Author Topic: Main bearings for M129 engine  (Read 3804 times)

zdzich

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Main bearings for M129 engine
« on: November 08, 2013, 03:54:30 »
Can anyone tell me if main bearings in M129 engine from 68 250SE are the same like in M130 engine from 68 280SE ? The first set has the part number 1080300040 and the other one 1300300040. I have a problem with locating the main bearings for a reasonable price but I found main bearings for M130 engine for under $150. I need a standard size, 60 mm. Thank you

ja17

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Re: Main bearings for M129 engine
« Reply #1 on: November 08, 2013, 14:12:56 »
Always reference the engine number before you order the bearings. There are differences between the M130 and M129 engine bearings.  It looks like the main bearings for the M129 Mains are  MB#108 586 1703 or manufacturer #(H705/7 Std.). For the rod bearings the MB #(108 586 1003) or manufacturer #(71-2404 Std)

The rod bearing and rods design changed after initial production. The latest bearings supplied may need to be matched to the rods.

 **Note "Prior to assembly of rod bearings sets 71-2404 it is to be verified carefully whether the rods are with or without one or two lubricating channels (holes).   In either case, the replacement rod bearings have to correspond with the rods with reference to the relative lubricating system. If not it is absolutely mandatory  to drill the 3.5mm or moreover the second 2mm lubricating hole, each at 9 degrees from crown without burrs."

However, if you find a stock of NOS bearings, modifications may not be needed. Just make sure to use your engine number to ref. the parts you buy. Closely observe the rod bearing configuration when they arrive. If you find that you have to perform the "drill hole procedure"  it is not a big deal. Simply install the bearing in the rod and use the oil passage in the rod as a drill guide.  Carefully clean burrs from the new hole.

Use your engine number and verify all the information above!
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
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2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
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Benz Dr.

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Re: Main bearings for M129 engine
« Reply #2 on: November 08, 2013, 15:58:08 »
Don't worry about the lubricating holes on the rod bearings. MB had a recall due to excessive oil use and all of the lubrcating holes were eliminated on newer connecting rods.  This why most rod bearing sets will now come without these small holes.

This is for 280SL engines. 250SE engines may not of had the same oil use problems.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
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zdzich

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Re: Main bearings for M129 engine
« Reply #3 on: November 10, 2013, 04:06:21 »
Thank you very much guys for this info.