OOFFF! Rod knock on startup?

[///mpowered1]

I started my car today, I have not driven it for 3 days and temps have been in the 30*F range. The motor made what sounded to be rod bearing noise for less than a second. It continued to run smoothly afterward. I tried to ellicit the same "clunk" on startup several times during my errands to no evail. Is this the norm? Is my oil pump taking a crap? Any similar experiences with anyone in the community? Thoughts?

[97m3john]

Put a oil pressure gauge onit and see what you have before you destroy it.

[///mpowered1]

Cheers for the response. I have every intention on doing the opg test. In the meantime, has anyone experienced the same thing?

[nonphixion]

lifters

[TheNorthWaves]

fwiw the two M3's I've had (one high mileage and one low mileage) both sound kinda crappy like that when first started in the cold. It would be prudent to have it looked at though.

[turbosporttsi]

how many miles on the bottom end? what weight oil are you using?

(most likely lifters)

[///mpowered1]

85k on entire motor. 10k worth of service records from the origional owner. 5w30 mobil one.

[///mpowered1]

Alot of you are suggesting lifters. I've never heard that kind of racket from lifters before and I've owned dsm (mitsu eclipse turbo) 4g63t, notorious for their lifter noise.

[///mpowered1]

Could be however, seeing as it was sitting in the garage. Maybe the noise was amplified in the garage.

[JamesM3M5]

5W30 Mobil 1 is NOT the correct oil, it does not meet ACEA A3/B3 specs. Use BMW 5W30 long life or other ACEA A3 oils. We use Motul 5W40 for older engines (over 100k miles) and noisy valvetrains. Newer cars (esp aluminum block cars) get Motul X-Max 5W30 or E-Tech 0W40.

You probably have lifter tick. Rod knock sounds like someone is hitting the block with a hammer every revolution, and is quite a scary noise if you've never heard it before. Rod knock does not go away after a couple of seconds, either. It goes away once the rod seizes and blows the motor up, though.

[///mpowered1]

Very interesting James. Enlightening to say the least. I will have to change that.

[turbosporttsi]

agreed on the garage greatly amplifying the noise. there are a few other things that could make strange sounds similar to what you described, but none of them would go away in 1 second. i wouldn't worry about it. keep an ear out at cold starts on cold days for a while, just in case.

[art@rmeuropean]

Don't worry about it, these engines make a lot of noise and your garage makes them seem louder than they are. Just like mentioned above, rod noise sounds nasty.

[M Wringer]

Mine makes a bit of lower end noise, too, only when temps are below 40 degrees. It goes away in about a minute. It has done this for about a year,now has 108K. It seems if a rod bearing was seizing on the crank. it would have done it by now. A friend who is a BMW mech told me to change brands of oil. I called a friend who sells Swepco products and will try their oil on the next change due in about 3K. They use it in all their Bimmers with no probs.

[MIMI1]

if Im not mistaking 5W30 oil is too thin for S52 motors they are required to have 10W40 oil if non-synthetic and 5W30 if its synthetic

[JamesM3M5]

BMW Long Life 01 oil is 5W30, and is the recommended oil for M50/M52/S50US/S52, some S54, some S62, etc etc. The Castrol TWS 10W60 can be too thick for S50 Euro, S54, and S62 engines if the proper warmup is not followed, and subsequent VANOS issues have arisen esp on S50B32 dual-VANOS Euro engines. I like 0W40 Motul, since it meets some of the industry's most stringent requirements such as VW 503.01, MB 229.3, and ACEA A3/B4, Scores a 0W on the cold-crank-simulation for cold and temperate climates, and is 40-weight to ensure proper high temp/high shear use in performance engines without being too thick.

No conventional oil will meet BMW LL-01 specs, and I doubt any will meet ACEA A3/B4 specs, either.