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Old 05-21-2012, 05:04 AM   #16
hardwaregrrl
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Timing chain. edit Opps, SS got to it first.
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Old 05-21-2012, 05:53 AM   #17
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Quote:
Originally Posted by woodgrain View Post
If you think the rod bearings are gone, drain the oil and pull the oil pan off. If they're toast you'll probably find a nice little pile of copper coloured flakes/dust under the oil p/u screen.Easier than pulling a cylinder.Continue from there.

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Old 05-21-2012, 06:12 AM   #18
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Noisey motor

Hi, Just chimed in to read you have some noises. Based on the rough location and description, I agree that it could be in your timing chain area. Assuming that's the case then it's more likely that the chain guide plate and tensioner guide that are badly worn and the chain is starting to slap around. Unless you know that the chain and guides have been replaced in recent times then it would be wise to have it opened up, inspected & likely replaced. Better safe than sorry. At the same time I'd recommend replacing the crankshaft nose roller bearing and possibly the crankshaft timing chain sprocket. I've yet seen a cam sprocket worn to the point of needing replacement, but the crank sprockets do wear and are often overlooked. So they should, they turn twice the number of revolutions as the camshaft.

As you aren't overly familiar with the bike, I'd also recommend dropping the pan at the same, so the camshaft lobes and lifters can be inspected. It's not easy to see from underneath but if you can't get decent visibility try getting marco photo's of the camshaft and lifters and inspect them closely on your computer. Much easier some times.

While the pan is off keep an eye out for a small steel dowel pin (4mm from memory) that can end up in the pan and should be in the No 1 front main bearing carrier. Very rare that it happens, but if I've seen it twice where this pin has fallen out and made its way to the oil pan. The only way to replace it is to remove the timing chain gear and heat up the block and then with special puller tools extract the front main bearing carrier. Big job but best to check while the timing chain is apart, rather than find out a week later and have to do it all again. A standard check for me with every timing chain.

Assuming the cam lobes are ok, then pay special attention to the lifters as they are known to wear out on the ends and as mentioned earlier the resulting metal breakdown can be aggressive on the cam shafts. If the camshaft and or lifters need attention then the time to sort that out is while the timing chain & gear is apart. Cut corners with any of this and it will likely come back as to bite you one day.

You mentioned that the noise was not in the heads, but I'd check the rockers anyway. If you end up having the chain checked etc then you'll be resetting the rocker clearances anyway. While rare I have experienced rocker arm needle roller bearing failures in the past and they will make nasty clattery top end noises. If they are the problem you will likely find bit n pieces of rollers in the rocker cover, With the right tools and know how that one is not such a biggie.

Good luck & keep us posted on the result. Cheers.

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patanga screwed with this post 06-15-2012 at 07:53 PM
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Old 05-21-2012, 06:15 PM   #19
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Thanks to all (and plan of attack)

Thanks to each of you for the invaluable input. I am really grateful, and excited to be getting help from some of the legends (I have been lurking a lot) of the airhead world.

Here is my plan, please feel free to comment, suggest or trash any or all of it;

1.) Take rocker covers off, check valve clearances, check for bits of rocker bearing in the covers.

anything else to look for , measure, inspect whilst I am there?

2.) Drop the oil and filter (a week in the bike), drop the sump. Look for copper cloured bearing bits in the sump. Look for the carrier bearing dowel/pin in the sump. Look for any other bits that shouldn't be in the sump. Clean the oil pick up strainer noting bits that stuck to it. Make sure strainer is fitted properly. Visually inspect the cams and lifters from underneath (will use the photo trick!).

Can you guys give a bit more detail on how to inspect the cams and lifters? I guess I need to turn the engine over and get several looks at it to cover the cams? How do you see the lifters? Or is it obvious once I am there?

Anything else whilst under there?

3.) Take front covers off. Change timing chain, guide and tensioner (I already have these as was intending to change as part of the "Max love for an old girl" philosophy). Check the crankshaft timing sproket for wear (???). Check the nose bearing for wear/replace???

Anything else I should do whilst I am in there?

How do I assess the state of the Crank spocket?

How di I assess the state of the nose bearing?

Again, Thanks for the help, and I feel much better about diving into the innards of my old girl with your support.

Cheers,

Toby
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Old 05-23-2012, 07:14 PM   #20
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You could also use a timing light as see how the S mark holds when the revs go up and down ...should be a sharp image..double or blurry means a loose chain.
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Old 05-23-2012, 08:43 PM   #21
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Thanks Greg,

That is a good tip. Will do. Any suggestions/recommendations on the type of light to get?

Any other input/comment guys before I rip in on Saturday?

Cheers,

Toby
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Old 05-27-2012, 01:05 PM   #22
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My timing chain was slapping around pretty good but the "rattle" was steady when the engine was hot....and the timing mark was jumping all over the place.

My find:

New / old tensioner....the tensioner was hitting the engine casing.
.


Yup....she was loose.


I replaced it with a master link type chain. During installation I positioned the master link at the bottom of the lower gear which made getting the little clip on fairly easy.
I didn't change the gears...didn't have the proper pullers / patience for that. I think the new chain will probably outlast me anyway.

I hate to say it but the symptoms you describe make me think a rod bearing is going south.
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Old 05-27-2012, 05:21 PM   #23
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Question Update

Hi All,

OK, so I ripped into the old girl on the weekend. First time in these parts of an airhead.

I found it very hard to read the OT mark under the timing light (perhaps inexperience, or it was jumping hugely)???
No bits of roller bearing in the rocker covers - Good.
No one valve lash miles bigger than the others - Good
Actually some of the lash was too small, one virtually (.04mm) nil. - not good??
Sump not sludgy - good
Under the strainer - one tiny piece of alloy (1-2 mm), a few bits of silicone, about ten little chunks of what looks like plastic/bakelite from the tensioners - Not too bad.
No pile of copper bearing bits - Good.
No 4mm carrier dowel - Good
Oil filter (from BEFORE the noise started (ie changed 1000 km ago) disected and no bits found - Good
Inspected the cam lobes from underneath/turning engine on kickstarter from under (prettty reasonable view actually) on signs of pitting/scoring - Good
Pulled the timing chest to bits, no bits lying around - Good
Chain looks fine (even pretty new) but no way to tell so out she comes.
Both guide and tensioner are missing a small amount of material, (probably accounts for chuncks in sump), but not really chewed to pieces.

So, here's the questions:

How do I inspect the Lifter faces?
How do I tell if the crank sprocket needs changing?
Why was the engine making the noise? could it be rod bearings without copper bits in sump (as above)?
What should I do next?
BTW the engine has decent (150psi) compression, and doesn't blow oil smoke.

As always, very grateful for your input,

Toby
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Old 05-27-2012, 08:03 PM   #24
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The lifter faces will have pits in them if they are damaged. Looks like flaked off chrome. Shine a light into the lifter bore to see if cam lobes are damaged. the cam is often still good just need new lifters.

I always change the gear on the crank shaft. This is recommended by others. Supposedly the large gear on the cam is OK to leave alone. The bearing at the front of the crank some will reuse. I never got one off that I didn't damage or if I did it had a bump in it anyway. I change that.

Two parts of doing a timing chain to watch out for. First is getting the crank gear off. A good, not cheapo, gear puller will work but make sure you use a button on the crank nose. These gears sometimes come off rather easy and other times they are on hard and will need a lot of force. Don't use too small a puller. The nose of the crank can be damaged when pulling the gear, that's why always use a button here. The last one I did I even used heat and when it moved it made a big POP. It was on tight.

The second thing is getting the master link together. The link goes on the back side of the chain so it's hard to finagle it together. I could do a timing chain job in just a little over two hours but the last one I played with getting the link on for over two hours so the job took 5 hours. Good luck with yours.

I don't think rod bearings are expensive. I've reused bearings and replaced them because I had them anyway. You might as well look. I think they can fail in more than one way and there don't have to be copper pieces to see. Also replace the rod bolts. Do you have the tool for those?
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Old 05-28-2012, 11:33 AM   #25
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You could back your lash adjusters way back and then mover the lifters off the lobes to look at them.

Look very closely at the teeth. I suspect you see that one side of the teeth have a different curve. Make sure one of those junks of silicone you saw hasn't ended up in the bottom of the oil fill port for the hydraulic tensioner. That could cause your symptoms. If the chain is the source of the noise I suspect that you will be able to find signs of it hitting the cover or bearing web.

That noise could be anything or nothing. I wish you could have listened a bit more closely with the stethoscope but, like a lot of this stuff, some experience and wherewithal comes in handy.

Did you inspect the oil filter that was in the bike during the problem? No pinched white O-ring? The filter bypass ball feels OK?
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Old 06-03-2012, 05:15 PM   #26
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Good News?

Hi All,

I pulled the barrels and pistons.

I found the source of the silicon. The dealer who changed my pushrod tube seals (eight months ago) used plain silicone in there, and a ring of the stuff is peeling away on each! ARRRHG!

There is a ground out bit on the bearing carrier, but it seems to be behind the timing chain guide.

The lifters are good. The bores look good. The rod bearings both feel good both ends.

The rings are not broken.

Here's the questions:

How "proud" should the valves be of the top of the chamber level? they are all raised, but only a little on one edge of the inlets?

The exhaust rockers have some pitting on the faces. It seems pretty minor, but how critical is it?

When I put the rings into a bore with the piston (so they are in straight) the gap at the end is about 1mm. Is this too large? Should I just get some new rings?

I am going to replace the big ends whilst I am here.

I suspect the noise was from the tensioner not working properly due to bits of silicone/tensioner face blocking the hydralic fill port. Is this possible?

Any other thoughts and suggestions?

Thanks in adavance.

Toby
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Old 06-03-2012, 08:12 PM   #27
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That's what I suspected way back. Yes it's possible. Especially if you found some silicon laying in there?

Brand new BMW rings most often gap out of spec.

I would have to see the rockers but they weren't the source of the noise. .

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Old 06-11-2012, 07:02 PM   #28
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A few things to be sure about

Ok!.. This job isn't majorly difficult but there is also a lot that the novice can stuff up, so a few things to check:

A general rule with all things BMW airhead; If the part to be removed/fitted is an interference fit from factory, it will need to be warmed up to remove/refit. Overlook this step at your own peril. The crank nose bearing should only need to be warmed for the puller to remove it, (replace it, do not reuse. Not worth the risk) but the crank sprocket may need a bit more heat. (not glowing of course.) Make sure to use a copper button/coin/washer with centre hole to take the punishment of the puller centre bolt, rather than hurting the crank nose. When heating up the sprocket don't do so on concrete floor (use a clay brick) as that stuff has a tendency to explode when heated by a direct high flame torch.

As you have gone as far as pulling the barrels off you may as well extract the lifters and cam shaft and check them. If the lifters look ok then then operating surfaces should have a slightly convex surface. You can test this by holding two lifters against each other as per the photo and they should be able to rock against each other slightly. Plus you should be able to see light between them as you hold them up to a light source, Here are a few images from a T/C and lifter job I did a little while ago. Warning!! removing & refitting the camshaft is a different, more involved (i.e. gearbox out) procedure on the earlier twin row chain models.

I'll start with the lifters: This is what they look like when worn.




Assuming yours don't look like those above the next check is the convex surface test I mentioned. If you don't get the result below and they are flat topped (i.e. No convex or light gap) then they are one step away from looking like those above.




Regards the sprocket and bearing, make sure to use heat, A hot air gun (not a hair dryer) or hot oil should be fine for the bearing. If using a gas torch make sure not to get the flame too close to over heat or damage the bearing or sprocket.. You just want to warm it up so it grows enough to get over the crank nose. (refit image below. Same procedure for sprocket and bearing) Gently tap on the inner bearing race only when fitting.




As for the crank sprocket, they are usually a pretty tight fit so a little more heat might be needed. (not glowing hot though) Gently tap on using a suitable sleeve. Nb: the above image shows the crank nose bearing being fitted, but obviously the sprocket goes on first. Just demonstrating the fitment is all.




Once you've got the sprocket on and timed correctly, then comes the fiddly job of putting the link back in. Firstly, make yourself a link holding tool using the old tensioner spring per photo below. (easy & cheap)..... Regards the chain; these days I use a single short zippy tie between the link ends to hold the chain together (Where you can see the pliers in the second image below). A pair of needle nose pliers as per the same photo does the job as well, but they do have a tendency to slide back and off just when you need them to hold. Plus the zippy tie will free up an extra hand to make fitting the link easier. Once you've got the link in and the clip secured (the link clip is directional BTW and needs to have the closed end fitted in the direction of rotation) just snip the zippy tie off and it's done.




If you look at the timing chain tensioner in the photo below you will see the three tools that I use for the job. 1) is the pliers/ now a zippy tie. 2) a recycled tensioner spring 'link holder' tool and 3) is the tensioner lock out tool, made from an old O.E. steel based T/C tensioner rail. (# 2 & 3 cost nix and are easy to make), Nb: The later, all plastic type T/C tension rail can't be used to make the lock out tool.




Next; make sure you bleed the hydraulic tensioner piston. Very important!!!!... First; remove the fitting tool from the above image. Next; pump some oil in to the funnel top section and then actuate the tensioner rail until you feel that the piston has been bled of any air. You will know when this is good by the way it feels.



Make sure to lube the sealing lip of the oil seal on the cover before refitting the cover. Oil lube the timing chain tensioner rails and chain before putting the cover back on. Do NOT use gasket sealer on the new timing chest cover gasket. Be sure to fit the two small (new) gasket spacer washers to the top of the timing chest cover where they belong.

Oh & when you reinstall the camshaft and lifters, make sure to lubricate the operating surfaces and bearing journals with some engine building lube so that they don't run dry on start up.

Close it all up and don't hook up the battery until the front cover is on a secured. (same before you take the front cover off. Disconnect the battery or you risk shorting out the alternator diode board with the cover when it touches the live 'farkles').... Next:...... Tappet adjustment...... Ignition timing....... Carb tune and you're away.

There's nothing like testing yourself by biting off more than one can chew, but be very careful as there are some jobs/lessons that can get very costly as, when & if things stuff up.... If you're not sure...Stop! before going any further...... Someone on the forum will have the answers. This job is ok for those willing to have a go and with some technical engine knowledge, good tools and ability behind them, but there are also some jobs better left to the specialists. Good luck with your repair..

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Old 06-11-2012, 07:47 PM   #29
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Patanga that's great!

Thank you for posting those up!
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Old 06-11-2012, 08:26 PM   #30
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No Worries!!!

Quote:
Originally Posted by ozmoses View Post
Thank you for posting those up!
All Good ozmoses.. Just hate to see a noob jump in and risk damaging a beautiful 247.. These things a simple by design, but they're a lot more than just lawn mowers too.

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