e34 525iT engine sounds like a deisel

[markwascher]

Hello all,

This is my first post here so thanks for reading. I bought a 1995 525iT with 165,000 miles a few months ago from a guy in Oakland and am in the process of sorting out a few maladies. My main concern is that it has developed an engine knock that is most noticeable when cold. It never goes away just gets a little quieter. It sounds like a deisel knock. At first I thought it was just lifter noise. My experience with stuck lifters is that it sounds more like a clack clack, or tick, tick, and normally after a few seconds or minutes of starting the cold car it goes away. This sounds like a knock, knock and doesnt go away. I am concerned that a rod bearing is worn.

The vehicle was maintained by Bavarian Professionals in Berkely CA, where the engine oil (Chevron 20w50 turbo bbl) and all other fluids changed religiously at shorter intervals than BMW advises. It does not burn or leak oil. The compression is all good and the engine runs smoothly with good power. One freindly club member suggested I use conventional 0w30 Amsiol. Any thoughts out there?

Also there is a clunking sound coming from the front end that I decided was warn out stabilizer links. Got new links form autohuasAZ and will replace them this weekend to see if I am correct.

Another fun one was fixing the drivers window regulator as the window was out of track and not sealing. It was a gleeful moment to simply change the position of the regulator adjustment screw to get it to work. Otherwise I would have had to drill out the rivets to the regulator and replace with bolts to replace the regulator.

Any help on the knock sound would be most appreciated.
Thanks
Mark

[Ross]

Piston slap.
Excessive piston to cylinder to wall clearance. As the pistons warm up they expand and the noise is less. No solution other than overhaul.
It won't really harm anything, the noise is a reminder that the engine isn't fully warmed and should be driven gently.

[Claude]

Hello all,

This is my first post here so thanks for reading. I bought a 1995 525iT with 165,000 miles a few months ago from a guy in Oakland and am in the process of sorting out a few maladies. My main concern is that it has developed an engine knock that is most noticeable when cold. It never goes away just gets a little quieter. It sounds like a deisel knock. At first I thought it was just lifter noise. My experience with stuck lifters is that it sounds more like a clack clack, or tick, tick, and normally after a few seconds or minutes of starting the cold car it goes away. This sounds like a knock, knock and doesnt go away. I am concerned that a rod bearing is worn.

The vehicle was maintained by Bavarian Professionals in Berkely CA, where the engine oil (Chevron 20w50 turbo bbl) and all other fluids changed religiously at shorter intervals than BMW advises. It does not burn or leak oil. The compression is all good and the engine runs smoothly with good power. One freindly club member suggested I use conventional 0w30 Amsiol. Any thoughts out there?

Also there is a clunking sound coming from the front end that I decided was warn out stabilizer links. Got new links form autohuasAZ and will replace them this weekend to see if I am correct.

Another fun one was fixing the drivers window regulator as the window was out of track and not sealing. It was a gleeful moment to simply change the position of the regulator adjustment screw to get it to work. Otherwise I would have had to drill out the rivets to the regulator and replace with bolts to replace the regulator.

Any help on the knock sound would be most appreciated.
Thanks
Mark

Does it sound like this : http://s34.photobucket.com/albums/d106/tarheelbimmer/535/?action=view&current=DSCN1580.flv ? if so and if you have a manual transmission chances are that this noise is generate bye a twin mass flywheel

[markwascher]

I have an automatic transmission. Thanks for the link. Unfortunalty my feeble computer could not run it.

[markwascher]

Thanks Ross. I was hopeing that it was somthing that didnt require evacuation of the bank account. What would happen if I floored it with the engine cold? Would it help if I changed motor oil to conventional 0w30 Amsoil?

I see that you have a 89 535i. Sweet car. My summer car is an 88' M5 and its the greatest car I have ever owned. Love that engine.

cheers
Mark

[healtoeit]

What would happen if I floored it with the engine cold?

nothing really. I almost have to floor my car when it is cold every morning get out of my neighborhood, the car is just sluggish when cold, but when it warms up it will be nice and peppy!
now, if you are asking what the car would do when it is making the chugging...
I had this happen to my car for a little while, it happened for about a week or so then stopped. Only would happen under cold. If i revved the engine to 1k rpm and held it there for about 30 sec to a min the car would be fine (my take was the engine was warming up).

[Morgenster]

Piston slap or excessive carbon buildup in the cylinders. Run a few cans of carbon cleaners through the fuel at high revs for long periods (with the car warmed up of course). I've tried a few products and so far the only one with real noticeable results was most expensive (zenox injector and valve cleaner from Marly), but I don't think you can get it in the US.

[Ross]

I don't recommend hard acelleration or high revs until the engine is warmed fully. It's not unlikely the noise you have is the result of being driven hard when cold.
I doubt carbon build-up will be causing this as the noise is worse when cold. Detonation from carbon build-up will be worse withe engine warm running a leaner mixture.
Different oil won't change it either, there isn't enough of an oil film on the cylinder walls to effect this.
Just treat it gently when cold as any engine should be and live with the noise.
For years I drove a Corvette that had an engine with cold piston slap that was pulled out of a newer Corvette and replaced under warranty because of this issue. I suspect the assembly tolerances were too loose to begin with on this one. Anyway it found it's way into my car, it sounded pretty noisy when cold but warmed up was fine and took lots of abuse.
Don't worry about it.

[markwascher]

Thanks again Ross. I will follow your recommendations and happily live with it.

[markwascher]

Thanks for the feedback. Shortly after transferring ownership of the new panzer I found a nice long gradual uphill staightaway and mashed the throttle venting a cloud of carbon into the atmosphere, sorry Al. (engine being warm of course). I plan to enjoy that on a regulat basis which should narrow things down to the piston slap. Which I will happily live with.

[Blitzkrieg Bob]

could it be our old friend.... VANOS?

Try to see if the noise is coming form the front top of the valve cover, the VANOS system can get noisy with age.

I had my Touring start up like an old deisel VW when I changed the oil to 0w40...It likes heavier 15w50.

[attack eagle]

my non vanos has lifter tick that goes and comes when running anything lighter than 10w40. So I just run 20w50.

[markwascher]

It has 20w50 in it now. The sound does seem to be coming from under the valve cover. What would cause the VANOS to be noisy?

[Blitzkrieg Bob]

It has 20w50 in it now. The sound does seem to be coming from under the valve cover. What would cause the VANOS to be noisy?

Bad Vanos unit, weak timing chain tensioner or broken rails.

you need to really listen to the noise and try to feel/hear where it is coming from.

[Paul in NZ]

you need to really listen to the noise and try to feel/hear where it is coming from.
Use the FORCE Luke.....