Jeff's Random Motor Rebuild Disassembly/Assembly Questions Thread.

[2002Scoob]

I'm just going to turn this thread into 'Jeff's random rebuild questions'

Today's pondering I'd like the group's feedback on is my clutch.

It's been holding and driving fine, no slipping and decent pedal feel (for what it is), no chatter either.

But upon disassembly yes.... the flywheel looks like it could use resurfacing, and I'm not sure how to gauge how how much life it's been through, and how much it might have left.

Right now financially I'm below a shoe-lace budget, so I'm tempted to throw it back in and drive it till she doesn't any more.... but if someone were to raise some concern I'd consider it.





So yah.... if there's any cheap tips or tricks to extending the life of these components while it's apart, chime in!

I've already done some basic cleaning and re-greasing of the throwout bearing, so I think that's good for another 30k.


Sent from my iPhone using Tapatalk

[Simeon]

There's plenty of meat on that clutch. The flywheel should probably have been cleaned up the last time the clutch was changed but what can you do?

 

if it was working fine when you pulled it it should be fine now. It will certainly do you while you keep your eyes on the prize of getting this back in the car ASAP. Just keep telling yourself, this is the stop-gap engine...

[2002Scoob]

58 minutes ago, Simeon said:

Just keep telling yourself, this is the stop-gap engine...

 

I'm trying. But I'm terrible at half-assing things.  Especially when it comes to the motor. This will be my gauge as to where I take the next rebuild, and I still wanna drive the piss outa' this motor and enjoy it while it's in there. It has the potential to be a hellova' upgrade over where it was at. 

 

I'm currently dialing in and cleaning up the piston/rod assemblies, and unfortunately there's a gram scale on the workbench... 

 

My next question later today will be in regards to matching weights of the pistons/rods, and how close is close enough gram-wise. But I want to weigh and photograph everything and get real numbers.

 

If there's room to improve with moderate effort while I'm waiting for the cylinder head to be completed, It's worth doing!

 

1 hour ago, Simeon said:

There's plenty of meat on that clutch. The flywheel should probably have been cleaned up the last time the clutch was changed but what can you do?

 

 

Good to hear, and was my impression as well. You guys are my over-the-shoulder double-checkers with allot of the stuff as I'm pretty much solo-ing this. All the help is greatly appreciated. 

 

[TobyB]

You have to use that clutch- otherwise, you'll have a half- used clutch kicking around,

and one shouldn't discard useful things!

(this is how I justify it- reuse is better than recycling!)

 

As to balancing weights, exact is best.  BMW has limits (I forget what they are- 5 grams?) and they're

pretty close to 0, but the closer to zero difference you get, the less vibration and internal

strain on the engine.  YOU get to figure out when it's good enough!

Practically speaking, I found that I could get it very close pretty quickly, (like, to a gram)

and then moved on.  It's the setup and cleaning that takes time, the actual balancing,

once you get the hang of it, goes pretty quickly. And you get better with practice.

 

Happy grinding,

t

 

[2002Scoob]

15 minutes ago, TobyB said:

You have to use that clutch- otherwise, you'll have a half- used clutch kicking around,

and one shouldn't discard useful things!

(this is how I justify it- reuse is better than recycling!)

 

As to balancing weights, exact is best.  BMW has limits (I forget what they are- 5 grams?) and they're

pretty close to 0, but the closer to zero difference you get, the less vibration and internal

strain on the engine.  YOU get to figure out when it's good enough!

Practically speaking, I found that I could get it very close pretty quickly, (like, to a gram)

and then moved on.  It's the setup and cleaning that takes time, the actual balancing,

once you get the hang of it, goes pretty quickly. And you get better with practice.

 

Happy grinding,

t

 

 

Thanks Toby! Look for a post regarding weights and such later tonight. 

 

Maybe have some suggestions waiting on safest locations to focus weight-relief in reply? That will be my followup question for sure.

 

The rods I feel will be pretty easy to match by focusing on the flashing from the forging process, and I gotta finish de-rusting all them as well. The pistons, I could use some experience-based guidance for sure. 

[2002Scoob]

Follow-up....

 

The water-jackets are one area of the motor I'm a bit baffled as how to get rust-free. (the other is the oil passage dropping down from the head into the block) 

 

I ordered a few liters of this gunk off Amazon and will be giving it a try.

http://www.evapo-rust.com/

 

What I'm thinking is to hot-glue some scrap alloy plate to the openings and make the water-jacket of the block water-tight, and fill up the block and let soak over-night. I'm hoping 2 liters is enough...

 

Depending on how that goes I might also soak the main bearing caps and some rods again to further reduce any surface rust that might be on them. 

 

[Son of Marty]

For the oil passages get a brush set using very hot water and dish soap brush out every one you"
ll be surprised how much gunk will come out of a hot tanked engine

[Dudeland]

Can you bring it to someone to hot tank?  You have to put a price on your time. 

 

M

[2002Scoob]

Mehhh. my time is free. 

 

Also, from my understanding hot-tanking doesn't remove rust, just dirt, oil, and grime, and Rust is my biggest challenge on this motor. 

 

I'm optimistic about the Evaporust stuff... My expansive 3 videos I watched on Youtube support my decision,  well see how it goes. 

['76mintgrün'02]

I'll bet you can seal off the block using tape, instead of hot glue.

 

As Toby mentioned, electrolysis is a cool way to remove rust.  Not from the passages in the block, but from the connecting rods... and stuff.

 

There are a lot of how to videos online, but you basically just dissolve washing soda (or baking soda) in water and dangle the parts in it, connected to the negative charge, with another piece of iron (sacrificial) in the bucket, connected to positive.  It is so easy that it is really fun.  The rust literally washes off, after not much time at all in the bucket.  It will be electro-molecularly clean!

Tom

 

[xr4tic]

Is rust in the coolant passages really a concern?  How bad is it?

[jimk]

Visible caked rust in the internal areas should be wire brushed to avoid it from coming loose at a later date.  Surface rust is of no concern.  Outside caked rust is up to the owner to make it "look nice" or not.

Clean the two oil galleys (one vertical and one horizontal drillings) with 30cal bore brush and finish swab with an oiled bore patch.  Then clean the small oil leads to the main bearings and finally air blow the main horizontal galley for anything that may have been pushed from the main bearing galleys back into the horizontal main galley.

Stuffing stuff into the galleys to plug or the use of tape is not a good deal because of the potential to leave some and have a ruined day later on.

Going out of your way to make it look nice sometimes is not the best way to go.  And no paint in the insides, it comes loose later.

Edited August 8, 2017 by jimk

[2002Scoob]

All great suggestions. I do want to remove as much rust from the water jacket, it's pretty gnarly in there and want to make sure not only that the new water pump doesn't get roached by large flakes of rust coming off, but also keep temps down.

I have no plans to soak anything but the jacket, all oil passages will be dealt with as Jim recommends. I've spent some time cleaning them up as is, but they'll be double and triple cleaned after paint, and before assembly. (And of course no paint on the insides! )

Just got done rust removing the tail end of the block... how bout some gnarly before and after shots?




Sent from my iPhone using Tapatalk

[2002Scoob]

Now... on to the big question of the night.... I've sidelined the balancing efforts in favor of of pulling my original crank shaft. To take a look see. All bearings look surprising great, and the journals too...

Is there any sound reason why I shouldn't just re-use the one from my original block???

Left is the original, the right is the donor.

Should there be any reason to suspect a major difference in dimensions?

And did BMW make any efforts from the factory to balance the crank/flywheel assemblies? Which might be an argument to keep them together?

Here's my thinking why-

The crankshaft from the donor motor has some issues. Mainly-

1. The input shaft bearing is rusted into the tail, and pretty badly. Without buying a special puller that I'll likely break I'm afraid it's going to be allot of work to get out.
-
The one in the original is clean and still in great shape.

2. The locating dowel for the flywheel is almost rusted away.... I had thought to remove it and machine a replacement, but also allot of work.
-
The original is pristine

3. There's some minor pitting in the journals that's fine, but one moderate gouge that I need to sand and polish down, and the bearings that were removed have some suspicious galling....
-
The original? Looks decent. Both journals and bearings are in nice shape comparatively.




What's yall's thoughts??

I have a new set of main bearings and the machinist feels the rod bearings are good enough.


Sent from my iPhone using Tapatalk

[PaulTWinterton]

IMHO, if the machinist says it's within spec and they can polish to satisfaction, you are in good shape.

 

The dowel I believe can be removed and a new one put it.  No biggy.

The rear hub may have a groove where the rear seal has been rubbing.  If polishing won't remove it, make sure to use a shim so the new rear seal does not run in the same groove.  Check the front hub for the same issue.

 

I think the machinist could remove the transmission input shaft bearing without too much problem.  I did mine under the car using a drift, hammer, and 6 slices of bread.  Yes I said bread, stuffed into the hole behind the bearing and compressed with the drift until the bearing popped out.   Some PB Blaster the night before helped, I think.  Watch some Youtube videos on the subject of "removing pilot bearing" etc.

 

Unless some the experts here have better opinions, I'd use the original crank and rods.  I presume you are using new pistons.  If rod bearing are not too expensive for you, I'd get new ones also.