RB25 NEO Timing/TDC

[Danowner]

Hey there, so I've started a DIY project of changing out my Oil pump/ Front main seal/ Water pump/ Water pump + timing, which has turned out to be a lot harder than expected. I had a few questions about the engine's timing + Top dead center, when dissasembling the engine/ putting it all back together.

So, when I was pulling it apart, I put it all in top dead center, all timing marks on the cams + harmonic balancer all aligned, still with the old timing belt on it. Then, when attempting to take off the Harmonic balancer, I had to loosen the main crankshaft bolt, which in result, caused the engine to rotate the timing, which threw off the marks a little bit (Keep in mind, timing belt still all attached, so all timing moving together), but I see people on youtube doing similar maintenance to me, always say "BEFORE ANYTHING, MAKE SURE THE ENGINE IS TOP DEAD CENTER, OR YOU'RE F***KD". SOoooo, my logical mind thinks of my situation this way:

If I were to literally get the crankshaft, and literally spin the shit out if it (Red circle), then I'd be in a bit of trouble, because I'm guessing one revolution of the harmonic balancer, isn't 1 full revolution in the engine right? 

- But in my case, because it went out by like literally 1 or 2 teeth, I can just spin it back, make sure it all aligns, and if it doesn't, I'll just have to align the crankshaft first, and then the cams (I'd literally only be spinning it back by a tooth or 2, as seen in the next pics)

I'm not super knowledgable of engines, as I'm kinda learning as I go, so hence my question.

Here's how much the timing went out, when I was taking off the harmonic balancer:

So that is how much it went out, whilst the timing belt was still all connected and tensioned, so how I look at it, is that when I put it all back together, all I'll need to do, is chuck the new timing belt on, tension it, and then make sure all the marks line up, before firing up the engine again right? - and if they don't, then I'll individually just spin it back by the tooth or 2, that it's out by, then put timing belt back on, and happy days?

Cheers guys, appriciate any help with this one!

[Ben C34]

13 minutes ago, Danowner said:

m guessing one revolution of the harmonic balancer, isn't 1 full revolution in the engine right? I

13 minutes ago, Danowner said:

one revolution of the harmonic balancer, isn't 1 full revolution in the engine right? 

 

One revolution of the balancer is most definitely one revolution of the engine.

 

The amount of error you have is not of concern, just turn the relative cam sprockets, crank shaft back to where they should be..... Not sure why they have moved in that direction from undoing the nut though.

 

What you need to do is not spin the engine in such a way the pistons hit the valves.2 revolutions for one engine cylce, the cams spin at half speed etc. Maybe just read a bit more about a 4 stroke cycle to be more confident with what is happening

[Danowner]

7 minutes ago, Ben C34 said:

One revolution of the balancer is most definitely one revolution of the engine.

 

The amount of error you have is not of concern, just turn the relative cam sprockets, crank shaft back to where they should be..... Not sure why they have moved in that direction from undoing the nut though.

 

What you need to do is not spin the engine in such a way the pistons hit the valves.2 revolutions for one engine cylce, the cams spin at half speed etc. Maybe just read a bit more about a 4 stroke cycle to be more confident with what is happening

Yeah that's what I thought, like I said, any rotations that it's gone out, have been done as though the engine was just running, still with the timing belt connected. So when I place the new belt on, and tension it all up, it will still be all aligned.

One thing I'm worried about though, is moving the car, as I'll need to move it to my mates house to pull out the engine, when the car is in neutral, the engine won't be rotating will it? Only if I put it in gear and it rolls. I might just chuck the timing belt on etc whilst I chuck it on the trailer, just to be safe.

[Ben C34]

10 minutes ago, Danowner said:

One thing I'm worried about though, is moving the car, as I'll need to move it to my mates house to pull out the engine, when the car is in neutral, the engine won't be rotating will it?

Honestly man i struggle  to believe that is an actual question.

[Duncan]

No, it wont turn.

[Danowner]

*EDITED*

Edited March 19, 2021 by Danowner

[Danowner]

On 13/03/2021 at 6:08 PM, Ben C34 said:

Honestly man i struggle  to believe that is an actual question.

Ok, so I've been thinking about the whole timing situation, I apologise for the stupid question, was just a bit stressed that I've f**ked my engine forever, never to be able to get the timing right again lol. 

- Soo, I am thinking (I know, it hurts), and I'm going to have to pull out my engine regardless to replace the oil pump, as I need to take off the sump, now even when I went to put my timing belt back on, upon chucking on the old timing belt, to make sure the crank doesn't spin anymore, It spun a little bit with the force of putting the belt around the cam gears. Nowwww

- Technically, if I were to put the cams both in line with their marks perfectly, then I were to find TDC for just the crank, and make sure all 3 marks on cams + harmonic balancer, all align, then I'd have TDC wouldn't I? As I fear now that I never actually had TDC when I pulled it all apart, so thinking of it as though I had to do timing again from scratch, I'll just make sure first of all, the cams marks line up, then lastly, isolate the crankshaft, and make sure that lines up too right? And then I've got true timing again? 

- Also bit of a side note, to find TDC of cylinder 1 ( closest cylinder to cam gears), I could even take out coil + Spark plug, get a long solid plastic rof of some sort (So it's not metal on metal), chuck her in the bore, and rotate the crank, until it reaches it's highest point + it lines up with the mark on the oil pump? 

Sorry for the novel, but cheers guys!

[Duncan]

Firstly, don't worry about replacing the oil pump. I thought from the first post that pic on a stand was your engine but I think it was just and example. Unless you have some reason to suspect an oil pump problem, leave it there, because as you say the only practical way to change it is engine out. You would only change an oil pump when rebuilding an engine and checking out the rest of the oiling system at the same time.

Regarding timing. Yes you have to be careful, but on the other hand it's not black magic and the timing marks are there for a reason.

Yes, you can use a something through the spark plug hole to find TDC for cylinder 1. Ideally something with a plastic not metal end but even then a screwdriver is a pretty common choice.

What you CANT do, is turn the crank or cams a significant way without a timing belt on. RBs are interference engines which means if the crank turns without the cams (or vice versa), the pistons will hit the valves. 

So, any adjustment you make to either crank or cams by more than a few degrees, do it slowly (watching for resistance suggesting a valve is impacted) and evenly across the engine and both cams.

The timing marks show you with reasonable accuracy that the crank and cams are at TDC1. You don't need more than that for a timing belt install because once they are the right relative position and the belt is on, the engine (top and bottom) is safe to turn as required and you just set the base timing by adjusting the crank angle sensor.

Basically....you are overthinking this issue. If the second and 3rd pic in the first post are from your engine the cams are 1-2 teeth out, just turn them back into place. Assuming the crank is the same (few degrees out), just turn it back too and put the belt on.

[Danowner]

4 hours ago, Duncan said:

Firstly, don't worry about replacing the oil pump. I thought from the first post that pic on a stand was your engine but I think it was just and example. Unless you have some reason to suspect an oil pump problem, leave it there, because as you say the only practical way to change it is engine out. You would only change an oil pump when rebuilding an engine and checking out the rest of the oiling system at the same time.

Regarding timing. Yes you have to be careful, but on the other hand it's not black magic and the timing marks are there for a reason.

Yes, you can use a something through the spark plug hole to find TDC for cylinder 1. Ideally something with a plastic not metal end but even then a screwdriver is a pretty common choice.

What you CANT do, is turn the crank or cams a significant way without a timing belt on. RBs are interference engines which means if the crank turns without the cams (or vice versa), the pistons will hit the valves. 

So, any adjustment you make to either crank or cams by more than a few degrees, do it slowly (watching for resistance suggesting a valve is impacted) and evenly across the engine and both cams.

The timing marks show you with reasonable accuracy that the crank and cams are at TDC1. You don't need more than that for a timing belt install because once they are the right relative position and the belt is on, the engine (top and bottom) is safe to turn as required and you just set the base timing by adjusting the crank angle sensor.

Basically....you are overthinking this issue. If the second and 3rd pic in the first post are from your engine the cams are 1-2 teeth out, just turn them back into place. Assuming the crank is the same (few degrees out), just turn it back too and put the belt on.

Yeah, well I've got to take the engine out regardless, as the front main seal needs replacing, as does the oil pump gasket, had a leak down there since I bought the car, wanted to finally get it fixed, pretty sure I've got a leak around the oil sump too it turns out. 

I was looking at pics I've taken, and from what it looks like to me, this is already in the correct position right? 

(Coolant is there from taking off the water pump)

- also, when it comes to the crank, if this mark lines up with the oil pump mark, both cams line up with their marks, but then the harmonic balancer is lining up with say it's middle mark, how tf does that make sense? When the harmonic balancer is meant to line up with the far left mark on it, with the mark on the timing belt cover

[Duncan]

The R32 GTR manual explains the process, but you are thinking of it backwards. The belt does not determine the pulley locations.

Put the crank and cam pulleys aligned to the marks as best you can, then put the belt on.  The tensioner needs to be pulled out of the way using the allen key slot. Once the belt is on release the tensioner and turn the crank at least twice to set the right tension, then tighten the tensioner nut.

It is pretty hard to get the teeth wrong, just go with it. Once the engine is running use a timing light to set the base timing (RB25 is different to rb26) and it will all be good to go.

[Danowner]

17 minutes ago, Duncan said:

The R32 GTR manual explains the process, but you are thinking of it backwards. The belt does not determine the pulley locations.

Put the crank and cam pulleys aligned to the marks as best you can, then put the belt on.  The tensioner needs to be pulled out of the way using the allen key slot. Once the belt is on release the tensioner and turn the crank at least twice to set the right tension, then tighten the tensioner nut.

It is pretty hard to get the teeth wrong, just go with it. Once the engine is running use a timing light to set the base timing (RB25 is different to rb26) and it will all be good to go.

Yeah that's what I was saying, what I'm asking, is, If all marks on the crank + two cams line up, belt is on, should the harmonic balancer line up with the 0° (far left) notch, or will it not line up with that 0° mark?

[Duncan]

On an rb26, when the belt is on correctly and the crank pulley mark is aligned with the oil pump mark, when fitted the harmonic balancer would be at 0o timing.

I don't know if an rb25 neo has marks that start at 0 or not. Some engines start at 10o etc, and required base timing is different too (noting that can be set in some aftermarket ECUs anyway)

Assuming your balancer is in good condition, it does not matter where the balancer timing mark ends up when you assemble it. You can and should freely rotate the engine once the belt is on. The harmonic balancer is located by the woodruff key in the crank. If you want, you can turn the engine with the balancer on and something soft in cylinder 1 spark plug hole to determine actual TDC.

It is possible for the outside of a balancer to fail and spin relative to the inside because it is just 2 parts glued together with rubber. If the outside of your balancer turns independently to the crank after installation it is NFG and needs to be replaced.

[Danowner]

5 hours ago, Duncan said:

On an rb26, when the belt is on correctly and the crank pulley mark is aligned with the oil pump mark, when fitted the harmonic balancer would be at 0o timing.

I don't know if an rb25 neo has marks that start at 0 or not. Some engines start at 10o etc, and required base timing is different too (noting that can be set in some aftermarket ECUs anyway)

Assuming your balancer is in good condition, it does not matter where the balancer timing mark ends up when you assemble it. You can and should freely rotate the engine once the belt is on. The harmonic balancer is located by the woodruff key in the crank. If you want, you can turn the engine with the balancer on and something soft in cylinder 1 spark plug hole to determine actual TDC.

It is possible for the outside of a balancer to fail and spin relative to the inside because it is just 2 parts glued together with rubber. If the outside of your balancer turns independently to the crank after installation it is NFG and needs to be replaced.

Yeah, so I've got brand new balancer, new oil pump, new water pump, new timing belt kit. So what I'll do, is line up the crank mark with the oil pump, and the 2 cams, then that's TDC technically, then what I'll do is chuck a plastic rod of sorts in cylinder 1 before turning over the engine, to double check it's all good

[Danowner]

So I ended up doing the job, all went to plan perfectly. I also was able to take off the sump + oil pump without taking the bottom frame off, it was absolutely the hardest most fiddly thing I've done, but magically I got it done haha. Rea-sealed the oil sum with gasket, and again, magically more than a year on, I've got no leaks at all, and it's all working perfectly. Here's a few after images: 

And just my luck, after installing it all, my CAS just died - pulled it apart and found it was full of metal shards, from what I could only assume something rubbing on something inside. Couldn't get the car to start (As the CAS controls the spark), so I cleaned it out with electric contact cleaner, and got it started. Bought a refurbished CAS from AliExpress, and it honestly felt brand new, had it in for more than a year also, and again, working like a charm.

Edited June 30, 2022 by Danowner