Welp. S50B32 Rebuild Time... - Page 3

JST · 05-26-2021, 09:09 PM

Damn. Aren’t they just…pieces of metal? Wtf are they made of?

Nick M3 · 05-26-2021, 09:50 PM

well, according to my shitty calipers, the #3 journal is a little less than .2mm out of round. so *definitely* not going to be just slapping new rod bearings in. bearings are available in .25 and .5, so hopefully it can be cut to .25.

It was pointed out that if I need to, the S54 crank is an option.

Nick M3 · 05-27-2021, 01:23 PM

Good news! Further searching found the Mahle ring kit. Which is the OE part. For about 20% of the BMW cost. So that’s back on the table.

Nick M3 · 05-30-2021, 07:45 AM

Got the engine broken down yesterday. Aside from the rod bearing, it looks fantastic inside.

I’ve been hunting around for a replacement crank, but it seems pretty likely that i’ll need to get this one repaired.

JST · 05-30-2021, 09:02 AM

You mentioned the S54 crank up thread—is that not viable?

Nick M3 · 05-30-2021, 10:04 AM

Quote:

Originally Posted by JST

You mentioned the S54 crank up thread—is that not viable?

I know it’s viable. I’m just not 100% sure about which running gear is needed to make it work, and the cost / time equation on that is probably not better than fixing this one.

In particular, the S54 crank requires S54 rods (no biggie - I have to replace the rods anyway), but it also requires S54 pistons. Which creates some extra work as I’d have to bore the block.

Now… I haven’t checked the cylinder bores yet. If they’re off and the block needs to be bored, then that changes the calculation.

JST · 05-30-2021, 11:16 AM

Is the s54 block the same as the s50 in other respects? Just slightly different bore (and stroke?) or is it totally different?

Also this is your reminder to buy at least one spare S54 now and pack it in Cosmoline, while they are still cheap.

Nick M3 · 05-30-2021, 01:12 PM

Quote:

Originally Posted by JST

Is the s54 block the same as the s50 in other respects? Just slightly different bore (and stroke?) or is it totally different?

Also this is your reminder to buy at least one spare S54 now and pack it in Cosmoline, while they are still cheap.

Identical stroke (crank driven), slightly greater bore. S54 pistons require a little bit of alteration to the skirt in order to clear the S50 oil squirters. And, I believe, 0.5mm overbore.

The reason why I can’t just drop in an S54 crank is that the rod journals are too narrow.

Nick M3 · 06-01-2021, 02:54 PM

So... Talking it over with a machinist friend, the S54 crank may be back on the table. It looks like the width of the small end of the rod doesn't really matter, which would let me put the S50 pistons on S54 rods on the S54 crank.

Which would give me a convenient drop in solution.

And speed has real value, given that I have maybe 6 weeks to get this done, or else it's probably going to sit for a *while*.

Nick M3 · 06-02-2021, 10:58 AM

Fingers crossed. The whisper network pointed me at a guy who may have a crank...

05-26-2021, 09:50 PM	#22
Nick M3 Relic Join Date: Oct 2003 Location: Bethesda, MD Posts: 12,456	well, according to my shitty calipers, the #3 journal is a little less than .2mm out of round. so definitely not going to be just slapping new rod bearings in. bearings are available in .25 and .5, so hopefully it can be cut to .25. It was pointed out that if I need to, the S54 crank is an option. __________________ 2011 M3 2006 Sierra 2500HD 4WD LBZ/Allison 2004 X5 3.0i 6MT 1995 M3 S50B32 1990 325is 1989 M3 S54B32 Hers: 1989 325iX 1996 911 Turbo

05-27-2021, 01:23 PM	#23
Nick M3 Relic Join Date: Oct 2003 Location: Bethesda, MD Posts: 12,456	Good news! Further searching found the Mahle ring kit. Which is the OE part. For about 20% of the BMW cost. So that’s back on the table. __________________ 2011 M3 2006 Sierra 2500HD 4WD LBZ/Allison 2004 X5 3.0i 6MT 1995 M3 S50B32 1990 325is 1989 M3 S54B32 Hers: 1989 325iX 1996 911 Turbo

05-30-2021, 07:45 AM	#24
Nick M3 Relic Join Date: Oct 2003 Location: Bethesda, MD Posts: 12,456	Got the engine broken down yesterday. Aside from the rod bearing, it looks fantastic inside. I’ve been hunting around for a replacement crank, but it seems pretty likely that i’ll need to get this one repaired. Attached Thumbnails __________________ 2011 M3 2006 Sierra 2500HD 4WD LBZ/Allison 2004 X5 3.0i 6MT 1995 M3 S50B32 1990 325is 1989 M3 S54B32 Hers: 1989 325iX 1996 911 Turbo

06-01-2021, 02:54 PM	#29
Nick M3 Relic Join Date: Oct 2003 Location: Bethesda, MD Posts: 12,456	So... Talking it over with a machinist friend, the S54 crank may be back on the table. It looks like the width of the small end of the rod doesn't really matter, which would let me put the S50 pistons on S54 rods on the S54 crank. Which would give me a convenient drop in solution. And speed has real value, given that I have maybe 6 weeks to get this done, or else it's probably going to sit for a while. __________________ 2011 M3 2006 Sierra 2500HD 4WD LBZ/Allison 2004 X5 3.0i 6MT 1995 M3 S50B32 1990 325is 1989 M3 S54B32 Hers: 1989 325iX 1996 911 Turbo

06-02-2021, 10:58 AM	#30
Nick M3 Relic Join Date: Oct 2003 Location: Bethesda, MD Posts: 12,456	Fingers crossed. The whisper network pointed me at a guy who may have a crank... __________________ 2011 M3 2006 Sierra 2500HD 4WD LBZ/Allison 2004 X5 3.0i 6MT 1995 M3 S50B32 1990 325is 1989 M3 S54B32 Hers: 1989 325iX 1996 911 Turbo

05-26-2021, 09:09 PM	#21
JST 195 Join Date: Oct 2003 Posts: 24,607	Damn. Aren’t they just…pieces of metal? Wtf are they made of?

05-30-2021, 09:02 AM	#25
JST 195 Join Date: Oct 2003 Posts: 24,607	You mentioned the S54 crank up thread—is that not viable?

05-30-2021, 11:16 AM	#27
JST 195 Join Date: Oct 2003 Posts: 24,607	Is the s54 block the same as the s50 in other respects? Just slightly different bore (and stroke?) or is it totally different? Also this is your reminder to buy at least one spare S54 now and pack it in Cosmoline, while they are still cheap.

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