Common RB problems and answers

Discuss the RB20, RB25 and RB26 series engines.
ATpossible
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Common RB problems and answers

Postby ATpossible » Fri Jan 25, 2008 12:00 am

I wanted to start a thread to add to one of the stickeys that lists all the problems the RB engines have from Rb20/Rb25/RB26 and through the different generations.

then if you know of a proven solution post that too.

if you are posting a link to somewhere put a quick title so people know what it is

I'm not at my computer with all my favorites so I'll just do the obvice...

Rearly R32 engine had a crank collar issue where the snout was made to short and oil pump failures happened at high hp and high rpm. the late R32, year 93 and up, fixed the snout and the r33 and r34 had good cranks as well.

either i'd check your crank

JUN makes a crank collar that you press on to fix itSome people weld on materialSome buy a new crank, usually the R33

Please add what you have learned


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240z4u
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Re: Common RB problems and answers (ATpossible)

Postby 240z4u » Fri Jan 25, 2008 3:04 am

Uh, my series 2 RB25DET from an R33 has the crank snout issue.



Evan

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Shocker
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Re: Common RB problems and answers (240z4u)

Postby Shocker » Fri Jan 25, 2008 4:10 am

Problem: Parts are expensive as ****.

Solution: Buy an sr20, or keep the KA. Have a lot of money. Quit cars, try crocheting.

ATpossible
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Re: Common RB problems and answers (240z4u)

Postby ATpossible » Fri Jan 25, 2008 11:50 am

sorry to hear you had a problem with your crank. no sure on a explanation for you but sorry.

thanks for the added input guys, real helpful

please dont post unless you have a series response.

here is a link to the crank collar issue only one pic tho and some info...zerothread/225404

unfortuantely i dont have the link to my favorite explanation i read a long time ago

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240z4u
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Re: Common RB problems and answers (ATpossible)

Postby 240z4u » Fri Jan 25, 2008 12:44 pm

Okay, I deleted my smart *** taurus comment. That still does not fix the fact that the very first bit of information in your sticky is WRONG!

Don't be sorry that my crankshaft has the short snout, I did my research and knew exactly what I was getting into. You may want to edit your post to reflect correct information so I can delete this one.

Lesson kids? Its smart to assume that you will need the crank snout sorted out.

Evan

I would suggest NOT spoon feeding info, rather giving a list of keywords that NOOBS should be searching to make them well informed. That way they can make thier own educated decision

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DriftingisLame
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Postby DriftingisLame » Fri Jan 25, 2008 3:28 pm

I have an r34 NEO crank with a short snout, it definately wasnt totally fixed after late model r32's.

How many people have actually lost motors due to this? I've heard about it most on this forum than any other, but seriously, has anyone lost a motor due to the crank snout being too small? Please let me know!!

Only time I've ever heard of this being a problem is on 8500rpm+ circuit racing GT-R's.

If anyones had a problem with the crank snout, please give us the specs of the motor and what it revved too, and the damage.

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240z4u
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Re: (DriftingisLame)

Postby 240z4u » Sat Jan 26, 2008 7:08 am

Search the skyline forums for failure rates.

I don't know how often it actually happens but for the money that it costs to fix, its stupid to leave it. Your talking blown motor, and toasty turbo if it totally fails. Granted my turbo was under $700, but imagine losing a 2k dollar turbo because you cheaped out on the snout.

I paid about $400 to have my crank welded and re-balanced locally. Worth every penny to know I am not setting my daily driver up for failiure.

Thank you for confiriming that the posters comment re. the snout issue is incorrect.

Evan

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silviasgp06
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Re: (240z4u)

Postby silviasgp06 » Sat Jan 26, 2008 12:03 pm

yeah, snout problem is only a high RPM issue from what i can tell and have heard from the aussies, but its worth fixing when you have time to get it done and the motor is out.

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Coolwhip
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Re: (DriftingisLame)

Postby Coolwhip » Sat Jan 26, 2008 1:15 pm

DriftingisLame wrote:I have an r34 NEO crank with a short snout, it definately wasnt totally fixed after late model r32's.

How many people have actually lost motors due to this? I've heard about it most on this forum than any other, but seriously, has anyone lost a motor due to the crank snout being too small? Please let me know!!

Only time I've ever heard of this being a problem is on 8500rpm+ circuit racing GT-R's.

If anyones had a problem with the crank snout, please give us the specs of the motor and what it revved too, and the damage.
A local buddy of mine had the pleasure...zerothread?id=159259


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bumblebtuna
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Re: (Coolwhip)

Postby bumblebtuna » Sat Jan 26, 2008 6:16 pm

friend of mine with a series 2 lost oil pressure because of this aswell resulting in a fried motor.

i ditched my short snout Neo crank for an r33 26 crank.

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Shocker
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Re: (bumblebtuna)

Postby Shocker » Sat Jan 26, 2008 6:24 pm

I actually just got this crank issue fixed. Collar was like 166 shipped from nengun, ****ing machine shop raped me, $232.00 for it to be machined, BS write up, they saw high dollar motor and crank and went to town....

Heres pics anyways.

BEFORE:You can kind of see the wear marks on this crank stock.

AFTER

Now I also just removed the Oil pump from my old rb25, it only had about 65k miles on it, the drive/collar was EXTREMELY worn, I was soo surprised, now this is only with BPU upgrades.... I'd bet at the rate it was wearing around 100k miles it might have severely slipped, and even sooner with the power I had planned to make (500hp) and reving to 8k.

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bumblebtuna
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Re: (Shocker)

Postby bumblebtuna » Sat Jan 26, 2008 6:50 pm

bling bling yo!

my machine shop apparently has the same mentality as yoursthink he wanted 200ish to machine my bad crank.

well worth it though

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GhostRider240sx
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Postby GhostRider240sx » Sun Jan 27, 2008 5:37 am

Do the rb20s have the same issue?

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Shocker
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Re: (bumblebtuna)

Postby Shocker » Sun Jan 27, 2008 6:38 am

bumblebtuna wrote:bling bling yo!

my machine shop apparently has the same mentality as yoursthink he wanted 200ish to machine my bad crank.

well worth it though
Yeah If I had to do it again tho, I'd have told him it was a 4.0 liter jeep crank. I talked to my buddy at school who is a machinist... he told me I should have taken it to him, his shop would have been around 100 dollars lol.

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Re: (Shocker)

Postby KlanjacOFF » Sun Jan 27, 2008 8:29 am

Is this the collar you bought?

http://www.nengun.com/jun/oil-pump-collar-drive

I'm guessing it works with the RB25 even though it says 26. Guess I'm going to go ahead and do this while my engine is out. So I dont need to measure anything for the machine shop, just take it to them and they will know?

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Shocker
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Re: (KlanjacOFF)

Postby Shocker » Sun Jan 27, 2008 9:42 am

KlanjacOFF wrote:Is this the collar you bought?

http://www.nengun.com/jun/oil-pump-collar-drive

I'm guessing it works with the RB25 even though it says 26. Guess I'm going to go ahead and do this while my engine is out. So I dont need to measure anything for the machine shop, just take it to them and they will know?
Yeah they are the same. It comes with directions, they should know what to do as long as they are half decent machinists.

Yes the rb20 has the same issue.

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Re: (Shocker)

Postby ATpossible » Sun Jan 27, 2008 12:32 pm

good added info and nice pics...any other problems people know of and solutions for?

like the too much oil in the head problem? not real informative on it but read some threads stating that the oil pump moved to much oil to the head and there wasn't enough in the sump

heard of people doing a drain back in the head and others putting a restrictor or both etc...

any other problems people can think of? and answers to the above problem since i keep hearing different answer im not sure how to address it

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Shocker
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Re: (ATpossible)

Postby Shocker » Sun Jan 27, 2008 5:49 pm

I've heard confusing information on the whole restrictor/head drain mod. The Aussies (Sydneykid) seem to think its needed. However some Japanese tuners say it is not.... I don't know, I plan to run dual restrictors now and no drain lines, also an oil cooler will be installed as for its a must on a circuit car, which I plan to attend quite a few track days.

skylinegrl13
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Re: (Shocker)

Postby skylinegrl13 » Tue Jan 29, 2008 5:03 am

this has been discussed to death:http://www.skylinesaustralia.c....html

but i really like Bob H's explanation here:http://forums.hybridz.org/showthread.php?t=128438on why this "problem" isn't as big as everyone makes it out to be.

btw ATpossible, although it's a good idea this thread so far is just a rehashing of other threads, and not in a good way. you might want to do some real research first and set up a more structured 'sticky' before you throw it out to the kids.


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Postby BoostFab » Tue Jan 29, 2008 5:32 am

let's make this an official thread for you-fix-it problem and solutions. perfect thread for consolidating all the scattered or lost information.

let's clean up nonsense & off topics and keep this thread technical and leave opinions out, please don't post if you don't have anything to contribute, also external links are no good here either: quote it if you will.

keep it coming boys/gals.

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Postby Coolwhip » Wed Jan 30, 2008 3:48 am

Aftermaket cams (non-tomei) don't have cut outs like the OEM Cams to allow access to the head bolts when installed in the head.

This is something to consider since most people running cams will have headstuds installed at this time, and ARP as well as others require you to re-torque yoru headstuds after its initial heat cycle.

(Pics to come)

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Postby Coolwhip » Wed Jan 30, 2008 3:50 am

When having machine work to the bore, it is recomended to use a dummy head/torque plate to simulate a torqued head. Without going into the technique use of the above practice...

You may use a torque plate from a L-series motor during the machining process.

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Postby Coolwhip » Wed Jan 30, 2008 3:53 am

When moving to much higher lift cams such as Tomei ProCams all RB series motors require you to machine the head to allow the cam lobes to pass.

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Postby Coolwhip » Wed Jan 30, 2008 3:54 am

Lifter problems?

The Z32 solid lifter kits are the same kits for the RB20/25

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Postby Coolwhip » Wed Jan 30, 2008 4:00 am

Many aftermarket Pistons such as CP, HKS, Tomei, JE allow valve relief for higher lift cams such as big daddy 10mm+ cams.

Wiseco and some others pistons crown / dome isn't tappered the same as the others and actually cause Pistons to Valve clearance issues when using high lift cams.

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mello88
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Postby mello88 » Wed Jan 30, 2008 11:06 am

Problem: You want to replace your oem RB20 water pump and found a great deal on a RB25/RB26 pump (slotted hole). Bad idea in my experience, because the RB20 and RB25/RB26 water pumps are different and the 25/26 pump will not seal the water passage on the 20 block and your pump will leak. I don't know if this is true for all RB20s, but my early ("RB20" on timing cover) has this issue.

Solution: Just buy the correct RB20 (non slotted hole) pump and be done with it.

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Re: (mello88)

Postby mello88 » Wed Jan 30, 2008 11:09 am

Problem: Double check your throttle body shaft seal for boost leaks. Not sure if this is just caused by old age or what, but my RB20 TB would leak boost from the TB shaft seal underneath the TPS. Not a common place people check for boost leaks, I was surprised when I found it.

Solution: I spoke to MaxBore.com to have them bore my TB and replace any seals, and supposedly the RB20 (and 25?) throttle body shaft seals are not replaceable. Buy a new-used TB and be done with it.


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