two spun bearings on my RB25

[ariansworld]

I spun two bearings on my Rb25 series 2 motor. #2 & #5 are spun. My mechanic put everything together. He's some old mexican guy in the family. Im pretty sure he thought this build would be easy. Guess not since he fucked it up. Anyways, I bought everything new for the motor. Here is the list of parts I have on the motor

Greddy metal head gasket
Arp headstuds
Cp pistons (standard size)
Eagle Rods
AcL bearings (standard size)
N1 oil pump
Oem water pump
Nismo thermostat
Stock intake mani
stock turbo
stock exhaust mani
stock ecu
stock smic


And everything else is stock. This all happened under 100 miles after the build. Here's pics of the crank shaft and rods. Im posting to see what could of went wrong and if I can save the crank and just go 10/10 on it? Also, when the car broke down on the freeway, I was spooling the whole way when I was just cruising around 50mph. After a few miles the car suddenly died down and I pulled over. I popped the hood and my exhaust mani was glowing red. What happened? :(

Please help!

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0043.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0048.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0044.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0045.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0046.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0047.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0040.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0038.jpg
http://i60.photobucket.com/albums/h13/aecqmc/SAM_0039.jpg
http://i60.photobucket.com/albums/h13/aecqmc/SAM_0041.jpg

http://i60.photobucket.com/albums/h13/aecqmc/SAM_0036.jpg
http://i60.photobucket.com/albums/h13/aecqmc/SAM_0037.jpg
http://i60.photobucket.com/albums/h13/aecqmc/SAM_0042.jpg

[eklips3]

thats looks like some pretty bad scoring on the crank. if the bearing made a deep enough groove in the crank in anyway its pretty much done.

by my guess the connecting rod caps werent tprqued down properly or you might of dry started the motor . did you prime the oil properly ?

[KaminaSan]

I spun two bearings on my Rb25 series 2 motor. #2 & #5 are spun. My mechanic put everything together. He's some old mexican guy in the family. Im pretty sure he thought this build would be easy. Guess not since he fucked it up.

Greddy metal head gasket
Arp headstuds
Cp pistons (standard size)
Eagle Rods
AcL bearings (standard size)
N1 oil pump
Oem water pump
Nismo thermostat
Stock intake mani
stock turbo
stock exhaust mani
stock ecu
stock smic


And everything else is stock. This all happened under 100 miles after the build. Here's pics of the crank shaft and rods. Im posting to see what could of went wrong and if I can save the crank and just go 10/10 on it? Also, when the car broke down on the freeway, I was spooling the whole way when I was just cruising around 50mph. After a few miles the car suddenly died down and I pulled over. I popped the hood and my exhaust mani was glowing red. What happened? :(

Please help!



There doesn't seem to be anything wrong with what your mechanic did, except maybe for timing.

Let's break this down(No pun intended), boosting while cruising, glowing exhaust mani, stock SMIC.

Sounds like your timing was WAY too advanced, or possibly running lean.
This led to your combustion temps being very hot, along with your turbo running hot, spooling all the time, which overpowered and megaheat soaked your little SMIC, which led to even hotter air temps, which led to pre detonation.

Advanced timing/ running lean/detonation caused the bearings to shit themselves, not your mechanic.

P.S. I see you are in Corona, CA. It's been 98+ around here. Have you heard the excuse "It's too hot for turbo cars!"

There is a reason.

[Sileighty_85]

That Rods overheated, my guess just by looking at it is Improper Bearing clearances
In conjunction with improper timing like Kamina said

how long was the engine running for?

[waxball88]

Most likely starved for oil. What was the condition of the oil pump? Properly primed?

I'm not a pro and please don't bash me, but "too hot temps" or a tuning issue isn't much of a cause for a spun bearing. Bending a rod, breaking/cracking a piston ring, cracking a ring-land, then i would say thats an accurate assumption.

When the bearing is starved for oil via a bad oil pump it can spin due to too much friction. And too much friction is a lubrication/oiling problem. The heat generated from the spinning bearing is what led to the discoloration/heat scoring on the rods.

We can all sit here and bullshit you by guessing at the pictures, moving you no where closer to back on the road. Take your crank to a machine shop see if they can grind the crank and make it salvageable with over-sized bearings.

[Sileighty_85]

Most likely starved for oil. What was the condition of the oil pump? Properly primed?

I'm not a pro and please don't bash me, but "too hot temps" or a tuning issue isn't much of a cause for a spun bearing. Bending a rod, breaking/cracking a piston ring, cracking a ring-land, then i would say thats an accurate assumption.

When the bearing is starved for oil via a bad oil pump it can spin due to too much friction. And too much friction is a lubrication/oiling problem. The heat generated from the spinning bearing is what led to the discoloration/heat scoring on the rods.

We can all sit here and bullshit you by guessing at the pictures, moving you no where closer to back on the road. Take your crank to a machine shop see if they can grind the crank and make it salvageable with over-sized bearings.

Incorrect timing=Knock (pre-detonation) = Fucked rod bearings

[waxball88]

Incorrect timing=Knock (pre-detonation) = Fucked rod bearings
I'm not saying it couldn't but RB's are known for oiling/pump issues. Spinning a bearing is most often caused by a lack of oil. So i would look into that before i suspected knock(detonation), unless the car was running with no tuning. A guy i know had his oil pump on his RB take a shit on him, luckily he had an oil pressure gauge and caught it right a way.

[Sileighty_85]

I'm not saying it couldn't but RB's are known for oiling/pump issues. Spinning a bearing is most often caused by a lack of oil. So i would look into that before i suspected knock(detonation), unless the car was running with no tuning. A guy i know had his oil pump on his RB take a shit on him, luckily he had an oil pressure gauge and caught it right a way.

he had an N1 Oil pump which pump out 80-90 PSI or some shit oiling shoulding be an issue (unless he had no oil) But then that would have affected all bearings and not just two.

Glowing manifold = Lean condition= knock

Not saying thats what happened, but possible cuz i had a customers engine spin a rod bearing cuz he slapped on a 2871R with no tune and ran it lean

[ariansworld]

thats looks like some pretty bad scoring on the crank. if the bearing made a deep enough groove in the crank in anyway its pretty much done.

by my guess the connecting rod caps werent tprqued down properly or you might of dry started the motor . did you prime the oil properly ?



The scratches on the crank where the two spun bearings are very light. They don't seem deep. How do I prime the oil properly?

There doesn't seem to be anything wrong with what your mechanic did, except maybe for timing.

Let's break this down(No pun intended), boosting while cruising, glowing exhaust mani, stock SMIC.

Sounds like your timing was WAY too advanced, or possibly running lean.
This led to your combustion temps being very hot, along with your turbo running hot, spooling all the time, which overpowered and megaheat soaked your little SMIC, which led to even hotter air temps, which led to pre detonation.

Advanced timing/ running lean/detonation caused the bearings to shit themselves, not your mechanic.

P.S. I see you are in Corona, CA. It's been 98+ around here. Have you heard the excuse "It's too hot for turbo cars!"

There is a reason.

Well my friend and I did the timing right before I left my house. That's when it broke down after 15 miles of driving. This was back in November of 2010. I haven't fixed it yet. Im in the process of rebuilding it. I had a vacuum leak as well. My vacuum was at 16. I couldn't find that damn leak.

That Rods overheated, my guess just by looking at it is Improper Bearing clearances
In conjunction with improper timing like Kamina said

how long was the engine running for?


Im pretty sure my mechanic didn't check the bearing clearances. It run for about 50miles total. And at one time it was running on 4 cylinders. I think 3 and 4 were out.

Most likely starved for oil. What was the condition of the oil pump? Properly primed?

I'm not a pro and please don't bash me, but "too hot temps" or a tuning issue isn't much of a cause for a spun bearing. Bending a rod, breaking/cracking a piston ring, cracking a ring-land, then i would say thats an accurate assumption.

When the bearing is starved for oil via a bad oil pump it can spin due to too much friction. And too much friction is a lubrication/oiling problem. The heat generated from the spinning bearing is what led to the discoloration/heat scoring on the rods.

We can all sit here and bullshit you by guessing at the pictures, moving you no where closer to back on the road. Take your crank to a machine shop see if they can grind the crank and make it salvageable with over-sized bearings.

The oil pump was new. All my parts were new when I did my swap. Every single part. No cheap stuff either. Yeah, I hope they can save my crank. I just took it Friday to the machine shop by my house. I took my block, head, and crank. They're charging me 75 to resurface the block, 75 to go 10/10 on the crank, and 35 to resurface the head. They also will balance the crank with my cp pistons, eagle rods, the front pully, and flywheel for 150.

I'm not saying it couldn't but RB's are known for oiling/pump issues. Spinning a bearing is most often caused by a lack of oil. So i would look into that before i suspected knock(detonation), unless the car was running with no tuning. A guy i know had his oil pump on his RB take a shit on him, luckily he had an oil pressure gauge and caught it right a way.

The only gauge I have is a boost gauge :/

[Sileighty_85]

Im pretty sure my mechanic didn't check the bearing clearances. It run for about 50miles total. And at one time it was running on 4 cylinders. I think 3 and 4 were out.

Im pretty sure that was your problem.

That guy should should not be building engines or calling himself a mechanic.

[KaminaSan]

Why were you rebuilding it in the first place.

Sorry to say it like this, but why would standard sized bearings be incorrect, if you had no damage to the previous crank?

I could understand if you spun bearings before, and then slapped in std size.

[ariansworld]

Why were you rebuilding it in the first place.

Sorry to say it like this, but why would standard sized bearings be incorrect, if you had no damage to the previous crank?

I could understand if you spun bearings before, and then slapped in std size.


I got the whole swap from my friends s14 for 2000. Came with the wire harness for s14, a clutch masters clutch, one piece drive shaft, and the tranny. Everything else stock and complete. I just decided to rebuild the whole thing since I had the money. Spent about 4,500 more on the swap on top of the 2k.

[waxball88]

The only gauge I have is a boost gauge :/
Definitely invest in an oil pressure gauge. 1 of the most important to have. Shit i personally know of 2 engines saved simply because of having one.
Sorry again about your engine man, shit sucks. But hopefully you can get it put together the right way.

[Sileighty_85]

Sorry to say it like this, but why would standard sized bearings be incorrect, if you had no damage to the previous crank?

I could understand if you spun bearings before, and then slapped in std size.

there are different sizes of Standard bearings by which you can find out by using the numbers on the Crank and Block

[ariansworld]

there are different sizes of Standard bearings by which you can find out by using the numbers on the Crank and Block



I went 10/10 on the crank. What bearings should I run? I know I would have to go 10 over on the bearings but what grade should I get them? Also, I was wondering if I should get my whole crank balanced with my eagle rods, cp pistons, harmonic balancer, and flywheel? And what size/ brand head gasket should I run? My price on a Apex 87 1.5 is 225. My pistons are standard size which is 86. Would it matter if I get the 87?

[Sileighty_85]

you'd have to read the FSM and use the formula and plastigauge for figureing out the bearing size.

I would advise to get the crank balanced.

Apexi is a good H/G. depends on how much the Head has been milled has well too. an 87 pi size H/G will be fine

[ariansworld]

you'd have to read the FSM and use the formula and plastigauge for figureing out the bearing size.

I would advise to get the crank balanced.

Apexi is a good H/G. depends on how much the Head has been milled has well too. an 87 pi size H/G will be fine

Thanks man. I appreciate everyone's help. So I shouldn't buy the bearings till I use the plastiguage? I don't have to have the bearings on to do that, do I? Also, I bought the crank collar for it and Im also buying the tomei oil resticktors. I need three right?

[KaminaSan]

there are different sizes of Standard bearings by which you can find out by using the numbers on the Crank and Block

Are we talking about OEM bearings or what he used(ACL)?

I know the SR "OEM SIZE" ACL bearings only come in STD, and STD with Extra Oil clearance. You can also get the oversize ones, but they aren't standard.

So ACL RB bearings have three different "Standard" sizes? Doesn't sound very "Standard"...

[Sileighty_85]

well not familiar with ACL but the way Nissan/Nismo and few other Japanese companies categorize their bearings is STD 0, STD1, STD2, ect

NISMO RB26DETT Engine Parts - Metal Main Inner Bearing (http://www.rhdjapan.com/nismo-rb26dett-engine-parts-metal-main-inner-bearing-12722)

But even still, When I rebuild a bottom end even if the crank wasnt touched I still plastigauge the bearings