N62 Engine Knock/Rattle
 

Wife fired up the car to head to work today and I heard a pretty loud rhythmic knocking/rattle coming from the engine, matched RPMs. Although it was loud outside, I could barely hear anything odd inside the car. Popped the hood and felt around, I felt nothing on either side of the engine (felt just below the valve covers), but do feel the pulse when I put my hand on the t-stat housing.

Just wanted to check in if based on that very basic diagnostic you'd come to the same conclusion as me that the water pump's bearings are shot. Unfortunately I forgot to check for play before heading to work myself, but the pulley's axial movement was definitely not perfect watching it spin. We're at 151k and I have no records of it ever being replaced so it's been on my to-do list anyways.

What else should I replace while I'm in there? I'm thinking hoses, belts, and any particular pulleys? Or the tensioner? DIY I just watched showed a pipe behind the t-stat as well (not the internal transfer pipe). I'd like to order parts today so I definitely get them by this weekend. Also WP brand recommendations would be appreciated.

Thanks!

So the attached diagram, #7 has been replaced recently. #2 is easy. # 8 looks doable. I'm not worried about #3 at the moment. Is #5 easy to replace? Also where does the lower branch of #1 go?

Would also appreciate any comments about BMW vs Rein vs Vaico hoses

Can you run that motor without the WP belt, even if only a few seconds? Might help with the diagnosis...

I could. Maybe after work.

I won't lose sleep if I replaced the WP and it wasn't the problem...... As long as I can find the problem.

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Easy is subjective. If you have the Intake Manifold off, it's right there and can be replaced in a few seconds. Otherwise, it's still easy, if you don't mind working in very tight spaces. #5 runs under the throttle body, but I changed it with only the plastic air ducts, filter box, and "rubber boot with resonator" removed, some long nose pliers, long screw drivers (to loosen the old clamps) and a lot of patience. :D One of the first parts I replaced when I bought mine.

All of #1, the upper radiator hose, can be seen if you just peer into the engine bay. It's a large hose right up front and easy to replace/follow with your eyes.

Just beware, if you replace #1, youwill most likely have to replace #5 as well because there is a nipple that connects the two which will fall apart and crumble if that hose is original/old. You might can clean it all out of the smaller Y hose, but why chance it?

Also, #5 has three single-use factory clips, which you'll need if you change that hose out. Or, just one if you go with just the larger upper radiator hose.

Thank you! Very helpful.

I know you posted in my other thread, but for those of you who don't know/didn't see it I had a leak rather recently that was from the hose on the underside of the expansion tank. So I decided then and there when I replace the WP I'll replace any hose I can that wouldn't add a massive amount of work.

I missed the order cutoff time to ship today so I'll just pop the hood tonight and see how visible the hoses are.

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One more pic to make it a little more clear - this one with the intake manifold off.

If you have small hands, or know somebody with small hands, that helps too. :D

Thanks again.

I have "big" hands but they're skinny, so generally don't have problems. Maybe I'll drag my wife out if needed... It is her car after all.

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Timely thread - I seem to have recently developed the same type of rattle. I'll poke around with a stethoscope this weekend to see if I can isolate where it's coming from.


I can concur with the previous warnings about the plastic nipple on #1 breaking. Also, any pipe (or temperature sensor) you disconnect needs to either be replaced or at a minimum its o-ring replaced, as the old ones will be hard and flattened and will surely leak when reconnected.