Hmmmm, some good and some bad to be honest. The valley looks nice and clean.... for a rover, which is a good thing. It doesn't appear that you even have enough wear in the cylinders to even need a re-bore at all. You can still see the factory cross-hatching very clearly, and probably just need to get that ridge removed. How many miles on it?

But I don't like how the pistons and combustion chambers are that dirty, and aren't very consistant either. I wonder if that is oil or fuel in the cylinders causing it. I'm particularly concerned over face of the pistons.... are they dented, or what else is causing that appearance in the photos? Also, do the cleaner looking chambers in the heads also have equally cleaner looking cylinders? Might have been some screwy injectors or something causing uneven fueling. Maybe send the injectors out to get cleaned,tested and balanced.

Got any pics of the lower end? how did the oil pan look? What about the other 5 cylinders?

-Hans

Follow-up Post:

Oh, forgot to add..... very nicely done with organizing the valvetrain, but toss those head bolts into the spare parts pile, you can't use them again for that purpose. The ones in the 4.0 can only be torqued once before they exceed their stretch limit.

-Hans

 

I just finished an engine, I hope you don't mind me jumping in. Not much wear in the cylinders judging by the few pics. I've been told it's possible to change a 4.0 to a 4.6 by using the 4.6 crank, rods and pistons if you are lucky enough to have the thicker blue stamped block.

 

Hi Hans,
I saw you were on tonight and hoped you would have some comments for me, thanks. I have no idea of the mileage. Someone before me had dropped this into a '94 d-90 but it hadn't been made to run in the vehicle. The block # starts with 50D, so it narrows down what it came out of to either a 97 d-90 or a 96-99 disco I believe... The flywheel has the magnetic pickups on it (shweet!, you know what that means) so I'm leaning toward it having come out of a disco. Oddly, the cylinders on the left side aren't nearly as fouled as those on the right. What you see on top of the cylinders I would best describe as "flakes" of fouling. I can't imagine they were just laying in there, could they have fallen from the heads when I removed them? There was some pretty gunky oil in the pan. I think it may have sat for a while. I have no idea why the valves on the ends (on both sides) look different. I wondered if they ran leaner because the intake didn't fuel them as well. When you say pic's of the bottom end do you mean the crank? I can run out in the garage and snap a couple.

Thanks,
Rod

Thanks for the interest Michael. If there is something I could post a picture of that might help diagnose, just say the word!

 

It's been my experience that humidity from sitting can make carbon do weird things once it's exposed to air so I wouldn't worry about the flaking etc. The valley doesn't look too gunked up either. I'd go ahead and clean it up as it looks like to me it's worth spending some time on.

 

yeah, if it's just flaking carbon it's nothing to worry about. It's just hard to tell in the photo if that's what it is or if the pistons were dented. So one side was more fouled than the other? Really starting to sound like a fuel delivery or ignition issue, and not something mechanical with the engine itself.

And yep, i was just curious how the crank area looked, and the back face of the block too.

But from what I see so far things are looking like it's ready to tear it all down and bring it down to a machinist for further inspection. Stuff like a pourous block or cracked cylinder walls would have to be done on a test stand like Robison described a few posts back.

-Hans

 

It looks pretty ordinary to me. The sludge and dirt is not too bad. Not a Mobil 1 motor but not really filthy either.

The cross hatching that Hans mantions seeing is usually visible even on 100k mile engines. As a rule the pistons will wear out more than the bore. So if you needed something new there it would be pistons.

The piston tops do not look dented to me. As someone else says that is just the look of the carbon after sitting.

There is some inconsistency in the appearance of the valves in the shots of the heads. That could indicate an engine or engine manegement system problem.

Here are the parts that commonly need replacement on Rover engine, to give you an idea what to expect:
- Exhaust valves and valve guides
- Valve stem seals
- Main and rod bearings
- Camshaft and lifters
- Rocker shaft assemblies
- Pistons

Here are some of the machine shop operations:
- tank clean everything
- check heads for flatness
- check deck surface on block, check crank bore in block for straightness
- pressure test block and heads
- perform complete valve job
- check pistons and cylinder bores. Deglaze if needed
- check crank, grind or polish
- rebuild rods w/ bushes, cut big ends if needed
- rebalance if desired
- rebuild front cover (tighten oil pump up)

Therre are also more complex repair operations like line boring the crank saddles or replacing a liner set. Hopefully your motor won't need those things.

Follow-up Post:

You might look at my thread from a few days ago on rebuilding a motor to see the operations.

 

I can't thank you enough for taking the time to reply John. The reason I'm doing this is because I want to learn more about what makes my Rover run and become more competent at being able to fix it. I also want more out of my engine. I put a 4.6 long engine in my other d-90 and I love the better performance, but all I really learned was how to bolt on ancillaries. So if you don't mind... What things can I do myself, and what things will have to be done by some one else? Can you give me a game plan?

Thanks for any advice you'd care to share!

Rod

 

I can't thank you enough for taking the time to reply John. The reason I'm doing this is because I want to learn more about what makes my Rover run and become more competent at being able to fix it. I also want more out of my engine. I put a 4.6 long engine in my other d-90 and I love the better performance, but all I really learned was how to bolt on ancillaries. So if you don't mind... What things can I do myself, and what things will have to be done by some one else? Can you give me a game plan?

Thanks for any advice you'd care to share!

Rod

Judging from your photos, it's time to find a good automotive machine shop and take the short block, cam, front cover, and heads there. Also don't forget the balancer and flywheel if you're getting it balanced.

Purpose built jigs are needed to pressure test the block and heads. When you start measuring you move from the realm of "mechanic work" to "machinist work."

The tasks of checking the crank for straightness, cracks, wear, etc . . . that sort of thing is similar whatever engine you are working on but purpose built fixtures will make the job a lot easier. We do a lot of them and that's what we have. You don't want to miss something important just to do it yourself.

Look at the photos I posted and it will give you an idea of what a good machine shop will look like and what tools it will have.

At our company we will have one guy pull a motor from a Rover and strip it to a short block. Then another guy breaks down the short block and front cover and heads and cleans everything. Then the third fellow does the actual measurement and machine work on those parts, assembles them, and they go back to the first guy for reassembly of the complete engine and refit to the truck.

So for me it's a team of three people to go from complete truck with blown motor to running rebuilt truck, and you are at the point where we change team members at our place.

 

Line boring the crank journals...... ugh, every time I hear that term I think back to the chucklehead that did the work on Dad's Ford 9N tractor engine. Gave us back the block and a box with the crankshaft caps in it.... with two different sets of markings on them and just loose in the box. Took a while to figure out which one went where.... and it wasn't much of a surprise when other issues came up later.

I can't stress this enough when I say that you need to use a GOOD machinist. There is a reason they cost more.... it's because they know what they are doing and don't cut corners that result in failure later on. And even in the case of known good machinists, I'd only take a Rover to them if they were experienced on doing work with aluminum blocks. No matter how many phone calls you make, or how much the shipping, it's still less expensive than having to buy and rebuild a second engine because you got a 'deal' on the first one.

-Hans

 

No matter how many phone calls you make, or how much the shipping, it's still less expensive than having to buy and rebuild a second engine because you got a 'deal' on the first one.

-Hans

Oy, isn't that the truth. I owned a shop, as some of you know. We had a customer that melted their engine and needed a cheap alternative. We found one that we thought was good, and after trying to deliver it 4 Friday afternoons in a row I said "that's it"! You will pay the original cost quoted, I ordered a new short block, and all was good. They had a month long nightmare, I had a month long super nightmare, and we lost our ass.

Do it right the first time.

 

Line boring the crank journals...... ugh, every time I hear that term I think back to the chucklehead that did the work on Dad's Ford 9N tractor engine. Gave us back the block and a box with the crankshaft caps in it.... with two different sets of markings on them and just loose in the box. Took a while to figure out which one went where.... and it wasn't much of a surprise when other issues came up later.

I can't stress this enough when I say that you need to use a GOOD machinist. There is a reason they cost more.... it's because they know what they are doing and don't cut corners that result in failure later on. And even in the case of known good machinists, I'd only take a Rover to them if they were experienced on doing work with aluminum blocks. No matter how many phone calls you make, or how much the shipping, it's still less expensive than having to buy and rebuild a second engine because you got a 'deal' on the first one.

-Hans

At our place there is a fourth person on the team that I forgot to mention - the parts man. The machinist would get a set of correct rod and main bearings from him and his assistant (the one who stripped it down) would assemble the machined parts using the new bearings and seals.

So the guy who does the final engine assembly starts with a put-together short block.

In every engine rebuild you have all those same team members but all too often they are not a team, they are a mechanic in a garage, a parts washer at a parts store, an unknown person at some machine shop, and a mailorder parts place. So none of the people work together, and often they don't even know each other. It's not a team at all. That's a big reason why engine jobs can go bad.

So we would not have a situation like your tractor story, because all our people are working together as they have for years. They can ask each other questions and interact. And we do not give work back in pieces like that. We do rebuild blocks for walk-in customers but we aways assemble whole engines before return to the owner.

The ideal situation is to find a place like that where you are, if possible. If you can't I'd suggest shipping the complete long block (that's the short block with heads, cam, rockers . . .all the stuff the machinsits look at . . . to someone who can do it all. Otherwise you assume all the responsibility for stuff you can't evaluate.