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-   -   DIY Rod Bearings e46 330i BMW - Options/Guide/Pics/ Video (http://forum.e46fanatics.com/showthread.php?t=795133)

MadBMW 09-30-2010 03:20 PM

DIY Rod Bearings e46 330i BMW - Options/Guide/Pics/ Video
Hi all,

Looks like I have some work cut out for me. I want to start a post for a DIY rod bearing (and possibly more) replacement in my 330i.

Long story short, looks like the filter was never changed for a LONG time. When I purchased the car I changed the oil and noticed the filter was all mangled and practically falling apart. Within a few weeks I had shavings of brass in my oil and a loud knocking sounds when the engine is revved. It has 119k miles and was strong when I purchased it about 2 months ago.

I have been searching everywhere and only found a complete DIY for a m5, which helps a little - anything out there for rod bearings on the e46, especially the 330i?

Video of the problem:

Here she is:
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Thanks a ton! :thumbsup:

paraklas 10-01-2010 05:21 AM

You might want to check out bluejeansonfire TT turbo install as the engine is taken apart in the FI section..

MadBMW 10-10-2010 10:31 PM

Some updates, more to come...

The start!
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Start by removing plastic bottom cover and cross brace which is the easiest part... from here on is not for the faint hearted.
Next the rack and pinion comes out. There are 2 bolts with nuts on the top side. The on on the right side of the car is easy,the left is crunched up against the pan and was pretty much the only PITA bolt in the job. When it comes to the tie rods, loosen the top nut in the wheel well and then use a sledge and hit the wheel metal (not the tie rod). After a bunch of sets of blows and a few beers - I finally popped them out. From there you have to take off the engine mount cross bar (YOU MUST SUPPORT YOUR ENGINE, we used the 2x4 and chain method, and worked great. )

Almost there...
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Swing down the sway bar freeing up the front of the oil pan. You have to also take a bolt out of your power steering pump so it can swivel away from the pan. Next take your pan off...

Bottom end internal cover... lots of sludge on the bottom of it.
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Have to remove the oil pump and splash cover.

Finally at the bearings!
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Now your at the bearings, pop the caps off and replace! I used a wrench on the flywheel to move around the crank to free up the con-rods.
Tips: You have to buy new bolts, plastigauge your new bearings to make sure they are in spec and make sure everything is clean as possible.

WALKD U 10-10-2010 10:39 PM

GL on the Repair.


MadBMW 10-10-2010 10:40 PM

Ty man...

ill be working on the bearings tomorrow--- Got the plastigauges to measure the wear...

So looking at some sites there are normal OEM bearings and there are +.025mm oversized.... with the engine having 120k miles do you get the oversized?

PEI330Ci 10-11-2010 03:58 AM


Originally Posted by MadBMW (Post 12333150)
Ty man...

ill be working on the bearings tomorrow--- Got the plastigauges to measure the wear...

So looking at some sites there are normal OEM bearings and there are +.025mm oversized.... with the engine having 120k miles do you get the oversized?

I've had the wrong bearings supplied to me by mistake before, and ended up having to machine the crank to make the 0.25mm bearings work. Funny thing though, the vendor wouldn't admit to their being a mistake, so I never knew what size the bearings were. We were seeing 0.016" clearance, where 0.025" is optimal. So that 0.25mm ends up being 0.009"......

I would order the normal sized bearings. The bearings are designed to wear, not the crank....so if somethings worn out after 120k, it would be the bearings.

I have to ask: Why are you replacing "just" the rod bearings?

Edit: Missed to type "just".

MadBMW 10-11-2010 11:40 AM

Thanks for the info.

What else should I be replacing? The Main bearings ? Oil Pump?


95blkmax 10-11-2010 01:01 PM

Project is coming along great! Keep up the good work and please continue the pictures!

Best of luck! And props on being one of the few willing to open up their engine on their own :)

MadBMW 10-11-2010 04:53 PM

Thanks for the props. This is my 1st time in the bottom of the engine... I did a head gasket on my 2nd bmw (93' 325) and had a lot of fun (kinda) doing it. I always try to do my own repairs - only way I can afford the ultimate driving machine :)

So very happy I found the problem(s). Rod Bearing 2nd from the front is the worst off. Looks like the little tabs melted off and its been spinning around in there. The 1st one looks to be also pretty bad. I'm guessing these are furthest from fresh oil or the most pressure. In reality they all are bad, which is pretty odd and a sign of very poor maintenance over the years.

Front is on the Right
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Front on the left - 1st 3 cyl
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front on the left - last 3 cyl
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Ordering bearings now....

MadBMW 10-11-2010 07:30 PM

Popped the 2 main bearings closest to the issue area and they have a little scoring and scratches on them... going to have to replace the main bearings too while I'm here.

Any reason why I shouldn't lightly sand any imperfections on the crank with say 600 grit paper? Sounds like a good idea....

MadBMW 10-14-2010 01:01 PM

I guess I'm on my own on this one :D

Can anyone point me to the engine specs for Main Bearing gaps? Rod Bearings are .025 i take it..

wildcat293 10-14-2010 04:03 PM

Looks fun, in some sick way I wish I had an excuse to dive that deep into my engine...

phamine 10-14-2010 04:26 PM

You can still use the crankshaft with the scoring?

ruckus323 10-15-2010 12:22 AM

Hey, congrats on taking on the job. You'll love the experience. I have a diatribe below, but please be patient as I have some years behind me on crank design, inspection, test and reman.

crankshaft journal repolishing: this is a tricky business and only done under dire circumstances ESPECIALLY while in engine/vehicle. Only do this if you feel you must and then I might argue you should replace the crank... You can bring DOWN minor ridges with emery cloth, but if you have valleys you have to let them be. If you try to polish out valleys you'll just make flat spots or lobe your journals. Choose an emery cloth finer than 1000 if you can. Microfinish (Ra) on cranks can go as low as 0.05 microns and the 600 grit is in the double digit micron which would gouge more than smooth down ridges. Long story made short, it's like your wet sanding bondo on your body job in that you have to bring only the high spots down and be very patient about it. You'll also want to use a long, full journal wide strip of your emory cloth wrapped around the journal and preferably pulled in only one direction with an even pressure. I don't think I need to say it, but you'll want to use a little bit of lubrication to protect the journal and help float the debris. Tricky business, be careful with your sliding and rotting components.

From the bearing pictures, it appears you only wore to the bronze-lead layer on the bearings and did not wipe them out too bad. From your journal pics, I can't see, but you probably have a decent journal finish on most except the journals that lost the tabs and possible adjacent journals communicating oil through crank oil holes (debris flushes out through these and on to the next victim journal). You'll want to inspect these very closely on the pressure side of the journal. This is the "top side" of the journal where the con-rod would transfer the combustion forces directly from piston to rod bearing.

other tips:
- replace your con-rod and main bearing bolts since I have to see a set that did not call for torque to yield or close to it.
- keep your rod cap and main caps with their original partners
- flush your lube system very well for debris
- check other lube protected parts such as camshaft (your oil broke down and got everything hot)

Alright, I'm rambling... :blah:

Good luck and enjoy!!

MadBMW 10-16-2010 01:45 PM

lol @ wildcat - rather not be diving into the engine... no car is quite the inconvenience! But she is something I don't mind working on :D

Phamine, the crank is a little scored but you cant really feel the imperfections. I just got the bearings in and going to see what the gap is. Hopefully not much more then .025. In reality a $2500 crank is out of the question anyways.

ruckus, thanks for all the good info... Going to get some emery cloth today... There were 2 bearings that lost their tabs and actually started to rotate. Are you saying that there might be something wrong with the connecting rods?

More to come...

tedfredrick 10-16-2010 02:06 PM

I am with Rucus about sanding the journals... only if it is raised. In my opinion 600 grit would be fine on hard steel like the crank but polishing is better if you have the time. You should check the factory finish requirements and make sure you meet them if you can. Make sure you check the cam because it is the farthest from the oil and the first thing to go when the oil isn't changed. I had a 1980 toyota with 60k (many years ago) and the cam was flat from bad oil. I put in a new cam and was good to go. If the beaarings were spinning on the rods make sure they didn't turn different colors which is evidence of heat damage.

ruckus323 10-16-2010 05:15 PM

agree with tedfrederick - give that con-rod and crank journal good once over and then a twice over checking for heat discoloration. You're really lucky the cap stayed on. Was the cracking torque on those rod bolts more loose than the others? Threads look pulled?

If the rod ID is not heat colored then it most likely has blackened (burned oil stain from gap of bearing back to rod). This is normal and tells you oil was there and it left grafitti saying, "F*^%! I'm hot dude!" :evil:

alwaysbored786 10-16-2010 05:41 PM

props for doing this yourself man. I would never want to have to do this

MadBMW 10-18-2010 12:40 AM

Thanks for the props!


Originally Posted by ruckus323 (Post 12355701)
agree with tedfrederick - give that con-rod and crank journal good once over and then a twice over checking for heat discoloration. You're really lucky the cap stayed on. Was the cracking torque on those rod bolts more loose than the others? Threads look pulled?

Everything looked and seemed in tact. The bolts cracked the same and nothing seemed stretched or loose - thankfully. Last thing I needed was a con-rod punching through the block. Everything kinda has that brownish haze on it like you can see in the photos... and break cleaner doesn't do anything really to get rid of it.

I am not really happy with the gap on the 2nd journal. It measures over .025mm in some areas. The crank would have to be machined if i were to use over-sized bearings. Then again it might actually be the inside of the con-rod that has worn. I see scoring in the inside, which is behind the bearings. Those bearings were spinning around in there for a while..........

I think ill put it all back together and hope for the best. If I have issues I can have the crank machined and get the oversize bearings or possibly a new con-rod. :hmm:

ruckus323 10-18-2010 10:07 PM

plastigage told you 0.025 inches or mm? I assume inches otherwise that would be a little tight for bearing clearance. I'm guessing your other rods were between 0.003 and 0.008 inches plastigaged??? I don't know the book specs for these cranks.

If you have 0.025 inches on your rods, you're going to hear some knocking when you out it back together.

If it makes you feel any better, only the M3 crank is $2,500, the standard 3 crank is only $1,200 from PelicanParts. Probably about $200 of real material and manufacturing cost :censor:
...but we all knew that about service parts.

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