[14wntr]

http://youtu.be/z_sZZ6KlJnE
Any ideas? Have you heard it before?

 

[2Wheelroadtrip]

Hard to tell where it is coming from. Maybe an exhaust leak? Maybe arcing from one of the plug wires? Were you working on something? Take a 2 ft piece of hose and hold it up to your ear and then move the other end around until you hear the noise the loudest to pinpoint where it is coming from. Good luck

 

[14wntr]

No arcing. No exhaust damage that I can tell. The noise seems to be the loudest towards the front of the engine. I cannot isolate it with a stethoscope. It sounds like something is slapping against a cover?

 

[SmokinJoe]

Sounds like it is coming from the valve cover as it increases with rpm increase likely due to a bucket that is too loose. Put a stethoscope on the valve cover. Be certain your oil weight and quanity are correct, about 1/8 inch below the top of the glass on the center stand with the engine off.

 

[14wntr]

I just went through all of the valves thinking the same thing. 1 intake was out .001. Fixed, no change. I am really thinking the chain is slapping like the tensioner is not working properly.

 

[gary45]

does sound like valve train noise - I have not run one of these motors with the valve cover off but might be worth trying - would be able to hear valves more clearly and see what the chain is doing - what did you do to adjust bucket .001 thou

 

[14wntr]

swapped out the bucket for a smaller one. It was a little too tight. Now it is in spec. The chain seemed loose and the other thing that stuck out as odd was the tensioner did not snap back when I pulled the drill bit out.

 

[gary45]

The KRS uses a semi-hydraulic chain tensioner. A spring loaded plunger puts a starting tension on the chain guide, but once the motor is running additional tension comes from oil pressure

found this on a IBMW post about tensioners and this is what mine felt like - spring tension all the time maintaining pressure on the chain with the engine off - it is possible for the chain to jump and damage the valves from what I have read

 

[JPSpen]

I certainly don't like the sound of that...

You may indeed have some kind of problem in the cam chain area...

A mechanics stethescope might help to isolate it a little more...

Whatever it is it doesn't sound good...

Maybe a really loud injector ?

More troubleshooting is def, def, definately in order.

John

 

[14wntr]

The first time I rode it, my first impression was the chain was slapping. Looks like I picked the wrong day to quit drinking.....

 

[dshealey]

My first guess would be that something in the chain tensioner or guides has failed. Not common by any means, but can happen on any chain driven valve system.

The tensioner is oil pressurized, with a spring to maintain some pressure on it when the engine is stopped. Possibly a clogged oil passage.

The guide rails basically never fail, regardless of BMW's unfathamable 36,000 mile replacement recommendation. However, it is certainly possible that one could break.

I would drain the oil and look for either plastic or metallic particles.

I did have a similar noise once, and it was the front exhaust flange broken, the weld had failed. You can check these by loosening the nuts holding the exhaust just enough to be able to pull the exhaust slightly out of the head, then trying to turn all four flanges. If one turns at all, it is broken and needs re-welding.

 

[14wntr]

My first guess would be that something in the chain tensioner or guides has failed. Not common by any means, but can happen on any chain driven valve system.

The tensioner is oil pressurized, with a spring to maintain some pressure on it when the engine is stopped. Possibly a clogged oil passage.

The guide rails basically never fail, regardless of BMW's unfathamable 36,000 mile replacement recommendation. However, it is certainly possible that one could break.

I would drain the oil and look for either plastic or metallic particles.

I did have a similar noise once, and it was the front exhaust flange broken, the weld had failed. You can check these by loosening the nuts holding the exhaust just enough to be able to pull the exhaust slightly out of the head, then trying to turn all four flanges. If one turns at all, it is broken and needs re-welding.

I REALLY appreciate the replies! I will do it!! I am understandably reluctant to dig into the motor if I dont have to. I will report my findings.

 

[jzeiler]

I think at this point I would drop the exhaust and give it a good going over as that was my first impression on listening to the video. Cheapest and easiest to do of all the options list so far.

 

[gary45]

swapped out the bucket for a smaller one. It was a little too tight. Now it is in spec. The chain seemed loose and the other thing that stuck out as odd was the tensioner did not snap back when I pulled the drill bit out.

page 91 Clymer manual has a pic of the tensioner taken apart - long spring should have pushed "piston" back out so your evidence/feeling points there

 

[14wntr]

page 91 Clymer manual has a pic of the tensioner taken apart - long spring should have pushed "piston" back out so your evidence/feeling points there

Agreed. I will check the exhaust again though in the AM.

 

[14wntr]

Well I loosened up the exhaust and tried to get things to move and there is nothing wrong with it as far as I can see. I am going to remove the valve cover again to have another looksee.

 

[New2rt]

That is noisy, I guess you're referring to the random ticking noise.
Doesn't seem consistent enough or a constant cadence for an exhaust leak but get a good cigar and blow the smoke around the exhaust and look for swirls.

It does sound like a random ignition arc but it should have a bad miss under load, pull the cover and run it in the dark or fill a spray bottle with water and give the wires a mist.

It also has a metallic sound to it, rotating the engine will put the timing chain slop on the tensioner side and the tensioner rail should take up the slack.
If you run it with the VC off you will get wet.

 

[14wntr]

There is no way I am going to run it with the VC off. I have uploaded a new video of the chain slop by moving the cams back and forth. I am not sure its normal. The tensioner rail does move with little to no resistance. The noise only presents when under a load and not in neutral. Here is the video link. http://youtu.be/Ym0nrgp_abs

 

[gary45]

looks like you have to pull the front cover and check the tensioner - at least you were right about the source of the noise - chain should be tight

if the chain was snug I would run the motor for a short period of time to be more clear of the noise and clean up the mess - wouldn't be the first time I've run a motor like that to isolate valve train noise, just not a K motor - yet

 

[14wntr]

I am glad you wrote. I was just napping on the shop floor waiting to hear something from someone. I guess its time to get into it. Got any advice for when the cover comes off? Anything I need to look out for?