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After 116k hard miles, I'm beginning to see a few signs that maybe it's time to tear down and rebuild my '98 M3. I'm getting more than enough smoke on WOT that enough people have told me my rings aren't acting properly. That plus a few leaks around the engine, I think I'm ready to bite the bullet and do a rebuild. I really only use the car for track, autocross and spirited driving, and I'd rather preemptively do this work versus wait until something bad happens and more work would need done. Currently, the only mod to the engine is the m50 manifold swap (3.5" intake and MAF, 24# injectors, tune, etc). I have already decided I'm not going FI on this, and want to stay close to stock.
My thoughts were to more-or-less rebuild the head (springs, valves, etc) unless they look like they are good. I'd like to bump up the compression slightly, and on the bottom, I'd do the normal oil pan stuff (oil baffle, and items in that general area). I'd like to keep the cams the same unless I find a great deal, and I rebuild the VANOS about 4 years ago.
My asking for recommendations is since I'm going this deep, what other areas should I consider replacing/upgrading? I'm sure I'm leaving out a few details, but I just wanted to get the conversation started. TIA.
'98 M3 5spd - '03 540it 6spd M-Sport
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Really surprised you feel like you need to rebuild at such low mileage. Have you done compression and leakdown tests yet to confirm whether it's rings or valves (or just valve guides) that are leaking?
1998 Titanium/Dove M3/4/5
2020 Toyota 4Runner
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Or valve stem seals. These are practically tractor engines and can run for hundreds of thousands of miles. But they are all 20 plus years old and many need a little work. Probably not a complete rebuild, though. You can spend $10k on a fully built performance long block if you are looking for an expensive project and want more power.
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I have not. I'll do that in the coming weeks (out of town for the next 3-4 weekends)Originally Posted by RightYouAreKen
'98 M3 5spd - '03 540it 6spd M-Sport
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I'd leave the block alone unless you absolutely have a reason to want to muck with the pistons. You also avoid having to pull the entire motor. You can just work on the valvetrain, or if you want/need to do the head gasket you can pull the head. If you're not upgrading to more aggressive cams or anything, probably the only thing worth touching in the valvetrain are the valve stem seals. If you want to do springs it's easy to do them at the same time, though I doubt they need replacing. On the bottom end you can do anything you want to down there by just dropping the pan, including rod bearings if you want to (though again they're probably fine).
I've thought about this a lot myself too as some sort of partial rebuild is in my future at some point. Though in my case it will mainly be part of installing new cams. I'll do springs/seals and VANOS at the same time. I've already done my bottom end with the reinforced pump/pickup and baffles. Assuming it compression tests fine at the time, I don't have any desire to pull the head or mess with the block.
1999 M3/2/5 - Titanium Silver - Track/Weekend Toy
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I'd slow down a little and do some extra homework before you spend a lot of time and money addressing the wrong thing.
Smoke on decel is usually an indicator of bad rings. But you said yours is on WOT. Smoke on acceleration is usually a symptom of valve seals.
Valve seals are relatively easy for a machine shop. And a great time to add cams.
I find it interesting you'd go to all that work replacing valves and springs and NOT do cams while you're in there. Schricks are decently expensive, but the Riot cams are only $465 or something after your core. If you're already pulling your cams to replace the valves and springs (which is of incredibly dubious value on a brand new engine like yours), why wouldn't you do the cams while the head's completely disassembled?
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
On-ramp hero
I'd also add to this that even simply switching brands/weight of your oil can make a noticeable dent in the amount of smoke produced.
'97 M3/2/5 Lux, AW/Modena, ~225k, many mods and lots of grip
Please lift when giving a point by
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Rather than spend $475 to redo your S52 cams (or $500 more for core charge if you don’t have any), you could sell your S52 cams for $350-400, add the $475 you would have spent to have Riot redo them, and put the $825-875 towards a pair of new billet core Schrick. I recall seeing them for $1100 or $1150 not too long ago.
CatCam in Europe may have new blanks it can profile to a Schrick spec for less. Also worth looking into.
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It is expensive to rebuild the engine to a high standard. If you have the disposable income then great. But you are talking many thousands of dollars to have a reputable engine shop do the work. There are definitely less expensive ways to go. Really depends on what you are after and willing to spend. S52 is less expensive than some but still not cheap.
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Something for all of us to aspire to!
And he lists the build on the following page.
QtheGenius may be jumping the gun on a bottom-end rebuild, but at 238k I'm in a bit of different boat. I don't have any symptoms of anything yet, but nothing lasts forever. I'm going to have to do the bottom end one of these days, and I've thought a lot about doing a high-compression piston when I overbore to get back to a round cylinder. But I also can't handle the thought of NOT DDing my car anymore, so race gas as a requirement is out. If it can't run on 93/91, I'm not interested. (Also not interested in ethanol - availability is just too spotty for me).
I think 11.5:1 is about the max you can run safely without getting into detonation issues, and this (for me at least) wouldn't be a no-holds-barred attack on hp. I kind of view that day like sending my first kid off to college (and it may even happen about the same time, too). Something to look forward to and dread at the same time.
But whenever that day finally comes, I'd think that an 86mm 11.5:1 piston, cams, and full bolt-ons should be good to juuust clear 300 at the wheels - which is exactly what that dyno shows.
The mindset behind an 86mm vs an 87mm piston is simple - I need to leave some room for the NEXT rebuild at 600-800k miles.
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
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I have 11:1 pistons and Epic Sport cams. I would not want more for a street driven car. It is very loopy at idle and easily breaks free the rear tires.
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I'm most of the way through your build thread. It's taken me almost ten year's worth of weekends to do 60% of what you've done. Truly impressive.
Two questions:
1. How did you decide on 11:1 and what were the drivers behind that? Did you bore up from the 86.4mm stock size (yeah, I mis-spoke a little up above)? I imagine at your mileage the cylinders were still nearly perfectly straight, so you didn't necessarily need to true them up and go to a bigger piston.
2. What kind of tune do you run given what you've done to it? I didn't notice that in the build thread (though I may have just overlooked it).
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
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The piston choice was the recommendation of the engine builder. I do not recall the bore but I can probably look it up at home. I wanted to stay with pump gas and something manageable on the street. The pistons are manufactured by JE. Just a the small bump to 11:1 seems to make a lot of difference. The cams definitely help as well. Plus the intake & exhaust is modified to push a lot more air through.
The tune is from Epic Motorsports (Randy Mueller). Out of Florida I believe. You can order direct or get through Bimmerworld. The cams & valve springs are from Epic as well.
Once you are into the engine there are a ton of small things you have the option to do in additional to the big things. It all adds up.
Getting a highly modified engine running well can be challenging (my experience anyway). It is also very satisfying once accomplished.
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Your experience helps those who follow avoid many of the pitfalls you've had to deal with.
My car is my daily for a couple reasons, but the main reason is that I don't WANT to drive anything else. I had a friend who bought a 911 and kept his Volvo to use as his daily. The problem was, every day when it was time to go to work, he'd look at both cars and pick the 911 every time. And I feel the same way - I don't want to be without the car for an extended period of time. I could do a month, but longer than that - sorting driveability issues for six months - would drive me crazy. And with kids from 6-14, I don't have the time to hang out in the garage for months at a time anymore, either.
This uncertainty around the time needed for sorting out these driveability issues really makes me think twice about this long-term plan to increase compression and build the bottom end. But the allure of the challenge - and the fruits of the effort - are just too much to resist. And as I said, your experience as a guide makes this that much easier for those of us following behind.
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
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