Noise from front engine casing.

zmh2012

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Lake District , uk
1200gs 2004

Have been working on the bike over the winter, the main job was replacing the alternator as it was badly cracked. Have replaced with bosche using existing pulley (drilled out) , the bike has not been started for a couple of months.

All went well - ish, new alternator with existing pully was about 5mm out of line with bottom pulley but all went back in ok. Started up and ran but there was a high pitch scraping noise from the front of the engine, did not go away with time (10mins), thought the bearing in the new/old (ebay) generator was duff so took the belt off and found the noise was still there. Thought I may of dropped a washer or something behind the main pulley so took that off . Noise still there, it does sound a bit terminal but hard to pinpoint where it was coming from, could be the bottom shaft bearing or the main shaft not sure but does not sound good. Oil is all as it needs to be but it is an old bike (as you can see by the state of the front panel.

Look forward to any thoughts before putting on trailer and taking to dealer for last rights etc.

Video of noise.

https://youtu.be/qxtwEpXvEMo

Thanks

Martin
 
The issue appears to surround the fact that the pulleys don't align. Presumably they did previously; does the crank pulley seat correctly when offered up to the crankshaft, or does it try to pull the crank forward, removing any vestage of free-play/float as you tighten up? Incidentally, why did the crank pulley need removal - I understood the belt & then the alternator could be removed without.

http://www.realoem.com/bmw/enUS/sho...25-BMW-R_1200_GS_04_0307,0317_&diagId=12_1435

I fancy you need expert opinion, so why not talk to you local dealer or one of our resident specialists.
 
Thanks for the reply, the newer bosche unit I think sits a 5mm forward of the Denso unit at the spindle, a well known parts provider stated you can swap the pulley wheel, which you have to drill out to do so (they have I think changed their info after I pointed this out), so the pulley is 5mm forward however I cant think this would of had an effect on the lower crank shaft spindle. With both pulleys removed (I removed the crankshaft spindle as I thought I had dropped something behind it that was now catching) the noise if from front crankcase somewhere. I agree it may be a dealer job .
 
Some of the more learned may not advise trying this.

does the noise go away if you remove the belt ( ie so the alternator isnt turning) and run the engine?

it may be you have over tensioned the belt, and your actually lifting the crank slightly ? or pulling down on the alternator spindle

Can you refit the old unit to see if the noise goes away ..
 
Santa-2512 said:
Some of the more learned may not advise trying this.

does the noise go away if you remove the belt ( ie so the alternator isnt turning) and run the engine?

it may be you have over tensioned the belt, and your actually lifting the crank slightly ? or pulling down on the alternator spindle

Can you refit the old unit to see if the noise goes away ..
Click to expand...
I thought the belt was already off in the op video? Is that not what we see, the crank end with the pulley wheel off?



Sent from my SM-N910F using Tapatalk
 
Slipperyeel said:
I thought the belt was already off in the op video? Is that not what we see, the crank end with the pulley wheel off?



Sent from my SM-N910F using Tapatalk
Click to expand...

Yes your are rignt , not paying attention. the noist sounds like something is moving, possibly a worn/ dry ball in a bearing prhaps.

Shame the OP couldnt keep the camera still for long enough to listen for longer
 
Santa-2512 said:
Yes your are rignt , not paying attention. the noist sounds like something is moving, possibly a worn/ dry ball in a bearing prhaps.

Shame the OP couldnt keep the camera still for long enough to listen for longer
Click to expand...

I agree, it sounds like a dry bearing, but without the alternator in place what/where could it be. BTW, let's assume the OP has the correct oil level at the outset?

The main bearings are shells, so assuming full oil pressure is present, they should be silent ........ http://www.realoem.com/bmw/enUS/sho...25-BMW-R_1200_GS_04_0307,0317_&diagId=11_3669.

Otherwise, the cam chain/sprocket sit behind there, but I don't sense a cam chain rattle from the vid. so presumably the tensioners are OK. Thats why I was wondering about crank end float earlier & whether the sprocket had any impact on this - it should not. BTW OP, has the front crankshaft oil seal been replaced?

However I do start to wonder whether we might all be trying to outthink this - with the alternator in place & maybe a 5mm machined spacer to correct the belt alignment, I do wonder whether the noise will simply go away when the outer cover is replaced. After all, the bike hasn't been used for months.
 
The problem with these, there are so many rattles that it is hard to identify which is normal and which is not.
You may have to:
Check the valve clearance and end float, visually check the cam chains then put the alternator back on, ride it and see how it sounds.
 
I had a similar screeching thing on my old 1150GS, not had the 1200 apart so not sure how similar they are. The problem was only that I had not seated the pulley wheel correctly.
 
Thanks for all the posts, the noise is definitely coming from the crank shaft pulley area , I had the belt on for a very short amount of time (short test drive). The bike has been laid up for 6 weeks whilst I carried out the alternator replacement so something may of dried out but the oils were good during this period. The alternator pulley is approx 5mm forward of the crankshaft pulley so it may of been pulling the crankshaft pulley forward very slightly , could this of caused the issue?

Have tried to take a better video and you can hear the noise is from the crank area I think. Trying to rack my brains to think if I have done anything stupid but its just a straight alternator swap (petrol tank off/ cambus computers out the way/ front suspension unit out/change unit,drill out pulley, install on alternator, replace belt, replace suspension/computers/tank. spacer out front panel so does not catch alternator pulley and start up . I though the noise was the alternator !

Motor is 14yrs old 56k .

Any other comments appreciated.

Video of noise.

https://youtu.be/bk99Xls0Bog
 
Does the tone change if you give the spinning thing a good blast of WD40?
It sounds like a dry plain bearing squeal.
 
Worst case if its not the oil seal take the cover off and have a look inside, you are almost there,
was the bolt reach the same on the alternator mount, could they be in too far on a shallower alternator mount??
 
I will check the bolt reach - it looked the same but obviously was 5mm off on the pulley when I put it together. Ive decided to have a go and pull the timing chain cover and see what is what - the local BMW place is booked up for about 3 weeks and its £90 per hour for them to have a look at it. Im coming to the conclusion it may be a dry bearing or its shifted in some why when I put the off centre tension on the crank end, even so its going to a touch and go if its worth fixing if its a complete rebuild for the engine. Was due due to go riding with some friends in a couple of weeks so really p****ed .

I did try the wd 40 but had no affect.
 
It still sounds to me to be localised in the front cover. Did you pull the front off yet?
 
No not pulled cover yet , am getting the oil seal and the puller frame sorted and then will try . Thanks for the engineering link- will contact them and see what they think. A friend is lending me a trailer if I need it.
 
zmh2012 said:
No not pulled cover yet , am getting the oil seal and the puller frame sorted and then will try . Thanks for the engineering link- will contact them and see what they think. A friend is lending me a trailer if I need it.
Click to expand...

I just took a pic of the inside of an old engine.
 

Attachments

  • 20190221_203559.jpg
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Its unlikeley that the belt out of line has damaged the engine,
There is a thrust washer/bearing which takes forward pressure on the crank from the clutch release bearing,
 
Thanks for the pic and the note about the thrust washer bearing , where about is this - is it shown on the pic above?
 
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