a desirable thing.

I agree with the hard run break in. When I rebuilt mine I fortunately lived in a mountain area, so would ride easy until fully warmed up, then get it in high gear at a relatively low speed starting uphill, then full throttle up hill for a few seconds, coast a little and low throttle for cool off to the next uphill, then repeat. The high cylinder pressure pushes the rings out against the cylinder wall, and will "seat" the rings much faster than easy running. There are a couple web sites about this.
 
#68 ·
John,
can't answer your question, but I have used compressed air to hold valves in place and replace a valve seal on a Ford motor. With the cams removed you put the cylinder at bottom dead center and then just apply your air through the plug opening. Since both valves are closed, the pressure holds them shut. If you do this you'll want to open the oil filler cap to allow easy escape of the blow-by. The adapter looks like a compression tester, only with a Milton quick connect on one end.
 
#74 ·
SitRep

Buckets from kind members on this site, plus a few more from MaxBMW and I have my exhaust valve lash back in spec. :)

Recapitulation: I did this because of excess oil consumption.
Installed new piston rings. Nothing done to pistons or cylinders. Not sure I needed to change the rings as the old ones looked good.

New valve seals on all valves.

No change to intake valves themselves. Machine shop did vacuum check and intake valves were good.

All exhaust valves were ground because of pitting on the valves; the exhaust valve seats were fine. I then shortened the valve stems to compensate for the valve grind and use a bunch of 2.9xmm cam followers I had from previous adjustments. I over-shortened the valve stems requiring me to acquire several cam followers in the 3.0xmm range.

Reassembly will begin tomorrow.

Stand by for pictures of things with my query:" What's this, and where's it go?" :histerica

Attached Pic shows nothing special, just exhaust camshaft in place for final check of exhaust valve clearance. Easier to do on the table than on the bike.
 

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#75 ·
Just to clarify, David is correct if you are applying air with the camshaft installed. With the camshaft removed, the valves are all closed so BDC is much easier (and safer) to work with to replace a stem seal. I don't know if a compression test would be feasible or accurate at BDC. I can tell you that on a Hughes 300 helicopter, it gets real ugly real fast when it gets away from you. I helped do a couple compression tests on the scheduled maintenance once upon a time. That was enough for me.

Curtis, I'm looking forward to seeing if the seals solve the oil use issue for you. I certainly hope so since I intend to ride mine as long as I can keep it running.
 
#76 ·
I just discovered this thread. Bet it's the stem seals. Has the engine ever gotten hot? or might the cooling not be what it used to be? maybe the water pump impeller?

It is fun to read a thread from a bunch of observant engine gurus with good photo skills. Hat's off to all of you.:wave
 
#77 ·
I've now had my 2000 K1200LT out for a couple of short rides.

All conditions normal, Sir!

New rings, exhaust valves ground, new valve seals, new rubber all round the crankcase ventilation system.

It'll take a few miles to tell if I've fixed the oil consumption problem, but I can't imagine that this engine isn't like new.

Thanks to all who offered suggestions and encouragement, and parts. :thumb:
 
#81 ·
Sounds good Curtis. Mine is starting to use a little oil between changes @91 K. I have not ridden it a lot since I got the GS then traded for the GT. But have a couple of trips planned for later in the summer that should get a better read out on oil consumption. If so I may just do the seals with the head on and see if that does it.
 
#82 ·
I suspect I could have gotten away with just doing the seals. But in the name of fixing things that aren't broken I replaced rings and had exhaust valves ground.

Compression and leak down tests before my tear down were acceptable, but I just didn't know what the problem was.

The exhaust valves had a mottled look on the seating surface of the valve but felt smooth. After I cleaned the valves of all the carbon deposits, the mottled areas became pits. So it seems that the pits were filled with carbon deposits and the valves were sealing pretty well.

So I am happy I did the tear down and ground the exhaust valve; replacing the rings was a waste of money.

Dave S modified a valve compressor tool by using a cam follower (bucket) which was a really great idea; it make the tool very stable and secure during the process.
 
#84 ·
I just looked and over the last 11 years and 91 K (miles) I have replaced only 1 exhaust and 3 intake buckets (@48 K), and one each intake @ 62 K and 76 K. Every thing was just fine at the 91 K check.
 
#85 ·
Resurrecting this old thread with an update on my oil consumption. I was using more and more oil between oil changes. Measurable as from the top of the sight glass to the middle after just 250 miles. So I got the valve spring compressor from David Shealy and replaced all my valve stem seals. The old ones did not look as bad as Curtis' but there was some evidence on the valve guides of "crud" under some of the seals.

I used a two at once approach to the cylinders and ran a "T" hose to #1 & #2 at the same time with all pistons at 90 past TDC. This approach worked well as there was no turning force as you would have with only one cylinder pressurized. I could also keep the cam gears tied to the chain as i didn't have to rotate the engine at all. I could leave the compressor in place for 8 valves then remove it and move the two hoses to the last two cylinders.

I finally had a chance to do a significant ride today and I started out cold with the oil level at nearly the top of the sight glass. After 250 miles of riding I checked and it was now down to the center dot on the sight glass. So no joy on the valve seals being the major culprit.

So maybe replacing the rings was not a waste of time and $$ a you suggested Curtis.

I really don't want to go back in and remove the cylinder head and replace the rings. For the cost of just the parts (over $700) I can get a used low mileage engine off ebay.

Feeling a bit frustrated now.
 
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#86 · (Edited)
Ok now that I have slept on it and the fact that Hermy's BMW has a 20% off sale I went ahead and ordered the gasket, rings, rod bolts, new valve seals as I have to take it apart I might as well get a full cleanup of the cylinder head. And I got the timing chain service kit for those wear items for less than the used engine I have been looking at on ebay. I am retired and what else do I have to do other than wrench and ride? Plus I have the GT to ride while the engine is down.
 
#87 ·
Well now that I have all the parts to re-ring the engine and do a valve job I may not have to. Bottom line after I replaced the valve stem seals and did a 250 mile trip there was a drop in oil level from the top to the middle. I changed back to Dino Castrol 20W 50 and after a 200 mile trip today the oil is still at the top of the sight glass. Go figure. I will try and get at least three or more good long trips in before I call it. But I had already decided even though I have the parts I would rather ride and add oil this spring and summer. It could have been the tired Mobile 1 as it was last changed at 98,464 and was due @104,464 but I did the transmission work and removed the intermediate housing (lost oil) and just topped it off @ 102 K. Finally changed to Dino @ 106,543.
 
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