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Discussion Starter · #1 ·
Hello forum members I have used the search function and was unable to find answer to my question. Have a 2002 745li, engine is sounding like a diesel. I suspect that it may be the timing chain guide rails. Wanted to know if they could be changed, without altering the timing chain. Would prefer not to alter the timing. Or would I have to take timing chain off to replace parts.

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Teenage Car Enthusiast
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Some BMW's start to sound like diesel around 50k... More commonly found in v8's and m engines....

Check the vanos solenoids, I plan on cleaning mine soon and this is what I've concluded as the mysterious diesel sound.
 

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How many miles? I haven't seen an n62 wear out chain guides yet. But to do the job is major engine surgery. You can't do it without removing the vanos gears, heads, upper and lower timing covers, etc
 

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Hello forum members I have used the search function and was unable to find answer to my question. Have a 2002 745li, engine is sounding like a diesel. I suspect that it may be the timing chain guide rails. Wanted to know if they could be changed, without altering the timing chain. Would prefer not to alter the timing. Or would I have to take timing chain off to replace parts.

Sent from my SGH-T999 using BimmerApp mobile app
If by diesel you mean a deep knocking in the lower front-driver's side of the engine, you may very well be talking about bad alternator bearings. If it's up a little higher toward the top of the engine, in the front, and sounds like rattling or tapping and gets louder when on or off the gas, then you may be looking at the timing chain guide rails. Timing the engine really isn't very tough once you have the cam timing jigs, and you can borrow mine if you need. I can't recall if I was able to do it without losing timing on quarterto8's car, but I'm pretty sure I did just remove the guides and not the chain (just removed the tensioners). I'll see if I can dig up the pictures.

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Discussion Starter · #6 ·
Thanks a lot for the valuable Information. Hear knocking sound when car is idle. When I press the gas, the knocking stops. So maybe alternator. Going to change oil and drop lower pan to confirm guide rails are intact. Is it hard to replace bearings in alternator.

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Yeah, I'm thinking its something else, not chain guides. I have heard alternators make knocking sounds. Use a mechanics stethoscope or a long screwdriver to find the source of the noise.
 

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Thanks a lot for the valuable Information. Hear knocking sound when car is idle. When I press the gas, the knocking stops. So maybe alternator. Going to change oil and drop lower pan to confirm guide rails are intact. Is it hard to replace bearings in alternator.

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Dropping the pan unfortunately won't get you far enough forward to see the guide rails, and there is no guarantee that a broken piece will actually make it to the pan either -- had one car where a big piece was still sitting up in the top end. You might try taking off the valve cover on the side making the noise if convinced it's a guide rail issue. But, if it's a deep sound and on the driver's side, just pop the belt off and spin the alternator by hand (sometimes it still feels normal, sometimes not, but definitely worth the few minutes to test this way).

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use a long screwdriver as a sort of stethoscope to investigate areas you think the noise is coming from.

Also my inclination would be to check your waterpump for axial play. The bearings in the pump are known to fail just enough to keep working but emit noise as well.

-Robbery
 
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