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Discussion Starter #1
Hey Guys,

New to the forum and now am a proud owner of an M3. I bought it for relatively cheap and understood it wasn't running. I got it home and started messing around with it, installed new coils, and sparks along with some fuses. Much to my surprise, it started immediately but, with a knock. If anyone could assist me with a "audio diagnostic" id truly appreciate it. Please see link below:

https://flic.kr/p/2jbiBHC
 

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It’s hard to tell from a video, but it could just be a loud vanos. These cars are noisy as hell even when they’re in good shape. Maybe send some oil for an analysis to get an idea of the bearing condition? Does the knocking increase with revs?
 

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Discussion Starter #6
It’s hard to tell from a video, but it could just be a loud vanos. These cars are noisy as hell even when they’re in good shape. Maybe send some oil for an analysis to get an idea of the bearing condition? Does the knocking increase with revs?
This could be awesome news! Yes in does increase with revs. I tried not to keep it on for long.
 

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knocking noise seems to be in the head rather than rod bearings.

maybe valve missing shim or vanos pump drive tangs missing one, or ex gf put rock into the oil filler. Open the valve cover and look around.
 

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I'm not sure that I'd drive it but if you do you can identify a failing rod bearing by transitioning from light acceleration (load) to coasting (no load) and back to load. The knocking sound will change and even quiet down during the transition.
 

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I would not drive that. I would check valve clearances first (but to be honest that sounds more serious) and pull the sump and filter to see if anything looks amiss (metal debris in sump pan).
 

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As long as you're sure you fully installed the spark plugs, that's rod knock. Absolutely no way that is a "loud VANOS".

I do see that the coils are not fully seated. That wouldn't cause the noise but it makes your spark plug work suspect of being an incomplete job.
So when I purchased the car I definitely noticed that the “incorrect” sparks were installed so I went and grabbed the new sparks last night. Took them out and installed them still had the same knock. Got the car I’m the garage today to remove the valve cover then realized that the valve cover was held on my “1” screw and but had a fresh gasket...weird and jacked up I know....while I inspected it, the only thing that I realized was missing was a spark plug seal on cylinder one. So far this is where I’m at...kinda sucks that someone would treat an M3 like this but this is my project so far. Let em know what you think.
 

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CharlesCarter881--

The technique I mentioned in post #8 can be used without driving the car, just bring the rpms up and let them fall slowly. You should be able to hear the transition as the failing rod bearing loads and unloads.

#8 I'm not sure that I'd drive it but if you do you can identify a failing rod bearing by transitioning from light acceleration (load) to coasting (no load) and back to load. The knocking sound will change and even quiet down during the transition.

--Papermaker
 

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E30M3 Race F10 535 R1150Rt M Coupe
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The old school way to determine a rod knock is best:
Engine running (if it's a rod knock, you have a finite amount of time before it becomes catastrophic.) and pull the spark plug wires off/on one at a time. When the compression is removed from the offending cylinder (fuel is added but no ignition source) w/o spark, the pressure in that cylinder is MUCH LOWER. The noise should change significantly.

Have a scan tool at the ready. Have access to all 6 ignition coils. Start car and disconnect the connector from #1 Ign. coil. Does the noise change by a large margin?
Shut car off, KOEO clear codes (you want the plugs to fire every-time during this test so clearing is necessary.) Reconnect #1.

Start car and do the same on #2, repeat the above all across all 6. Tell us if one of the coils disconnected produces a significant noise variation? If it does, it's a rod knock and you better get in there.
 

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MrMcar's recommendations is even safer than the load/unload method I mentioned. The load/unload method is helpful when you notice a noise and suspect it's may be a rod knock.
 

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Discussion Starter #15
MrMcar's recommendations is even safer than the load/unload method I mentioned. The load/unload method is helpful when you notice a noise and suspect it's may be a rod knock.
Yes I completely understand, so upon inspection I noticed a lot of things were missing as if somebody took off the valve cover started to do the job and then just boxed everything up. I noticed that the guard for the chain is missing along with a few other bolts.I can definitely tell that the knock or take depending on what you feel is best suited is coming from the top & not the bottom of the engine. Is it possible that if a shim is missing could possibly make that noise?
 

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It could. I can't tell from the video about the frequency. Is it engine speed or 1/2 engine speed?

I had a job arrive from another shop after a valve adjustment. They forgot to slide the finger follower back into place on one of the followers on cyl. #5.
It was a mess but ended up replacing the spring, keeper, top and stem seal. It turned out alright.
 

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Yes I completely understand, so upon inspection I noticed a lot of things were missing as if somebody took off the valve cover started to do the job and then just boxed everything up. I noticed that the guard for the chain is missing along with a few other bolts.I can definitely tell that the knock or take depending on what you feel is best suited is coming from the top & not the bottom of the engine. Is it possible that if a shim is missing could possibly make that noise?
Since the valve cover is almost off, it seems that the previous owner investigated the noise pretty thoroughly. You might call him and ask him what's making the noise? You've already bought and suspect the worst so he just might tell you. If that doesn't work yes, finish taking the valve cover of and check for the shims at every valve. If you find a shim missing you've solved some of your noise problem. Inspect the head for the missing shim (s). There are several oil return ports on the passenger side of the head. Make sure that you check them thoroughly as well as the cam chain tunnel. If a shim has fallen down into a oil return port you'll have to find it. It's probably in the oil pan. While your at it, block off all the the return ports and the chain tunnel after you've inspected them to prevent something else from falling into the sump. If you find the shim, great. Do a valve adjustment. I'm not really recommending it but if you can't find anything wrong, you might try having someone start the engine with the valve cover off while you listen for the engine noise. I'm not sure how fast and how much oil the S54 sends to the top end. After oil pressure develops expect a lot of oil.

Of you could just reassemble the valve cover and use MrMcar's method.

Good luck!
 

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Yes I completely understand, so upon inspection I noticed a lot of things were missing as if somebody took off the valve cover started to do the job and then just boxed everything up. I noticed that the guard for the chain is missing along with a few other bolts.I can definitely tell that the knock or take depending on what you feel is best suited is coming from the top & not the bottom of the engine. Is it possible that if a shim is missing could possibly make that noise?
Have you opened the valve cover and look around yet? What chain guide is missing?

As I said before that I think the noise is in the head and not on the butt.
are you sure the spark plugs and correct ones and not a too long plug causing piston hitting plug?
To check the shim missing or not, turn the crank until the cam lobe point up (along the cylinder direction and not to heaven since it's a tilted engine), then carefully reach in with bare hand (be careful there are small snakes in there ready to strike) and rocking the valve rocker -- you should not feel too much play or clearance with correct shim, but there should be ton of play if shim missing. I doubt this big noise is cause by shim. The big noise seems to be like piston hitting plug or vanos pump drive tang hitting something.

Open the valve cover and take some pics for us to admire at it.
 

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Discussion Starter #19
Have you opened the valve cover and look around yet? What chain guide is missing?

As I said before that I think the noise is in the head and not on the butt.
are you sure the spark plugs and correct ones and not a too long plug causing piston hitting plug?
To check the shim missing or not, turn the crank until the cam lobe point up (along the cylinder direction and not to heaven since it's a tilted engine), then carefully reach in with bare hand (be careful there are small snakes in there ready to strike) and rocking the valve rocker -- you should not feel too much play or clearance with correct shim, but there should be ton of play if shim missing. I doubt this big noise is cause by shim. The big noise seems to be like piston hitting plug or vanos pump drive tang hitting something.

Open the valve cover and take some pics for us to admire at it.
So I popped it open so far everything looks normal with the exception of missing a seal for cylinder one.
 
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