[bazzle]

I've seen untouched high mileage Nissan blocks still with the honing marks in them.
The scores "may" be from carbon stuck on the sides of a piston.
The polished bits near the top are prob normal wear marks too.

 

[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.

 

[james008]

Engine looks decent all in all from what I can see.
Head is in excellent condition, I agree that it has been replaced, it would be pretty uncommon for an original SD head to have no cracks between valves or around pre combs.
Pistons and rings would be standard size. As far as I'm aware there is no oversize stuff available and there is no need for it since the cylinder liners are replaceable.
Speaking of, it does look to be honed, the angle seems shallower than the factory crosshatch so the engine likely had a refresh.
The marks up near the piston crown are interesting. They kinda look like chips have been taken out?

Those big end bearings have definitely been replaced. That dull silver layer is on top of the copper layer of the bearing, so they aren't particularly old.
I assume the bearings are aftermarket since you say there is a logo on them. It would be interesting to get an idea of bearing clearance with plastigage or something since there was a bit of movement between rod and journal. Std spec is 0.035 to 0.089mm or something for new bearings and while there will of course be a tiny amount of movement with no oil film, the video you showed does appear to have a bit more movement than I'd expect.

All the SD33s I've pulled down have had SD22 stamped on the rods. Its normal.

Crank nut is 41mm, and have fun taking the pulley off, its held on with a locking cone that does not like to come off. I think the last one I did I used a big hammer and drift and whacked around the inside face of the pulley until the cone started to work loose.

 

[trev zd30]

held on with a locking cone

Hey @james008

Just so I understand what we are up against....

Do you mean there is a cone wedged between the crank and the balancer, held tight by the big nut?

Cheers

 

[james008]

Hey @james008

Just so I understand what we are up against....

Do you mean there is a cone wedged between the crank and the balancer, held tight by the big nut?

Cheers

Yeah, that's exactly it.

Actually TD42 uses the same setup, and I just found this which has a few things to try because apparently I decided flying blind was a better idea until now. The socket method sounds a lot easier than what I did...
Need Help with removing tapered Cone TD42

 

[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

 

[geeyoutoo]

As for journal sizing in previous pics, that is about parr for the course.

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

 

[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...

 

[geeyoutoo]

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?

 

[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?

 

[geeyoutoo]

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?

No No, if the crank needs grinding you need will slipper bearings to suit, the main bearings looked very good which indicated to me the crank should be OK, hence my question on the big end as we have not seen the big end slippers, then of course you need to check the little end at some time. But if big end bearings are fine it looks like the crank is in good nick.

 

[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.

 

[geeyoutoo]

Oh I thought I'd already put more detailed photos of the big end bearings in, apparently not:
View attachment 546083
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:
View attachment 546084

And all of the conrod cap bearings look like this:
View attachment 546085

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

Just starting to break through. Clean up the big end journals and slowly run your finger over the journal, amazing what the finger can sense. Are you able to measure the crank?

 

[Ethanissan]

Are you able to measure the crank?

Not myself, but next week I'll be wrapping up the main pieces and taking them to a local engine builder to get the crank measured, and ground if necessary, the liners measured and honed, or replaced if necessary, measuring the head warp etc and just generally recommend what needs doing. I'll be doing the assembly work myself, only getting the shop to do what I can't, because labour is expensive 😯

 

[geeyoutoo]

Interesting re head, no idea how they do it now but we never machined a warp out of a head, we would pull the head down on a mill table so the warp was taken out then reface the head and bolt it up which pulled the warp back out anyway.

 

[edb]

Hi Team,
from Caterpillar Engine Failure Analysis schooling wear to the top main bearing shells is a classic sign of engine over speeding --in engine bearing failure analysis wear to the upper shells is a place to look for this type of failure--along with other signs-- that over speed may have occurred.
Believe it or not, in an over speed situation the crank is actually picked up by the upward inertia load of the piston/conrod groups needing to be stopped and then pulled back down the cylinder with more force than is generated downwards during normal engine forces at full load and speeds.
In severe over speed the upper main bearing shells and sometimes the lower con/rod shells can fail.
My second hand MQ factory turbo SD33T Patrol went better than my brand new 2004 GU TD4.2ti did when I first drove it home and so I was disappointed with the GU--the Dealer had explained that it would take about 20,000K's to loosen the engine up and this proved to be true.
Enjoy your refurbished SD33T.
Regards,
Eddie B.

 

[Ethanissan]

Hi Team,
from Caterpillar Engine Failure Analysis schooling wear to the top main bearing shells is a classic sign of engine over speeding --in engine bearing failure analysis wear to the upper shells is a place to look for this type of failure--along with other signs-- that over speed may have occurred.
Believe it or not, in an over speed situation the crank is actually picked up by the upward inertia load of the piston/conrod groups needing to be stopped and then pulled back down the cylinder with more force than is generated downwards during normal engine forces at full load and speeds.
In severe over speed the upper main bearing shells and sometimes the lower con/rod shells can fail.
My second hand MQ factory turbo SD33T Patrol went better than my brand new 2004 GU TD4.2ti did when I first drove it home and so I was disappointed with the GU--the Dealer had explained that it would take about 20,000K's to loosen the engine up and this proved to be true.
Enjoy your refurbished SD33T.
Regards,
Eddie B.

I’ve never thought about that before, and yet it makes perfect sense. Because the conrod essentially propels the piston upwards as it straightens out, it’s got more inertia that the crank has to stop and reverse than at the bottom, where the conrod straightening out actually helps slow it down since it’s still propelling it upwards.
Thanks for that info, I hope that the wear happened prior to my ownership of the engine, I generally drove it at most up to 3k rpm, mostly much lower than that, but if it was me that caused it hopefully it was only in extreme circumstances.
Your info has always been extremely helpful and appreciated Eddie, without your knowledge we may well have not got the injector pump plunger figured out and unstuck for a much longer time.
And yes, when all is said and done hopefully I’ll be very happy with the engine after it’s rebuilt and broken in.