E34 525i Engine Knocking

[riverarb]

I have a 91 525i w/high mileage 230k, but runs great. Recently a "knocking noise" started from the front of the engine. First thoughts were the timing chain or tensioner. I utilized the ole' broom handle technique to listen to the engine, but I couldn't hear any knocking noises from the valve cover, timing cover or engine block???? ghead Sometimes the knock is faint, especially at start-up or cold, and then it gets worse. I'm a "do it yourselfer" mechanic, so please any info would be great! Go Army

[maci4life]

Originally posted by riverarb@Oct 18 2004, 05:31 PM
I have a 91 525i w/high mileage 230k, but runs great. Recently a "knocking noise" started from the front of the engine. First thoughts were the timing chain or tensioner. I utilized the ole' broom handle technique to listen to the engine, but I couldn't hear any knocking noises from the valve cover, timing cover or engine block???? ghead Sometimes the knock is faint, especially at start-up or cold, and then it gets worse. I'm a "do it yourselfer" mechanic, so please any info would be great! Go Army

[snapback]213668[/snapback]

have you tried different gas grades?? just wondering if it gets worse or better.

[d3ity]

The problem is your valve cover gasket, check your spark plugs, there may be a bit of oil around/on them, this is a definate indicator.

An hour, a torque wrench, and a gasket set will fix this problem

[billB]

riverarb

Somewhat I am thinking OIL and thus going NAVY on this one (liquid) and I'll share with you since you going army:

The Hydraulic Bucket Tappets can make this noise and it is very dependent on two variables:
1. Viscosity of engine oil used
2. Outside ambient temperature.

As such you must first check that your oil viscosity is matched to your ambient temperature.

Also as crazy as it sounds there is a very simple BLEEDING PROCEDURE. That is If this knocking noise can be heard, run the engine for 3 minutes without load at approximately 2,500 to 3,000 rpm (bleeding procedure) any air drawn in to the system via a defective O ring for example will cause oil foaming and thus knocking sounds.

finally I sincerely believe the synthetic oil adheres to all those parts at the top of the engine better than the regular oil. I recommend BMW synthetic oil; some swear by Mobile one...I don't or at least my car doesn't!!!

good luck
regards
billb

[riverarb]

Originally posted by maci4life+Oct 19 2004, 09:28 AM--><div class='quotetop'>QUOTE(maci4life @ Oct 19 2004, 09:28 AM)</div><div class='quotemain'><!--QuoteBegin-riverarb@Oct 18 2004, 05:31 PM
I have a 91 525i w/high mileage 230k, but runs great.* Recently a "knocking noise" started from the front of the engine. First thoughts were the timing chain or tensioner.* I utilized the ole' broom handle technique to listen to the engine, but I couldn't hear any knocking noises from the valve cover, timing cover or engine block????* ghead Sometimes the knock is faint, especially at start-up or cold, and then it gets worse.* I'm a "do it yourselfer" mechanic, so please any info would be great! Go Army

[snapback]213668[/snapback]

have you tried different gas grades?? just wondering if it gets worse or better.

[snapback]214010[/snapback]

[/b][/quote]


I've always ran the highest octane available, at times w/octane boost.

[riverarb]

Originally posted by d3ity@Oct 20 2004, 07:03 PM
The problem is your valve cover gasket, check your spark plugs, there may be a bit of oil around/on them, this is a definate indicator.

An hour, a torque wrench, and a gasket set will fix this problem

[snapback]215077[/snapback]

I replaced the valve cover gasket/plugs about 5k miles ago...This was before the knocking begun. Thanks for the input

[riverarb]

Originally posted by billB@Oct 20 2004, 10:53 PM
riverarb

Somewhat I am thinking OIL and thus going NAVY on this one (liquid) and I'll share with you since you going army:

The Hydraulic Bucket Tappets can make this noise and it is very dependent on two variables:
1. Viscosity of engine oil used
2. Outside ambient temperature.

As such you must first check that your oil viscosity is matched to your ambient temperature.

Also as crazy as it sounds there is a very simple BLEEDING PROCEDURE. That is If this knocking noise can be heard, run the engine for 3 minutes without load at approximately 2,500 to 3,000 rpm (bleeding procedure) any air drawn in to the system via a defective O ring for example will cause oil foaming and thus knocking sounds.

finally I sincerely believe the synthetic oil adheres to all those parts at the top of the engine better than the regular oil. I recommend BMW synthetic oil; some swear by Mobile one...I don't or at least my car doesn't!!!

good luck
regards
billb

[snapback]215207[/snapback]

This sounds like a winner, I'll change over to the synthetic oil this weekend. I've always ran Mobil 1 in my "92" 318i off the show room floor, good oil. Will I have any problems with the swap form conventional to synthetic ie...gaskets shirinking.