M20 Rings, Rod Bearings, Valve Job

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gump
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M20 Rings, Rod Bearings, Valve Job

Post by gump »

I am thinking about a partial rebuild for my 528e (M20). The major elements would include rings, rods bearings and a valve job. Of course all of the associated gaskets, seals and the "while you are there" things like timing belt, water pump, etc.

Now, I think I can do this job without pulling the motor. I've had the oil pan off as you can with the M20 and that's primarily what leads me to believe I can do this with the motor in the car.

What am I missing? What else should I consider?
Mike W.
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Mike W. »

While I've rebuilt many an engine, including BMWs, and I always include rings, I've come to a different thought now. Now I don't specifically know on M20s, but on M30s by the late 70s the rings just didn't seem to wear. I mean one time the end gap on the new rings was larger than on the originals. So unless there is more to the story, I might do the rod bearings, but I'd probably skip the rings.
gump
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Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

That's good input. Thank you. I will do a leak-down test before I touch it for no other reason than to have a benchmark.

If I am not getting any leakage past the rings and the cylinders look good, I might just leave them.

Stand by for results of the leak down test.
tn535i
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Re: M20 Rings, Rod Bearings, Valve Job

Post by tn535i »

You don't say how many miles on the clock ? If under 200k it's really unlikely you need to touch the rings or bearings. If I wanted to swap to higher comp pistons then I would consider but otherwise not. Some benefit from a refresh of the head and cleaning up all the valves and if I were into that of course do the t-belt if any doubt about it. Also do sintered timing gears. But I would only go into it if over maybe 150k and the compression test shows some irregularities.

These older M20 and M30 motors if cared for properly easily run 300k.

Still have and M20 I acquired around 24k that is in it's second chassis that was last examined for compression and valve lash at about 160k and there was nothing wrong at all. It's our project e30 that when it does get driven is wrung out hard. New belt and sintered gears in that motor.

On the other end of the scale we had an M20 i car a few years back of unknown history (5w-30 cheap oil change stickers) that was not well cared for that still ran OK at 300k+. It had some noisy valves that could not be adjusted out and it finally broke a rocker about 312k ? I rebuilt the head and it ran as smooth as a new motor with excellent compression numbers.

My M30 is at about 300k and still strong with good compression numbers. I need to check the valves again I suppose, but it has never been opened up and runs so well I forget it needs that periodically. I've had it a long time but only put the second half of those miles on it.

Where you are in these scenarios should dictate how hard you go looking for things to work on.
craigb93
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Re: M20 Rings, Rod Bearings, Valve Job

Post by craigb93 »

If you take the pistons out of the block DO NOT try to reassemble it in the car. It will need to be honed for new rings to have any chance of seating. The residue from any kind of beneficial honing cannot be adequately flushed out of the engine short of pulling the crank and then thoroughly cleaning everything with HOT soapy water. Honing residue is exactly the same as valve grinding compound except it is now applied to all internal bearing surfaces if left in the engine. Makes for a merry demise of any good engine.

Unless the compression/leak-down results are really off you are better served, as noted above, by leaving the whole bottom end intact and concentrating on renewing all cylinder head components. -Dick
gump
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Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

Reviving this thread. Since the last post I have checked valve lash and done a compression check:

Cyl PSI
1 150
2 140
3 145
4 145
5 125
6 135

As for the mileage question, the ODO stopped at 135k. It's probably actually 175k, more or less.

I want to make this car more fun to drive. I would like to rebuild the motor and upgrade it at the same time.

What do y'all suggest?
tn535i
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Re: M20 Rings, Rod Bearings, Valve Job

Post by tn535i »

Your compression numbers look a bit poor but not terrible. I would suspect valves before the bottom end so maybe do the head. I don't know if you said what year eta. A super e has possibilities of the e to i conversion which will help power a lot and detailed on this forum what you need, basically and e30 i head (which I would refresh) and I think (I Think not sure) the e30 i manifold will work. (It works in an e30) A plain eta benefits more from a chip than most other BMW's of the era and aftermarket or even copies are still around I believe. No doubt do the timing and upgrade to sintered gears for pom unless you have them already.

Aside from addressing things with the engine get a 3.25 diff or even higher ratio and that will help acceleration. The e's were generally geared for economy and lower revving but the engine can handle the higher revs without issue. Unless of course you plan to do a lot of highway driving and then it might not suit your plans.

An eta with a chip and i exhaust like we have in our e30 project car, backed up with a 3.46 diff, is just a quick to over 60 as my 535, maybe quicker. Same motor(no chip) in the old 4 door with an automatic and the 2.93 was pretty boring. Then again most new sedans are as quick as even a fast e28.
Mike W.
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Mike W. »

gump wrote: Jun 29, 2021 6:24 PM Reviving this thread. Since the last post I have checked valve lash and done a compression check:

Cyl PSI
1 150
2 140
3 145
4 145
5 125
6 135

As for the mileage question, the ODO stopped at 135k. It's probably actually 175k, more or less.

I want to make this car more fun to drive. I would like to rebuild the motor and upgrade it at the same time.

What do y'all suggest?
Unless there is an obvious problem like burning oil or rod knock, I don't think an engine rebuild will make any difference.

Looking at the bolded line I would say put in at least a 3.25 diff, maybe a 3.46 and or an e to i conversion. I seriously doubt your butt dyno or a stopwatch will be able to tell any difference with rings, bearings and a valve job.
gump
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Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

I am willing to go beyond my original premise.

I think I want to keep the basic M20 layout but I am happy to:

Change pistons / compression ratio (which pistons?)
Change ECU (megasquirt) coil near plug, MAP vs MAF, etc.
Change cam (which one?)
port/polish head
etc.
demetk
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Re: M20 Rings, Rod Bearings, Valve Job

Post by demetk »

More bang and cheaper with just a turbo.
gump
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Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

Not opposed to a turbo solution.

Cheap chinese Ebay kit?
Nothintoseeere
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Nothintoseeere »

Dont port and polish the head. Waste of time and money not to mention it will do nowt. Alina barley did any porting. Port matching to the inlet manifold yes, removing any casting imperfections yes but enlarging the ports no.

I once did an e to conversion. I used the 885 head which is higher flowing but dont use it if you keep the eta pistons. The eta pistons don't match the head and adversely affect the power output. With a big bore TB, 325i inlet and exhaust manifolds, euro eta engine and motronic 1.3 it managed 175hp which was less than it could have been.

The 731 head from a 320i is perfect. You maintain the engines compression ratio and the squish area are unaffected. Use the matching inlet manifold and 325i throttle body. The eta exhaust manifold strangles the engine above 4000 rpm so you may want change the manifold for the 325i item or a tubular system but from experience while new exhaust manifold does improve peak power output it reduce low torque a bit. If you got an exhaust manifold and system from a 325i would work quite well. That engine would do 170to 180 hp and be cheap to build and provide some smiles. Fuel economy will be hardly affected as well.

You could use the 325i (885) head with custom pistons. Vac motorsport sell them. You can up the compression ratio to 10.5:1, you can fit a 280 degree cam, the 325i inlet manifold, a nice tubular exhaust manifold and exhaust system and you could get 210hp or more but this a full engine build and will cost you alot more cash.

Cheap turbo equals fail. Personally if you want to use forced induction and you want a reliable engine i would not go with cheap kit. Reliable turbos cost real money.

Remember you have an old car. Its not a modern fast car and it never will be. You can have fun driving a 120hp car, 180 hp car or a 400 hp car if your happy with it. More horse power is not where satisfaction with the car should come from. There is a joy in motion.

Take it as far as you like but do it properly i.e use parts that work together and be happy with it.

Even though the 527i i once built was disappointing on the peak power front it drove well and i was happy with it.

Currently i am having an m30b35 engine built and having learnt my lesson i am having the engine built to be a copy of the alpina motor. Why reinvent the wheel when it has been done before.

You have four choices

1) leave it alone
2) 731 head and enjoy cheap thrills
3) alpina spec 2.7 and it will cost a fair bit.
4) FI and that will cost more and be no more fun to drive than 1, 2 or 3.

Id go for cheap thrills and enjoy the car for what it is.
Nothintoseeere
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Nothintoseeere »

Dont port and polish the head. Waste of time and money not to mention it will do nowt. Alina barley did any porting. Port matching to the inlet manifold yes, removing any casting imperfections yes but enlarging the ports no.

I once did an e to conversion. I used the 885 head which is higher flowing but dont use it if you keep the eta pistons. The eta pistons don't match the head and adversely affect the power output. With a big bore TB, 325i inlet and exhaust manifolds, euro eta engine and motronic 1.3 it managed 175hp which was less than it could have been.

The 731 head from a 320i is perfect. You maintain the engines compression ratio and the squish area are unaffected. Use the matching inlet manifold and 325i throttle body. The eta exhaust manifold strangles the engine above 4000 rpm so you may want change the manifold for the 325i item or a tubular system but from experience while new exhaust manifold does improve peak power output it reduce low torque a bit. If you got an exhaust manifold and system from a 325i would work quite well. That engine would do 170to 180 hp and be cheap to build and provide some smiles. Fuel economy will be hardly affected as well.

You could use the 325i (885) head with custom pistons. Vac motorsport sell them. You can up the compression ratio to 10.5:1, you can fit a 280 degree cam, the 325i inlet manifold, a nice tubular exhaust manifold and exhaust system and you could get 210hp or more but this a full engine build and will cost you alot more cash.

Cheap turbo equals fail. Personally if you want to use forced induction and you want a reliable engine i would not go with cheap kit. Reliable turbos cost real money.

Remember you have an old car. Its not a modern fast car and it never will be. You can have fun driving a 120hp car, 180 hp car or a 400 hp car if your happy with it. More horse power is not where satisfaction with the car should come from. There is a joy in motion.

Take it as far as you like but do it properly i.e use parts that work together and be happy with it.

Even though the 527i i once built was disappointing on the peak power front it drove well and i was happy with it.

Currently i am having an m30b35 engine built and having learnt my lesson i am having the engine built to be a copy of the alpina motor. Why reinvent the wheel when it has been done before.

You have four choices

1) leave it alone
2) 731 head and enjoy cheap thrills
3) alpina spec 2.7 and it will cost a fair bit.
4) FI and that will cost more and be no more fun to drive than 1, 2 or 3.

Id go for cheap thrills and enjoy the car for what it is.
gump
Posts: 37
Joined: Mar 10, 2019 12:03 PM
Location: Los Angeles

Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

Nothintoseere, thank you for the thoughtful and philosophic response. I appreciate the time and effort you put into it.

Follow up question: based on my current compression test readings, (1-150, 2-140, 3-145, 4-145, 5-125 & 6-135), I believe I will need to bore the cylinders and replace the pistons. If that is in fact the case, would you still lean toward 731-head solution or, given the necessity to purchase new pistons anyway, would you favor the 885-head solution?

Also, I assume the best source for either head (and manifolds) is my local junk yard. Agree?

THNX
Nothintoseeere
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Nothintoseeere »

The 885 head does flow more air but thats means nothing if you cant burn the fuel and expel the gasses.

If your buying new pistons you could do something close to alpinas engine. People this side of the pond had had 230hp from the e2i conversion with plenty of work to support it.

An m52b28 crank is a very good option too and you can use 325i pistons and the 325i head with the block being decked if i remember right. Thats a good way to produce an engine with a 210+hp but it will pull well from 2500 rpm.

However on balance i wish i had used the 731 head as with the eta engine it the simplest solution It may not flow as much air but the size of the inlet ports mean it allows the engine to produce more mid range torque. Thats what i like. I personally like a car that can accelerate strongly in 3rd gear.

It depends on what sort of engine you want. One that produce bigger numbers at higher rpm but ultimately is still not a quick car by todays standards or one that pulls well in the mid range (2500 to 5000 rpm) and does not pretend to be anything more than it is.

If your changing your camshaft bewary of wilder cam profiles unless your chasing higher power numbers at higher rpm. The most duration you can use with motronic and retain a stable idle is about 280 degrees. Schrick, catcams, dblias all supply suitable cams.

Also just because your compression number are low does not mean you need new pistons. You may need the bore rehoning and new pistons rings but your valves seats may be leaking. It might just be a head job. If it is the cheapest solution for you is 731 head casting and building up. I would not bother changing the camshaft as that new cyclinder head change alone requires a new chip and it will transform the car. Be sure to change your final drive ratio too. A 3.64:1 will really wake it up.

Bmw still have alot of parts. Use real oem and make a list and see what can be ordered.

I can probably find a 320i head over here. Angus bucanan workshops which is down the road from me probably has one as would fritzs bits in devon. There are a few on ebay too.
gump
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Location: Los Angeles

Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

Reviving this thread.

Have decided to rebuild the motor to stock specifications. Have short block and cylinder head at the machinist's. Discovered that the valve train (rockers and cam) were completely worn. Strangely, the cylinders, rod bearings and crank bearings all look good. Have found a good used cylinder head (complete) and am likely going to be able to use the valve train from that.

A couple of questions for the Hive Mind:

1. On reassembly, do head bolts, main bearing bolts and/or rod bolts need to be replaced? Are they a torque to yield type fastener?
2. I am in LA and buy a lot of BMW parts from Pelican. Their selection of engine parts for this vintage is somewhat limited. For example, they don't seem to have +0.25mm piston rings. Any suggestions?
3. There is a huge difference in price between OEM BMW parts and other mfgs. Where should I stick to BMW parts and where is it OK to buy 3rd party.

Appreciate any feedback.
turbodan
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Re: M20 Rings, Rod Bearings, Valve Job

Post by turbodan »

What is the casting number on the intake side of the cylinder head? Your 11-86 build date puts you just before the super eta changeover but you never know. If you have the 885 head you have a much better platform to work with.
Mike W.
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Mike W. »

gump wrote: Jun 06, 2023 2:11 PM Reviving this thread.
Strangely, the cylinders, rod bearings and crank bearings all look good.
No, not strange. BMW had metallurgy down pretty well back then, especially on the block. They're really hard and not wear prone.

A couple of questions for the Hive Mind:

1. On reassembly, do head bolts, main bearing bolts and/or rod bolts need to be replaced? Are they a torque to yield type fastener?
More an M30 guy, but even I know M20 head bolts are torque to yield and do need to be replaced. The others I'm not sure about.
2. I am in LA and buy a lot of BMW parts from Pelican. Their selection of engine parts for this vintage is somewhat limited. For example, they don't seem to have +0.25mm piston rings. Any suggestions?
Except that it's a sale for the machinist, why go with oversize pistons? Are they worn? You mentioned above that the cylinders were in good shape. No need to reinvent the wheel. But to answer your question, yes, parts can be hard to find like oversize rings. But with BMWs generally rings come with new pistons.


3. There is a huge difference in price between OEM BMW parts and other mfgs. Where should I stick to BMW parts and where is it OK to buy 3rd party.

Appreciate any feedback.
I've rebuilt I dunno, half a dozen, maybe more BMW M10 and M30 engines and I don't think I've ever used any BMW parts. That said, there may be more but poorer options now than in the past. The E28 535i I rebuilt back in '99 was starting to go thru a quart or so of oil between changes when I sold it. At that point it had 175K miles on my rebuild. I believe it was Nform rings which are made by Geotze(sp). Not perfect, but not bad IMO. I would tend towards German brands or Deves. I think they might do custom work too. http://deves.com/cars.php
gump
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Location: Los Angeles

Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

I've elected to go with the standard bore. I'd like to over-bore by 0.25mm but the pistons are crazy expensive. I've cleaned up the pistons and bought new rings: Goetze part number 08-133200-10.

Does anyone know:

a) what material the top ring is made of
b) what grit stone should be used to hone the cylinders

Appreciate any input!
turbodan
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Re: M20 Rings, Rod Bearings, Valve Job

Post by turbodan »

Standard bore size is fine, they just don't wear much.

I believe the top ring is chromed in these.
Mike W.
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Re: M20 Rings, Rod Bearings, Valve Job

Post by Mike W. »

gump wrote: Jul 19, 2023 7:34 PM I've elected to go with the standard bore. I'd like to over-bore by 0.25mm but the pistons are crazy expensive. I've cleaned up the pistons and bought new rings: Goetze part number 08-133200-10.

Does anyone know:

a) what material the top ring is made of
b) what grit stone should be used to hone the cylinders

Appreciate any input!
New factory clearance with all brand new parts is pretty tight on piston/cylinder clearance, just a hair over .001". But they're also pretty forgiving of wear. Again, M30, which is different, but a close relative of M20s, I've gone up to .006" with no issues. Zero, quiet, no piston slap, no oil consumption etc.

On grit, I just use what come standard with a cylinder hone. I've always used the 3 stones, 2" long, not the thousand balls like machine shops use. And it works just fine.

Oh, one more thing. Supposedly the bores should be cleaned with soap and water, not solvent, after honing. Not sure I believe it, but it's a thing.
gump
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Location: Los Angeles

Re: M20 Rings, Rod Bearings, Valve Job

Post by gump »

OK E28 hivemind, here's another for you:

I am having a hard time identifying part numbers for the two intermediate shaft bearings.

The shaft shows up on the RealOEM site: https://www.realoem.com/bmw/enUS/showpa ... Id=11_0407 but I cannot locate the bearings. My go-to BMW parts vendors, ECS & Pelican can't find them either.

Any ideas?

Thanks
turbodan
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Joined: Jan 09, 2007 10:19 PM

Re: M20 Rings, Rod Bearings, Valve Job

Post by turbodan »

gump wrote: Sep 11, 2023 5:16 PM OK E28 hivemind, here's another for you:

I am having a hard time identifying part numbers for the two intermediate shaft bearings.

The shaft shows up on the RealOEM site: https://www.realoem.com/bmw/enUS/showpa ... Id=11_0407 but I cannot locate the bearings. My go-to BMW parts vendors, ECS & Pelican can't find them either.

Any ideas?

Thanks
These bearings are not technically serviceable. There was a part number for them long ago that might be out there but the new bearings are not finished and must be bored to final size after installation.

I tried a set of them many years ago and couldn't figure out a way to finish them. Every M20 I've built since was with the original intermediate shaft bearings left completely alone.
turbodan
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Re: M20 Rings, Rod Bearings, Valve Job

Post by turbodan »

Google actually came through here. Part numbers 11-11-1-280-863 and 11-11-1-264-196. I think they were called "semi-finished surface bearings". Better name would be "don't fuck with these" bearings. Hopefully you haven't already removed them with violence. If you have, this guy was making them pretty recently, looks like they might be precisely machined and ready to install as is:

https://www.r3vlimited.com/board/forum/ ... s-upgraded
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