32gtr Rebuilt Engine Blown After Just 5000 K's - Help

[BlackR32]

Hi All,

Wondering if anyone can offer any advice...

I Just did a rebuild on my RB26 with the following.

New rings

Valve guides and so on in the head,

N1 oil pump

Brand new Crank R33 RB26

new bearings

Sump Baffles (Tomie)

oil restrictor in the head

and I drilled the sump return holes (in the sump)

new water pump and timeing kit.

that just about does it.

Now I put the motor back together all to spec and torque, I ran in the new rings with run in motor oil and all was well the car was driving fine... and FAST! but not long after I changed the oil from the run in fluid the I started hearing a nock...

and here I am today with a newly blown up motor and a whole lot of sad

I know the drill with oil pressure when starting for the first time and so on, and when the motor is cold, I was VERY careful...

Does anyone know what might have gone wrong>? did I miss anything?

Any help would be appreciated as I am just pulling the motor out to go again.

Cheers.

[N1GTR]

Sorry to hear, that sucks. Mine let go at 2800k's, so i know the feeling.

Get a good ECU and tune!

[Angus Smart]

So you've spun a main bearing??

which ones did you use? a bit more info on the parts that have failed would help out solve this.

[Adriano]

What did you set th big end bearing clearances to? Was th oil galleries thoroughly cleaned before reassembly?

[BlackR32]

I am pulling the motor out on the weekend, so I'm yet to see which bits got damaged but based on last time it will be the front big. oil galleries were all cleaned well and truly as for the clearences, I used factory bearings and crank all matching numbers for my block and so on and set all the torque to the factory settings... So when you say clearences what do you mean? suddenly I am feeling a little sheepish.

[blind_elk]

Not much point speculating on what happened. Get the egine out, strip it down, pics of the various bits.

Then we might be able to offer some theories.

[700HP-GTR33]

Is the fuel pump new?

Are the injectors new?

Are your running a stock ECU?

Are your Turbo's new?

Did you check your boost?

Are your plugs new?

Was it tuned...or were you running the same tune as before?

What pistons your running..stock or forged?

Lots of questions....

As stated post up some pictures and list what went back on the rebuilt motor.

[GTRsean]

What did you set th big end bearing clearances to? Was th oil galleries thoroughly cleaned before reassembly?

Pretty important this part, I used plastigauge to check oil clearance. Otherwise, pick up and spin a bearing.

[nuclear_skyline]

when you got it rebuilt, was the mains checked for straightness???

as in was it line bored???

[GTScotT]

I am pulling the motor out on the weekend, so I'm yet to see which bits got damaged but based on last time it will be the front big. oil galleries were all cleaned well and truly as for the clearences, I used factory bearings and crank all matching numbers for my block and so on and set all the torque to the factory settings... So when you say clearences what do you mean? suddenly I am feeling a little sheepish.

if your last motor died from a spun bearing to, then there is a massive chance, as in its most likly, that your stock crank and block had some material stripped off it,

so if this wasnt machined then that can kill the new motor, and then on top of this, when it was machine to fix it, or if it had been done in the past, then the clearances will be diffrent

, so the stock numbers on the crank and block will be wrong,

as said above, use plasti gauge to cheak them when you assemble a motor, you put a strip of this stuff sort of similar to blue tack across the crank, then tourqe the cap down, then remove the cap, and there is a gauge on the plasti gauge pack that shows the clearance size based on how far the pastigauge spred.

[The Dan]

use plasti gauge to cheak them when you assemble a motor, you put a strip of this stuff sort of similar to blue tack across the crank, then tourqe the cap down, then remove the cap, and there is a gauge on the plasti gauge pack that shows the clearance size based on how far the pastigauge spred.

Do not do this!

Plastigauge is for fools. It is not accurate in any way whatsoever.

His engine has most likely failed because he has not measured bearing clearances but plastigauge is a waste of time, you might as well not measure them at all.

Judging by his earlier post, he has no idea what 'clearances' are so it is probably safe to assume he has no idea what he is doing when it comes to assembling an engine.

Did you check ring gap clearances?

Piston to bore clearances?

Big end bearing and main bearing clearances?

Rod vs crank side clearance?

and the list goes on and on and on.....

The only way you will learn to build an engine is by doing it with someone who has a lot of knowledge in that area or if you have someone show you how to do it and then you can go about doing it yourself. Expect to break a few before you get it right.

[GTRNUR]

Yep like Scott's said there are so many things to check when assembling an engine. Pre-assembly checks and technicques are critical. If you cant drive a micrometer and dont know how to use plastigauge properly its a job best left to a pro. The most time consuming part of assembling an engine is all the pre-asselbly tolerance checks.

Before I install a crank and bearings in a block I check the machined block clearances, then the bearing clearances, and then compare them too the crank. Never take a machine shops word for what has been done.

Starting with a bare block, the main caps/girdle should be torqued to spec and the block crank sadel ID measured with a micrometer to make sure they are all indeed round and the same size. Then I install the bearings in the block, re-torque main caps/girdle and measure the bearing surface ID again, and compare them to the crank main OD. Then I measure crank thust surface distance and center main thrust with a micrometer as well and compare to be sure there is propper thrust. Next the crank is installed with oil on the bearings in the block and the main caps are slowly tightened wrist tight with a ratchet and then a torque wrench, all the while checkig the crank still turns freely. Last of all its all cleaned again and the mains are checked with plastigauge to ensure propper clearance. I write everything down while doing these checks, and if the phone rings... start again. If friends show up and want to talk BS while your doing this.. tell them to piss off till your done.

I generally assemble an engine twice completely before doing a final assembly. Its the only way to be sure everything is 100%.

[GTRNUR]

Do not do this!

Plastigauge is for fools. It is not accurate in any way whatsoever.

Can you elaborate on this?

Sure you can get inaccurate readings if your not careful, but my thoughts are if you do your checks a few times and compare with micrometer readings its safe.

[GTRsean]

hence the micrometer part. Lots of measurements as well, not just using plastigauge.

[The Dan]

Can you elaborate on this?

Sure you can get inaccurate readings if your not careful, but my thoughts are if you do your checks a few times and compare with micrometer readings its safe.

If you have a micrometer, why are you using plastigauge?

The only basic items you need to build a strong engine are:

Inside micrometers 20-50mm

Inside Micrometers 50-100mm

Outside Micrometers 0-100mm

Straight edge

Feeler gauge set

Ring compressors

Torque wrench 5-40nm

Torque wrench 40-250nm

$1000 in gear and you've got the basic necessities.

Any less and you cannot be accurate. How are you going to measure variation in journal thickness or tunnel size with plastigauge?

With plastigauge you have to be able to not move the crank even one thou otherwise you'll get a variation in readings. Plus the fact that its nearly impossible to torque the big end caps down without moving the crank just the tiniest bit. You don't even have to see the crank move for it to throw out your readings...you just have to THINK about the crank moving and it will throw out the readings.

Also...take your plastigauge and do the same journal three times and tell me how many different readings you get. You will be surprised.

When I build an engine, if the clearance is 2thou (if it's an RB) on the BE and I would prefer it to be 2.2 thou or 2.5thou, plastigauge is not that accurate, it cannot tell you the difference between 2-2.2-2.5 thou clearances.

[GTRNUR]

If you have a micrometer, why are you using plastigauge?

Habbit i guess. My engine building education came from someone who was pretty old school. Ive then learnt how to use the micrometer method since I began doing higher performance engine builds. Im not a mechanic by trade so I probably over check things but better to be safe than sorry. I figure if i check something 3 times and get the same measurement those three times then ive got to be on the money.

And yes it can be quite entertaining how badly plastigauge results can be affected if something does move. Though if it does move and your plastigauge is smered it would otherwise read as being too tight. If you check a few more times and it measures as more loose, and is consistantly the same width when torqued to spec you know its close. If its consistently the same then there is a problem, or you drink way too much coffee and cant assemble something without shaking...

[BlackR32]

First off, R32 GTR

Ok, SO I posted up a little while ago that my engine kicked it's self in the face after 5000 k's on a rebuild.

It spun a bearing originally and then after the rebuild, ran her in, just started to drive again on the new oil and so on and there it was a again, bearing failure noise...

The general concensus was that I needed to pull it down before anyone could give me any advice on what went wrong.

SO I have done so, heres the go...

All the bearings crank to block are perfect, ONE of the bearings crank to rod is toasted.... badly!!! Piston three to be more specific.

Everything else seems to be perfect... Now my trusted shop down here gave me one theory which is that something could be wrong with the rod it's self, perhaps the thread was just out or something resulting in a false torque down... This would mean to little or too much actual torque on the bearing and ultimately . . . Death to favourite motor.

N1 Oil pump is fine,

Rings and bore all good (new rings)

new crank... MIGHT get away with a polish... more on that to come. R33 GTR Crank

baffle in the sump

restrictor in the head

head reco'd

basically the motor seems fine other than that one bearing...

can anyone provide any more advice?

I am thinking of replacing the the rods, bearings and oil pump at the very least even thouh the pump is fine or seems to be.

alright then, so regarding the above,,, I'm baffled and a little scared of putting it all back together just to blow up in my face again...

Any help and all theories would be great!

Thanks in advance for any help.

[The Dan]

Didn't we come to the conclusion that you didn't take any measurements for clearances and it failed because of this reason?

Or was that someone else?

[STATUS]

i reckon someone did not get the clearances right. Bearings only die in new engines for two reasons DET and clearance.

[BlackR32]

Hmm, Ok in the last post though someone suggested using a plasti guage to do this and then someone else said that was a stupid idea and doesn't work.

What is the best way to ensure the clearance is perfect?

Thanks for your help guys