Rattle from front of engine

[Aviationmx]

99 11rt 50 K miles. mobile one twin oil syn

 

I've been chasing a rattle for a week now, eng sounds fine when cold but after warmed up it developes a rattle that sounds like the lower front of the eng. I was hoping for a cam tensioner (left or right) but neither seem to be the cause.

 

I'm not sure if the alternator has the ability to rattle or if there's another item in the middle of the eng that can cause a rattle..any help is appreciated.

[dirtrider]

Morning Aviationmx

 

Chasing engine rattles in the BMW boxer is at best difficult due to the many internal chains & harsh power pulses on the 2 cylinder engine.

 

Without being there in person it becomes difficult for us to help you find the noise unless you can give us a definite sound to compare to & an exact location of the component that is rattling.

 

 

In your case, maybe invest in a mechanics stethoscope then use it to define the location using both the stinger, then removing the stinger & using the open hose of the stethoscope.

 

Given the location you mentioned there is another timing chain up front with a hydraulic tensioner to keep that chain tight.

Over the years I have seen a couple of 1100/1150 BMW boxers with a front cam chain rattles. It could be a tensioner losing chain control or a stretching chain allowing the chain to rattle against something.

 

Have you removed the alternator belt then run the engine to see if that changes the noise?

 

Another thing to try is switching back to conventional 20W50 motor oil just to see if that changes the noise (sometimes it does) .

 

[philbytx]

If it is a rhythmic clacking in time with the motor, try the RH throttle body cam rattling against the stop !

[dan cata]

If it is a rhythmic clacking in time with the motor, try the RH throttle body cam rattling against the stop !

 

+1

 

The test would be to put finger pressure on the pulley while idle and see if noise changes or goes away

 

Dan.

[Aviationmx]

Thank you, all good info..

 

It was perplexing, a non rhythmic rattle that sounded like a loose chain had me thinking a real problem, but a loose TB butterfly would fit.

 

does this happen because there is too much slack in the throttle cable or is due to slop in the butterfly through rod ( bolt)? I'll try to apply pressure to the through rod to see if it changes...Which lead so me to this question- can i remove the toe pad on the lower fairing to gain assess or do I have remove all the tupperware?

 

I just want to confirm the issue and if it the TB, I'll add to the winter list of projects...

 

I should note that I have taking screw drivers and hoses and checked all the jugs (no rattle) and even tried to isolate the rattle in the front area (no rattle) although I thought the plastic cover in front wouldn't transfer the vibrations well. But I can see the rattle coming from a TB since there was no way to get to it w/ the fairings on. That would be great if it was the TB...lol

[philbytx]

Usually incorrectly adjusted throttle cables.

The RH throttle stop is adjusted when doing a TBS (NOT THE LH...do not mess with it!). You balance for the idle and set the throttle stop so that the cam is solid against it. You then adjust the cables (CAREFULLY and in small increments!) to get an even pull showing on the balancing instrument (manometer/Carbtune or that damn Frog electrickery contraption;)).

 

There are several very good engine tune up docs on the site and also linky's to them. However, I would be happy to send them via Email, so PM me with your Email addy and I would be happy to send them all to you !

[dan cata]

If it's worn, no matter how you adjust the cables, it will rattle.

 

Dan.

[Aviationmx]

Yes, it's the r/h TB rattling...it's strangest thing, the butterfly is almost popping-I guess is the vacuum intake on the other TB (?) . I slacked the throttle cable just for fun, but the butterfly feels like its on the stops, just has some slop in the TB...

 

I thought I did a thorough spraying of both TB's when I was doing the TPS/Sync service (with TB cleaner), wouldn't I have noticed a decel if the TB leaked? or is more of a weak spring deal?

 

In any case thanks, it would have taken away to isolate...

 

 

[flars]

"...If it's worn, no matter how you adjust the cables, it will rattle..."

yup. Although 50K is early for wear to have occurred. You can get rebuild kits direct from Bing with a phone call.

 

My bet would be the cable is too tight on the right side, holding the butterfly just shy of the stop. DO NOT adjust the stop. Just do a normal throttle body sync, which does NOT involve that stop in any way.

[snod]

There is a kit available from Bing USA. The kit includes a new throttle shaft, pully, and plate. That has cured the rattle on both of my RT's. There are folks that have replaced the bushing on the throttle shaft, but I know of no kit for that procedure. The kit from Bing is about $90 a side?

 

Edit:

 

Looks like FLARS pointed you to the same place as I was typing.

[NonComp]

With 65k miles on it, mine just clicks. Sounds like a noisy injector (which is what I thought that it was).

[philbytx]

Generally, the clacking noise is due to inadequate slack in the throttle cable and can be adjusted out. If it is incorrectly adjusted, clacking gaily and ignored, it could cause unnecessary wear on the TB butterfly spindle.

 

Ok, I will now expand upon my post...firstly, I am entirely anal .

 

OK, so you did an anal valve job, installed new plugs and you backed off the throttle cables at the TB's and at both the fast idle and throttle and it currently sits with both sides on the EXISTING cam stops.

 

Your bike idles unevenly and you CANNOT obtain a good, even idle (an even manometer!) by just using just the BBS (previously cleaned) and/or the BBS settings are apart by more than, say, 1 full turn.

 

If the idle is slightly uneven but you have a nice even pull off idle and throughout the range, IMHO, you probably don't need to sweat the finer details.

 

However, if you are unhappy with the the idle, you COULD utilize the RH stop to set the idle to as near a perfect balance, using the following TB Butterfly visual check coupled with your manometer (or whatever).

 

Firstly, you just need to expose your TB intakes and view the angle of each butterfly with a flashlight comparing the LH (benchmark!) to RH in relation to each other. Unless previously messed with (a whole 'nother issue!), you should use the LH TB cam stop as your baseline. The stock butterfly open angle setting on my R is 10 degrees and on the RT only 5 degrees.

 

Then, setting the BBS's at, say, an initial 1.5 turns each (really, as long as they are even!), gently adjust the RH TB stop (won't take much!) so that you have EVEN or near as dammit even, columns on your manometer (slightly fiddle with the BBS to nail it) and the bike idles at around 900 rpms. You can then finely adjust the BBS's to get the bike at the recommended 1000rpm + 150rpm (R1100) or 1100 +/-50 (R1150RT) setting and they should be within 1/4 to 1/2 turn of each other. You then check your manometer (or whatever!) settings to see if you have the same even columns throughout the rev range.

 

You CAN utilize the RH stop adjustment to flow match the idle IF NEED BE. The old "don't mess with the throttle stops" chestnut has been debunked a few times and you can certainly find articles on it the subject by doing an Oilhead Throttle Body Stop search on the Internet.

 

I used the above method on BOTH my bikes and both idle evenly and pull evenly throughout the RPM range. This all started because when I bought my "pre-loved" R1100R, it idled badly and, upon checking, was quite badly tuned and, after some frustrating times trying to set it, I researched it, discovered the articles and so decided to use this method.

 

During the last 6k on my R1150RT, I was not happy with the idle and so employed the same methodology and nailed the idle with a very slight incremental move of the RH throttle stop.

 

YMMV and I recommend you do only that with which you are comfortable.

[Aviationmx]

I'll order the rebuild kit for the big winter servicing I'm planning.

 

Ironically, I was heading down Phillby's recommendation all ready.

 

Idle was actually at 1200 rpms and was strong w/ a slight miss, I have noticed the access hole for the BB airbleed on the r/h side and although i had run through the TPS/valve adj/TB sync tuning...I looked up the standard adj on the air bleed screws or BBS- for the RT I had that at 2 turns. SO after adding a bit of slack on the throttle and the choke cables to make sure there wasn't any tension on the TB's at full stop, I checked the BBS on the R/H (fairings are in place) and had it 2.5 turns. I backed the BBS to 2 turns and did a seat of the pants check on power...I can't tell the l/h BBS settings w/ the fairing in place.

 

the idle decreased to 1000/+-100rpms and is smoother but harder to start (requires part throttle when cold) but it seems like smoother power and less vibration at 4k+ rpm (could be my imagination).

 

I'll carry a screw driver around and slowly adj the r/h BBS for a while, but it's seems the TB is quieter at idle and the fuel mixture is more even. I will have to revisit the TB set ups and this time will consider the throttle stop adj ( I didn't want to adj on my first try at tuning).

 

This does have me wondering if i missed the tuning the first time, I did have the manometer at an even pull on both jugs as well as i could , but maybe I just too far out on the BBS's. When I bought the bike the idle was at 800 rpms, the TPS voltage was low and I bumped it up to the .380v min....and maybe got a little happy on the air mixture.

 

Again, I'm just relieved that it was not an internal chain issue and will happily have the butterfly chirp at idle for a couple of months. We have a couple of months of perfect riding weather here in NC and think I'll go with this current tuning for now.