My Broken R32 Gtr Story - Pics Inside

[siksII]

So after looking for a well set up gtr for years I finally snapped this one up in March:

http://www.skylinesaustralia.com/forums/topic/420966-1993-r32-track-ready-600hp/

It was pretty much what I wanted:

-top shelf suspension

-no rust

-good interior

-600hp

-all the mods I was after, circuit ready but still streetable

Before i got it, i spoke to the tuner and got compression/dyno tested along with detailed inspection by a workshop just to be safe, all came out well, engine ran great and car was one of the best the workshop had ever seen.

In the 5 of so months I had it I have done the following:

-fitted the twin 12 inch thermos

-removed them

-fitted a gktech fan

-removed the fake brides and replaced with r33 gtr seats

-chassis setup adjustments

-General maintenance - fluid changes etc

After finally getting the handling, tyres and brakes to where I wanted them, I was going to take it Wakefield for the first time this saturday..so thought I better take it for a good drive last Sunday night to iron out any issues before the track..

In short...

-Heard strange vibration at 3500-4500rpm but very minimal, ignored for approx 3 minutes

-Looked at oil temp, 110, thats higher than normal

-Clutched in and watched oil pressure, it dropped below minimum so turned it straight off and rollled to a stop

-Towed it to workshop

-Workshop tested oil pressure, its very low.

So i went to check out the motor since its pulled apart already:

-crank main journals ruined

-big end bearings are ok

-oil pump is good (some strange marking but this couldnt have happened during operation)

-no bearing material has escaped around the engine since the first stop is the oil filter

-its very unlikely oil surge caused this

-usually when oil surge happens the big ends go first but they are in much better condition than the mains

-this indicates the mains were probably the wrong size to start with, got chewed out, caused low oil pressure which then damaged the big ends

-i was very lucky not to spin a bearing in typical rb26 style, stopped it just in time

the main bearings are so worn that they got squashed into a U shape

I guess this is the risk you take buying a built car.

Thoughts? Do you agree or disagree with wrong bearing clearances being the cause?

Motor was running 2000kms old 10w-60 Castrol TWS

Pics for your enjoyment

[GTScotT]

There is no mention of line boring or new studs for the crank, so I assume it was simply reused. There is also a lot of wear on the oil pump drive so I doubt the crank ever went to a machinist to be checked or polished. However I would assume the bearings deformed before the crank out of shape.

My assumptions would be that the builder simply honed the block and threw in a set of pistons and rods. Then reused the crank bolts which had been over stretched and the torque settings in the FSM were meaningless. So the crank ended up over/under/unevenly torqued and made crank to bearing clearance a little too close for comfort. I have also seen bearings crushed out of round due poor workmanship during the build process.

Always look for a built motor to be proven by usage when buying this sort of thing. Never buy a car with a brand new motor unless it comes with warranty from the builder.

On the bright side the rods should be fine, so you can probably mic up crank bore with NEW OEM bolts and see if they are within spec. If they are OK a new crank and new bearings will get you rocking. Otherwise you will also be up for a head gasket and potentially rings (if you don't like what you see when you get the pistons out of the block).

Good luck.

[abr33]

Do you know if it was blueprinted or even measured up when they built it?

[blue_vl_t]

Not good, strange that the rear head oil drain is on upsidown?

[siksII]

Thanks Scott, when buying a car like this of course there is a fair bit of risk involved, im not suprised at having some issues but since we cant be 100% sure of the cause, just asking for thoughts.

The motor and entire car is a good quality build so you would hope not to hit these issues but shit happens

Im picking up a new crank on the weekend, apart from bearings and crank the motor looks good so it should be back together very soon.

The line at the back of the head is really an extra breather rather than an oil drain (contrary to popular belief)

[Ben C34]

That sucks man, hope you get it sorted soon.

Not good, strange that the rear head oil drain is on upsidown?

That's because it is a vent! Edited September 6, 2013 by superben

[GTScotT]

Im picking up a new crank on the weekend, apart from bearings and crank the motor looks good so it should be back together very soon.

Just make sure the crank bore is right before you put a new crank in, and DO NOT use ARP studs unless you get it line bored. Get new OEM crank bolts and use the correct torque settings. It might be hard to mic the crank bore with the rods still in there but you should definitely do this if possible. Finding out the journals are out of round once you do a second crank will only be heart breaking.

Furthermore, I realised if the crank may have been walking due to the poor tolerances and caused the damage to the oil pump drive. Another reason to consider getting a micrometer on the crank bore and making sure all the journals are right. Again do not use studs unless you are going to get the block line bored.

Also, if you buy a brand new crank check the bearing grades and try to get one with all Zero's. This will be a right pain but it will mean aftermarket bearings in 'STD' size will be a good match and gives you good piece of mind. I was blessed with an all zero crank when I built my SR and all tolerances with ACL Race STD size bearings were spot on.

With a little finesse you will revive this motor and have a good strong unit.

[siksII]

The way the standard oil pump drive is, that small amount of marking is normal, maybe it looks worse in the photos than it really is.

Yep everything will be checked before putting it back together including the tunnel.

I know what you mean about the bearing grades but I dont have time to try and find a perfect one, I have already arranged to buy a brand new crank.

So given the big ends were relatively better compared to the mains, you agree it would have been caused by a mistake with the main bearings?

It shouldnt have been surge since its got all the usual oil mods, takes around 9L/oil per change too.

[GTScotT]

There is a minor amount of scoring on one of the rod bearings but it would be expected that a small amount of bearing material would have made it through the filter and done that. No major issue.

The FS thread confirms the use of ACL bearings which are harder wearing that the OEM items, so a small amount of foreign body will cause some form of scoring. Remember that bearing material is intended to absorb a small amount of foreign matter and should do so without harming the crank, however hard bearing shells are often needed for high load applications. A way around this is to use softer (OEM spec) bearings on the mains and harder bearings on the rods (IE ACL Race). The intention here is to have some level of material absorption at the main bearings before oil travels to your rod bearings. As the crank is secured at multiple points the bearings take a shared load and the rods are the ones which take more of a beating.

I do agree that it appears to be an error in assembly to the crank girdle. What specific error I am unsure, but I would mostly suspect the fasteners as it is uncommon for the tunnel to warp in a motor worthy of rebuild. It is more likely that the fasteners were reused and caused the crank to walk ever so slightly. Remembering also this is a switchable AWD the crank would get a lot of load when the ATTESSA engages, hence the walk if the motor was not built right.

A small error in the grand scheme, and easily overlooked when rebuilding a 'running' motor - as many people do.

[StevenCJR31]

Which crankshaft did you buy? An early 32 crank or a late 32 / 33 crank?

[siksII]

Im picking up a brand new R33 crank (long nose) same as what was in the motor already.

[Guilt-Toy]

Not good, strange that the rear head oil drain is on upsidown?

lol.. it looks like a rear oil "feed"

never seen that before

[blue_vl_t]

That sucks man, hope you get it sorted soon.

That's because it is a vent!

Fair point, I have one in my own engine, just never seen one up that way.

I would have thought that breathers from the rocker covers would be more effective as the rear oil "drain" would be submerged in oil sometimes.

Then the rear oil "drain" connecting to the block/sump equalized the pressure and removes the need for air to travel up the oil return galleys due to blow by.

Anyway back on topic, engine build, yada, yada

[siksII]

So what main bearing clearances are people generally running? I hear 2 thou is common? What is the factory spec?

[abr33]

So what main bearing clearances are people generally running? I hear 2 thou is common? What is the factory spec?

Depends on oil and pressure etc.

I run 2.5 thou, with redline 15w/50 oil at about 70 psi

I suggest blue printing bottom end. Plastiguages are shit

No idea on factory spec

[Ben C34]

Fair point, I have one in my own engine, just never seen one up that way.

I would have thought that breathers from the rocker covers would be more effective as the rear oil "drain" would be submerged in oil sometimes.

Then the rear oil "drain" connecting to the block/sump equalized the pressure and removes the need for air to travel up the oil return galleys due to blow by.

Anyway back on topic, engine build, yada, yada

this guy explains the vent towards the end of the page. Not sure if it had been posted on this site before. http://mobile.dudamobile.com/site/TheSkyLife?url=http%3A%2F%2Fwww.skylife4ever.com%2F2011%2F04%2Frb26-engine-assembly-how-to-build.html#2807

[T51B1]

Is it possible that whoever built the motor used too much torque on the main bearings?

When building mine, I had to double check that the torque specs for the mains was correct in the book. The builder could have used a tighter torque on those than called for (33ft lbs I think, can't remember exactly) and then not gauged them? Just a thought.

[siksII]

I guess any mistake was possible in the previous build - that does sound likely.

Motor is running again, quick turnaround. Builder used standard size acl race bearings along with the new crank - they measured up perfect with 1.5 thou clearance on the mains.

Just doing done final stuff before I pick it up this weekend.