I'm in the process of removing the head on my N14 and I was a bit silly. I loosened the main crank bolt before I put the engine in time. I didn't want to snap the timing pin with the huge torque needed to remove the crank bolt, so I didn't want to have the pin in place, but I should at last have got it close to in time. Right now I think it's about 60 degrees out.

I think I'll have to remove the cams so that I can safely rotate the crank without a risk of hitting the valves.

Can somebody just confirm for mw that the cam bolts on the N14 are NOT reverse threaded, correct?

Thanks!

Oh, also am I right that I can't change piston rings with only the head off? I don't think I have piston ring issues but if I can easily do it at this level of tear down I'll do so.

 

The timing pin is what holds the crank when you tighten a new bolt, it can handle loosening.
The cam gear threads are regular thread.
If you can rotate the cams to where no valves are open, you should be able to get away with not removing them. But I don't remember if that's possible with this motor. Also if you remove the spark plugs, you can rotate the crank slowly and stop if you get resistance. The pistons are equally at about 50% of their stroke when the timing pin is in, so if you're close you shouldn't be in danger of pistons hitting valves.

What do you mean by only the head off? You might be able to unbolt each rod and pull the pistons out from up top, but sometimes a ridge builds up at the top of the bore preventing that. Otherwise, I think the transmission has to come out so you can unbolt the flywheel and then undo all the main caps to get the crank out.

 

Confirmed, cam bolts are not reverse threaded. So far, I haven't found any "left-hand" threads on my '07 MCS.

Don't even think about changing piston rings with only the head off. There's oil squirters and crankshaft in the way, and you'll need to pull the tranny to get the crank out. Doable, sure, but hardly worth the effort.

 

I watched tis video that makes it look like a simple case of removing the oil pan, unbolting the con rods and pushing the piston out the top. Not so?

 

First I've heard of removing pistons from the BOTTOM of the engine... I've always been of the belief that you always remove pistons from the top?

As for the timing, as long as the crank pin is installed when setting the timing, should be good. I also read you don't want to rely on the pin when removing or installing the crank bolt, but you want to use the special crank tool for tightening the crank bolt. (the tool that bolts on in place of the crank pulley)

 

I got my wife to stamp on the brakes and had it in gear while removing the crank bolt. This works well IME but there is some slop due to the clutch / flywheel springs so really didn't want the pin in there.

Yes I realised after posting this I don't actually need the crank in time right now. I can remove the chain and the head, then set the crank time before re-assembly.

 

I made a bad assumption after reading the first post. Johne123 is correct about pushing them out thru the top, just gotta be careful around the bearing journals --- not a lot of fun working under an installed engine. If there is a ridge build-up, it can be removed before pulling the pistons.

I'm in agreement with Njaremka about the special tool for crank bolt removal / installation. I'm told the locking pin is OK for holding the crank in place during the process, but I feel better using the correct tools.

Why is the head being removed?

 

So if I whip the oil pan off, is that going to give me direct access to unbolt and push the piston out?

The head is coming off in a last desperate effort to get the thing running right. Currently badly miss-firing at idle to the point of undriveable. I've been attacking this for months without winning. I've replaced the entire fuel system, swapped out nearly every sensor, sent the ECU for testing, checked all the wiring and of course replaced spark plugs.

I did a compression test and had about 200psi on C1, C2 and C4. C3 was a bit lower at 180psi but went up with a drop of oil suggesting piston rings.

I then did a leak down test and found while C1 was a very respectable 5% leakage, C2, C3 and C4 were all closer to 20% and the results varied each time I rotated the engine and re-tested, suggesting valves.

I also see what appears to be wet oil running down the intake valve stems, so I want to replace the valve seals.

I'd probably leave piston rings on C1, C2 and C4 well alone, but thought maybe replacing C3. If it's lots of work I won't though. 180psi is still within spec and a bit of engine restore could bring it back up.

 

To get the oil pan off, you might have to drop the exhaust pipe. Then there's an oil pump and a "splash guard" to be removed, allowing access to rod bolts. Not a big chore, just a bit more work.

You mentioned it's an N14. What year and mileage? Were there any codes indicating which cylinder(s) misfired. You don't mention replacing coils. They're often the cause of misfiring. Hopefully you're using a Bentley manual for procedures and torque values, and https://www.realoem.com/bmw/enUS/select for illustrated parts list. If sending the head out for a valve job, they'll want a stripped-down head --- no accessories attached. You'll need to replace pretty much all the gaskets / o-rings / seals involved and there's a bunch. I suggest getting a kit that includes injector and valve stem seals, then furnish these seals to the shop so they can install them. Injector seals need a special tool that a shop should already have --- you don't want to do these seals with out this tool. BTW, these kits usually don't include the head gasket --- at least two different thicknesses are available. Let the shop tell you which thickness you need, based on material removed, if any.

Doing the timing chain / guides too? Different kits are available for this job, instead of buying separate pieces. Hopefully you checked timing and chain stretch before starting teardown.

Keep us posted ---

 

I'll be interested to hear what your cylinder walls look like once you get the head off. I had leakdown numbers very close to yours and all of my cylinder walls were scored to the point they needed to be re-bored/new pistons, etc...full rebuild in other words. I wasn't having misfire issues, but eventually melted a big hole in the side of #3 piston. This was on a 127k mile N14 with no maintenance records, mind you.

A word of caution on using Restore. It WILL clog your Vanos solenoid screens. I tried it twice. I had to pull the Vanos solenoid both times and wash it out with brake cleaner. Good luck!

Restore FAQ - Scroll down to the VVT question

 

Interesting info, do your engine had about 20% leakage and that stopped it running well? I had actually read between 10-20% is not that terrible. Still compared to the 5% of C1 it's clearly not great.

Head off today. Too dark for photos but cylinder walls look good. Pistons do have some play, maybe 0.5mm in the bore but taken up by the spring of the sealing rings. I guess this is normal?

Valves look nasty as expected. A couple look wet (but cant be sure it's not leakage from coolant or fuel when pulling the head. C4 valves clearly have more carbon.

No timing kit in this photo, so don't judge which valves are open and closed.



My neighbour said I shouldn't mess with the piston rings. He said just replacing the rings will not help, I have to hone the cylinder and use a slightly bigger ring. I don't have a honing tool and fear I might just make it worse. 180psi ain't bad.

 

Oops, I completely forgot about about the crank pulley holding tool. It was only a year ago i used mine.

 

My engine was actually running pretty well except for the fact that it burned a quart of oil every 500 miles or so. I was cruising along at 70 mph on the interstate one day and it started misfiring and bellowing blue smoke. When I pulled the head I found the hole in the piston.

For the record, someone had been into my engine prior to my ownership. #2 piston has been swapped and there were bits of timing chain guide in the oil pump pickup. Someone had band-aided it together enough to sell it. I bought it with 123k miles and I'm rebuilding at 127k.

I wanted a project car. As a wise man once said, "be careful what you wish for."

 

I got the gasket and timing chain kits today. Need a little help identifying all the seals.

Top to bottom I think is:
Intake Manifold
Thermostat housing
Not sure? Downpipe to exhaust?
Bottom green one looks like throttle body (didn't remove it) and what are those other 2 small o-rings for? All three came together in a pack.



The gray colour one is a weird material like compressed fibre.


And for interest here is the timing chain next to my old one. Based on the wear, how many miles do you guess the engine has done? I know what the ECU thinks but I gotta wonder, given all my troubles!

 

Don't forget to get the intake valves clean. You mentioned some valves are wet. With the head out of the car it's pretty easy to walnut blast. I kind of missed that in the list of things you tried. Also, make sure to inspect valve seats.

 

Those chains look almost exactly the same. How did the old one check out for stretch?

Did you get a head gasket set? That fiber ring look like it could be the turbo-to-manifold gasket. I’m sure as you start pulling things apart, and comparing old gaskets to the new, it will become apparent which goes where.

Are you planning on replacing valve stem seals? They can be a major source of oil consumption in higher mileage engines. If you’re removing the head anyway, it’s an excellent time to do so.

 

Yep, cleaning the valves is the primary reason the head is off. Also the valve stems. And just to snoop around to check or anything else.

That is the 'strech' you can see. Both chains are aligned at the other end. So it has about half a chain links width of wear. 2-3mm?

Yes that's all in the head gasket kit. I removed the manifold and turbo as one piece so maybe that's why I don't recognise the grey seal.

I was wondering if the bottom set (big green plus 2 o-rings) might be for the water pump? I didn't remove that.

Now I have an important question:
What the hell is this on my exhaust valves?!

At first I thought it was carbon, but it looks like a metal plating of some sort, or molten metal? In the photo I scratched the surface and you can see it is metal like under the black coating, maybe bronze colour. However one set doesn't appear to have it at all. I don't see any such coating on google images.




Another question - I notice the cup in the intake valves is not exactly central. However they do not appear to be positioned in the same direction in my engine. Why is it like that and should they be in a specific orientation?

 

I just noticed the metal stuff is on the head as well as the valves. So I'm thinking something was melted in the cylinder?!

Any ideas? Blown turbo impeller in a previous life? Someone had this car before me and it was category C. That means it was an insurance write-off due to high cost of repair, but the owner purchased from insurance company, repaired and put it back on the road after passing safety)



P.S.S No sign of problems in the engine block.

 

Scrapped back some of the deposit with a knife. Looks like sand, kind of yellow white.

It came off more as powder than chunks so couldn't get a piece under the microscope.



Strange thing is, cylinder 2 has none, despite still having nasty intake valves like the rest. If this were oil/addatives from the intake side, I'd expect to see it on C3 as well... Same with fuel deposits. Hmm..

This is C2.

 

I rebuilt my 07 S engine earlier this year. Had really bad oil consumption, like you. When I took the head off the exhaust valves looked just like yours, maybe worse. I tried to scrape it off...wouldn't budge. Got out the dremel and ground it all off, down to the valve material. Cleaned up the head, rebored the block .5mm over, upsized the pistons and rings, and has been great since. The pistons were all badly scored, most likely the source of the oil consumption. The timing chain had been changed previously because the car was misfiring badly, due to chain stretch. Here's my theory...the chain stretched due to low oil and age. Allowed the car to misfire for a while without significant issue, but deposits built up on the valves. Those break free, fall into the cylinders and because they are so hard, score the cylinder walls, dramatically increasing the oil consumption in my case. (1 qt every 250 miles) All that oil being burned ends up coating the exhaust valves, and since the chain is stretched, those valves get more exposed to heat than they would normally be. Oil deposits continue to build up on the valves, and
we end up with what I had, and you have. I did what you are doing...clean up the valves, address the leak issue (I changed valve stem seals too...), make sure it's all clean. Re-assemble...and enjoy!



Not good!

What is that?

Dremel to the rescue!

Rebuilt!

Back together (until the tranny went...ugh)