S54 Engine Rebuild questions and journey

[SliM3]

One other item worth considering is a fresh set of rod bolts.

[Darbshaw]

One other item worth considering is a fresh set of rod bolts.

I’ve priced it out as of right now for using ARP bolts either way. Figure I’ll go with this and head studs for just a little extra piece of mind.


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[SliM3]

I’ve priced it out as of right now for using ARP bolts either way. Figure I’ll go with this and head studs for just a little extra piece of mind.


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Good deal. I’d recommend getting the rod big ends honed if going to ARP. They have a lot more clamping force so you want to make sure the ends stay concentric after applying full torque. If I remember correctly it’s not that expensive. I want to say < $100.

[Triqzy]

So in my previous post, I found that my head gasket was blown due to the mid-range rpm rattling. I was able to get my head pulled today to find a completely demolished head gasket and a toasted piston on cylinder 2 and a couple of pistons that are pretty porous looking. This now leads me to a rebuild in mind. I am gonna cap off my previous post as this title fits the current issue better now and we'll start the journey now! //Please keep in mind this is all completely new to me, I grew up racing quads but my dad did the building and I didn't retain much from that time. So A LOT of stupid questions will be coming.

The current mileage is 164k

My current plan for my M3 is to eventually supercharge it and probably sit around 400-500 wheel. Tbh I like the idea of the non-intercooled supercharger kit with the ability to add the intercooler should I desire some more power. I am already planning to do an MLS head gasket while I'm here just to bulletproof its boosted future.

My questions come in regards to the bottom end of the engine. The cylinder walls look in fairly good shape and no obvious and apparent damage to anything besides the melted and porous bits of pistons. Since I am going to be getting new pistons, rings, etc, I plan to get the cylinder bore honed to get a truly fresh start back to it. New aftermarket pistons will run me roughly $1400 for just the head itself, let alone the connecting rods if I cannot reuse the current ones. I can fetch cleaned and used OEM pistons with conrods for roughly $300 shipped to my door. I read earlier that the weak point of these engines when power hunting is the rods and head gasket but they are good up to roughly 600 or so which I truly don't see myself ever chasing from this car/engine.

Would I run into any issues with a rehoned bore and running stock pistons and that stock diameter? Obviously the process to hone it takes away the material and would mean the ring gap would increase. Does anyone know how much is acceptable for these engines? Or if this is even a possible approach? Or does wanting/needing the engine honed pretty much ruin my chances to run the stock pistons and rods to save some money.

Last bit to start, is there even any real benefit to running new aftermarket pistons? Minus obviously being brand new but like power or efficiency gain? Or is it really only recommended for those true high boost high HP setups?

Thank you for everyone that is going to contribute or tag along for the ride! I may not respond to everyone's posts all the time but I do appreciate you all. As of right now, I am a little sad but really optimistic and excited about the journey ahead of me. If anyone is on this forum is around the Charleston/Huntington WV area and wants to tag along with a helping hand in person I wouldn't mind meeting a new friend along the way. I'm going to be doing all of this out of my decently small one-car garage on jack stands so it'll be a fun time.

Folder with pictures of the parts post teardown: https://drive.google.com/drive/folde...IN?usp=sharing (Hopefully it will give you guys access to the whole folder)

Could you expand on what you meant by "mid-range RPM rattling"? Was this a noise you noticed in the exhaust note? Or was the engine itself rattling/shaking during the mid-range? Currently suspecting a blown HG on my M3

[Syfon]

Good deal. I’d recommend getting the rod big ends honed if going to ARP. They have a lot more clamping force so you want to make sure the ends stay concentric after applying full torque. If I remember correctly it’s not that expensive. I want to say &lt; $100.

My machine shop told me, due to the s54's connecting rods being of a cracked design, they can not be re-sized. The shop owner was making reference to the one rod which had the spun bearing. As far as I understand, this applies to s54 rods in general (regardless of whether that particular rod has a spun bearing or not).

I replaced rod #3 with a used item from an lci variant. I did not have any machine work done to the rods/pistons. Just had everything cleaned and decontaminated.

I am using ARP rod bolts. FYI, if you're m3 is post February 2003 build, ARP rod bolts are the same for Euro spec S50B30 / S50B32 & S54B32.

[Pavlo]

Re-sizing isn't exactly what it ends up being, more of "make the hole round again" as ARP will turn it into a slight egg. 03+ rod bolts seem to have more clamping than ARP and will actually work the other way.
Mix-matching internal engine components isn't bad, but things do need to be weight matched and the rotating assembly balanced any time you do. Though all the S54 parts that I've measured always come out on-point right away.

Stock main bearings are plenty good for the engine and never really have any problems. I personally run ACL race for the rods, in part because they have a copper layer and will be easy to keep up with using oil analysis, and in part because they are also fairly soft and have a tendency to not eat your crank up as they begin to fail. Race bearings in general are soft and will wear quicker, but they are easy on the crank. S54 will always go through bearings (despite what people may tell you), there is no magic way to defy physics.

As for piston rings, Mahle is who makes the stock pistons and they will sell you the correct rings for them, just measure your stock ones and order from them.

If you need any parts, I have plenty of extra rods/pistons/pumps... Let me know if you can't find something you need.

One more thing: if you have mid range rattle noises you may have a poorly matched flywheel weight. My old S54 rattled a rod bolt out with an E36 M3 14lb flywheel +pressure plate combo (had the rattle), current setup I switched to the JB racing Grand-Am spec 20lb part and its been doing great.

[Syfon]

Re-sizing isn't exactly what it ends up being, more of "make the hole round again" as ARP will turn it into a slight egg. 03+ rod bolts seem to have more clamping than ARP and will actually work the other way.
Mix-matching internal engine components isn't bad, but things do need to be weight matched and the rotating assembly balanced any time you do. Though all the S54 parts that I've measured always come out on-point right away.

Yup, the machine shop weight matched the replacement rod & balanced the rotating assembly!

This is my first time assembling a motor, so there a lot for me to learn!

[Darbshaw]

Could you expand on what you meant by "mid-range RPM rattling"? Was this a noise you noticed in the exhaust note? Or was the engine itself rattling/shaking during the mid-range? Currently suspecting a blown HG on my M3

So if you’ve ever cleaned your icv the sound that it should make is something to what a cleaned icv sounded like. I noticed this between 2-3k rpm ish range, high gear and like quarter throttle.

I really really do suggest from my experience now, if you’re suspecting a blown hg spend the $40 to buy a compression tester from autozone. (The tented one for me didn’t have the right adapter) I’ll link my old thread for the plinking when I get home today!

Sorry on the long response, life’s been busy lately


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[Darbshaw]

Sorry for the delay guys!! Life’s been super busy and I finally had a day off midweek because I have to work the weekend.

I got my head dropped off at the machine shop yesterday with new valve stem seals! Very excited to get that back and semi reassembled to have it out of the way.
I was also able to get the front all torn off and everything disconnected minus the transmission wiring harness and she’s almost ready to come out!! Good excitement finally, just waiting on being able to rent a cherry picker to get her pulled.

This is going to be my first time building an engine as well so it’s going to be interesting to see how it all plays out. A lot to learn and a lot of questions 😁


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[Darbshaw]

Okay so I will most definitely be getting my rods machined once I get the ARP bolts. I’ve already come to terms as well with the rod bearings being a consumable, so ACL is the way to go for the price. I’d have to replace mine 3 times or so to take advantage of fcp’s discount.

Maybe I’ll decide to go with uncoated mains and just stick with true oem. I was looking at the TIS manual for this and there was stuff about the gap measure and different color coded bearings for clearance purposes.
Although you can just buy a set of main bearings and says nothing about clearances or color coding. So is it safe to assume that this is nothing to worry about?

Along with that are the main bolts one time use stretches as well? I didn’t even think about this and budget them in but they don’t seem “too pricey”

Thanks for the heads up on the mahle rings! I actually found some through an eBay vendor sized for the s54 and they’re only like $175. Any idea what the pricing would be straight from mahle themselves??

Again, sorry for the delay and the multiple posts. Formatting is tough on the phone. I have been busy the past couple weekends with life and haven’t been able to give the M much love. I really do appreciate all of your contributions!!


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[Darbshaw]

Little update, engine is pulled and the next step in the process starts! excited to get this thing torn down and to the machine shop.
Head should be done this week as well, some slight corrosion damage on the inside of cylinder 2 but the guys at the shop don’t suspect it will cause much an issue at all.


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[Syfon]

Along with that are the main bolts one time use stretches as well? I didn’t even think about this and budget them in but they don’t seem “too pricey”

I can't remember if the main bolts are one time use (I'm pretty sure they are, check the relevant TIS document). I replaced all 14 main bolts.

Make sure you replace the head bolts too.

Great work on getting the motor pulled! Now go full anal and clean every single component including the entire bay! I slowly worked through my engine bay and degreased/scrubbed everything. I then scrubbed every engine component. It will be nice when it's all back together and it's literally clean just like it came from the factory

[Darbshaw]

I can't remember if the main bolts are one time use (I'm pretty sure they are, check the relevant TIS document). I replaced all 14 main bolts.

Make sure you replace the head bolts too.

Great work on getting the motor pulled! Now go full anal and clean every single component including the entire bay! I slowly worked through my engine bay and degreased/scrubbed everything. I then scrubbed every engine component. It will be nice when it's all back together and it's literally clean just like it came from the factory

Thanks man I’m excited now that I’m actually making some progress.

Oh the cleaning has already commenced, I got some degreaser and brushes and have been going to town as I pull components off or while some are still on. My timing cover itself had such a thick layer of crud it was a little nasty. Kinda forgot that it’s supposed to be that aluminum color.


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[Syfon]

Thanks man I’m excited now that I’m actually making some progress.

Oh the cleaning has already commenced, I got some degreaser and brushes and have been going to town as I pull components off or while some are still on. My timing cover itself had such a thick layer of crud it was a little nasty. Kinda forgot that it’s supposed to be that aluminum color.

You just reminded me, I need to clean my timing case cover too. Still has grease and shit all over it!

I'm hoping to get the timing chain/guides/case cover on soon, along with the head, cams, vanos and time everything.

Life just gets in the way sometimes.

[Darbshaw]

You just reminded me, I need to clean my timing case cover too. Still has grease and shit all over it!

I'm hoping to get the timing chain/guides/case cover on soon, along with the head, cams, vanos and time everything.

Life just gets in the way sometimes.

Trust me I totally understand with life getting in the way. I have to work this weekend so I have tomorrow off and decided to use the night to tear down the engine.
Picking up the head tomorrow and swapping them with the block and crank. Fingers crossed they can get away with just honing the engine and we’ll be making some great steps. If they do have to bore it out, just going to slow the process.


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