Re: 1976 BMW 530i "Eleanor" rebuild project
Posted: Sat Feb 01, 2020 7:59 pm
Moving onto measuring gudgeon pins.
I moved to a more thorough blueprinting spec sheet to capture various measurements.
I also took the opportunity to remove the old piston rings from each piston. There are three rings in total per piston.
One of the rings broke when I removed it. I didn't use any tools to remove the rings, only my hands. While these rings are strong, they are VERY brittle!
A close examination of the oil scraper ring shows the importance of regular oil changes. Because this engine has only seen conventional oil thus far, the scraper rings have sludge build up inside them. This is a sign of irregular oil changes.
I moved back to measuring the Gudgeon pins. Here, I'm measuring the diameter.
And the length. Each pin was within spec.
I also measured each piston per recommended measure points. Each piston measured out within spec as well, surprisingly.
It's also important not to forget the Gudgeon pin bushing. This bushing is press-fitted into the upper connecting rod and provides a wear surface for the Gudgeon pin to roll on.
I don't know of any other effective means of removing these bushings, so I rely on a small metal saw to remove them.
It is VERY important to stop frequently and ensure that the conrod itself isn't being cut into. Here, the bushing is almost cut entirely.
And success! the bushing is free from the conrod.
Next, because it was a nice day, I took advantage and wheeled the block outside for degreasing and pressure washing.
Because the block is over 200k miles, I also decided to remove the freeze plugs. To remove, simply take a chisel or other flat object that can withstand a 5 lbs hammer, and hammer the side of the plug until it gives way. I noticed with this block that the plugs did not swivel inside their holes, instead, the entire plug pushed in, requiring me to fish each plug out with channel locks. In order to remove, I had to tap the channel lock handle downwards to provide the force needed to deform the plug enough to be removed. The top of the channel lock against the engine block served as a fulcrum point.
And just like that, the plug is removed.
And I thought the coolant passages looked TOO clean...here, I uncover evidence of serious buildup.
And, just like the plug, buildup can be observed on the coolant passage walls by each cylinder. I made sure to focus some of my pressure washing directly inside these channels.
I found it simpler and less time-consuming to just knock each plug inwards at once, and then use the channel locks to remove them.
Here's a closer look at the scale buildup on one of the plugs.
Once again, the pressure washer is employed.
And the block is now pressure washed. I did soak it in Zep degreaser but forgot to take a pic.
Of course, the problem of exposing any sort of untreated steel to water is flash rust. Not a problem though, as the next step is to electrolytically remove all rust from this block.
Regardless though, the block IS cleaner, despite the inability of the pressure washer to completely remove the smeg.
There is more smeg on this side...that's some caked on dirt!
Now, the part the block has been waiting for! I have a container large enough to hold the block, six 2' steel rods, and some washing soda.
**CAUTION** (if you choose to replicate this) Be sure to NOT, I repeat, NOT use STAINLESS steel for cathode rods! Using stainless steel with this process will produce hexavalent chromium - a DEADLY toxin. Remember the movie "Erin Brockovich"? The chemical that was poisoning her clients was hexavalent chromium!!
Again, NO STAINLESS STEEL!!!!
Also, make sure to use WASHING soda, not BAKING soda. The washing soda is important, as it serves as an electrolyte for the current to better pass through the water.
As I was going to place the block level down into the container, I wanted to use the oil pan bolts to ensure the block stands off the bottom a little bit. Here I'm leveling out each bolt to ensure each one is equally supporting the block.
The block is now off the stand, ready for its rust removal bath!
Filling up the container. Note that the cloudy water is merely the washing soda mixed up in solution.
I chose to use a head bolt to serve as the anode connector.
Here, I've placed the cathodes at strategic points in the container.
Electrolytic rust removal requires that the cathode and anode be within direct "sight" of each other. If either is blocked, or otherwise out of "viewing" angle, then the rust removal cannot occur. That's why I have six cathode rods in total; So each can "view" all sides of the block at once, ensuring a thorough rust removal process occurs.
Here, I've used 12 AWG wire to connect the six cathode rods together as one. Note that I bridged the two middle rods, this is to ensure a somewhat equal voltage flow occurs within the circuit.
The block itself is NEGATIVE. The steel rods are POSITIVE. Reverse these polarities and rust removal will not occur.
Just a couple minutes in, I saw the first significant bubbling occur. The grease is being pushed away by the hydrogen and oxygen gas that's forming. This is also confirmation that the washing soda is sufficiently ratio'd as the electrolyte.
More to come.
Mike
I moved to a more thorough blueprinting spec sheet to capture various measurements.
I also took the opportunity to remove the old piston rings from each piston. There are three rings in total per piston.
One of the rings broke when I removed it. I didn't use any tools to remove the rings, only my hands. While these rings are strong, they are VERY brittle!
A close examination of the oil scraper ring shows the importance of regular oil changes. Because this engine has only seen conventional oil thus far, the scraper rings have sludge build up inside them. This is a sign of irregular oil changes.
I moved back to measuring the Gudgeon pins. Here, I'm measuring the diameter.
And the length. Each pin was within spec.
I also measured each piston per recommended measure points. Each piston measured out within spec as well, surprisingly.
It's also important not to forget the Gudgeon pin bushing. This bushing is press-fitted into the upper connecting rod and provides a wear surface for the Gudgeon pin to roll on.
I don't know of any other effective means of removing these bushings, so I rely on a small metal saw to remove them.
It is VERY important to stop frequently and ensure that the conrod itself isn't being cut into. Here, the bushing is almost cut entirely.
And success! the bushing is free from the conrod.
Next, because it was a nice day, I took advantage and wheeled the block outside for degreasing and pressure washing.
Because the block is over 200k miles, I also decided to remove the freeze plugs. To remove, simply take a chisel or other flat object that can withstand a 5 lbs hammer, and hammer the side of the plug until it gives way. I noticed with this block that the plugs did not swivel inside their holes, instead, the entire plug pushed in, requiring me to fish each plug out with channel locks. In order to remove, I had to tap the channel lock handle downwards to provide the force needed to deform the plug enough to be removed. The top of the channel lock against the engine block served as a fulcrum point.
And just like that, the plug is removed.
And I thought the coolant passages looked TOO clean...here, I uncover evidence of serious buildup.
And, just like the plug, buildup can be observed on the coolant passage walls by each cylinder. I made sure to focus some of my pressure washing directly inside these channels.
I found it simpler and less time-consuming to just knock each plug inwards at once, and then use the channel locks to remove them.
Here's a closer look at the scale buildup on one of the plugs.
Once again, the pressure washer is employed.
And the block is now pressure washed. I did soak it in Zep degreaser but forgot to take a pic.
Of course, the problem of exposing any sort of untreated steel to water is flash rust. Not a problem though, as the next step is to electrolytically remove all rust from this block.
Regardless though, the block IS cleaner, despite the inability of the pressure washer to completely remove the smeg.
There is more smeg on this side...that's some caked on dirt!
Now, the part the block has been waiting for! I have a container large enough to hold the block, six 2' steel rods, and some washing soda.
**CAUTION** (if you choose to replicate this) Be sure to NOT, I repeat, NOT use STAINLESS steel for cathode rods! Using stainless steel with this process will produce hexavalent chromium - a DEADLY toxin. Remember the movie "Erin Brockovich"? The chemical that was poisoning her clients was hexavalent chromium!!
Again, NO STAINLESS STEEL!!!!
Also, make sure to use WASHING soda, not BAKING soda. The washing soda is important, as it serves as an electrolyte for the current to better pass through the water.
As I was going to place the block level down into the container, I wanted to use the oil pan bolts to ensure the block stands off the bottom a little bit. Here I'm leveling out each bolt to ensure each one is equally supporting the block.
The block is now off the stand, ready for its rust removal bath!
Filling up the container. Note that the cloudy water is merely the washing soda mixed up in solution.
I chose to use a head bolt to serve as the anode connector.
Here, I've placed the cathodes at strategic points in the container.
Electrolytic rust removal requires that the cathode and anode be within direct "sight" of each other. If either is blocked, or otherwise out of "viewing" angle, then the rust removal cannot occur. That's why I have six cathode rods in total; So each can "view" all sides of the block at once, ensuring a thorough rust removal process occurs.
Here, I've used 12 AWG wire to connect the six cathode rods together as one. Note that I bridged the two middle rods, this is to ensure a somewhat equal voltage flow occurs within the circuit.
The block itself is NEGATIVE. The steel rods are POSITIVE. Reverse these polarities and rust removal will not occur.
Just a couple minutes in, I saw the first significant bubbling occur. The grease is being pushed away by the hydrogen and oxygen gas that's forming. This is also confirmation that the washing soda is sufficiently ratio'd as the electrolyte.
More to come.
Mike