[Ethanissan]

Thought I'd start a seperate thread for the engine rebuild instead of doubling the size of the car's build thread.

Blank first post so I can edit it later to summarise.

 

[Ethanissan]

Engine is on a stand, head is off, and everything is accessible to inspect:

The big head bolts on the passenger side and under the rockers were very tight, as they should be, and needed me swinging off the breaker bar to get them undone, and the smaller set of bolts up the drivers side weren't as tight, but probably by design, I haven't looked at the torque specs or pattern for them yet.

I'll do this in lots of smaller posts, as it'll be reeeeaally long otherwise

 

[Ethanissan]

On first inspection of the head, already extremely happy, no visible cracks in sight, looks like I might be in luck after all:

I then got the head over to a bench and cleaned it up some, still no cracks in sight, not looking too bad for just rubbing with some rags:

I'm not sure why, but all of the exhaust valves have white build-up on them. It can be scratched off and looks powdery once it's broken off. I've taken photos of each individual cylinder to show how good they are, this is why I'm doing it in more than one post:

 

[Ethanissan]

Plenty of carbon build-up, as to be expected in an old sooty diesel.

On first inspection of the block it's pretty clear to see that the oil coming out the sides of the head gasket was everywhere in-between the gasket and block:

After a wipe down though, it's looking even better than the head:

the old N/A sitting sadly in the background. Maybe it'll get a chance to roar back into life for a while as I'm building the turbo motor.

This piece of garbage can go in the bin:

 

[Ethanissan]

So to recap so far, top end looks great, Dad's pretty certain they've put a new head on this thing the last time it was apart, which is awesome news, I'm genuinely really happy about that, means almost no matter what else happens, this engine is going back in the MK 😁
Valves look great, probably replaced when the head was, all the rocker assembly looks awesome, I'm hoping that maybe the injectors were done at the same time, but I'm thinking of getting them tested anyway just to be sure none are dribbling; that would spell the end of the engine, as Landy would testify to if he was still active.

 

[Ethanissan]

Now onto the not so great news. It might've seemed above that I can just buy all new genuine gaskets for the engine, give it a good clean inside, put it all back together, and have a recently rebuilt engine all well and good, but that's probably not the case.

While the top end has clearly been rebuilt, Dad's suspecting that the bottom end hasn't been touched, or has been touched but put back together the way it was.
Basically, there's a lot of play in the pistons inside the bore, and the thing that worries him most is that there's a small amount of rotational play as well; as in, you can rotate the pistons slightly either way.

The other thing too is that it looks like the bores have been honed, but probably not much. Problem is you can also see some pretty significant scratch marks up the sides of each cylinder too, perpendicular to the crank and gudgeon pins. So it seems that the bottom end bearings, and/or the gudgeon pins, have some play in them. It also seems like after the bore was honed they either didn't replace the rings, or replaced them with standard size, not oversized ones to suit the hone, which could be contributing to the piston play.

If you rock the pistons side-to-side in the cylinders they knock against each side of the wall as well, not sure if this is normal but dad suspects this is where my engine had a noisier, knockier, and generally slightly rougher idle than the farm ute we've got.

Pics of the cylinder bores, and a video of the piston movement, to come.

 

[Ethanissan]

A rule of thumb is 0.001" play per inch of bore and bearing diameter, give or take a little depending on how it will be driven.

Does that include rotational play? That's the bit that Dad said concerns him as that's to do with bearings, not bore, rings, or pistons.

 

[Ethanissan]

If you only have 0.001" play per inch of bearing diam you will get 2 tenths of bugga all rotational play out of that.

Righto, I’ll get these photos of the bores soon and a video of the play, and measure it while I’m out there. But first, dinner 😁

 

[Ethanissan]

Photos first, video in a sec.
I know there's some dust and stuff down in the cylinders at the moment, but everything's coming apart anyway so I haven't been as careful as I probably should be.
Piston #1

The piston is clearly rotating on the gudgeon pin here and contacting the cylinder wall, also taking away the carbon buildup at the top of the cylinder ^

Piston #6

Piston #5

Again, piston is contacting the wall near the top (bottom of image) ^

Piston #3

Piston #4

 

[Ethanissan]

The thing with all of the images above is that all of the scratches line up with how the piston twists on the gudgeon pin. There's no score marks inline with the pin, in a way that suggests the pin is loose side-to-side at all, so I'm wondering if perhaps the rings are standard size, not oversized, and just too small for the cylinder after it's been honed; or even the original (worn out) rings and just need replacing.

Anyway here's a video of how much movement there is in piston #3 (similar for all):

they're noisy when they hit the cylinder wall, which is what I was referring to earlier when talking about the noisier idle than the ute

 

[Ethanissan]

A lot will be revealed when you pop a piston out.

Yep, sump will come off tomorrow, I might start poking around the timing system as well to see how that all goes together and comes apart (worst case I forget how to put it back together and I look it up, the internet is a good thing), so hopefully then all the bolt-ons will be off tomorrow and it’ll just be a blank block with the crank, cam, and pistons in it, and oil cooler on the side. Then I’ll be able to see if the main bearings have much side-side movement with it all still assembled, and pistons out to inspect the gudgeon pins.

I tell you what, this is going to be a good thing to have around too:

Sent from my iPhone using Tapatalk

 

[Ethanissan]

Don’t believe everything you see in those books. Be prepared to question things. They are a good guide, mostly.

Oh yeah, I’m well and truly aware of that,
Here at home alone I’ve got diffs that don’t conform to it’s listed ratios and other little things it gets wrong that I can’t recall off the top of my head. I’m hoping at least it’s diagrams of the engine assembly are close enough for me to figure out from, if not take some torque specs from as well.

 

[Ethanissan]

Bit of an update, but more to come tomorrow when I pull it apart further.

I am suspecting based on everything so far, and what I'm about to talk about, that whoever 'rebuilt' the motor last time did it very much dodgy, or maybe inexperienced is the right word? I think cheaply fits. Don't get me wrong, I'm about as inexperienced as you can get in terms of rebuilding an engine, having never done it before, but I understand what needs to be done during the process, and I'm learning from other people as well.
Basically, it looks like the last rebuild was just done with a cheap rebuild kit, they didn't grind the crank, used non-oversized everything, and just put it back together (also don't seem to have touched the gudgeon pins). Doesn't seem like they've taken it to a shop for anything, except possibly a light cylinder hone, but with the looks of that scoring I'm starting to doubt that too.

On to what I've done since the last post in-between work:
I took the sump off, which was a mission because the gasket was seriously glued on there with gasket goo, and now I can at least see the bottom end:

Nothing obviously wrong, so I take the oil pump off, and start having a poke around, the big end bearings do have some side-side play in them, but as far as I'm aware there's nothing that you can do about that since it's the conrod itself that needs to be bigger to take the movement out.

All of the oil squirters under the pistons are intact, none snapped off which is perfect. I wonder if there's a better direction that these could be modified to spray, that better cools the piston?
Anyway, I'll trust Mr Nissan for now:

Great news too, the end caps have already been marked, so one less thing I need to worry about:

I got called into work so Dad ended up being the first one to take a big end bearing off, and uhh:

Yeah, pretty decently worn that one. And it looks like it's possibly had dirt trapped under it at one stage? It's weird, it doesn't have the brass bottom layer I'm used to seeing in pictures, so I'm not sure what to make of the wear marks. The crank does have wear lines in it, but I can't feel any lip with my fingernail so I'm not sure. There's a good chance the crank didn't get ground back to flat and round during the last rebuild, or if it did they didn't match it with oversized bearings, which along with general wear, would definitely help explain my generally low oil pressure.

My summary of their rebuild:
Based on how much gudgeon pin movement there is, I'd say they took the sump off, slapped some new bearings in the bottom, without removing the crank, lightly rubbed the cylinder walls with a hone, put a new head on, and hopefully did some other top end stuff, we'll see though.

I haven't pulled a piston out yet, that''s tomorrows job, so we'll see how the rings look, because just like the bearings, there's a good chance they didn't match the rebuild with oversized parts. That would explain this, what Dad's assuming ring gap mark, and the blowby the engine has always had (where the ute has significantly less):

I went and talked to an engine builder in Caloundra on Wednesday, to get a general gist of what he thought should be done to the engine, and pricing, and it turns out he's a really nice bloke, who actually knows and has past experience with this engine, which is just awesome.

He's aware of the liner protrusion requirements in case it comes to getting new liners, he's actually the one who told me about all the oversized stuff to suit crank grinding and bore honing as well, and reminded me that worn bearings can cause lower oil pressure.
Once I get it down to a bare block, and can get all the bits to him in pieces, we'll have a look over them so he can tell me what he recommends with the bores, crank, pistons etc. Hopefully he should be able to source the new parts we need as well, oversized and all.


For those of you who just want to get back to watching landline :
Bottom end is pretty loose, worn, and looks like it was cheaply rebuilt. Will be like new when I'm done with it.

 

[Ethanissan]

Most 6 cyl engines, the TD included, have 7 main bearings, in this order, where main bearing = 0 and big end = |
0 | 0 | 0 | 0 | 0 | 0 | 0 (one bearing in between each piston)

The SD, along with a couple old petrol engines, like the infamous mopar slant 6, have only 4 main bearings
0 | | 0 | | 0 | | 0 (one bearing between 2 pistons)

Here's a side view of the crank, where you can see the 4 main bearings, and the 6 big end bearings:

And a TD crank, for comparison (note the extra crank support)

The main disadvantage to this is less support for the crank, which just means more crank flex and if there's too much torque placed on it in the wrong place at the wrong time, there's a small chance of snapping it. Basically, don't let your emp get too high, and don't advance the timing too much. That's why I need to keep the spool in check when I get the 2052 on and working. Since the load is also placed on only 4 bearings instead of 7, I may go back to running a 20/50 oil instead of the 15/40, just to give the bearings some extra support. We'll see.

 

[Ethanissan]

Alright, been a couple days, I do need to stop setting deadlines for myself because I never meet them.

All the pistons are out:

Sorry John, your stand is getting some oil on it, oops...
Maybe if you let me I'll give it a fresh coat of paint before I give it back, as a thanks.

Anyway, we thought the conrod bearings on the cap side were worn?

Well look at them on the side that takes the incredible force of...
75hp.

Definitely some contact going on there, it's got some good wear on it.
I do wonder if the hot oil and low oil pressure contributed to that the couple times it happened badly. Although it looks like this has been happening for a while, the engine was definitely used before it was pulled and I bought it, wasn't rebuilt and not used. Pretty sure that doesn't happen in 15,000ish km.

In other news, I really need to stop assuming what the story is behind this engine, because it keeps being proved badly wrong the deeper I get. So I said before that the top end was rebuilt and the bottom wasn't touched, then that the bottom had new bearings but the pistons and pins were original, but now I'm going back on that as well.

The big end bearings have definitely been replaced, and as suspected by standard-spec ones, not oversized, as there's a brand and 'std' stamped on the outside.
And all the twisting movement we thought was gudgeon pin is big end. The gudgeon pins feel brand new, and probably almost are, but again, not assuming anything, we'll see what the engine builder says.
The crankshaft looks good:

Again, I'll see what the professional opinion is on that.

And oddly enough, all of the connecting rods, so probably the pistons as well, have been replaced by SD22 ones (4cyl version of the SD33)?
I know they're the same, maybe they could find 22 parts cheaper than 33 ones, not sure, it just seems odd to me. Not fussed about it though, as far as I know it's only the stamp that's different. I just hope they're OEM, or equivalent quality:

And here's a photo of some scoring on the side of a piston to finish off:

So yeah, next I guess is figure out how to get the harmonic balancer off, as I don't have a socket big enough. May just have to go out and buy one, or get creative.
After that it'll be timing cover off, make sure everything has been marked properly at the factory, and get the injector pump off I guess.
We'll see how I go with the harmonic balancer first.

 

[Ethanissan]

Alright, good progress, it's basically down to a bare block now, with a couple exceptions.

I got the harmonic balancer and timing cover off, and for some reason didn't take a photo? Oh well, I used the socket method mentioned in the TD thread you linked James to get the balancer off, and it actually came off relatively easily.

I also didn't take photos of taking the injector pump and oil cooler off, but here they are off:

One of the things I often see mentioned is the oil cooler on the SD getting clogged up with crud from the cooling system, and I've never taken it off before so I was curious to see what it looked like on the inside. There's definitely build-up in the bottom corner where the water doesn't really flow, but I wouldn't say it's completely clogged up so that's good:

Cam and IP timing gears after I removed them (cam gear is sat on top of the IP gear, which seems to contain the governor?):

Here's the engine with both removed, getting ready to take the main bearing caps off and the crankshaft out:

All the caps removed:

And finally the crankshaft out:

Crank and cam out:

And for reference here's a size comparison between the main bearings and the big end bearings, the mains are obviously significantly larger, not sure if it's the same on a conventional 7 main bearing 6 cyl but my initial thoughts are that it's due to there only being 4 mains:

 

[Ethanissan]

And here's the main bearing wear pattern:
bearing 1, worn on the outside, which I guess is just a result of crank flex?

#2, worn pretty evenly which is good:

#3 is worn towards the rear 2 pistons:

And #4 is worn again towards the outside of the block:

I can only assume the reason they seem worn away from the pistons would be because it's on the top, the levering action of the combustion downwards on the inside of the bottom bearing pushes the outside up into the top of the bearing. Which might not make sense without a couple of re-reads but I know what I'm trying to say

 

[Ethanissan]

Not bad for an old engine, lead indium coating just getting a polish.

Yeah, these bearings have definitely been replaced though, they've got a brand and "std" stamped on them. Not sure how long it's been since the engine was rebuilt, but I'm not surprised it's needing a rebuild now after it was accidentally abruptly awoken from it's years-long sleep like this:

Just lucky dad made me hook up the cooling system before I turned it over...

 

[Ethanissan]

If they sat STD then that is even gooderer. Wipe the journals clean and take a few shots of the main and big end journals, the main journals look good through the oil but is that only oil on the big end journal in the last pic of crank or a a wear mark?

In the picture of the crank I think it's a smudged oil mark, because all of the crank's journal surfaces look good, but I'll go double check later to be sure.

When you say them saying standard is a good thing, is that just because the new bearings won't need to be as oversized if the crank needs grinding?

 

[Ethanissan]

hence my question on the big end as we have not seen the big end slippers

Oh I thought I'd already put more detailed photos of the big end bearings in, apparently not:

That's them laid out from number 6 - 1 in that order. A bit hard to see in this picture, and also that's the 'power' or 'push' side of the bearings, whereas the main bearing pics I put up are of the 'pull' side, not taking any combustion force.

Pretty much all of the conrod bearings look like this:

And all of the conrod cap bearings look like this:

I'll go take photos of the main cap bearings now for comparison, as you know they're the aforementioned 'power' side.