1996 R1100RT-Hard rapping sound coming out of the right side

[Werner Karl]

I just started up my RT for the first time in 9 weeks.  She idles normally but when I bring the RPMs up it starts to rap on the right side.  I tried to localize the sound with a stethoscope.  Sounds like it's somewhere in the right cylinder.  Any advice on what I should be looking for?  Where to start?  It ran fine on my last trip.  Thanks in advance.  Werner

[szurszewski]

Mileage and recent maintenance?

[Werner Karl]

DATE	MILEAGE	SERVICE
9/19/2019	33625	TRANSMISSION//REAR END OIL CHANGED
		FUEL STRAINER AND FUEL FILTER REPLACED/ALTERNATOR BELT REPLACED/
		REPLACED BRAKE PADS F& B/REPL REAR BRAKE ROTOR/
		CHANGED BRAKE FLUID/REWRAPPED DISINTIGRATED PARTS
		OF WIRING HARNESS/REPL FRONT AND BACK TIRES WITH MICHELIN PR3
		REPLACED LEFT CYL CAM COVER/ADJUSTED VALVES/WK
5/14/2020	36940	OIL/FILTER CHANGE//OIL MOBILE ONE 15W50/FILTER BOSH 72161WS/
		DRAIN PLUG TORQUE 23 FT LBS/WK
10/13/2020	38992	REPLACED REAR TIRE/RIM WITH REAR TIRE/RIM FROM PICKLE(HAS 12000 MILES
		ON IT) REMOVED TIRE/RIM HAS 5300 MILES ON IT-WK
10/29/20	39946	OIL/FILTER CHANGE//OIL MOBILE ONE 15W50/FILTER K&W/DRAIN PLUG TORQUE
		23 FT LBS/TRANSMISSION AND REAR END OIL CHANGED 85W140 TRAHSMISSION
		TORQUE 22 FT LBS BOTH FILL AND DRAIN BOLTS REAR END TORQUE 17 FT LBS
		BOTH FILL AND DRAIN BOLTS/WK
1/16/2021	42752	OIL/FILTER CHANGE//OIL MOBILE ONE 15W50/FILTER BOSH 72161WS/
		DRAIN PLUG TORQUE 23 FT LBS/WK
4/1/2021	44907	REPLACED FORK SEALS AND OIL/INSTALLED GALFER BRAKE LINES
		REPLACED OIL FILLER O RINGS
04/16/21	46728	OIL/FILTER CHANGE//OIL MOBILE ONE 15W50/FILTER BOSH 72161WS/
		DRAIN PLUG TORQUE 23 FT LBS/WK
		REPLACED REAR TIRE/RIM WITH ORIGINAL REAR TIRE/RIM (HAS 5300 MILES
		ON IT) REMOVED TIRE/RIM HAS 20000 MILES ON IT/SCRAP-WK

[Werner Karl]

Sorry, forgot to state current mileage-47479

[Jim Moore]

I'd be a little concerned about the cam chain rails. They've been known to break on these engines.

[Werner Karl]

doesn't sound good.  Could that result in  parts falling into the crankcase?

[Lowndes]

Pry open the valve cover and shine a light down along the cam chain, top and bottom.  You can see "some" of the guides (outboard ends), maybe see any splits or sides hanging off.

 

Might try cranking it with the cover off and listen to it that way.

[Uncle Mike]

Chris Harris has a Youtube video of chasing down an engine noise. Turned out to be loose ends on the push rods. Another Youtube video shows the replacement parts had been redesigned. 

 

 

[Lowndes]

Another source for too much noise is excessive end-play on the rockers. Clymer says 0.002" to 0.016" max.  That would be the total axial movement of the rocker shaft as opposed to the end gap measurement with a feeler gauge in any one place.

[dirtrider]

On 7/30/2021 at 1:01 PM, Werner Karl said:

I just started up my RT for the first time in 9 weeks.  She idles normally but when I bring the RPMs up it starts to rap on the right side.  I tried to localize the sound with a stethoscope.  Sounds like it's somewhere in the right cylinder.  Any advice on what I should be looking for?  Where to start?  It ran fine on my last trip.  Thanks in advance.  Werner

Morning Werner Karl

 

Can you explain the "rap" in more detail? Does it sound 1 per rev (every crankshaft revolution) or 1/2 crankshaft RPM? (camshaft speed)

 

Things like rocker arm end play or a pushrod noise are lighter sounding (more of a heavy ticking) than a rapping noise. Also, neither come on suddenly as they progress gradually. 

 

After a lay-up for 9 weeks you might have a fuel injector acting up causing a poor spray pattern therefore a knock at cylinder firing  (if you suspect this try some Techron concentrate in your fuel tank) then ride it a bit. 

 

If it is a heavy sounding knock you might (I stress might) have a piston contacting the cylinder head due to carbon build up, but this doesn't happen suddenly, it is usually more progressive (unless a piece of carbon broke free then ended up between the piston & cylinder head). You might run a WOT  cranking compression test to see if your compression on the problem cylinder is excessively high (indicates carbon build-up).

 

On a broken cam chain guide, those can be quite noisy but they are more of a rattley slapping noise than a hard rap. (but don't discount it as a possibility as you haven't really defined your rapping noise yet). Typically on the BMW boxer engine a cam chain rattle, or rocker end play, or loose push rod end is also noisy at hot engine idle. 

 

Can you equate your RAP to something sounding similar in nature, or man made???????? 

 

As you have found, diagnosing an engine noise is very difficult even when leaning over the engine, it is WAY/WAY/WAY more difficult diagnosing an engine noise over the internet.

 

One thing I typically use in engine knock diagnosis in a short solid-wire-core spark plug wire, I strip a short section in the center down to bare wire then install that (special plug wire) between the spark plug & the existing spark plug wire.

 

That allows the engine to be run but I can quickly use a shorting wire  to short that bare section to ground to quickly kill that cylinders spark then allow it to re-fire again. If killing the spark changes the knocking noise that can be used as a diagnostic  tool. 

 

 

 

 

[Werner Karl]

I'm happy to report that it was something simple.....Removed the Tupperware this morning, started her up, let it idle to get a little heat to the cylinders, and then slowly increased the rpm.  At about 1400 RPM the noise was back.   It turned out to be the right throttle body shaft rattling back and forth in synch with the right cylinder!  2 short squirts of WD40 and it quieted right down.  Thank you to everyone who responded to help.  Needless to say, I'm happy that it wasn't the cam chain rails!

[Uncle Mike]

I guess the solution is ride more often! As temperatures allow here in the Southwest!