resurfacing block screwup

[bimmer7410]

Greetings
SO i am currently halfway through my first amateur engine rebuild. Its a BMW v8 purchased used (n62b44).

I got the heads cleaned and checked so all is good there.

Its the block part where I might have screwed things up.

First off, I used roloc discs to remove the gasket material that I could not remove with the plastic scraper. The roloc discs left some light abrasive marks, so then I used a sandpaper block and sanded across the deck. A two for one whammy.

I've read that folks have used roloc and sandpaper with success, and I have also read that others have heard horror stories. I am trying to see what my next steps might be, as I cannot take the engine to be decked by a pro (way over budget already!)

I also need to make sure I have cleaned all the grit out of the oil passages (had them blocked off) and cylinders (did not have them blocked off). The plan was to apply some solvent to the cylinders and vacuum them out.

I know ive screwed up, but I am hoping I can recover this.

These are pics BEFORE I sanded. After the sanding, its quite smooth (but now i have sand crystals to clean out...)

Ntvb6Cfl.jpg

RMNvze5l.jpg

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Thanks in advance

[Breeze1]

If you can't take it to a pro I guess your best bet is to clean things up, put them back together and give it a try. You might need to check tolerances accross the block and correct anything not compliant, but I'll let a pro advise on that. If you had blocked off the oil passages I don't see why they'd be cause for worry. About the cylinders, personally I wouldn't apply any solvant and wouldn't vacuum them out, but rather blow off all the grit with a powerful air compressor, as it seems to be more efficient, then apply a microfiber to remove any left-overs.

[bimmer7410]

If you can't take it to a pro I guess your best bet is to clean things up, put them back together and give it a try. You might need to check tolerances accross the block and correct anything not compliant, but I'll let a pro advise on that. If you had blocked off the oil passages I don't see why they'd be cause for worry. About the cylinders, personally I wouldn't apply any solvant and wouldn't vacuum them out, but rather blow off all the grit with a powerful air compressor, as it seems to be more efficient, then apply a microfiber to remove any left-overs.

Thanks for the reply.
Yeah, I bought a straightedge and feeler gauge to be delivered tomorrow to check out the straightness.
I dont have an air compressor, might look into borrowing one. Yesterday I started the process with compressed air.


Ive gathered quite the set of tools through this project..nice

[jclausen]

I've had a tech use a sharpening stone

[bimmer7410]

I've had a tech use a sharpening stone

Interesting, hadnt heard this one. Makes sense as a sharpening stone is similar to higher grit sandpaper. The form factor is good too as its a large block.
Gonna look into that..

[bimmer7410]

Took some measurements
Seems the inner cylinder walls have too much material missing from them. I am able to fit the .05mm feeler gauge in between on both block surfaces vertically.
I read that the limit going across the engine longitudinally is 0.10 mm, and transversal is .05mm. The transversal test fails in the middle cylinder wall areas

Sharpening block gets here today.

My next question is, how likely is the difference of .06-7mm to cause a HG failure?

[ross1]

I've had a tech use a sharpening stone

If you have a NEW stone it is at least pretty flat. I've used this method on Subarus with success but that deck is considerably smaller.
I see you've ordered a straight edge so go around and carefully check. Unless you really wailed on the Roloc discs and put a divot in it you are probably fine.
Do I need to mention that you should use the best gasket you can buy, be sure all the bolt holes are pristine clean and dry and follow the torque procedure correctly.
The gasket is there to forgive imperfections and allow some movement.

[bimmer7410]

If you have a NEW stone it is at least pretty flat. I've used this method on Subarus with success but that deck is considerably smaller.
I see you've ordered a straight edge so go around and carefully check. Unless you really wailed on the Roloc discs and put a divot in it you are probably fine.
Do I need to mention that you should use the best gasket you can buy, be sure all the bolt holes are pristine clean and dry and follow the torque procedure correctly.
The gasket is there to forgive imperfections and allow some movement.

One can only hope at this point. Deck was cleaned, measured and appeared to be pretty much in spec. Heads are now on and tightened according to the TIS instructions (30nm,90 degrees, another 90 degrees)
I'll report back with results for completion sake

[bimmer7410]

Got the motor started. Havent done any compression tests yet, too nervous that I'll get a bad reading and have to tear the whole darn thing down again

[White94RX]

Well how does it run? If you don't have any issues, then don't worry about it!

[GrantLeben24]

im speaking from the position of a machinist who has resurfaced a few blocks in my day, the best advice i can give you is go get some machinist stones (norton makes a pretty good one, its a 4 inch round stone with different grits on each side) and stone down each side, dont use degreasers or carb/brake cleaners on the stone, use oil with it, and spend about 10 minutes on each bank using circular motions. you should be able to see the high spots and low spots contrast when you wipe it down (and wipe it down often).

[bimmer7410]

Got the motor started. Havent done any compression tests yet, too nervous that I'll get a bad reading and have to tear the whole darn thing down again

Runs decent so far. Idle isnt perfect yet as im chasing the reason for a camshaft code that wont go away despite the sensor and harness testing good..

im speaking from the position of a machinist who has resurfaced a few blocks in my day, the best advice i can give you is go get some machinist stones (norton makes a pretty good one, its a 4 inch round stone with different grits on each side) and stone down each side, dont use degreasers or carb/brake cleaners on the stone, use oil with it, and spend about 10 minutes on each bank using circular motions. you should be able to see the high spots and low spots contrast when you wipe it down (and wipe it down often).

I'll definitely keep this in mind for the next time I do this

[White94RX]

Camshaft code? Rough idle? Sounds like timing.....

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[bimmer7410]

Camshaft code? Rough idle? Sounds like timing.....

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I cant agree.
There are specific codes for offset timing. The camshaft sensor code present refers to the absence of data IMO. This is signified by the lack of a reading while the engine is running
The engine doesnt run rough, but the idle can be irregular. See my thread here for the live data symptoms https://www.bimmerforums.com/forum/s...5#post30317525

[White94RX]

So why is there an absence of data

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[bimmer7410]

Question of the month at the moment!
If you see my video, all the sensors provide updates but that one. Checked harness, voltage, and it checks out.
At this point I'm researching for the next troubleshooting step.
Timing would set a code and the engine would likely run pretty rough, I'd assume. Besides, I triple checked the timing before I put it back together

[bimmer7410]

So, an update to the thread title: project is a failure.
I got the motor running a few months ago and have been working on various items slowly since.
Today I noticed a persistent white smoke coming from the tailpipe. I let it idle for about 20 mins just to be sure.

Super freaking disappointing, that's for sure. Not even sure where or when to go from here.

Kinda hard not to break the sites cursing rule right now.

[ross1]

Maybe coolant. Does it smell like coolant?
Keep in mind that these exhaust systems can harbor a huge amount of moisture, in a humid climate(Houston?)you might need to make a highway run to burn it all off. If the reason for your overhaul was a head gasket issue there is likely residual coolant in the exhaust so same scenario to burn it off, cross your fingers for the cats.
I wouldn't call it a failure yet and, even though I haven't seen it, the block deck doesn't concern me too much.
Run it a while and see what happens, worst case is what you've already assumed.

[bimmer7410]

Maybe coolant. Does it smell like coolant?
Keep in mind that these exhaust systems can harbor a huge amount of moisture, in a humid climate(Houston?)you might need to make a highway run to burn it all off. If the reason for your overhaul was a head gasket issue there is likely residual coolant in the exhaust so same scenario to burn it off, cross your fingers for the cats.
I wouldn't call it a failure yet and, even though I haven't seen it, the block deck doesn't concern me too much.
Run it a while and see what happens, worst case is what you've already assumed.

Houston is correct
The rebuild was due to purchasing an engine with an unknown history
Doesnt smell like coolant as I am running water in the system during this preliminary phase where I iron out the kinks and prepare it be a daily driver.
The plan was to flush the water and oil after about 20 miles of driving.

I havent really pushed it yet. I'll do so once I finish with the front end

Im thinking, if I do continue to get water vapor, I will first try to tighten the headbolts a few more degrees, and if that doesnt work I'll purchase new HGs and try the copper spray.

[Critter7r]

If all you have is some "white smoke" from the exhaust, then depending on how bad it is and whether it's actually smoke or condensation, I'm not sure I'd sweat it.

[bimmer7410]

If all you have is some "white smoke" from the exhaust, then depending on how bad it is and whether it's actually smoke or condensation, I'm not sure I'd sweat it.

After the initial disappointment, that’s what I’m going to do for now.
It’s definitely condensation

[White94RX]

I will first try to tighten the headbolts a few more degrees, and if that doesnt work I'll purchase new HGs and try the copper spray.

If you torqued them properly the first time around, I would highly advise against that. The last thing you want to do is break one, or tighten it to the point where it loses its clamping force. When you torqued them the first time, did you follow the correct sequence? And did you do bolts the bolts, and then check them a second and third time before moving on to the next torque setting? As the gasket compresses, you'll need to go through them more than once on the first setting to make sure the gasket is compressed all the way.

[Critter7r]

After the initial disappointment, that’s what I’m going to do for now.
It’s definitely condensation

Then you've nothing to worry about.

And +1 on not torquing the head bolts down any more. If they were done properly at reassembly, tightening them further will only cause problems.

[bimmer7410]

If you torqued them properly the first time around, I would highly advise against that. The last thing you want to do is break one, or tighten it to the point where it loses its clamping force. When you torqued them the first time, did you follow the correct sequence? And did you do bolts the bolts, and then check them a second and third time before moving on to the next torque setting? As the gasket compresses, you'll need to go through them more than once on the first setting to make sure the gasket is compressed all the way.

Then you've nothing to worry about.

And +1 on not torquing the head bolts down any more. If they were done properly at reassembly, tightening them further will only cause problems.

Let me correct that: it's definitely water vapor, but is not condensation from the air. Steam is very likely being produced at spark. The motor has been allowed to warm up for 20 mins or so, and steam just keeps pouring out. Its not very thick, but it is definitely noticeable.

I did indeed follow the TIS instructions where the bolts must be tightened in a certain order. I did not check the torque settings after giving the gasket time to compress though. I agree that tightening when the bolts have been tightened to spec is not a good idea, but it is looking like they might be a bit looser than they should be, based on the bolded above.
Also, the 90 degree (1/4th of a circle) turns were estimates. Since there is no actual final torque value given, I am not sure what to set my wrench to in order to check the current n/m value. From what I've seen on other topics, the final torque should be around 130 newton meters.

So while it is a bit of a risk, I still think it may benefit to tighten the bolts a bit based on the info available.

[Critter7r]

If the steam in the exhaust doesn't smell like coolant, and barring any other running problems, I would just live with the excessive condensation coming out of the exhaust.