Rebuilding my -96

[buildit]

I really enjoy reading build threads and this is my first e31 project.

A year ago I bought a -96 cosmoschwarz 850 with 220 000 km. It had four different makes of tires, a completely botched exhaust, a bad rattle from the driveshaft, mice had been living under the engine cover and it had problems with engine cooling. All the electronics work though

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[buildit]

During the past months I've slowly been labeling cables and connectors, taken the drivetrain out and disassembled the engine down to the bare block.

Found a few bolts rattling around the oil pan. The oil pump was only held on by one bolt and one of the crankshaft bolts had snapped.
Not sure how the engine survived without any damage.

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[henryc]

Yikes--- Those loose bolts are scary! Looks like you have something to keep you busy during the winter months- perhaps you will be able to take a mid-winter holiday to a warm, sunny climate to relax and recharge. Looking forward to the E31 updates!
What part of Sweden are you located? I use to work for Volvo Penta of the Americas and frequently visited Goteborg for purchasing and engineering meetings- really enjoyed my time there. (Both in the winter and summer months!).
/Henry

[rockytt]

Yikes is right!
Glad this one has found the right home and will be on her feet again

[buildit]

What part of Sweden are you located?

I'm in Malmo in the south. Looking forward to winter. I'll just close the workshop doors and it can winter as much as it likes outside

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[buildit]

Been cleaning up all the pistons and crankshaft mounts. Soda blasting and then cleaned up in the ultrasonic cleaner.
Now neatly packaged and waiting to be mounted.

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[dragon850]

Bad idea blasting the pistons. It looks like the iron coating has been taken off.
Alusil block pistons are specially treated with a thin coat of iron to be able to run in the bare bores.
If you wanted to clean them, ultrasonic cleaning is the only way to go.
You might need to look for new ones. Sorry.

[buildit]

Bad idea blasting the pistons. It looks like the iron coating has been taken off.
Alusil block pistons are specially treated with a thin coat of iron to be able to run in the bare bores.
If you wanted to clean them, ultrasonic cleaning is the only way to go.
You might need to look for new ones. Sorry.

I'm not sure if soda would be able to strip the film, it's very weak and I used extremely low pressure.

The pictures might be a bit misleading because I can still see a thin film coating but now I'm looking for pictures of new pistons to compare with. You wouldn't happen to have a picture of one?

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[dragon850]

I'm not sure if soda would be able to strip the film, it's very weak and I used extremely low pressure.

The pictures might be a bit misleading because I can still see a thin film coating but now I'm looking for pictures of new pistons to compare with. You wouldn't happen to have a picture of one?

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Well the iron coating is very thin, comes off with a light scratch. I use toothbrush to clean them and ultrasonic bath.
I have seen a new piston and it looks darker in color.

[dragon850]

Well the iron coating is very thin, comes off with a light scratch. I use toothbrush to clean them and ultrasonic bath.
I have seen a new piston and it looks darker in color.

Not saying this is 100% dead pistons but at this point hard to tell.

[cartoonz]

next thing we'll see is that he "honed the cylinders"....
Sorry, those pistons are junk now.

[TedBobo]

Sorry, those pistons are junk now.

So, how costly is a new set?

[cartoonz]

So, how costly is a new set?

one bank is NLA...
I'd want to see better pictures of the "cleaned" pistons to be sure. If that coating IS gone, they are toast... but it may be tougher than low pressure soda.. we shall have to see.

@buildit - DO NOT "hone" your cylinders... do nothing to them. maybe give them a nice acetone wash, but that's it... and be sure to re-use the original rings, clocked to the original positions... you did keep track of all that, right?

[buildit]

next thing we'll see is that he "honed the cylinders"....
Sorry, those pistons are junk now.

Not to worry, I only made one potentially huge mistake

Took the pistons to a specialist today and the coating on all of them is good. Big relief.

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[buildit]

Tearing down the engine revealed another few interesting bits.

The air hose for emissions control https://www.realoem.com/bmw/enUS/sho...94#11721704306 had been wrapped in electrical tape and someone had tried to to create an internal support out of plastic tube that had collapsed under the heat. Completely blocked the hose of course.

The knock sensors weren't feeling that well.

One of the coolant hoses on the back was completely worn away and had a big hole in it. Most likely the cause of the issues with cooling

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[buildit]

Rebuilt the starter motor. Stripped, blasted, repainted, new outer gear with rubber dampers and all nuts and bolts plated.
The last picture shows the power cable coming out the wrong side but that's fixed.



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[Fatandre]

That thread is fun to watch. Keep it going

[TedBobo]

That thread is fun to watch. Keep it going

Ditto!

[buildit]

Watching paint dry so I cleaned up various bits and pieces.

Engine support brackets (the rubber mounts were split in half!), coolant pipes, covers on the back of headers and engine...

The bolts for the subframe are going in the bin



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[72tpik5]

Nice work indeed. This is an inspiring thread.

[buildit]

The oil in the oil filter canister was unbelievably disgusting. The supporting dome is missing and the top has a few broken tabs so those will be replaced.

The transmission cooler looked a bit crusty but I was able to straighten out all the fins and even refit the original stickers




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[Fatandre]

wow
amazing progress!!!

[buildit]

Waiting for parts (most frustrating thing in the universe) so I started cleaning again.

Upper part of the oil pan has had a tough life. Rock hard dirt and oil. Took me two days to clean!

Done one intake manifold. Under the awful paint job and the detritus left behind by mice it is in really nice shape



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[TedBobo]

Nice!

[buildit]

Got parts for the alternator today. New bearings, slip ring and regulator. Not entirely happy with how the black plating on the pulley turned out so I'll have to redo that.

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