Bad weekend (discussion about running bearings)

[darinz]

One of mine had spun. It had both shells on one side of the big end! Even then the only noise that could be heard was the slight tap where the piston was hitting the head. The scariest thing is there was so light sign of the actual damage inside. Also my rev limit is set at 6000rpm. Sure I hit it a lot and I running 10lbs boost.I hear what your saying about clearances. I'll discuss this with my engine guy and see what he thinks, but sounds like opening them up would be a good idea for my application.

[perana]

[QUOTE=Mettler]I'm pretty sure a guy on here spun a bearing after a reasonably recent rebuild... anyone else remember about that and who it was?

Yeah that was me LOL.My dad rebuilt it,and it spun and knocked some bearings.What he and some race car builder said is:1 oil starvation2 drainage to slow3 oil pump too much for the route the oil takesIn other words too much oil pressure and to long a path to drain back fast enough.Hope this helps. I'm yet to start up my single turbo vh but theres been a few mods to the pick up and pan. Cheers

[SuperHatch]

I'm pretty sure T45 spun a bearing in his shortly after a rebuild too.

[Carl H]

so it is an oil surge issue then...hrum.im curious to see what mettler was on about when it came to running a line directly to the oil galleys.im also curious to see how they are reducing pressure to the pump...larger drive gear for the oil pump?

[SuperHatch]

so it is an oil surge issue then...hrum.im curious to see what mettler was on about when it came to running a line directly to the oil galleys.im also curious to see how they are reducing pressure to the pump...larger drive gear for the oil pump?

Thats about the only way I can see of doing it. There's room inside the front cover for a larger gear, and making the chain longer is no sweat. The driven gear is just flat plate steel (or some other metal, not sure yet).

Would anyone be interested in an underdrive setup for the oil pump if I were to make a gear/chain set available? What do you think its worth?

[gs14racer]

Id jump on it stephen,

I spun number 6 on my first motor as well.

Another thing just out of curiosity if the motors that are spinning rod bearings are 1st gen or 2nd gen.

Mine was a first gen, i believe stephens was a first gen bottome end as well

[Guishnu]

This sounds to me like a very similar to the problem we get with RB engines. It makes no difference if it’s a 20, 25, 26 or 30 the problem remains the same. Apologies if im preaching to the converted but I’ll explain. Issue arises when running high flow/pressure (aftermarket) oil pumps on RB engines. The pump flows too much oil to the head at high RPM’s and there isn’t enough oil drainage capacity in the head to return the oil back to the sump. The sump runs low on oil and the head blows the oil out the breathers, this then starves the bottom end of lubricant, causing big end failure.

To fix this problem (on RB’s) is a multi-stage process, but basically you need too:- Fit a larger oil pan/sump- Fit a restrictor in the block & seal up the rear feed to stop as much oil going to the head (RB26 has this as standard)- Mill the oil drains out in the head to the maximum allowed in the gasket- Fit an additional oil drain into the back of the heads.

This is all stuff I was planning to do on my engines anyway… But what is the availability on Uprated ACL style race bearings for the VH45?

[SuperHatch]

Id jump on it stephen,

I spun number 6 on my first motor as well.

Another thing just out of curiosity if the motors that are spinning rod bearings are 1st gen or 2nd gen.

Mine was a first gen, i believe stephens was a first gen bottome end as well

Yea, mine was an Early bottom end.

I don't see why that would matter unless the casting inside the block changed. The only physical difference I can see after taking both apart is that the old motors have main studs and the new motors have bolts.

I'll see about the gear/chain setup... I'll let everyone know.

[SuperHatch]

After looking at the stock setup again, I think I can make something that will pretty easily install into these motors and reduce pump speed by 7-13%. I'm dropping off the stock gear at the materials analysis lab at work to find out what material it is. Once I know I'll get some on order. It shouldn't take me long to do a DWG of the higher tooth count gear. I can then have it waterjetted, detail it by hand, and have a test piece. If everything checks out nicely I'll have a batch of them made. I'll supply the gear with an appropriately lengthened chain, the setup will use the stock gear on the crank. Price should fall in less than $100. Hope that sounds good to everyone, expect total turn around time less than 2 months.

Jerry, if you want to be a guinea pig let me know...

[Chrispy300]

Interested in a underdriven sprocket and chain! Probably have three for some of the other Aussie VH guys too.

[Mettler]

Good stuff Superhatch, it'll be interesting to see what results you guys get from this!

So I wonder if running avgas all the time has killed the seals? Interesting thought. My motor hasn't been apart so all O rings are still factory?

Yeah that is interesting, although I imagine the factory Nissan O-rings would probably be Viton... though old o-rings are s*** no matter what material!

The factory oil passages seem sweet to me... they all have the same inside diameter and I see no reason for any problems in that department. Once the oil is up to pressure it should be fine!

[darinz]

Id jump on it stephen,

I spun number 6 on my first motor as well.

Another thing just out of curiosity if the motors that are spinning rod bearings are 1st gen or 2nd gen.

Mine was a first gen, i believe stephens was a first gen bottome end as well

Mines a 1st gen as well. And it spun #6! A few to many coincidences there I think!!!!

And get this. Engine builder was inspecting the crank prior to grinding and has found a crack in it! It is through the journal for #5 and 6 psiton. There isn't anything visible to cause a stress point ie no oil feeds etc. It is just in the journal parrallel to the engine. The crank is perfectly straight as well!There is no indication of any detonation in the piston, head spark plugs and the motor has been running an the rich side. So the crack is a bit of a mistery?So anyone in NZ have a spare VH45 lying around? We're just going to start with a new motor and replace bearings before putting it in.

[holeset]

try nizbits , we picked up a low k complete front cut for bout 1700 from memory,ive got a bottom end thats also run a bearing if ya want to pursue the rebuild option,we didnt bother cause of the cost,its got a damaged rod and journal and signs of very high ks

[darinz]

try nizbits , we picked up a low k complete front cut for bout 1700 from memory,ive got a bottom end thats also run a bearing if ya want to pursue the rebuild option,we didnt bother cause of the cost,its got a damaged rod and journal and signs of very high ks

Might be interested. Do you want to give me a call at some stage? 0275 330637.

PS I guess it is #6 as well?????????????????

[holeset]

journals 3 and 4 i was gonna polish it,are you in auckland much,i got the crank at work if you wanna look,ill give you a buzz ,the rod is blue from the heat but when we heard the knock we pretty much shut the motor down straight away

[dsagers]

Judging from the numerous failures of rebuilt engines, sounds like buying a used engine is much cheaper and will last longer.

It might be different in Auckland, but engines seem rather cheap here in the USA.

On one of my muscle car engines I run it one quart low in the pan with three more quarts in an accusump, and with an electric switch I can pressurize the oil system before starting the engine.

http://www.cantonracingproduct...=2410

[koukimatt]

The other thing he mentioned was that the oil has a bit of a mazelike pathway from the filter housing all the way to the back of the block and up to the middle rail where it feeds the mains.

They don't bother with this, and plumb a line from the filter straight into the front of this rail in the front of the block (under the water pump) using a modified -12 fitting.

I found some awesome pics of a VH45 teardown here:

http://www.turbo-infiniti.com/...be7b1

Specifically, these:





Mettler, could you or your superstock builder point out where the feed for that rail is? The black opening immediately below the water pump looks like it has a hex-head fastener sealing it up. The smaller silver opening below that one looks like a mount point for a timing chain guide, so that's not it. I also wonder about the 2 larger discs with hex-head sockets.

Edit: I was going to be lazy and hope someone would figure out what I was talking about in my description, but I pulled up The Gimp and circled the objects in blue/cyan:



Can someone with a torn-down VH try removing those fasteners/seals and show us what's inside?

Edit: I'm too impatient to wait for a reply so I'm doing my own analysis with the pictures available. The black fastener below the water pump appears to be positioned directly over the crank:



There is a round hump at the top of the crank case that goes the length of the block, positioned directly over the main bearings; note the hole for an oil feed in each main bearing... right over the hump. I'm guessing that the hump is the main oil gallery; this fits with the illustrations in the 1994 Q45 Factory Service Manual.



There isn't a picture that has both the gallery hump and that black fastener/seal under the water pump in view, so I don't know if they are in line with each other. But I bet that black seal is some kind of port/access to the main gallery for drainage during maintenance; that's probably the location Mettler's stockcar builder tapped for an oil feed.
Modified by koukimatt at 12:20 AM 5/1/2009

[Mettler]

Yeah that's the spot, directly into the front of the main oil rail through the middle of the block.

On a VH41 it's not a hex fitting, it's a blank plug directly in the center and a hex fitting in the back end of the block.

I don't think they're there so much for maintenance or drainage as they are because there needs to be holes for machining. I am not sure whether the gallery is machined out, but I daresay it would be, because the rough texture of casting would make it too easy for particulates to build up and make sludge in the heart of the engine.

Those two bigger hex fittings you circled go into the water jackets.

[Wes M]

Looking at the diameter of the plug (and therefore the oil rail) and then at the diameter of the holes feeding oil to the crank shaft I'm thinking there may be a considerable pressure drop by the time the oil reaches the last bearing. Though if this were the case one would expect problems on nos 7 & 8. Is there only a single feed for the oil rail (the one on the front)?

Is there anything unusual about the oil feed through the crankshaft to number 6 big end? Is it longer or differently angled?

[Wes M]

Hi Darinz,

Did your engine builder spot the crack visually or through magnetic particle inspection? Have you got a picture of the location?

If you come through Auckland at any stage I'd be keen to crack test it - it will show the full length of the crack and may help find the cause. I find it quite a coincidence the location of the crack and spun bearing..

[Carl H]

this problem sounds hauntingly familiar like some high power SBC engines...heads get all the oil while the mains get none...perhaps it would be a worthwhile investment to run a dedicated line from the filter tree to the mains?

[Wes M]

I was thinking the same.. The plug in the front is conveniently located for that.. tho ideally you'd want to run a line to the rear end of the oil rail to balance the pressure.

[koukimatt]

Looking at the diameter of the plug (and therefore the oil rail) and then at the diameter of the holes feeding oil to the crank shaft I'm thinking there may be a considerable pressure drop by the time the oil reaches the last bearing. Though if this were the case one would expect problems on nos 7 & 8. Is there only a single feed for the oil rail (the one on the front)?

I think the main gallery is normally fed from the rear of the block (where 7 & 8 are), so it would be the other way around: 1 & 2 would be drying out. Mettler's stockcar builder acquaintance apparently ran an extra feed to the front of the main gallery, via the port at the front of the block; so the main gallery on that motor is being fed from both ends... right?

[Mettler]

Hang on, don't go judging the inside diameter of the main oil gallery by the size of the plug in the front! As you can see by the design of it, the plug couldn't physically be any larger anyway because there simply wouldn't be room for it without interfering with the water pump etc. The plug's size does not imply the oil rail is that small.

On a VH41 the plug looks bigger, check it out:



I don't think there are any pressure problems with regards to the size of the oil gallery, or any pressure loss to the front of the motor... Nissan surely wouldn't have cocked that up! After all, the oil pump design is excessive overkill!

And I'm not sure whether he said the main gallery is fed from both ends, but it certainly makes sense... unless all of the oil is routed directly into the front and the rear feed blocked up?

Spun bearings can be caused by a number of issues... and it's probably best to try and address them all. It makes sense that frothed up oil could be one of them, and bearing clearance could be another. Just kill all those birds in one go and you should be alright!

[darinz]

Hi Darinz,

Did your engine builder spot the crack visually or through magnetic particle inspection? Have you got a picture of the location?

If you come through Auckland at any stage I'd be keen to crack test it - it will show the full length of the crack and may help find the cause. I find it quite a coincidence the location of the crack and spun bearing..

Here are a couple of photo's of where the crack is. You can't see it in the photo's due to the flash but it is just visible with a close inspection. The crack is right at the end of the magnet and runs across the journal at 90*.





I'm down in Auckland a bit so I'll sort out to bring it down and you can have a look at it. Finding out what happened would be a good thing for all of us!

[Wes M]

Hang on, don't go judging the inside diameter of the main oil gallery by the size of the plug in the front! As you can see by the design of it, the plug couldn't physically be any larger anyway because there simply wouldn't be room for it without interfering with the water pump etc. The plug's size does not imply the oil rail is that small.

On a VH41 the plug looks bigger, check it out:



I don't think there are any pressure problems with regards to the size of the oil gallery, or any pressure loss to the front of the motor... Nissan surely wouldn't have cocked that up! After all, the oil pump design is excessive overkill!

And I'm not sure whether he said the main gallery is fed from both ends, but it certainly makes sense... unless all of the oil is routed directly into the front and the rear feed blocked up?

Spun bearings can be caused by a number of issues... and it's probably best to try and address them all. It makes sense that frothed up oil could be one of them, and bearing clearance could be another. Just kill all those birds in one go and you should be alright!

I was presuming (dangerous I know) that the plug existed there because the rail was drilled through the front of the block. This being the case the ID of the rail couldn't be greater than the size of the plug. Unless (and someone would have to confirm this cause my gearbox is in place at the moment) there was a larger plug on the rear end of the block.

VERY interesting your observation on the VH41. The fact that the size of the plug - and possibly therefore the size of the oil rail are larger in the VH41 might hint that this was an improvement nissan made to a deficiency found in the VH45?

I'm aware of the common causes for bearing failure, but what is unique in this case is that it is always the same bearing coming unhitched. That would seem to rule out things like frothy oil, bearing clearances etc. These might be contributing factors no doubt but not the root cause.

Has anyone heard of a similar bearing failure in the VH41?

[Wes M]

Here are a couple of photo's of where the crack is. You can't see it in the photo's due to the flash but it is just visible with a close inspection. The crack is right at the end of the magnet and runs across the journal at 90*.

I'm down in Auckland a bit so I'll sort out to bring it down and you can have a look at it. Finding out what happened would be a good thing for all of us!

When you say 'across the journal at 90*' do you mean longitudinal to the crankshaft direction? Or at right angles to the length of the crank? Cracks in the longitudinal direction are sometimes caused by grinding. Transverse is a different matter.

I'll be away down south this coming week but will be back again the week after.

[gs14racer]

I had a pic laying around

It goes all the way thru circled in red, the real question is where does it tee off to the portion circled in yellow

[darinz]

When you say 'across the journal at 90*' do you mean longitudinal to the crankshaft direction? Or at right angles to the length of the crank? Cracks in the longitudinal direction are sometimes caused by grinding. Transverse is a different matter.

I'll be away down south this coming week but will be back again the week after.

Longitudinal to the crank. Where the flash reflection is, is exactly where the crack is.

[CrazyTrance]

Has anyone thought about doing an accusump setup on these things? I mean, it would increase continuous supply of oil to the engine, but at the expense of oil pressure. Problem solved!! Just a thought, it's probably not that easy.

I know it's practically mandatory when you drop an lsx engine in a 240sx and try to draft it..

I'm kind of surprised that the engine is having problems draining the oil form the head. If i'm not mistaken the holes circled below are the drainage holes, correct? They look pretty large to me... idk though.



Also, i happen to have a hard copy of a first gen 1990 VH45 i found in the junkyard one day . I scanned this in so you could all compare it to the 94 fsm. But to me the oil channels and circuit look to be the same. But i realize this does not give the specs on the diameter of the holes. ALSO scanned in the specified pressures.





Dug up these old pics i took when i was making sure the timing chain guides had been replaced before i dropped it in.

Now to me, like someone else suggested before, The oil galley bolt for the head does look significantly larger on the back of the block than the front..





Modified by CrazyTrance at 8:15 PM 5/1/2009

Modified by CrazyTrance at 8:19 PM 5/1/2009

Modified by CrazyTrance at 8:23 PM 5/1/2009
Modified by CrazyTrance at 9:37 PM 5/1/2009