Member
Hi Everyone,
So just a little backstory on this project. I've pulled the motor out of my 320i, it was running pretty good when I pulled. but the entire timing cover was covered with a good 1/2 inch of oil goop, it was getting 6 mpg and drank oil like my mom drinks coffee at 8am, other than that everything was pretty good. Fast forward a month and a half and I have the engine complete disassembled, as well as pretty much everything in the engine bay taken out. Just last week I ordered all the parts that are going into this build and they arrived like 2 days ago, still waiting to get the camshaft back from RaceTEP.
I'll stop blabbering and get down to the point of this post. I need to decide if I should take on the task of putting the motor back together myself or if I should hand it over to a shop that really knows what they're doing. Keep in mind that I bought this car in July 2021 and I haven't really worked on cars before then, so I've only got about 9 months of experience under my belt. During the time that I've had the engine apart I've pretty much non stop researched various engine rebuilds, how to accurately take measurements, how to put everything together etc. So I think I have a decent idea of what I would have to do.
The thing holding me back from just going ahead and putting it all back together is the stories i've read of people doing the exact same thing as me, getting it all back in the car, driving it and the thing blows up 20 minutes later. I understand the level of exact preciseness that has to go into an engine rebuild and I'm just worried that I could make the same mistake. I'm pretty slim on money right now and I really don't want to gamble with it, but I'm not opposed to bucking up and paying someone who knows exactly what they doing to do it for me, at the same time it would be amazing to put it all back together and have that satisfaction once its all done.
With everything I mentioned, what do you guys think I should do, I'm stuck in the middle right now. But I would love to learn how to do something like this, and be able to prove to my parents that I'm not just doing this car stuff as a little hobby.
Thanks in advance!
-Cole W
Member
IMO you could do it knowing that certain details need to be taken. One of the reasons the platform is still around is it's a simple robust engine to build by the DIYer. That says a lot about what BMW got right with the first 4cyl.Originally Posted by HappyE21
Basic engine knowledge applies to all so good time to crash course with this one if you choose.
Rings and ring gaps, orientation of ring pack upon insertion. Bearing clearances using plastigauge, notch to notch orientation along with rod direction. Proper torque for all bottom end and head bolts (mainly the critical ones). The rest is really straight forward sealing.
Putting the head back on setting cam timing at least with notch on cam to crank pulley notch.
There's plenty of us on here that can help. Just it's a forum and time return to post can be longer than instant. Some members are above average doing a few motors. Some way above average at knowing book manuals and reference material. This forum and your will could do this IMO. Another great reference is the 2002faq forums for engines. Seems a lot more responses on weekends.
https://www.bmw2002faq.com/forums/fo...-and-other-02/
Blow up? maybe bearings and clearances, putting rod or main caps on incorrectly opposing notches would do it. Other than that and completely screwing the ring pack or critical oring for the oil pump tube on mounting it can't see it happening. Oil starve or run bearings mismatched sure it won't last long. Yes if anything happens it's gonna in the first 20min or so running. Mismatched bearings take longer and eventually spin then kill it.
You seem organized and know not to just "throw it together". I'll quote my race buddy who says "Sometimes the best engines are built on the shop floor".
88 M3
91 318is
91 318i
83 320is
08 X3 3.0si
"If it flys, floats, or f*cks, rent it!"
Member
Having a shop build your engine is not guarantee that you won't have problems. Of course, with any machine work you won't have any choice but to send it out to a shop, but for the assembly you might as well go slow and careful, and learn along the way.
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There is a series on YouTube by Technics Daley you might want to watch. It goes through an m10 rebuild. https://m.youtube.com/watch?v=cNitHSDcevs
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@HappyE21, assuming that is your car in your profile picture, is the color Coronagelb or Golfgelb?
Member
Makes sense on the blowing up part, I think if I make 100% sure I have everything right I should have that problem, fingers crossed. I have the Haynes manual and the BMW blue manual so I'll follow those closely. I think between the help of this forum and the 2002 forum and my own research I should be able to pull it off. The shop I really wanted to have put the engine together wont email me back or call me so I guess I really don't have a choice anymore. I'll have to buy a couple more measuring tool but that shouldn't be a big deal.
I've watched a couple of his videos on the m10 rebuild, great videos, he goes into a lot of detail.
It's Koronagelb, although the entire car has a terrible rust problem, in the engine bay, floor pans, almost every body panel, sunroof, window seals and especially the trunk. I spent the last week or two fixing the rust in the engine bay in prep for the shiny new motor, all the other rust is the next big leap of faith in this project. Thankfully the interior is pristine.
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Pictures of almost everything I ordered:
image_50392321.jpgimage_67198209.jpgimage_67140353.jpgimage_50382849.jpgimage_67202817.jpg
More on next post, only lets me do 5 pictures
Member
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I think I'm going to have all the machine work done this week. I still have a couple more measurements to take to make sure everything is within tolerance, but I just want to know what exactly I should have the machine shop do. I think at the minimum I will have them deck the block and the head, but what about line honing, cylinder honing, pressure testing and/or magniflux, ect. This motor was running well when I took it apart, so I don't want to spend more money than I have to.
I have another question about shaving the cylinder head, would this be a good idea or even worth the money. I think stock compression ratio on the 320i is 9.3:1 and I'm not sure how much a fifth inch or so taken off the head would effect how the engine runs, camshaft has +.5mm lift over stock so that will have to be taken into consideration. I know people have done it, but I don't know exactly the pros/cons.
Member
Biggest items to me are
Bores, re-hone and new rings
Deck flat maybe a skim passes to clean up block
Valve guides replaced if need be if not just new seals
Head valves and seats checked cut if need be; perfect time if needs valve job to do so.
Rods checked for trueness and re-bush the small end if need be.
Rare ever to need a line bore. I've never had one done. Mains and rods I shoot for .002" clearance, street maybe .0015" but everyone has their spec. If hard race use I shoot for .003" on the rods depending on oil pump and other oil feeding parts.
Just give the machine shop the pistons and rods so they can check themselves what should be done. When assembling you can double check ring gaps, and bearing clearances.
Skim head to clean up unless taking off a lot to bump compression. 0.020" is plenty to take off if adventurous will bump almost 0.4-0.5 compression. Factory is 8.8:1 and should get 9.2-9.3 arena. Clean off the hard edge after machining of the chambers (leaves a fingernail like edge around the head chambers which is a hot spot) Just sandpaper the edge by hand is enough but can use a sand roll and zip it off smooth faster not going to hurt anything.
88 M3
91 318is
91 318i
83 320is
08 X3 3.0si
"If it flys, floats, or f*cks, rent it!"
Member
Thank you for the deets, I’ll post an update once I get everything back from the shop, probably sometime next week.
Member
Check the trueness of the crankshaft, in most cases the trueness will be there since the crankshafts have not been subjected to high horse power in these m10 motors 1.8L or 2.0L, also check the journals of the crankshaft are within specifications. I did this for a 2.0 L crankshaft I got from John and found even after the many years of age it had it was still in specifications,, machine shops have the machines to test trueness of rotation or you can make one for few dollars,, journal measurement is done using a micrometer. Once you know the condition of the main journals(big end) and the rod journals you can fit the proper bearing size, in the 2.0L crankshaft mentioned above standard size fits just like new. More than likely a polishing of the journals will suffice unless there has been wear.
Randy
Last edited by 320iAman; 04-19-2022 at 12:07 AM.
Member
Randy, I measured all the crank journals and like you mentioned they are all pretty good. I think I'll be able to run standard bearings on these. Things get a little sticky when started measuring the cylinder bores. Every cylinders taper and out of round where out of the 3.5045" +- .0004" spec. The worst cylinder seemed to be #2, out of round was .0027" and taper was .0014" I will post pictures below of all the crank journal and cylinder bore measurements.
I called a reputable machine shop in the area today and told them what I had measured, the guy seemed to know quite a bit about the m10. He said I would probably need to rebore the cylinders. I really wanted to avoid doing so but I guess if I have to I'm left with no choice.
The machine shop also gave me a quote for the following
-deck block + head
-rebore + install bushings and rod bolts on conrod
-disassemble + reassemble piston and conrod
-rebore + hone + tank + measure block
-replace guides + tank + assemble head
-balance Rotating assembly
-resurface flywheel
Block: $370
Head: $430
Piston/conrod: $260
Balance: $225
Flywheel: $25
Total: $1,310
This is my first time doing this so I'm not sure how fair these prices are. I'm going to call around a bit more and see what other shops have to say and what they will quote me.
If anyone has any ideas if the block will actually need to be bored out let me know, it would save me a lot of money and time if I didn't.
Here are the measurements:
image_6483441 (11).JPGimage_6483441 (12).JPGimage_55415491 (4).jpg
Member
First let me say that machinist's especially today are undervalued (not paid enough) and underappreciated. I'll rant but this seems to be especially true as we move to a throw away generation.
Prices today I'd say that's probably fair on the head. Rest is probably fudged a bit but hey gotta make $ somewhere. If was me and this isn't being cheap it's just doing only what's needed.
I don't see that taper being too much for an older engine. I'd maybe have them deck the block but that's it; if it really needed it. If clean enough check flatness and long as clean flat can just use without decking. Buy a flex hone and just hone it myself.
https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1
buy a quart of the cheapest store brand atf and follow directions. Re-ring; New Federal Mogul (Goetze) rings cause they are excellent, my next pick would be Deeves/Hastings rings. Check ring gaps and orientation and install. Factory gaps are about .013" or so and fine for a street built keep on tighter side (Haynes manual probably has specs) for longevity and better oil control.
Rods shop can check for true and condition but they will probably not check just replace bolts bushes etc cause easier and makes money. Example of rods price wise can buy a set of reconditioned for same price so that seems reasonable. Example from IE https://www.iemotorsport.com/product...g-rod-set-m10/
Head and valve job is where have no choice unless can install guides(not me) and cut valves at home(Neway). If needs guides then will need a valve job to keep valve contacts concentric to the head. If no guides needed can save there but still need the seats etc checked. The head valve job is definitely worth $ vs just lapping them and tossing back together. I've lapped myself and it's easy but thats where I'd spend a few extra $ to have perfect valve sealing(Neway if diy but not for everyone).
Flatness of head same as block if it's flat and clean no real need to machine it but can get some cheap gains having it milled down several thou plus cleans up the surface.
sidebar a bit with coffee
Balance hmmm nah. Mostly stock engine there's not much to balance on an M10 unless getting into blueprinting rods pistons etc. Which in all honesty is close enough from factory to survive 7k rpm all day out of the box. Crank, rods, pistons are all close enough within a few grams which is much better than most engines. Plus it's a inline 4pot where two cylinders are on exact plane cancelling out the other two. The parts being balanced is usually enough compared to say a V engine. The m10 doesn't even have a harmonic balancer on the nose. Being 8v head etc all plays into harmonics imo only when pushing the boundaries and or stroking to larger displacement would harmonics get crazy enough to warrant a harmonic crank balancer (m3 s14 pulley).
Assembly of pistons to rods you could do yourself. The machinists love when someone want's them to put together pistons to rods or favorite is when someone drops off a whole head assembled and wants them to disassemble, machine, reassemble afterwards (dealership techs) it's all $ extra.
Bore will almost always measure out of round slightly by design. This is also why some diyers get into trouble self honing with 3stone IMO. Bores are only round when the head is fully torqued down. They might have a slight egg shape without the head usually not detectable unless measuring close. This is why boring at a machine shop is done with a torque plate. Well a good shop anyways.
Flex hones are hated on but back in the day for re-ring jobs they were all over the place. Now days only way to find is online. CoincidenceThey allow to hone without changing the surface shape by design.
Meh enough for now or I'll talk in circles. Need beers, it's too early.
Last edited by autox320; 04-21-2022 at 06:33 AM.
88 M3
91 318is
91 318i
83 320is
08 X3 3.0si
"If it flys, floats, or f*cks, rent it!"
Member
autox320 I appreciate the in depth response. I agree, machinist need to make money somewhere, those machines aren't cheap and that's what business is all about. At this point I really don't care how much the machine work is, it just means I have to work more to pay it all off. I've already put about $3200 into this rebuild and I'm expecting to spend another $2000, or somewhere in that neighborhood. I purchased 89mm goetze rings from IE, but i guess I'll have to return them and get some bigger rings. I'll go ahead and do all the other machine work if i have to rebore or not.
I called a couple more shops today and they all came to the conclusion that I would need a rebore. So... I think that is what I'm going to do. Although the car is kinda a shitbox, and is very rusty, i think it would be cool to have something that doesn't look to great but looks brand new under the hood.
So, taking the safe route and getting an overbore I know I'll have to get oversize pistons and rings, and that really opens up a lot of options of what i could do with this motor. I found a 2L crank on ebay for $200 that is in pretty good shape https://www.ebay.com/itm/25549052179...0AAOSw~IBiWejy I thought if I have to get new pistons I may as well spend another $200 and get some more displacement.
On the topic of pistons, I know ill have to get 2L pistons for the e21 head, IF i get a 2L crank. Correct me if I'm wrong but the only difference between the 1.8L and the 2L pistons is that the wrist pin is further down the piston. The conrods for the 1.8 and 2L are both 135mm? so I should be able to reuse those. I purchased new bushings, standard rod and main bearings, so kinda taking a risk that the 2L crank i would get would be in spec.
I think the most promising pistons I've found so far are the ROSS forged pistons available on IE for $650 https://www.iemotorsport.com/product...d-pistons-m10/ If I where to get those I would do a 90mm bore, 10:1 compression, E21 head casting, 135mm rods, 2.0L crank... if all of that checks out with you guys. it says they take 8-10 weeks to make which kind of sucks but it gives me some time to save up some money.
Again, I would like to save the money and keep the original bore, but thinking about it another $900 or so for some forged pistons and another ~200cc doesn't sound too bad, I'd hate to get the thing back together and have it run weird because i cheeped out and didn't get an overbore. Whatever the machine shop says i should do i think i will, these guys know the m10 pretty well and i don't think they're pulling my leg. C & D Engine Performance in Kirkland, WA is the shop.
Let me know what you think about this. Thank you again for all of the help!
Cole
Member
I'd check with IE on choosing the ROSS pistons for street. From what I remember they are mostly race use. While being a high end piston for race use they are expected to be hot and warmed up. Street use is daily short trips etc might not be ideal. Unless they've changed the alloy I'd think JE, Wiseco may be a better choice. Pretty sure the alloy's are different.
88 M3
91 318is
91 318i
83 320is
08 X3 3.0si
"If it flys, floats, or f*cks, rent it!"
Member
Re-boring the cylinders, they usually go to 2nd oversize in piston diameter because of availability, I concur that honing is probably all they really need, They mention balance the rotating assembly, thats check the balance the crankshaft-which is its straightness and then each piston with its wrist pins, rings, connecting rods with with nuts and bolts and big end bearings are weighed on a scale to see if they are within 1 gr or so of each other all four, the lightest one is chosen as standard and rest are reduced in weight by grinding the bottom big end of the connecting rod--metal projection there until all 4 are within 1 gram or so of each other, more sophisticated balancing, balance each piston dead on-cut weight from overweight pistons and weighing each part to match the weight--this is more of a blueprint job along with many other items- which is the higher end of rebuilding these motors.
Not a bad price--looks like honing the cylinders is whats going on, you'll have a like new or so M10 motor, it will last a long time.
Randy
Last edited by 320iAman; 04-23-2022 at 07:58 PM.
Member
Randy, so you really don’t think the cylinders need to be bored out, even with almost a 3 thou out of round? The shops are telling me different things, some say yes, maybe and no. Possibly my measurements are a tad bit inaccurate since this is my first time doing this, but I used the bore gauge properly and read it correctly.
Would balancing only be necessary if I made changes to the rotating assembly? Or is it just something that needs to be done with every rebuild. I had already bought standard size bearings, if the conrod big ends get bored out would I need oversized bearing?
If I was to do the 2L conversion approximately how much more hp would I be looking at? The cam will be a 286 regrind and that is the only other modification to the engine. Would I need anything else other than the 2L crank and pistons to make it work?
- - - Updated - - -
makes sense, I know that forged pistons expand a little more than the stock aluminum pistons. You are correct that most my trips will be short. I will look more into the JE pistons on raceTEP. Where do you get the wiseco pistons?
Member
Reboring the cylinders is only necessary if they out of specifications which it looks like its not, so honing will do, as too putting in the 2.0L crank into 1.8L motor-the stroke moves from 71 mm to 80 mm which raises horsepower to about 125 hp, 286 cam will support the motor better than stock 264--get more air and fuel in--286 is a good upgrade--There is one who did this already here and he is quite happy with the results, he did opt for new pistons as I recall, many pistons out there Carrillo, Ross. etc and they can be adjusted to compression sought, 9 to 1,, etc.
balancing the rotating assembly keeps vibration and flex down as all weights on the crankshaft are technically equal through out the crankshaft when its spinning, when two pistons are going up, 2 pistons are coming down, equal weight up to equal weight going down on the connecting rods so the crankshaft has even weight on it while it spins.
also, here in California when you change the displacement of the motor you have to submit the changes to BAR and CARB and pay a fee to do this , then they approve it and your good to go for instance the Catalytic converter used on 1.8L is used on much bigger motors so CARB would not have to issue an exception and then you have to put a different Catalytic converter in to keep it street legal.
Randy
Last edited by 320iAman; 04-26-2022 at 11:39 AM.
Member
I’ve got the block and the crank loaded up in the car ready to take to the machine shop tomorrow, they’re going to take a closer look at it and tell me what needs to be done on it. Hopefully they’ll give me the good news and it won’t need to be bored, it’ll save my pockets at least. If not then, JE pistons and 2L crank it is, which who knows I might do it either way, it’s only another $1000 or so and I’ll probably be this deep in the motor one time.
I think I’ll have them balance the rotating assembly or weight everything at a minimum. They told me they will check the crank for straightness when I bring it in. Washington doesn’t have any smog regulations that I know of, so going for 2L shouldn’t be a problem in that sense.
So say the shop tells me I’m gonna need to bore the block, I think I’ve decided JE pistons are my best bet? With 2L displacement what would be a good reliable CR to run 9:1? 10:1? I’m not too sure what exactly higher and lower compression ratios achieve other than altering fuel efficiency and horsepower. This shop seems to value their time and storage of parts so I’m going to order them as soon as I know if I need to. JE says they take 2-4 weeks to make, ROSS 8-10 weeks, CP 3 days?
I hope to get this thing on the road by the summer so the quicker the better, but I also don’t want to rush anything. How long has similar machine work taken you guys? How long did it take from getting everything back from the shop to back in the car?
Member
Here is a brief explanation on compression ratios:
"Higher compression ratios allow the same combustion temperatures to be achieved with less fuel. That leads to a longer expansion cycle, more mechanical power output and lower exhaust temperatures."
Lower compression ratios are generally used with a turbo set up.
8.8 to 1 is stock for 1.8L, 9.5 -10 to 1 will work well plus still use premium or Hi-test gasoline.
Randy
Member
Ok that makes sense. I dropped the block and the crank off yesterday at C&D engine performance, they said they’ll get back to me sometime next week with what needs to be done with it. I’ll give everything else to them once they tell me. I’m excited to get this motor back together, it’s a little nerve racking seeing it in a hundred pieces.
Member
Also, the guy at the machine shop said I will need HD valve springs for the 286 regrind, is this true?
Member
Usually 292 up for beefier springs-it wont hurt the valve train, 264 reground to 286 removes the base circle on the lobes with full base circles-new billet oversize eccentrics are not needed, not sure about regrinds though, may not need them.
One of the important items is to keep the geometry the same for the crankshaft and camshaft that is they are parallel--in line honing of the mains should be enough if needed at all, then there center to center distance maintained between the camshaft and crankshaft- although the chain tensioner should take care of that.
Randy
Member
I think I'll just run the stock springs, autox320 said they worked good with the same regrind.
The machine shop got back to me today and said they will have to bore the cylinders out... ok whateverI just ordered a 2.0L crank on eBay, looked to be in pretty good shape. Hopefully the standard bearings will work on it, I'll mic it when it arrives.
https://www.ebay.com/itm/255490521794
Now for the overbore itself, what should I bore it to? I think I will at least go to 91mm although I've read people going to 92mm and even 93.4mm like on the s14 block. I want this thing to be reliable and capable of driving entirely on the street. the s14 bore probably isn't the smartest choice but does anyone have experience with a 91-92mm bore? I bought a victor reinz head gasket, I think the bore on those is 90mm, would it work with a larger bore?
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