530iT M60b30 rattles when hot

[31Hertz]

Good day to you all! M60b30 Alusil block with 60K miles. Heads and oil pump with 160K miles. Fresh 10w40 oil change/10w30 previously. I have checked the oil pump--there were no bolts missing from either the pump-body or the pump mounts, but the chain-drive was floppy and some body-bolts were slightly loose.
There is a noise apparent when engine is hot. It seems to come from the passenger bank of cylinders. It is a mid-pitched rattle when revved to the 2K-3K range. It is not like a can of marbles--the sound is more controlled-if that makes sense. There is also a rhythmic tap-tap-tap with a similar pitch at idle. Also at idle it almost sounds like there is a squeaky wagon-wheel in there.
I used a dowel to try to pinpoint the source. When I place the dowel on any of the forward-most valve cover nuts, the sound is louder than any other location. Since I tightened the oil pump chain, the sound became less "chaotic" --assuming a more predictable cadence. This leads me to believe that the lower timing chain and the oil pump chain were rattling around with different frequency causing all sorts of noise, but now it is only the lower timing chain. Does it sound like I am on the right track here?
What is my recourse? Do you think it might be the tensioner on the pass side of the block? Is this something I can merely remove and replace, or does it require priming and/or aligning. --Yes I would like it to be an easy fix:p
Does anyone have any thoughts or suggestions as to what might be going on here if I have deduced incorrectly?
Thank you all in advance for any helpful advice you may be able to offer.
This is a kick-ass forum, and I am truly sorry that I have not posted in nearly two years. It has been a very interesting interim.

[Tiger]

Pull plugs out... maybe one coil went bad.

[31Hertz]

Sorry, I neglected to mention that I changed all 8 plugs with new NGKs less than two weeks ago. Thank you Tiger for pointing this omission out. None of them had alarming appearances, and all of them looked similar. They were merely "worn" as you might see in any spark plug chart. Sound manifested itself prior to my changing plugs.
I put the dowel up against each coil and against each boot as well as the valve cover directly surrounding the plugs, but did not hear the sounds I described previously.
I used the dowel-to-ear test on the water pump, power steering pump, A/C compressor, at the throttle body, on the exhaust manifold, on the intake manifold, all over the valve covers, and on the oil pan... The front valve cover nuts were where the sound made itself evident out of all the locations I tried; which leads me to believe that the timing chain may be involved.

Also, there appear to be no "driveability issues." Idle is smooth. Power is acceptable, and there is no stumbling or missing. Fuel consumption appears to be normal @ 20mpg city & 26mpg hwy. It is not burning oil either.

[whiskychaser]

If it were the timing chain, wouldnt it rattle more on (your) driver's side as the tensioner is on the other side? Any chance this is a belt tensioner pulley?

[Tiger]

Good point... belt tensioner pulley rattles when it is worn out.

[31Hertz]

I certainly would not discount that as a possibility... It certainly would be a helluva lot easier to fix.
So do you fellers think that since the sound seems localized on the passenger side of the block that it would be the A/C tensioner system roller? This really does make sense when you take into account the fact that the sound was most prevalent at the front-most valve cover bolts, and none of the other VC bolts. It would also explain the "squeaky wheel" sound (kinda like the sound Sherman tank tracks make). --I am going to run with this idea--barring any earth-shattering evidence to the contrary.
Thank you very much. It is nice to see familiar names on the ol' forum after such a long absence--really thank you! It may take me some time; but I will report my findings...
P/N 11281731220 $36.93 autohausaz (belt looks OK)

[Tiger]

Please do yourself a favor... if the age of the belt is unknown... change it... if it is old... like 5 years or so, change it... if it is squealing, change that darn thing!

I just worked on a MB serpentine system... dang belt sounded like squealing grinding water pump bearing going... nope... not water pump at all... nothing wrong with pulley either... it was the serpentine belt fraying at multiple points... 10 or more to be exact... Changed it out and dead silent.

I remember a Chevy Impala with Corvette engine... has a ticking noise... he thought it was water pump going bad... I told him change belt first... No... he won't... pulled engine apart to change water pump... reinstall same belt... same damn ticking! Wonderful... then he changed the belt and noise gone...


I installed Ruville on BMW... from BMA.

Rockauto has Uro pulley for $14.80... the part 11281731220 (qty:2, same part number as AutohausAZ) is for thtensioner.... The other one 11281731838 is for the idler pulley (qty:1) It comes with 2 years warranty. I just installed Uro pulley on MB and it seems the same quality as others I have installed... and Rockauto 2 years warranty is piece of cake.

Uro is now OE to Jaguar, VW and Audi... for what part? I have no idea...

Rockauto also has cheap belts too... Dayco for $8 and $13.73

[whiskychaser]

+1 on changing the belt too.
But before shelling out, why not run it for a short time without the belt to confirm the diagnosis?

[31Hertz]

Well... OK.:p
I think you are both right. Thanks again.

I will run the car sans belts for a couple of minutes to see if the noise is still there. I will keep a close eye on the temp gauge whilst doing this!

I know for a fact that the P/S serpentine needs to be changed (It has cracking on the inside). The A/C belt looks basically brand new, and what confounds me is WHY ON EARTH somebody would change out the A/C belt and not change out the worn P/S belt when it has to come off anyway to get the new A/C belt on. Will blunders never cease?

The PS pump could use a new pulley too.

re URO: I believe I bought a couple of Volvo 940 wagon tail light lenses and side marker lenses for my 635CSi which were URO branded. Eastern European maybe? Seemed OK quality; fit decently. The damned reverse lenses popped off after a short time on the Volvo lenses; which was the exact reason I replaced the originals (which were16 yrs old). Luckily I caught the new lenses in time, and super glued the clear bastages back on. I will look at Rock and weigh my choices after running sans belts.

What you fellers are saying is really making sense to me. Bear with me as mo diagnostics is run, funds are appropriated, and my slide-show is prepared to present to B.&C. I have to fill out the proper forms and submit them to the CFO/B.&C. once a conclusion has been reached.:D:D:D Please excuse my corny sense of humor...

Thanks again, Giff

[632 Regal]

there are 2 different size rollers going on there, ask me how I know. Both of mine were worn yet only one was limp enough to scream for replacement. Belt replacement is a no brainer but some new ones can be problematic as my conti squeels at startup to charge the battery. Yes full voltage on a charger and no issue, don't charge and get a squeal. Car runs much better on a full charge.

Bottom oil pump chain is within tolerance your good to go. Very surprised no bolts backed out but on an alusil they may have got that memo and used loctite.

[genphreak]

It's common for the main (ie top) roller near the tensioner roller to fail, but they only start to squeak. If the belt is slipping you'll get squeal, that is contamination, wear or a faulty tensioner. It's kinda worth changing the lot in one go, and keeping the parts that are still serviceable as spares jic. That way you know it will all hang together out front for a long time.

[31Hertz]

And the answer is... timing chain lower tensioner piston assembly.
It turns out the A/C tensioner "springer thinger" bushings were worn causing the whole tensioner assembly to angle toward the block. The A/C belt was riding on only half of the pulley. I replaced all of the belts and the "springer thinger." --Then the water pump decided to piss all over the front of the engine. So that + t-stat is new too... I had already installed the metal t-stat housing. However... None of these were the source of the rattle. I pulled out the old tensioner piston, and it had half the spring force as the new unit. I put in the new ass'y and voila! all is well now. NO RATTLE!!! I will now continue to enjoy this car once again.
Thank you all for your kind assistance. Keep on Bimmin y'all!

[632 Regal]

You should systematically go through all the maintenance items. Sounds like the previous owner only replaced items that went bad. Look through the maintenance schedule and replace all belts, hoses, waterpump, bleed the brakes etc etc. Maintenance items are maintenance, not like an old chevy where you only replace broken stuff lol. I went through mine when I got it and do maint as it says, 100k and never any problems.

[genphreak]

x10 to that Jeff. Amen! Hail the Automative Lords, and Burn More Wallet!

Oh- and to the OP: thanks for sharing the final solution.

Those lower AC tensioners are painful- I turned the bolt the wrong way to loosen one before, broke the damned thing... luckily I was obeying Uncle Jeff's 'law' at the time, and I had a new one to replace it with anyhow. It wasn't quite buggered before I got to it. Amazingly, despite the PO's best (or worst) efforts, (i.e. everything (eg nothing) done preventatively by a mechanic with even less of an idea than the guy who was paying him.

I find it helps to think, in the process of buying hundreds of dollars worth of parts to replace all those around something little and cheap that broke, that all these parts ***must*** be replaced at around 'inspection' time, Eg. every 100,000km.

LMAO...