V8 Rattle On Start-Up

[Marcus]

My 2003 (only 50k miles) 540iA makes a tremendous rattle on start-up when cold, then disapears as soon as the engine is running. The problem does not occur when starting the engine warm. Do I have a timing chain tensioner problem?

[edjack]

bashes the guides to hell.
Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.

[ME_264]

Mine had 158K miles on it and made no noise. Realizing that I hadn't had a "cash leak" in over a week I bought one for $50 bucks and put it in. No idea if the old one was good or bad but I fixed the cash leak for the week!

[Craig in Canada]

...the "they all do that" VANOS knock in low oil pressure conditions from the more deadly chain slap?

My dad's 540 has made a burst of knock/rattling on startup for a while but it sounds just like the VANOS knock which will come back if allowed to idle with the AC off (especially before ARX+RotellaT). If it's something different, I'd like to investigate to tell for sure. I don't think the tensioners are really expensive but on the other hand I don't want to throw money at something that doesn't need it.

[william540i]

This was mine at 240K miles (or there abouts)... I noticed a slight metalic tap/knock/ding while the motor was running... It was pretty noticable at start-up, but smoothed out to an annoying, hardly noticable constant tap... It didn't start out low then get louder... It just happened one day and stayed constant until I replaced all the timing parts... I initally thought the tensioner went bad, but when that didn't fix it, I tore into the motor more to find all kinds of nastiness (<--- word?)... I would think you would be able to see the tensioner move in and out if it was not holding pressure overnight... Look through the oil fill hole in the valve cover and rotate the motor by hand... 1-1/8 inch socket on the crank bolt and don't worry about breaking it loose by turning it in either direction!!!

This is with the valve cover removed...


This is why replacing the tensioner didn't fix my issue... The wear exceeded the limit the adjuster could handle... As a temp fix on my initial attempt, I put a washer in the cap of the adjuster to allow an extra 2-3mm's of adjustment until all these parts came in... Here are the tensioners...








This is the extent of chain stretch after 240K miles... I could have left the original in there (IMHO), but I had the new one so in it went...


I would imagine if you put a mechanics stethoscope on the tensioner, you would be able to hear if it is coming from there...

I hope this helps!!

Cheers!!

[edjack]

look for pieces of plastic. If you find them, it's for sure that the guide lining is breaking up.

Chain slap is a hellacious sound, and, I believe, is a major cause of the failure of the guides.
Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.

[edjack]

the engine.

You have taken very good care of that engine, from the looks of the clean internals.

Did you remove the lower pan, and find plastic debris there?
Ed in San Jose. BMW CCA member since 1987 (Nr. 62319). Golden Gate Chapter. '97 540i 6 speed. Build Date 3/97. Aspensilber over Aubergine leather.

[Craig in Canada]

Well, the chain would be slapping due to lack of tension. The lack of tension could be due to either extreme tensioner pad wear, missing pieces of tensioner pad, or a weak tensioner. I guess it's more the case of the weak tensioner "early failure" that I'm concerned about (without having to pull the oil pan).

I guess it's unmistakable, then, when it's chain slap? It can't be confused with VANOS knock or HLA ticking?

[mgattmch]

My local indie (Lewis Allen of Munich Motorwerke, Houston, this guy is superb!) found the problem immediately. The rear bearing had fallen out of the starter motor. Starter motor was replaced and all is now fine on start up.

[eurodavid]

Wow, William540i, that is some seriously clean inner stuff on the beast V8 engine. Can really tell you've taken care of her, running it good and hard so she cleans herself out and doesn't get all junked up. Also, you are right, that new chain (I bet after a few hundred miles & braking in) is probably now the same length as that 240k miles chain. How the heck you keep your outside lower engine nooks & crannies so clean? That a/c pump (that is the a/c pump lower left of the engine pic, yes?) looks brand new from the shine of the silver.

[Whorse]

My local indie (Lewis Allen of Munich Motorwerke, Houston, this guy is superb!) found the problem immediately. The rear bearing had fallen out of the starter motor. Starter motor was replaced and all is now fine on start up.

wow thats a new one for me