1967 250SL housing bore & torque specs

[rbarr]

Greetings to everyone, I'm a new member and in need of some info. I hope I'm in the correct section.  I am rebuilding original engine and in process of taking block to machine shop. On the block, just the center main bearing surface is black and two machine shops suggested  that engine may have overheated and may need Align Boring. They are requesting I get the Housing Bore & Torque specs when I bring in block to inspect. I cant seem to find it anywhere. I would appreciate any help on this subject.
Thank you   Regards, RBarr

[Cees Klumper]

Every relevant spec will be in the Tabellenbuch which I have. But I am not familiar with 'housing bore' - do they mean the standard diameter the main bearings fit into (so essentially the outside diameter of the main bearings)? And the torque spec for the main bearing caps?

[rbarr]

Yes, I think that's what it is.. diameter of outside bearing and torque for bearing cap..  I'm driving to east bay tomorrow to go to machine shop. 50 miles from my home in Ben Lomond. Since covid a lot of shops closed down. each town has only one shop and have to wait 3 to 4 months to have any work done. would these specs be in Technical Manual? I just became a full member so I can access it.

[Charles 230SL]

https://www.sl113.org/wiki/Engine/Start?action=download&upname=MBEngineSpecs.pdf

..would these specs be in Technical Manual? I just became a full member so I can access it.

hello rbarr, MB engine specs are in the Engine section of the Technical Manual. Unfortunately I don't think the specifications provide outside diameter of the main bearings.  Did you spin the center main bearing?   

 

[rbarr]

Hello Charles, thank you for replying..yes, I checked the tech manual with no luck .. I don’t think I spun a bearing. I actually drove car with no apparent engine problems to mechanic back in the 90’s. It bellowed a lot of white smoke when on freeway on the way there but that’s it. Engine sounded fine but worn. Mechanic replaced with a used 230 engine and I have had original engine on engine stand since then. It has sat in my garage since then until my son and I dismantled it last week. The bearings look very worn with good wear but no deep scratches like I spun a bearing. Also backside of bearing was black also. I’m not sure why machine shop would require that spec. I would think they would align with the other 6 main bearing areas on block to check if damaged..

[stickandrudderman]

It's good that your machine shop want to line bore the block; it shows they care about doing the right job.
However, it's concerning that they are unable to determine for themselves the correct spec.

[ja17]

The early BBB should also have the specifications for align-boring the engine block for the main bearings. I'll look it up this evening if you still need it then.

[rbarr]

Yes, thank you Ja17.. I ordered the BBB but won’t get it until next week. I would appreciate if you give me the align Boring specs tonight.
   Cees, thank you for explaining to a layman like myself what in-line boring is.
   Charles, I guess I’ll find out when I take to machine shop if I spun a bearing. Stickandrudderman, you must be a sailor which is my other passion.. I want to do the job right because this pagoda will be passed onto my daughter who will then pass on to her son.
I’m glad I joined this group! Thank you all…

[ja17]

Here is a photo of the page in the TDM...….
Crankshaft Bearing Basic Bore (for 250SL etc.)  67.000mm-67.019mm
Permissible out-of-round  0.01mm
Permissible taper of basic bore   0.01mm
Overlap of crankshaft bearing shells in basic bore +0.02 +0.05mm

Torque for the main bearing cap bolts is 65 ft/lbs.

[rbarr]

ja17, Thank you so much for the bore specs. I actually  went to San Leandro machine shop yesterday morning and left with some frustration. All they did was use a straight edge in all 7 bore areas and said that they couldn’t do an align bore with their machine because the block was too old due to pin holes on block. Im just a backyard mechanic so I really didn’t understand that. They told me there’s another machine shop in San Francisco that works on older model cars. So it’s off to SF but a least I have the specs with me now. They told me to torque the cap back on to spec and use a micrometer to measure diameter and said that since they can’t do the job, they didn’t have time to do that themselves. The machine shop that I’m actually using in Watsonville has a boring machine but has to send me elsewhere because they don’t have anyone else to run machine let alone have time to train anyone. Their align bore guy is completely paralyzed due to a motorcycle accident. I’m determined to do this rebuild correctly so wish me luck ..

[ja17]

Good luck, hopefully you will not even need the align-bore operation.

[rbarr]

Thank you Joe, keeping my fingers crossed that I won’t need it either …

[rbarr]

Ok, looks like my I  wont need align boring after all. whew, that's a relief..  I do need some help on taking the last piece off the block. I took the intermediate gear off but how do I take out the gear shaft? I took off the nut, lock washer, washer, half moon key, spacer, gear, spacer, half moon key, & bolt with washer. The BBB doesn't tell me how the shaft goes out. I tried turning that brass spacer but no luck! info will be greatly appreciated. Thank you...  Help Joe!

[ja17]

It goes out the injection pump side. You have to have it's vertical timing gear out first. The bronze bushing next can be removed out of the front side.

[rbarr]

Thanks Joe,

Now it's off to the machine shop to bore cylinders 40 over. Number #1 cylinder hole was pretty bad so instead of putting one sleeve in and using standard pistons, I've decided to buy 83mm pistons from Metric Motors in CanogaPark CA.
Again, Thank you Joe..

[Benz Dr.]

Thanks Joe,

Now it's off to the machine shop to bore cylinders 40 over. Number #1 cylinder hole was pretty bad so instead of putting one sleeve in and using standard pistons, I've decided to buy 83mm pistons from Metric Motors in CanogaPark CA.
Again, Thank you Joe..

I heard that Metric wasn't selling to anyone these days because they were running out of old parts.

[rbarr]

I don’t know anything about that? I was given their number from an old friend in Scotts Valley CA. Who owns Rick’s Mercedes Shop. All he does is work on late model Mercedes. I called Mike at Metric Motors (800-622-6867) and he had both standard pistons complete(82mm) & 83mm pistons which are $18 cheaper per piston.. I should have them by the end of this coming week.

[Kevkeller]

Just wondering why you didn’t take it to Metric Motors to begin with. They seem like they are experts on these engines.

[rbarr]

Actually Metric Motors are the best in the state. If I was going to have anyone rebuild my engine it would ONLY be them. But I’ve had my 250SL for 35 years and I have always maintained it myself from camshaft replacement to clutch, driveshaft etc and scheduled maintenance. I may be 71 but driving it isn’t the only pleasure I get from it. Working on it all these years and always realizing the beauty of its design and technology from 1967.. to me it’s perfection from that decade compared to other vehicles of that time period. I get as much pleasure working on it as I do driving it.
    Plus, my son’s an ASE certified mechanic & used to manage the whole fleet at Speedy Shuttle when they had the airport contract in Honolulu… 56 sprinters, 4 Mercedes’ R class limos, sedan limos, etc.
    This gives me Quality time to spend with my son rebuilding this gem and a reason to spend more time in our home in the Santa Cruz mountains.

[rbarr]

Hello, This message is for Benz Dr.   

You are actually correct! I just spoke to Mike at Metric Motors this morning and he said that they normally don't sell specific parts due to shortages and back order items. But he does make exceptions when it helps both parties. I'm selling him my used 230 engine since I have no use for it and he in turn will rebuild and put it in his inventory. And he did say and I quote " that rarely happens"