M10 + E12 Carnage & Rebuild

[kbmb02]

19 hours ago, R.I.P.B.M.W. said:

   Following along with Ace's recommendation (+1), I wholeheartedly agree with replacing the stretch rod bolts. I would imagine the stretch portion of the bolt shaft will get even thinner when retorqued to/or higher than the spec (as some might want to do). In my experience I've only seen one rod exit the side of a block from a wrong gear selection on a high speed downshift and its over revving the motor. The other stretch bolt incident was with a Volvo flywheel and its stretch bolts. All the parts for the flywheel/clutch repair came in on Friday, except the ordered flywheel bolts. Vehicle had to leave that Friday to head north and service advisor and customer made the decision to reuse the old flywheel stretch bolts. The next week we heard that halfway into the trip the flywheel bolts let go and... instant carnage. Save a little money now or, maybe, try to find a good used 47+ year old m10 motor later. Replace all stretch bolts=piece of mind.

 

Curious: Where did you find a stretch spec for M10 OEM rod bolts?? I'm not aware of that. And, did the Volvo in the data point you offered use same type/grade/size flywheel bolts as the M10?

 

A few images of ARP bolt stretch in action (not OEM bolts), and recorded data. (In applications where rods are removed - race applications, for example, after X number of seasons - the bolts can be checked for stretch.)

 

8 hours ago, ajordan282 said:

I am planning to go ahead and replace the oil pump. As I understand it the 320i pump is the exact same, just swap over the pickup assy.  I assume the pickup will be the same elevation in the pan - I am aware that changing pickup elevation can also have some *dire* consequences.

 

Yes, you can use a 320i pump with M10 pickup. Inspect the pump as you install the pickup, check for smooth movement of the piston in the pressure relief bore (I've seen them bind in new pumps due to sloppy machining/assembly at the factory). -KB

 

 

Edited October 8, 2023 by kbmb02

[mccusername]

I am the least qualified of the commenters so far but I would say that if you're concerned about the condition of your head re: 9.5:1 pistons and detonation, you should be worried about 9:1 pistons and detonation. Concentrate on getting the head truly sorted and then use 9.5:1 pistons. That's what these engines used in Europe, not a problem.

 

I would get the injectors tested/rebuilt because it's easy and almost all of them are out of spec. But I would also wait and see how the KF pump behaves before messing with it.

[TobyB]

Soooo...  the rod bolts on an M10 are not stretch in plastic deformation.

They are multi- use bolts.  As in, as long as they are undamaged, they can be reused.

 

GRacer and I have had similar experiences- old, reused, BMW rod bolts are good to 7500,

but the ones made in the last 20 years are NOT guaranteed to be good over 6500.

 

SO:  if you want to replace rod bolts- and that's never the worst idea in the world-

then the ONLY ones that make sense are the ARP bolts.  Yep, they're well over $100 a set,

and they are NOT going to give up on you.  Anything else, and I would strongly recommend

reusing the stock BMW bolts.  I run stock rods and bolts and have run a redline as high as 7800,

although I don't know how much I'd recommend that...

 

As to the head acne, I guess clean it up and see how much it smooths out....

if the head's otherwise good, I'd think trying it is probably worth the head gasket, and

if it gives trouble, THEN see if someone will weld it for you...

 

t

 

[ajordan282]

23 hours ago, kbmb02 said:

 

Curious: Where did you find a stretch spec for M10 OEM rod bolts?? I'm not aware of that. And, did the Volvo in the data point you offered use same type/grade/size flywheel bolts as the M10?

 

A few images of ARP bolt stretch in action (not OEM bolts), and recorded data. (In applications where rods are removed - race applications, for example, after X number of seasons - the bolts can be checked for stretch.)

 

 

Yes, you can use a 320i pump with M10 pickup. Inspect the pump as you install the pickup, check for smooth movement of the piston in the pressure relief bore (I've seen them bind in new pumps due to sloppy machining/assembly at the factory). -KB

 

 

 

very much appreciate the heads up on the oil pump re: shit aint built like it used to be.  and as far as the bolts - to make sure I understand what you're showing - they stretch 4 thou between final assembly and recheck after racing a few seasons?

 

15 hours ago, TobyB said:

Soooo...  the rod bolts on an M10 are not stretch in plastic deformation.

They are multi- use bolts.  As in, as long as they are undamaged, they can be reused.

 

GRacer and I have had similar experiences- old, reused, BMW rod bolts are good to 7500,

but the ones made in the last 20 years are NOT guaranteed to be good over 6500.

 

SO:  if you want to replace rod bolts- and that's never the worst idea in the world-

then the ONLY ones that make sense are the ARP bolts.  Yep, they're well over $100 a set,

and they are NOT going to give up on you.  Anything else, and I would strongly recommend

reusing the stock BMW bolts.  I run stock rods and bolts and have run a redline as high as 7800,

although I don't know how much I'd recommend that...

 

As to the head acne, I guess clean it up and see how much it smooths out....

if the head's otherwise good, I'd think trying it is probably worth the head gasket, and

if it gives trouble, THEN see if someone will weld it for you...

 

t

 

 

thanks for the additional info on the rod bolts!  current machinist is more than willing to weld the head, just doesn't feel its necessary at this time.  he does warranty work for the local honda dealer repairing all of their 18+ 1.5 turbo heads that crack, re: shit aint built like it used to be. i'll press him on the detonation issue.

 

21 hours ago, mccusername said:

I am the least qualified of the commenters so far but I would say that if you're concerned about the condition of your head re: 9.5:1 pistons and detonation, you should be worried about 9:1 pistons and detonation. Concentrate on getting the head truly sorted and then use 9.5:1 pistons. That's what these engines used in Europe, not a problem.

 

I would get the injectors tested/rebuilt because it's easy and almost all of them are out of spec. But I would also wait and see how the KF pump behaves before messing with it.

 

thanks, this FI rec is sort of the conclusion I've been reaching.  Appreciate the feedback on CR as well.

[OldRoller]

Open to correction as I am not an 'expert', but as for as I know there are no 'torque to yield' or stretch bolts used on the M10.

Inspect all fasteners, use the torque specs judiciously. By all means replace what you suspect for your own piece of mind. 

 

As others have said, be careful with procurement of replacements. Quality of manufacture and materials used has diminished greatly over the last decade.

[kbmb02]

1 hour ago, ajordan282 said:

very much appreciate the heads up on the oil pump re: shit aint built like it used to be.  and as far as the bolts - to make sure I understand what you're showing - they stretch 4 thou between final assembly and recheck after racing a few seasons?

 

A substantial portion of engine building is measuring and checking.

 

Re: rod bolts - let’s be sure to clarify that info was for those curious / display, it does NOT APPLY to OEM rods and bolts. I’ll come back to this later with more info on the ARP bolts. -KB

 

 

[jimk]

Even below the plastic zone, each time steel is loaded to a level of stress greater than it has been to previously, it will not return to it's original dimension, (if I remember correctly from the Strength of Materials class).

[ajordan282]

3 hours ago, jimk said:

Even below the plastic zone, each time steel is loaded to a level of stress greater than it has been to previously, it will not return to it's original dimension, (if I remember correctly from the Strength of Materials class).

 

And now things come full circle.  I skipped many an ME class to build this baja car for the school.  After 10 years of being run hard by dumb college kids, I had the opportunity to buy it back from the team earlier this year.  While running and driving, it needs a bit of restoration work as well - but the 02 (which I couldn't pass on only a week later) is the priority.  If only I'd skipped on building this thing and gone to class, I'd be able to decide whether to replace the rod screws...and have more room in the garage  😄

 

Update: I have decided to ship out my kfish and injectors for inspection/cleaning at H&R.  Hoping to put my tally mark on the 'good' side upon completion despite a few things I read here.  I enjoyed talking to Marty on the phone and look forward to a satisfactory experience.

 

 

 

Edited October 9, 2023 by ajordan282

[AceAndrew]

36 minutes ago, ajordan282 said:

I'd be able to decide whether to replace the rod screws...and have more room in the garage  😄

 

 

Neat formula baja.  

 

As for skipping class..... since COVID you can find this class on youtube.

 

Case in point, my former professor now has a complete structures II playlist .... for your long-commute listening.

https://www.youtube.com/playlist?list=PLJN7mr1gK7YWprPrRf-hC4beBnPPAkQpV

 

[Conserv]

On 10/8/2023 at 9:43 AM, ajordan282 said:

 

… How concerned should I be about detonation as far as maintaining the 9:1 comp? 9.5:1 piston availability is making that route tempting. But I don’t want to have to go thru this process again. I have no issue running pump high test foreva and eva. 
 

I have only ever heard of ‘02 detonation issues with a 10:1 compression ratio, and reports of that are certainly not consistent or uniform. The 10:1 ratio is generally a type 121 head setup, as it was used on early Euro-market tii’s. I’ve swapped my ‘76 2002 from 8.1 to 9.5 (E21 head) and my ‘73 tii from 9.0 to 9.5 (E12 head) and have never experienced pre-detonation on either. I generally use 93 octane, but I’ll bet 91 octane would suffice.

 

Regards,

 

Steve

 

[ajordan282]

42 minutes ago, Conserv said:

I have only ever heard of ‘02 detonation issues with a 10:1 compression ratio, and reports of that are certainly not consistent or uniform. The 10:1 ratio is generally a type 121 head setup, as it was used on early Euro-market tii’s. I’ve swapped my ‘76 2002 from 8.1 to 9.5 (E21 head) and my ‘73 tii from 9.0 to 9.5 (E12 head) and have never experienced pre-detonation on either. I generally use 93 octane, but I’ll bet 91 octane would suffice.

 

Regards,

 

Steve

 

 

i very much appreciate the input. Likely going with the very-German-but-mystery-manufacturer 9.5:1s from Old timerteile. I did manage to find a set of NOS 9:1 Kolbenschmidts but I don’t see much strong reason to go that route at this point. 

[TobyB]

Detonation can indeed be an M10 problem-

but it's not super common, like some other head designs.

My ONLY concern with this head is that one combustion

chamber's going to have a whole bunch of hot spots from

the ring damage...  

 

t

 

[ajordan282]

Little update:

 

The head went on the milling machine and it became apparent that someone had previously gone at it with a 'whiz wheel'. They love to advertise these things as if they don't remove material.  I've always called bull-ish...now I have the proof.  Luckily it smoothed up fine, just took a few more passes than expected.  It had not been decked before, so there was plenty of material there.

 

Block was magnafluxed and checks out.  He honed the cylinders and found that they were out of round in some regions on all four cylinders.  He suspected it had something to do with running on broken rings.  Also the wrist pin bushings were super worn out.  Block was already at +0.5mm, so going to +1.0mm.  With Stefan @ Oldtimerteile's +1s being out of stock for ~10 weeks I'm exploring some alternatives to keep this project moving.

 

I'm taking this opportunity to patch up the driver frame rail.  While under the car working at it, I took a good look at the trans and thought it actually looked like a G-245 housing (from what I'd seen shopping around).  Climbed up on the rack and got in the car - sure enough it's a got a 5th gear!  Finally a win on this project lol.

 

Sent my injectors and injection pump to Marty @ H&R last Monday.  By Saturday I received my equipment back.  I asked him to check/calibrate everything.  He offered to visually freshen it up a bit, and I am very happy with the results (below).  He found the pump to be super strong but out of time, which he fixed.  He also replaced a couple seals that were slowly weeping oil.  He checked my work on the WUR and said it was good.  Also fixed a broken spring in injector #2, maybe this caused the burnt piston!  Anyhow, great guy to work with and very fast turnaround!  Would definitely recommend him.

 

More to come....

 

Edited October 17, 2023 by ajordan282

[ajordan282]

got some neat-o slugs of loomneeum with the Saturday mail

Edited October 23, 2023 by ajordan282

[gracer]

Nice looking slugs!   What clearance does the manufacture recommend?