Very loud noise when accelerating- sounds like belts
 

Out of no where x5 started overheating. It had dumped all my coolant. I added water and tried to get home after car had cooled a bit. It continued to overheat so left it and came back a few hours later with coolant. Added and started driving, but all of a sudden the made loud high pitch squealing noise when accelerating. Water pump had broke and was dumping coolant. I assumed that the squealing was just from the wet belts.

Towed car home, ordered new water pump and belts. Goods arrived, and reinstalled all. Added coolant, and let the car idle for some time. It seemed a bit noisier than usual. When I started to accelerate, the same loud squeaking noise is made. Im hoping that this is because the belts got wet from a bit of coolant overflow when adding Zerex G05. Ill check tomorrow, but I get the feeling noise will still be there.

When car had been towed home and I drove into garage, it felt like power steering had gone.

Any suggestions?

Thanks in advance- this site has been great for DIY and helped me with issues along the way of installing the water pump.

Did you verify the tenisioner pully/accessory bearings were all in good condition prior to installing new belts?

Each pully must be spun by hand, feel for roughness/listen for ANY noise.

Sounds like TiAg is about right, I would not use after market coolant ,one it will rot out your new water pump thermostate and radiator.Trust me I learn the hard way.

Spray the belts with belt dressing to see if that takes care of the problem.

also make sure you routed the belts correctly. Its easy to screw up the routing if they were removed. And we're pretty sure the zerex G-05 is the same stuff BMW sells except in a different color. I've seen that a number of places. Regardless, thats all I've ever used on my 3 BMW's and it seems to be fine.

Thats also partially because it was cheaper when I bought it, and I havent finished the bottle. The BMW stuff is pretty cheap now, so no reason NOT to use OEM, but there are alternatives to OEM.

+1 on the belt routing! I recently had the belt on the wrong-side of the idler pulley on my N62! (after I had to remove the belt during timing cover replacement) It would squeak a bit when you blipped the throttle). I was delirious after working on it all week and did-that somehow.

Anyway - I didn't notice it was a problem until I noticed a wear-mark on the belt that didn't look right. It was rubbing on what I believe are the transmission cooler lines. Just very slightly....


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Thanks for the advise and taking the time to respond. Noise was good for first 20 seconds then was there again. Took fan and belts off and started the car and there was no noise. Bearings/pulleys seemed fine. There had been a little too much slack in the belt. This time I did a better job of tightenning up the belt- see DIY link for belt replacement and tightening- Belt Replacement Instructions (Incl. Fan Removal)
And now its all good.

I'd replace both tensioner pulleys. The screeching noise was the bearings telling you you now have a time bomb. OEM will run you ~$200, cheap insurance IMHO.