So I Pulled My Rb25 Neo Down Over The Weekend...

[kitto]

Hey all, so i pulled the head off of my 39,000km RB25 NEO over the weekend, Reason for pulling head off is to drill out the oil drains which i've now done and fit oil restrictors. I still need to die grind away the two rear drains.

So as i pulled the cams out and the lifters out, i noticed that the exhaust lifters have excessive amounts of wear, whereas the inlet lifters look like they should on a 39,000km old engine. The exhaust lifters look like they have done 200,000km, not 39,000.

Here's a photo for reference.

Sorry i dont have a photo of one of the inlet lifters to compare, but it is far far better than this one. It just seems a bit excessive to me. Engine was completely un-opened and it looks as though oil flow to that side of the engine is fine, No excessive wear on the cam or cam journals.

Any ideas?

Now, onto oil feed sizes.

I was under the impression that RB25's used two 1.5mm oil restrictors, when i went to measure them with a 1.5mm drill bit, they did not fit. Unfortunately that was the smallest drill bit i have, so i'll have to get some smaller drill bits and see what size they actually are.

VCT Oil feed, i was also under the impression that the VCT oil feed only had a 1.5mm oil restrictor. This is DEFINITELY not the case here, there is NO restrictor at all.

This is a little concerning, as the NEO head doesn't have the extra external drain for the VCT like the S1/S2 RB25's do. It relies on draining back through the oil return holes in the block.

When i pulled the cam covers off, there was evidence of oil breathing out through the breathers. This is normal yes, but i there was a nice amount of film there for an engine that came out of a street car with low kms.

This engine is going to be used for track work, so it'll spend 95% of its time at high revs, so obviously controlling the oil in the head is needed. I'm doing what i can to control it, but i am totally unsure about what to do with the restrictors and VCT feed. Oil pump used will be an N1 (Standard on the NEO).

Any input would be great.

Thanks.

[The Mafia]

39,000? I bet it was 139,000.

NEVER trust an imports odometer. They are so easy to change.

[urtwhistle]

soming tells me that your car has a different dash to what it originally had in it. my 100 thou neo had way less wear on the lifters then that. And yes normally they do have an oil restrictor in the VCT. The question is, has the head come off before and has some 1 already put restrictors in it.

[kitto]

Its definately low km champ, everything else points to it being a low km engine. Everything was pretty nice and shiny still, Pistons have a very low amount of carbon build up. Coil pack loom looks new, fuel rail is still nice and shiney, bottom end has no sludge build up, head is clean, underneath the cam covers are like new etc.

It was bought off a member on here wrecking a car, not an importer.

The exhaust lifters are the only parts showing this kind of wear.

[JonnoHR31]

No rb25s have a dedicated vct drain, they all drain through the normal drains with all the other oil. The external hose that everyone calls the vct drain is more of a breather.

There should definately be a restrictor somewhere in the vct system, the head would flood in no time without it. Its unlikely but is it hiding further down the oil gallery?

The R33 RB25s have 3x1.5mm feeds, however the neo might be a little smaller due to having solid lifters, never seen for myself though.

[STATUS]

139k

[kitto]

No rb25s have a dedicated vct drain, they all drain through the normal drains with all the other oil. The external hose that everyone calls the vct drain is more of a breather.

There should definately be a restrictor somewhere in the vct system, the head would flood in no time without it. Its unlikely but is it hiding further down the oil gallery?

The R33 RB25s have 3x1.5mm feeds, however the neo might be a little smaller due to having solid lifters, never seen for myself though.

Ahh i see, yeah i always thought it was a dedicated VCT drain. Its really difficult to see down the hole for the VCT feed, however i think i eliminated the fact that the restrictor may be elsewhere, after using the compressed air gun into the main oil gallery, you get a large amount of air coming from the VCT feed as you would expect from a 6mm hole. And obviously a lot less air coming through the head feeds. I tilted the block on its side and put some clean oil into the main gallery as well. And yep, oil pissed out of the VCT feed. So there is no restrictor there for it.

139k

Can you explain why only the exhaust lifters show this wear?

[JustinP]

My Neo doesn't have a restrictor in the VCT feed either, I have it appart at the moment.

soming tells me that your car has a different dash to what it originally had in it. my 100 thou neo had way less wear on the lifters then that. And yes normally they do have an oil restrictor in the VCT. The question is, has the head come off before and has some 1 already put restrictors in it.

[kitto]

My Neo doesn't have a restrictor in the VCT feed either, I have it appart at the moment.

Ok, so i'm not the only one! Yay.

How far are you going on the strip down of yours justin? Have you pulled your lifters out?

Also, have you measured your restrictors?

[KiwiRS4T]

I have just had my RB30 out (RB25 DET head with hydraulic lifters and vct). Installed 2 x 1mm restrictors (had 1.2mm) and left vct alone. Drilled and tapped 2 x 20mm holes in the sump and ran 2 hoses up to a catch can (1 might have done). Had some lifter noise on start up but it went away after a few minutes and has been fine. Oil no longer spurting out of head everywhere - have revved it in lower gears but haven't been back to the track yet. I don't think you need that drain from the back of the head but install a fitting for a sump breather while the engine is out - you can always plug it if you don't need it.

[kitto]

I have just had my RB30 out (RB25 DET head with hydraulic lifters and vct). Installed 2 x 1mm restrictors (had 1.2mm) and left vct alone. Drilled and tapped 2 x 20mm holes in the sump and ran 2 hoses up to a catch can (1 might have done). Had some lifter noise on start up but it went away after a few minutes and has been fine. Oil no longer spurting out of head everywhere - have revved it in lower gears but haven't been back to the track yet. I don't think you need that drain from the back of the head but install a fitting for a sump breather while the engine is out - you can always plug it if you don't need it.

Yeah, you and i were discussing this the other day.

I'm doing mods to the pan to vent it to the catch can, so that is sorted.

What size was your VCT feed if you can remember?

So you dont seem to have any issues with lack of oil at idle and low RPM?

I'm concerned about reducing the amount of oil to the head if the exhaust lifters are showing the wear they have, i'm baffled as to why they are that worn.

[Simon-S14]

get us more pics

[JustinP]

The head is fully stripped down, but the head builder is doing it all. I haven't even seen it since I sent it off. He has said everything is in perfect condition though, except for 2 valves which had some water sitting behind them for a while. There was some corrosion / pitting on them and they will be replaced.

I haven't measured the restrictors but I bought 2 x Tomei 1.5mm restrictors (stupidly!), they look exactly the same size as the stock ones in the block. I couldn't find wire of the right size to compare the two though. Drill bit is a good idea, will try that tomorrow.

Ok, so i'm not the only one! Yay.

How far are you going on the strip down of yours justin? Have you pulled your lifters out?

Also, have you measured your restrictors?

[JustinP]

Yes good idea I would like to see pics of the head where the 5 x oil drains between the cylinders are, as well as the two big rear oil drains.

I have asked my head builder to drill those 5 x oil returns out to 9.5mm and I want to make sure I have described it to him properly. I decided to do this after I sent it off and I can't remember what it all looks like on the head side!

get us more pics

[kitto]

Yes good idea I would like to see pics of the head where the 5 x oil drains between the cylinders are, as well as the two big rear oil drains.

I have asked my head builder to drill those 5 x oil returns out to 9.5mm and I want to make sure I have described it to him properly. I decided to do this after I sent it off and I can't remember what it all looks like on the head side!

I can get more pics, but not until Friday/Saturday, i only go up to my shed on the weekend, too far to drive during the week.

There are some, not many, but there are some photos to show which holes need to be drilled out.

Yes i drilled mine out to 3/8" (9.52mm)

[JustinP]

Cheers

I can get more pics, but not until Friday/Saturday, i only go up to my shed on the weekend, too far to drive during the week.

There are some, not many, but there are some photos to show which holes need to be drilled out.

Yes i drilled mine out to 3/8" (9.52mm)

[KiwiRS4T]

Yeah, you and i were discussing this the other day.

I'm doing mods to the pan to vent it to the catch can, so that is sorted.

What size was your VCT feed if you can remember?

So you dont seem to have any issues with lack of oil at idle and low RPM?

I'm concerned about reducing the amount of oil to the head if the exhaust lifters are showing the wear they have, i'm baffled as to why they are that worn.

Got the restrictors here (bit expensive for what they are but not a lot of money):

http://www.trademe.co.nz/motors/car-parts-accessories/nissan/engines/auction-442961050.htm

I bought the RB30 block with the machining done so vct feed T-eed off oil pressure switch and I haven't touched it. No issues so far will let you know when i have hit the track.

[Ke55pig]

I'll take photos of my lifters out of my 75k neo later tonight head of due to ureparible corossion

[kitto]

Ok, small update. I spoke to my friend who is an engine builder about the lifters. He can't be sure until he has a look over the head, but he suggested either poor maintenance (lack of oil changes), abuse to the engine (starting engine and not allowing it to warm up) or possibly overheating of the engine could have caused the exhaust lifters too look as they are.

Today i decided to pull the bottom end down. I removed all the pistons and the crank. And needless to say, all the bearings are worn and will have to be replaced at the minimum. It doesn't look like they have starved of oil.

My conclusion is its had a very poor service life. Possibly had its first service far too late and may have only had one other service. I know it has been service once here in Australia, as it had a bursons oil filter on it. I would say its also been started, thrown in gear and driven. As thats what most people do;, start > throw in gear > throttle > BAM, heaps of engine wear. Given that most engine wear is caused on start up/warm up. But unfortunately the average person doesn't care/know. i think this is where this engine has received all its damage from.

I'm very very pissed off and frustrated to say the least. This was meant to be an engine to get my car running again until i've finished building my RB26. This is another really annoying set back.

I'm not sure where to go from here. Do i replace all the bearings and rings and set it back to Nissan tolerances. Or for a little bit more money i could put some CP forgies in it, then you might as well put arp bolts in the rods, but for a bit more you could just buy forged rods anyway. Now the crank is out i should get a crank collar fitted and have the crank grub screwed. It just snow balls out of control. Where the hell do i draw the line, a line that i'll be happy with knowing the engine is going to run happily for a decent amount of time to come.

Unfortunately today has got me really questioning myself why the hell i'm into cars, wasting so much money and time and every time i eventually get the damn thing going again, it just breaks something else. Really frustrated and over it! end rant.

[Jap_star]

I get like that all the time. But try and remember the joy when it does work.

Just a bit of bad luck with this motor