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Going in for the big surgery tomorrow.. rod bearings replacement

18K views 98 replies 32 participants last post by  jamiepeers 
#1 ·
This is it. My beast has accumulated 128k miles recently and on a cold start i'm hearing what sounds like rod knock. ONLY on a cold start though. I've heard it before many many times but every time i would pop the hood to listen it sounded like it was my vanos. I cold started my car while it was parked next to a wall when i was leaving work and i heard the noise again but this time it sounded like the sound was coming from underneath my car. After a little bit the sound disappeared. When i got home i pulled into my garage and revved slowly but i couldn't hear any knocking.

Is it possible to have intermittent rod knock????? I always thought that once rod knock was present, it was always there.


Anyways, I'm scheduled to take the beast in tomorrow after work to get the rod bearings replaced. Qais over at South Bay Autohaus is the specialist i'm entrusting with the work. South Bay Autohaus - Hawthorne, CA
I was going to spend the money i've been saving on a super charger but i figure that a super charger kit is pretty useless without the car. I'll keep you guys posted.
 
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#2 ·
I was going to spend the money i've been saving on a super charger but i figure that a super charger kit is pretty useless without the car. I'll keep you guys posted.
Yupppppp. Dont ya hate when that happens :grrrrr: :sad2:
 
#9 ·
i didn't know what piston slap was until you mentioned it. I saw a couple of videos on youtube featuring 'piston slaps' in GM cars and the noise i hear from my car on a cold start doesn't sound like that. I guess i'll find out once and for all tomorrow where all my engine noise is coming from.
 
#5 ·
There's nothing wrong with throwing parts, PMs at a car you wish to maintain, but have you gotten any second opinion on the diagnosis? Do you have a sound clip??
 
#8 · (Edited)
no sound clip but i'll definitely get one tmrw when i leave work.

The plan is to drop off my car tomorrow night at the shop and have Qais check for rod knock thursday morning along with everything else i want him to. Even if he finds that my rod bearings are fine im going to have him change them anyways.


EDIT: I took a sound clip after work today. Sorry for the bad quality.
<iframe width="420" height="315" src="http://www.youtube.com/embed/8qHl9-YbEi0" frameborder="0" allowfullscreen></iframe>
 
#10 · (Edited)
at 128k miles and a super charger in the near future i'm glad to have found a specialist i can trust to change out my rod bearings. When people super charge their beast they usually spend a significant amount of money on 2 additional items:

1) BBK
2) Clutch/FW


Im just adding a third:

3) Rod Bearings.

And i've been on this board since 08. If YOU think you've read too many rod knock threads imagine what i've been going through the past 4 and a half years kinggf
 
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#12 ·
Good luck. As weird as it sounds, I hope you find significant wear on your rod bearings - it'll make you feel incredible that you fixed it :)

Also, it's been quite awhile since this board has seen anyone with an actual case of confirmed rod knock due to big end bearing wear. People were starting to lose hope that our rod bearings are weak points - many were starting to think it an internet myth! ;)
 
#18 ·
I'd love to see how many confirmed cases of rod bearing failure out of many thousands of S62 engines exist.
Many have had this identical inquiry over the years -
Best I can infer from 11 years of being here/ reading/ researching is less than 100.

Somebody challenge this but back it up with facts- Thx

The 209,000 mile old Anthracite started up just fine in 7 degree weather today; no noise, just like every other day in the prior 13 years.... :byee55amg



Good luck. As weird as it sounds, I hope you find significant wear on your rod bearings - it'll make you feel incredible that you fixed it :)

Also, it's been quite awhile since this board has seen anyone with an actual case of confirmed rod knock due to big end bearing wear. People were starting to lose hope that our rod bearings are weak points - many were starting to think it an internet myth! ;)
 
#13 ·
I had a very similar experience to you - slapping sound that went away when warm, only heard on cold starts, sounded like it was coming from the underside of the car. It was pretty violent at times. It turned out to be a combination of a busted exhaust hanger and the exhaust smacking some metal piece on the underside of the car.

My mechanic simply welded the hanger, and bent the metal piece out of the way and it was all good.

GL!
 
#24 ·
I looked at a M5 for sale a few years ago - it hadn't been started for a while (was being sold by a friend of the owner), and when I started it up, it had a LOUD knocking that definately sounded like it was coming from under the car. My first thought was rod knock. But after running for 15 minutes, it went away. Pretty sure it was VANOS noise, all the oil pressure had bled off because the car had sat for so long. Heard the same noise a couple years later, from my car, after changing VANOS o-rings.
What you describe does sound like VANOS noise.
But, I don't think it will hurt any thing to have the rod bearings changed if you are planning on adding a S/C. Provided its done correctly.
 
#35 ·
Don't pay more than 2 grand. A competent shop can do it for that easily and shops that have done the job several times can do it for somewhat less than that. Most shops will quote a flat fee regardless of how long it actually takes them to complete the job, unless they overrun due to some unforseen issue. Don't expect the shop's per hour rate to apply in most instances.
 
#37 ·
my car and Qais are very well acquainted. The previous owner took it to him for most of the maintenance.

he quoted me about $2090.00 to do the job. I just got home from dropping it off at his shop. Its funny because he's trying to talk me out of it haha He's putting the beast up on a lift tmrw morning and hes going to listen for rod knock or whatever noise present at the time.

on another note, the rental i got is a brand new toyota yaris. this thing accelerates in first like our car does in 5th below 1500 rpms haha. bluetooth connectivity for music and stuff is a nice feature though.
 
#42 ·
Not to put you down and don't take this the wrong way,but your clueless on rod knock!!Your motor sounds perfect. I'll bet anything it's not rod knock or any thing of the sort.Worse thing comes to worse its the t.c or just the stainless on the down pipe amplifying the sound waves.

Why you think the guy was trying to talk you out of it??Your tearing down a motor built from the factory (Bmw M Built)to have a grease monkey changing bearings:eek:.One mistake on tq specs, then you will have a real rod knock 100% for sure.Just being honest with you bud.
 
#38 ·
I posted up a sound clip on the first page for those of you interested. Its hard to hear the sound at first but as the video progresses the sound is more prominent.
 
#39 ·
My money is on VANOS chain tensioner, #8 here. That doesn't sound like any of the confirmed rod bearing cases I have heard on video here. I would be hugely impressed if your shop found a different source and saved you a bunch of $. But if you want to do it as PM anyway, it's your car and I wouldn't question that decision.
 
#40 ·
+1, does not sound like rod knock. Could be the tensioner or the vanos spring diaphragms losing tolerance. (#3 and 5)
 
#43 ·
Maybe i should've posted up a sound clip a long time ago! haha

here's the thing though, i already changed my chain tensioner...some of you may remember that fiasco :) and i was pretty sure that broken chain guides would present itself in my oil pan and would leave gashes on my valve cover? if it is # 8 in this diagram RealOEM.com   BMW E39 M5 timing gear timing chain top is it something i can work on at home?
 
#46 ·
the sound is there sometimes on a warm restart. I just got my clutch and fw done not long ago and i checked the exhaust. I'm pretty sure it wasn't touching anything.

Qais should be giving me a call pretty soon. i'll keep you guys posted on what he says cherrsagai
 
#50 · (Edited)
Hey,

That is the same sound I had on my car, that freaked me out for a month. It turned out to be my exhaust. It sounded IDENTICAL to what you have in the cabin. Have the mechanic look at the exhaust under the car when he has it on a lift.
 
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