M70 Rebuild Thread.

[dragon850]

For us looking to do something like this for our hybrids rebuild, what does something like this cost? Ball park is fine.

The labor for the head rebuild was very reasonable $800. I was quoted as high as $1900.
Found a shop in town that did an amazing job as you can see!

[TedBobo]

The labor for the head rebuild was very reasonable $800. I was quoted as high as $1900.
Found a shop in town that did an amazing job as you can see!

That's very reasonable!

[dragon850]

Put the engine on the lift to replace the seals at the back of the engine before putting it back on the stand and proceeding with the rebuild.


ForumRunner_20151004_193813.png

The upper coolant cover was not easy, bolts were very corroded even after using penetrating fluid. I worked them back and fourth slowly, but still couple had buggered up threads. I rechased the threads in the block, went to lowes and purchased new m6 bolts.
Torqued them down to 10nm each.
Used renzosil on the new gasket, just to make sure because the old gasket was super hard to remove even after ultrasonic cleaning.


ForumRunner_20151004_194445.png

Replaced rear crankshaft seal, pushed it out using a metal plate. Re installed using rubber mallet and gental tapping. Used renzosil on everything.
Aluminum after ultrasonic cleaning..


ForumRunner_20151004_194718.png

[thelongeride]

Looks good. Do you know how much was machined from the head? I may go with a shop machining and cleaning the head and do the rest myself, since I am looking to get experience.

[dragon850]

Looks good. Do you know how much was machined from the head? I may go with a shop machining and cleaning the head and do the rest myself, since I am looking to get experience.

Not sure on the specifics on how much was taken off but it was bare minimum because the heads were not warped. I HIGHLY recommend having an experienced shop do the valve guides, they cannot be hammered out and special puller and press needs to be employed.

[dragon850]

Did a little work on the block today.
So originally I used Roloc disc to prep the block, like this:


ForumRunner_20151007_202340.png

But when I started to use it I noticed I am creating some fine swirls in the surface:


ForumRunner_20151007_202452.png

I stopped and did more reaserch, turns out many experienced machiene shops use block sanding instead. The application is much more even and surface comes out smoother. Here is the pic where I did some block sanding with 600 grit sand paper. What do you guys think about this method? The surface did look smoother than with the previous method.


ForumRunner_20151007_202903.png


ForumRunner_20151007_202934.png

Now about carbon removal, after doing some research ended up trying gasket remover, like this:


ForumRunner_20151007_203133.png

It worked like magic, spray on, wait 35min. This stuff literally melts carbon, worked it a bit with a tooth brush to get the stubborn spots out:


ForumRunner_20151007_203326.png

Finally followed up with simple green and the result! :


ForumRunner_20151007_203432.png

Last thing, I noticed my upper large oil pan is missing some chunks of aluminum on both sides, looks like someone cut them out. Can someone tell me if there were bolt threads in those two places? Basically trying to figure out if I nees new pan or if I can Re use this.


ForumRunner_20151007_203715.png

[cartoonz]

At this point Ed, you're nuts if you don't pop the rod caps off and take out those pistons. You didn't even have rags stuffed in the holes when you went to town on the decks, there's no way you didn't get aluminum filings in the cylinders. Plus, cleaning the ring lands is a good idea anyway - just don't break a ring!
Take your chances if you want, but if it were me... I'd only want to do this job once.

[dragon850]

At this point Ed, you're nuts if you don't pop the rod caps off and take out those pistons. You didn't even have rags stuffed in the holes when you went to town on the decks, there's no way you didn't get aluminum filings in the cylinders. Plus, cleaning the ring lands is a good idea anyway - just don't break a ring!
Take your chances if you want, but if it were me... I'd only want to do this job once.

I did stuff the rags down the Cylinders while block sanding, but you are right regarding the pistons. Now can the piston cap bolts be re used? What are the torque spec on them?

[thelongeride]

Did a little work on the block today.
So originally I used Roloc disc to prep the block, like this:


ForumRunner_20151007_202340.png

But when I started to use it I noticed I am creating some fine swirls in the surface:


ForumRunner_20151007_202452.png

I stopped and did more reaserch, turns out many experienced machiene shops use block sanding instead. The application is much more even and surface comes out smoother. Here is the pic where I did some block sanding with 600 grit sand paper. What do you guys think about this method? The surface did look smoother than with the previous method.


ForumRunner_20151007_202903.png


ForumRunner_20151007_202934.png

Now about carbon removal, after doing some research ended up trying gasket remover, like this:


ForumRunner_20151007_203133.png

It worked like magic, spray on, wait 35min. This stuff literally melts carbon, worked it a bit with a tooth brush to get the stubborn spots out:


ForumRunner_20151007_203326.png

Finally followed up with simple green and the result! :


ForumRunner_20151007_203432.png

Last thing, I noticed my upper large oil pan is missing some chunks of aluminum on both sides, looks like someone cut them out. Can someone tell me if there were bolt threads in those two places? Basically trying to figure out if I nees new pan or if I can Re use this.


ForumRunner_20151007_203715.png

The holes in the upper oil pan may be similar to what I cut in mine. They were cut to reach two of the oil pan bolts. Not required if the transmission is off. You should be ok if the pan is not warped or otherwise damaged. The holes have been documented in oil pan gasket change thread.

[dragon850]

Thank you, that make sense. I do see the upper oil pan gasket has been changed at one point by the reddish sealant used there. I will re use the pan.
Now...where was I, back to the garage to pull the pistons.

- - - Updated - - -

OK, so what is the torque value for these piston cap bolts and can they be reused?
Will I need a ring compressor to fit the pistons back into the bores after cleaning?

[dragon850]

Well, that's something you don't see every day.


ForumRunner_20151008_142552.png


ForumRunner_20151008_142609.png

I am glad I went ahead and removed the pistons, quite a bit of carbon in between the rings:


ForumRunner_20151008_142752.png

But also wear on the rod bearings:


ForumRunner_20151008_143007.png



ForumRunner_20151008_143022.png

[dragon850]

I will need a new set of rod bearings.

[dragon850]

So I cleaned the bores and was examining them. 2 Cylinders have visible vertical scratches, however when felt with a bare hand or a fingernail it feels very smooth and does not catch... Is this acceptable?


ForumRunner_20151008_145222.png



ForumRunner_20151008_145232.png

Rest of the bores look like this:


ForumRunner_20151008_145313.png

[dragon850]

Let's clean some pistons!


ForumRunner_20151008_150146.png

[bmw528e11]

Is that your engine after SC abusement?? What kind of oil did you used?

[dragon850]

Is that your engine after SC abasement?? What kind of oil did you used?

No, this is a donor engine that I got for $300. Unknown milage, very minimal crude build up in the engine, so good oil was used.

[dragon850]

Block sanding is going pretty well with 600 grit. Hope this block is ok, what so you guys think about those bore scratches, they are undetectable on touch.

ForumRunner_20151008_161524.png

[Mikekugel]

According to the BMW Torque manual, you replace the connecting rod bolts.

- - - Updated - - -

According to the BMW Torque manual, you replace the connecting rod bolts.
https://www.penskeparts.com/Diagrams...5&rnd=03192010

[dragon850]

OK, I will add them to my ever increasing list of parts.
What do I have to torque them to??

According to the BMW Torque manual, you replace the connecting rod bolts.

- - - Updated - - -

According to the BMW Torque manual, you replace the connecting rod bolts.
https://www.penskeparts.com/Diagrams...5&rnd=03192010

[sleepy81]

By the look of that blow by on the pistons you may need new rings. Check acceptable factory ring end gap. If new rings you should probably get a light hone which will give a better idea of scratch depth. Give this job to a specialist familiar with Nikasil but I defer to other members who have had experience here.

[cartoonz]

By the look of that blow by on the pistons you may need new rings. Check acceptable factory ring end gap....

That much is true

...If new rings you should probably get a light hone which will give a better idea of scratch depth. Give this job to a specialist familiar with Nikasil but I defer to other members who have had experience here.

That part is suicide.
First off, these blocks are Alusil, not Nikasil.
Run a hone down that hole? > Throw the block away.

[Mikekugel]

Ed, Here is the BMW Torque manual http://tedserbinski.com/files/bmw_torq.pdf Looks like Rod cap bolts need to be oiled, (30 weight I imagine), then initial torque is 5NM then final torque is 20NM but you ought to use a Torque angle gauge such as the OTC 4554 to confirm the Torque angle of 70 degrees. Torque angle is a bit more accurate than just a torque wrench. Use it on the head bolts as well. I agree on the rings being replaced especially with a Boosted engine! Look into gapless type rings. Now is not the time to be in a hurry to get the thing put together. Don't even think about honing an alusil cylinder block. If you cannot feel anything from the scoring, it probably won't be a problem.

[garylafortuna]

What is the story on honing the alusil cylinder block? Is alusil a process whereby the surface of the cylinder is hardened or coated, and could be destroyed by honing? And is there not a process available to re-coat the surface?

[Mikekugel]

Here is a bit about Alusil and honing, which can be done, as can sleeving, but I'm betting not many places are capable of doing it well. http://www.sunnen.com/NewsDetails.aspx?NewsID=11

[dragon850]

Ed, Here is the BMW Torque manual http://tedserbinski.com/files/bmw_torq.pdf Looks like Rod cap bolts need to be oiled, (30 weight I imagine), then initial torque is 5NM then final torque is 20NM but you ought to use a Torque angle gauge such as the OTC 4554 to confirm the Torque angle of 70 degrees. Torque angle is a bit more accurate than just a torque wrench. Use it on the head bolts as well. I agree on the rings being replaced especially with a Boosted engine! Look into gapless type rings. Now is not the time to be in a hurry to get the thing put together. Don't even think about honing an alusil cylinder block. If you cannot feel anything from the scoring, it probably won't be a problem.

Thanks for the info, will be ordering new rod bearings and bolts. Still contemplating if I should change the rings or not, I have some experienced people telling me I do not need to do this.. However other experienced people are telling me its a good idea... I guess Goateze is the preferred ring manufacturer, more reasonably priced then bmw...
This is how the pistons are coming out so far:


ForumRunner_20151009_170047.png