Video: 97 m3 engine knock/rattle

[m3f_hardtosee]

If a pulley was bad enough to make that kind of noise it would be obvious and probably chucked the belt off. Dropping the pan would have been the first thing on my list

Sounds like a bottom end noise. I would have tried to pinpoint this with a stethoscope before tearing the head apart. Depending on your mileage, the head probably already needs a refresh if it's being taken off, however I wouldn't do this before finding the culprit of the noise. Additionally, I haven't heard of the hydraulic lifters in these engines failing. I think they get old and 'soft fail' and become loud.

Valvetrain inspected and compression test complete, no issues observed/noted, compression 150+ on all cylinders.



Oil pan is coming off today, will update with what we find.

[m3f_hardtosee]

Cylinder #1 - spun rod bearing. Visible play when oil pan removed; removal of cap revealed the bearing having slowly been eating itself.


https://plus.google.com/photos/11424...99452154830753


Still puzzling given no loss of oil pressure or low oil level. Will be cleaning up al internal surfaces and replacing bearings, as well as taking care of oil pump while we're in there.

[m3f_Tock172]

What's your game plan?

[m3f_jayjaya29]

What's your game plan?

Will be cleaning up al internal surfaces and replacing bearings, as well as taking care of oil pump while we're in there.

Read much?

[m3f_haus]

OP, I'm curious if you ever had any oil analysis done? I've read that certain detectable metals (or even worse, visible particles) in the oil can indicate the beginnings/existence of a spun bearing, at least if it's a slowly progressing failure and doesn't happen instantly due to some catastrophic failure. I just wonder if there was potentially a way to know about this before it got to the point in the video.

[m3f_jayjaya29]

If you see high levels of chromium in your used oil analysis that can mean that the bearings are wearing out.

[m3f_matty.]

Traditionally you want to look for high copper levels in the analysis. Google or look here in the e46 section for more info since this is much more of a concern on the s54 engine..



OP, it doesn't look like you will be able to do a simple bearing swap as it looks to have damaged the crank which means that the crank will have to be pulled and resurfaced or the imperfection will eat another bearing in no time flat.

[m3f_hardtosee]

OP, I'm curious if you ever had any oil analysis done? I've read that certain detectable metals (or even worse, visible particles) in the oil can indicate the beginnings/existence of a spun bearing, at least if it's a slowly progressing failure and doesn't happen instantly due to some catastrophic failure. I just wonder if there was potentially a way to know about this before it got to the point in the video.

No, I had never done oil analysis. The car has been a daily driver for the last couple years, regular preventative maintenance completed in a timely/professional fashion, whether by me personally or my mechanic.



I still have the oil, although at this point I'm sure we can already predict what would be found.

Traditionally you want to look for high copper levels in the analysis. Google or look here in the e46 section for more info since this is much more of a concern on the s54 engine..



OP, it doesn't look like you will be able to do a simple bearing swap as it looks to have damaged the crank which means that the crank will have to be pulled and resurfaced or the imperfection will eat another bearing in no time flat.

How can you tell that the crank has been damaged w/o the bearings having been removed? I respect your opinion but I'll withhold my own judgement until we remove the bearings and get a good clean view of the journals.



If there is damage to the journals, agree- crank will be pulled and resurfaced or replaced.

[m3f_matty.]

No, I had never done oil analysis. The car has been a daily driver for the last couple years, regular preventative maintenance completed in a timely/professional fashion, whether by me personally or my mechanic.



I still have the oil, although at this point I'm sure we can already predict what would be found.



How can you tell that the crank has been damaged w/o the bearings having been removed? I respect your opinion but I'll withhold my own judgement until we remove the bearings and get a good clean view of the journals.



If there is damage to the journals, agree- crank will be pulled and resurfaced or replaced.

You only posted one pic in your google+ so I'm not 100% but it looks like the crank surface after removing the affected rod cap, no..?



In regards to UOA, I have been doing them on my oil changes since taking ownership of this car since I wanted to know the motor condition. It is not definitive, BUT actually gives some useful data as to what is normal for the engine in comparison to future tests which might indicate something 'abnormal'. The database at Blackstone tracks s52 motors in general so they give you a comparison to what they have seen over the years, very useful. Also, will tell you in their is dirt, ie poor air filtration or vacuum leaks. Coolant presence, indicating cracks in water passages or head gasket. Copper and iron indicating bearing, wrist bushing, or cylinder wear. Fuel, indicating possible injector issues or rings. IMO all useful when used in conjunction with other diagnostics.



My last test came back slightly elevated on copper. The tech said not to get worried but keep an eye on it for the next intervals. If it stays up there I will be changing bearings in advance of a failure.

[m3f_Solaris99]

You only posted one pic in your google+ so I'm not 100% but it looks like the crank surface after removing the affected rod cap, no..?


In regards to UOA, I have been doing them on my oil changes since taking ownership of this car since I wanted to know the motor condition.

I've been doing UOAs on all of my cars since 2008. I never had any major impending issues detected by it, but Blackstone once suggested I switch to race oil in one of my cars even for street driving. Wadded that car up shortly after, though. Then I saw regular synthetics in other cars hold up extremely well, even for track use. It's good to know how well your oil is working and making sure nothing is mixing with it.


A good resource is bobistheoilguy (Google it). The forums contain useful info from very experienced people about UOAs.

[m3f_matty.]

Interesting. Did you wreck the car or did the engine blow after the oil, and what spurred Blackstone to recommend it..?

[m3f_Solaris99]

Interesting. Did you wreck the car or did the engine blow after the oil, and what spurred Blackstone to recommend it..?

I wrecked it on the street. They saw high iron in my samples, which they said tends to be from excess wear at steel parts. It was an LS7 and I did take it to the rev limiter a lot.

[m3f_hardtosee]

Well, it looks like matty and some other user's suspicions were correct- the journal has scoring and damage or depositd metal near the radius @ the edge of the journal surface.



The #1 rod also has a nice little chunk taken out of it.



https://plus.google.com/photos/114248591978616121453/albums/6103176123262224033?authkey=CMW4yrSB5NK1XQ



Expert opinions welcome, but I'm pretty sure this calls for the crank to be resurfaced and cyl #1 rod to be replaced, at the very least.



In the interest of time, I'm going to either purchase a replacement engine or small block.



I like the idea of starting with a small block and building it up, the mechanic I'm working with has significant experience with engine builds. Neither of us have built an S52 before, but we're both excited to do it.



Thoughts on which is more cost efficient (used/trusted small block build up, or a regular engine swap) are welcome

[m3f_englishtom1596q]

It's not called a small block lol that would be in reference to small block v8's. What you're thinking of is Short block which means just the bottom end with rotating assembly or long block which is the whole motor (not including accessories).


Now that's cleared up, yes you are better off buying a decent motor to swap in. Look for one with lower mileage with maintenance history so you don't have to open it up. Just swap your accessories onto it and drop it in. The time you buy a new crank, rods and gaskets you'll be around a grand. Then add in machine work and you're close to the money for a lower mileage motor. Unless you plan on full on building your motor then it isn't worth it to try and save it. You can sell what you have to offset the costs

[m3f_englishtom1596q]

Unless of course you want to put a small block Chevy motor in their like an LS7... In which case by all means go right ahead! Lol