benjihana

Hey guys, not sure if I have one or multiple issues...

The car is doing the following:

Loud metal on metal grind noise that I can't pinpoint that sounds like it's coming from an accessory, but really not sure. Rattle/grind at idle. Goes completely away at a higher RPM. Car shifts fine. Car runs fine... with one exception:

If I pull up to a red light and sit for about 15-20 seconds, then try to go, I have a dead throttle. RPMs go up, but no movement/power. At about 3k it kicks in, and the car drives completely normally. No noise/no power loss. If I slow down to turn at a red light, for example, where I'm stopping briefly but not waiting, I get zero power loss.

Any clue? Anyone experienced this? No alarms, no check engines, no performance/drive issues other than the power loss. Just at a loss here.

henny

Almost sounds like you are low on tranny fluid. I would definately get that checked before driving around too much more. It seems odd that you wouldn't get a transmission error though.

benjihana

It is odd! The grinding is way up front, though. I'm not sure where but it definitely sounds like it's on the accessory belt.

Only things I can think of would be the tension pulley bearing going bad or the water pump going out, but haven't had a heat warning (although these cars are notorious for their WPs and we have no way of knowing until it's boom). If they are going bad or the bearings are grinding/catching, could that cause it to catch and the flywheel to cause the power issues?

Jim165

This only applies to the electric pumps used on the 6cyl cars, not the V8s...

benjihana

I know that they are mechanical, I was referring to the inability to ever see water temp in these cars until it's too late.

nairb

I also have an 08 550. at 70000 the water pump pully bearing was starting to make noise.
Changed the pump and all is quiet again. Don't know about the transmission. mines manual.

benjihana

I've really got to figure out how to see where the grind is coming from. Is there any accurate way to assess this other than sticking my ear down there?

pradden

I had a similar issue, however it was coming from the rear. My indi mechanic put the car up on the rack with a technician in it. He got the car up to 40/50mph (on the lift) and my mechanic used a stethoscope on both spindles and on the diff. We pinpointed the sound to bad wheel bearing. Got it replaced, all is good now. Good luck! Let us know what ends up being the solution.

benjihana

Glad you got it fixed! Was it only making noise when you drove it or also when you were sitting idle?

e6t.lab.rat

Use a mechanics stethoscope like this one:

Mechanic's Stethoscope

This helped me diagnose a bad water pump among others. I had a tensioner (adjacent to alternator) that squealed so loud, kinda like a horny cat in the middle of the night. Applied some spray lube on it and the noise went away. Good luck.