Sounds like a slight rod knock

[m3boost]

I'm in need of some input... This is for my e30 s50 turbo m3..I rebuilt the engine cause it was starting to smoke. I bought 86.5 mm JE pistons with eagle rods. So the engine had to be slightly bored. I used new main and rod bearings all stock. Everything was plastic gauged and tolerance was basically in the middle of what its allowed. The car at first start up, had a loud ticking noise in the valve train.. I removed lifters and found two that were completely squashed, so I replaced them. To make a long story short, I replaced all of them. The engine is now quiet with the exception of what sounds like rod knock. You really can hear it unless you really know what you're listening for. If I accelerate to 2000 rpm, it's heard a little louder. But if I start driving it, then it can be heard with ease. I can not seem to pin point where its coming from even with a stethoscope. I can point to the general area which is around rod 5,6 and transmission housing..

Things I've done so far,
1) I removed the engine to plastic gauge everything again and it's with in specs.
2) Since it's an s50 in a e30, it requires the oil pan from a e34 with it's built-in tray. I didn't have an issue before when it was stock, but I went ahead and remove that tray and placed the oem tray for the s50 on the block.
3) with the car at 2000 rpms, I disconnected one coil at a time to see if the knock would null on a particular coil, and there was no change in the sound.
4) Also, forgot to mentioned that I placed new oil squirters
5) today I finally installed an oil pressure gauge. It reads 60 psi at idle on cold start, and reduces to 22psi once it's warm. It increases as the rpm's go higher.
6) it also has a brand new s52 flywheel, clutch, pressure plate, throwout bearing, and pilot bearing..
7) made sure spark plugs were tight.
8) At cold start, the noise is not heard or atleast I can't hear it. Only as it gets warm

I have basically have ran out of options. The head is from a 93 325i with my m3 cams and trays.
So any input would be greatly appreciated. Thanks

[M-technik-3]

Your coils and extensions have you checked them? maybe you are having an interment misfire? I am chasing a misfire issue in my car right now and it's driving me nuts because it keeps appearing in different cycles.

[m3boost]

Here's a video i took of the sound.. There's slight valve train noise since I took the cams out to check all lifters and timing...The noise I'm concern is heard at the bottom end. oil pressure at idle when fully warm is 10 psi and will rise to 40psi at 3000 rpms...65psi at cold start

https://youtu.be/npMAknQTPgg

[e30davie]

Just a random thought, did you check the journal diameters with a micrometer or did you just plastigauge? Having not alot of experience my understanding was that plastigauge was more of a good guide....Although considered good enough for most applications...

[M-technik-3]

How were the hydraulic lifters did you check them? These can be loud and will sound like a rod knock as well?

[m3boost]

How were the hydraulic lifters did you check them? These can be loud and will sound like a rod knock as well?

They have all been replaced with new ones... That same noise was there before they were replaced. I just removed the cam and trays to check the lifters again two days ago. Wanted to see if any of the lifters were collapsed..

A little history.. this s50 engine ran good for 3 years boosted until it started smoking alot so I decided to just rebuilt the whole engine.. I used 86.5mm JE pistons and eagle rods. New standard main including bolts and rod bearings all plastic gauged also new oil squirters. I had to use another head cause I found a slight crack.. I used a 93 325i head that had straight valve springs instead of the tapered ones. I used the original cam trays and cams..I put it all together and installed the engine in the car. At first start up, I had a lot of lifter noise along with that knock. I removed the engine again, I replaced all lifters with new ones and plastic gauge the mains and rod bearings again. All measurements were in the middle of the tolerance.

I reinstalled the engine, at first start up, the lifter noise gradually went away but the knock was still there. I supported the engine and removed the oil pan and removed the windage from the oil pan and since i forgot where I left the windage that came with the s50, I ordered a new one and used that one instead. Someone told me to check the oil pressure, so I installed a pressure gauge and it reads 60psi at cold start and gradually lowers to about 10 psi when fully warmed. It will rise to 40 psi at 3000 rpm. with stethoscope, it seems like the noise is coming in the area of number 6 and transmission housing.. It does have a new dm flywheel, clutch, pressure plate, and throwout bearing.. The noise is there regardless if I press the clutch pedal.

[CptPhilmeister]

PLEASE let me know if you come across a solution to this.

Your case is the closest I've seen to mine (even the youtube sounds!) and I've done a lot of searching and forum chats where I've been consistently met with "Vanos! Vanos!", only to swap out a 3 year old vanos kit with a brand new one along with all new seals and STILL being met with this sound.

My next attempt will be replacing the Rod Bearings.

I had two independent mechanics both check the car and they have suggested two things:
1. Rod Bearings or just a bad rod altogether.
2. Something hitting the flywheel or the chain tension being off.
Both then followed up with the same assumption of the sound coming from far too close to the engine to be a flywheel noise and should look into Rod Bearings.

In my case so far:
- Noise only heard after the engine has reached peak operating temp.
- Noise exists whether clutch is pressed/depressed. No change.
- Noise heard when on consistent RPM's (driving along the highway at 75mph@~4000rpm).
- NO noise heard under load (stepping on it to speed up) and I've seen no change in performance. Engine pulls strong, no smoke issues etc considering it is coming up on 200K miles at some point this year.

I've also tried thicker oil, which subdues the sound for a while but has it ending up coming back anyway.

Let me know if you come across any other solutions. I'll update here post Rod Bearing change as well. I need this noise gone!

[m3boost]

PLEASE let me know if you come across a solution to this.

Your case is the closest I've seen to mine (even the youtube sounds!) and I've done a lot of searching and forum chats where I've been consistently met with "Vanos! Vanos!", only to swap out a 3 year old vanos kit with a brand new one along with all new seals and STILL being met with this sound.

My next attempt will be replacing the Rod Bearings.

I had two independent mechanics both check the car and they have suggested two things:
1. Rod Bearings or just a bad rod altogether.
2. Something hitting the flywheel or the chain tension being off.
Both then followed up with the same assumption of the sound coming from far too close to the engine to be a flywheel noise and should look into Rod Bearings.

In my case so far:
- Noise only heard after the engine has reached peak operating temp.
- Noise exists whether clutch is pressed/depressed. No change.
- Noise heard when on consistent RPM's (driving along the highway at 75mph@~4000rpm).
- NO noise heard under load (stepping on it to speed up) and I've seen no change in performance. Engine pulls strong, no smoke issues etc considering it is coming up on 200K miles at some point this year.

I've also tried thicker oil, which subdues the sound for a while but has it ending up coming back anyway.

Let me know if you come across any other solutions. I'll update here post Rod Bearing change as well. I need this noise gone!

I'm gonna pull the engine out.. and take everything apart again. I'm assuming one of the wrist pin clip might have gone loose..But I'm just going to start from scratch..I'll let you know..here's video of the sound.. notice how its heard louder from the bottom.

https://www.youtube.com/watch?v=npMAknQTPgg

[cbr]

That sounds a lot like the ticking I get in my e36 M3 with low oil levels due to the hydraulic lifters not having enough pressure. Have you run the motor for 5-10 min and/or verified you have enough oil around your pick-up?

[LowR3V'in]

looks just like what i went through.
if it is, the piston and block are trashed :(
i took pictures in my m30 build thread.
deep ass valley the pin made up the side and piston hole oblonged.

You hope its a bent pulley or piston slap i'v even read about the flywheel can knock.
just sweet sweet lies to tell yourself.

[m3boost]

looks just like what i went through.
if it is, the piston and block are trashed :(
i took pictures in my m30 build thread.
deep ass valley the pin made up the side and piston hole oblonged.

You hope its a bent pulley or piston slap i'v even read about the flywheel can knock.
just sweet sweet lies to tell yourself.

Thats what I'm thinking already.. I do have a spare block.. At this point, I just want to find out what is causing it.. I would hate to take everything apart and not find any convincing evidence of the issue.. but we'll see..

[CptPhilmeister]

Any luck finding the culprit?

I haven't had a chance to take mine to a shop to take a look at the bottom end.
:(

[m3boost]

Any luck finding the culprit?

I haven't had a chance to take mine to a shop to take a look at the bottom end.
:(

I just took it to the machine this past Monday. I did take the head off and oil pan.. Didn't see any visual issues.. But I told the machine shop to take everything completely apart and check for all clearances..

[CMBusch]

Do you have the oil check valve installed on the underside of the head?

[m3boost]

Do you have the oil check valve installed on the underside of the head?

yes