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nissubaru nissubaru is offline
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Default Used Replacement Motor on Stand - Should I Do Rod Bearings? - 04-11-2019, 06:04 PM

85k miles on the motor, was just gonna do new gaskets all around including the rear main seal but not the front crank seal. I figure the front crank seal can be done without too much hassle if needed in the future but I'd rather not drop the trans in 20k miles for the rear main if I can do it now.

That's all fine and well, but I gotta ask about doing the rod bearings while I'm in here. King replacement bearings are pretty cheap considering the price of a "new" motor so it seems like a smart move, but is it worth the time, cost and risk associated with it?

For some this might be no problem but personally I've never messed around with the internals of a motor or torquing/angle to spec. It's really not that hard to pull a motor and put another one back in, but I imagine I could really **** things up if I didn't do the bearings correctly.

Part of it also comes down to the torque wrench used and how accurate that is. So I bought a used Precision Instruments M1R200HX off eBay, came with a calibration sheet but I'm gonna test it out on something else before assuming it's accurate. This wrench goes from 30-200 in lbs or 3.5 - 22.5 nM. Rod bolt spec is 20 nM + 70 degrees.

I'd feel better about doing the rod bolts if I had a nice Snap On digital torque wrench to use with the torque and angle settings, but I don't. Other torque wrenches also don't go down to the spec that we need for the valve cover, rod bolts, oil pan bolts etc so that's why I got the one I did.

So, should I just leave it alone or what?
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E90 M335i E90 M335i is offline
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Default 04-11-2019, 08:52 PM

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THE BEAST THE BEAST is offline
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Default 04-11-2019, 09:15 PM

For peace of mind, it should be done.
BUT, at 85k it SHOULD be fine depending on maintenance. Also its already broken in and ready to smash !
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codesx codesx is offline
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Default 04-12-2019, 09:13 AM

I would maintain two different torque wrenches.
The 7.4 ft lb for the valve cover bolts means you would need something that specializes in lower measurement to be accurate... assuming mechanical torque wrenches anyways. I'm not yet familiar with the digital and accuracy range.

I use a 5 to 50~ and a 30 to 250. I would believe both loose accuracy at their extremes, particularly lower extreme.


Curious on the name if I may...
Do you also have a Subaru? What model? Is it modded in any way?


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2008 335i Convertible, E93, N54, A/T (190,000+ km)
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Default 04-12-2019, 03:28 PM

I would use plastigage to verify clearances. Manufacturing isn't perfect lol. If you need clearance specs I think I have a link somewhere with that info.
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nissubaru nissubaru is offline
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Default 04-12-2019, 06:06 PM

Quote:
Originally Posted by codesx
I would maintain two different torque wrenches.
The 7.4 ft lb for the valve cover bolts means you would need something that specializes in lower measurement to be accurate... assuming mechanical torque wrenches anyways. I'm not yet familiar with the digital and accuracy range.

I use a 5 to 50~ and a 30 to 250. I would believe both loose accuracy at their extremes, particularly lower extreme.


Curious on the name if I may...
Do you also have a Subaru? What model? Is it modded in any way?
I have a 1/2" Craftsman beam torque wrench that I use for setting torque on lug nuts. But in my mind I look at that as +-5 ft lb since you're really just eyeballing it. I may get another torque wrench to cover a different range like you said.

As for the name, I used to have a 2008 Legacy GT and yes it was modified a bit. ********, boost controller, tune, Koni shocks and Swift springs. Wheels/tires. Nothing too crazy, great car just not as nice as the 335i.

The first half of my name refers to my 1990 Nissan 300zx twin turbo which I got before the BMW and sold the Subaru. Still have it, was modified before my ownership but I got it back in really good shape nowadays. There's always more work to do but I plan on keeping it forever if I can
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nissubaru nissubaru is offline
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Default 04-12-2019, 06:15 PM

Quote:
Originally Posted by Ancient8989
I would use plastigage to verify clearances. Manufacturing isn't perfect lol. If you need clearance specs I think I have a link somewhere with that info.
Funny you mention plastigauge. The TIS mentions using it which I get, but there's only one size bearing unless you go up a size. Apparently they no longer do the color coded bearing shells, theres only like 2 nowadays if you're talking OEM bearings and then King just does OEM size or one size larget.

I understand the point of Plastigauge but I wonder if it's really necessary other than for peace of mind?
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Default 04-13-2019, 01:20 PM

Quote:
Originally Posted by nissubaru
Funny you mention plastigauge. The TIS mentions using it which I get, but there's only one size bearing unless you go up a size. Apparently they no longer do the color coded bearing shells, theres only like 2 nowadays if you're talking OEM bearings and then King just does OEM size or one size larget.

I understand the point of Plastigauge but I wonder if it's really necessary other than for peace of mind?
Pretty much peace of mind. I'd rather be safe than sorry lol
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JuniorB JuniorB is offline
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Default 04-16-2019, 06:16 PM

Iím in process of finishing my n54 for my n52 swap. I thought about this also, Iíve heard all the bad with this engine, I figured Iíd do stage one turbos, wp, all new gaskets, pullies, done some small upgrades, besides going fbo. So this leads to the same question, my motor was a one, woman owner 60k on the clock. This engine was dry, with a few newer injectors from 08. Since I had it out, for piece of mind, I done all the baskets, blasting, complete oil pump cleaning blew out all the cylinder, new everything. I also wanted to do rods to since I was in there, kinda glad I did. I found that the uppers do take more of the load, they were even, but worn. The lowers were in good shape with minimal wear. I finished them off with a set of ARP bolts, be very careful how you torque these, do not use Bmw spec, or Arp. I found good info on another site, this op took in all the considerations when he done his. There is mixed opinions on bearing replacement without pulling a crank, if your knowledgeable and done this before, then youíll know the answer, lol. There is a huge piece of mind knowing that , if this is done correctly, with care, and patience, youíll never have to worry for quite some time.
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nissubaru nissubaru is offline
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Default 05-14-2019, 08:32 AM

I ended up replacing all the rod bearings with King bearings. Here are some pics of the original bearings after 85k miles and a mediocre oil change interval history. Junkyard motor, not mine.






I used Plastigage on 4 of the 6 rods, got tired of doing it towards the end and they all came out around the same clearance.

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Default 05-20-2019, 03:27 PM

Did you convert the clearance to mm or did you find specs in inches?

N54 (Rod)
RPM 7000
Oil 0-30 to 5W40
0.025 Min(mm)
0.048 Avg(mm)
0.070 Max(mm)
0.00098 Min(SAE)
0.00187 Avg(SAE)
0.00276 Max(SAE)
49.978 Size(mm)
0.0010 Ratio(mm)
1.968 Size(SAE)
0.00095 Ratio(SAE)
737 RPM-Clr Ratio
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nissubaru nissubaru is offline
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Default 05-20-2019, 04:08 PM

The other side of the Plastiguage has the measurements in mm. It was about perfect with .051mm

Regarding conversion though, I used this link as my clearance guide and it has measurements in SAE

Official S65 Bearing Specification/Clearance Wiki
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Default 05-21-2019, 07:42 PM

Quote:
Originally Posted by nissubaru
The other side of the Plastiguage has the measurements in mm. It was about perfect with .051mm

Regarding conversion though, I used this link as my clearance guide and it has measurements in SAE

Official S65 Bearing Specification/Clearance Wiki
Glad it worked out! I had my crank turned and ran the appropriate bearings and they came out fine too.
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