aNo94

What does it sound like when the tensioner is going bad on our V8s? I'm getting an constant rattle/flutter from what seems to be the passenger side of the engine.

If it's not the tensioner, what are other possibilities? I have pulled out and cleaned both VANOS solenoids on the passenger side about a year and a half ago and the timing chains and guides were inspected when I had the valve stem seals done this past October.

twh

Pretty easy to take off the belt and test for the noise.

EddieboyS

Could be the water pump. My 06 550 has 93k miles on it and I'm on my 4th water pump.

aNo94

Is it just a matter of removing the belt and running the engine for a bit?

And Eddie...jeez, what brand were the water pumps?

twh

I imagine you'll get some messages, like not charging since the alternator is not turning. But, it is that easy as taking the belt off. Alternately you can get an automotive technician stethoscope like I have. Very useful in these cases.

EddieboyS

1st 2 replacements were OEM under extended warranty. Not sure of the 4th as it was done by my new Indy shop.

aNo94

I'm going to replace both belts because as far as I know, they're original. If that doesn't stop the sound, I'll explore for noise from all the pulleys.

And Eddieboy, that is truly some bad luck with water pumps.

westsidebalto

Any chance it's the vacuum pump?

ripley

In the olden days before stethoscopes and the internet, mechanics would get their long screwdriver that had a hard plastic handle and stick the handle on their ear and the end of the screw driver on the suspect part.

Had to be careful with spinning things and belts though...

aNo94

I've considered that as well but the noise seems to stop when load is taken off from the belts...I turned the AC off to see if it made a difference and it did.