valve stem seal nightmare
 

I bought a 06 x5 4.4i with N62 engine. Decided to change the valve stem seals myself using the AGA toolkit; unfortunately I managed to drop a valve into the cylinder on #2 (engine was supposed to be at TDC or very close but somehow it must have been off, and the air pressure must have been too low to keep the valve in place).

Anyway, stupid question, but I assume my only option now is to remove the head?

To remove the head, my options are:
1. do it myself (I need all the camshaft locking tools, timing tools, etc)
2. take it to a shop.

This is (was) my daily driver, so now I'm without a car. I'm mechanically inclined but don't have the tools for removing the head, and I've never done this job before, so I need suggestions from anyone who has performed a head removal on whether to try it myself or not, where to get tools from, what to change "while I'm in there" and what kind of head reconditioning to do while it's off.

Did the stem of the valve drop all the way down that you can't pull it back up? With the cylinder at TDC I find it hard to believe that it could fall that far into the cylinder. Perhaps a magnetic probe can lift the valve high enough for you to complete the job.

Nice bikes, I have several bikes including a Cervelo, Felt, Motobecane, Cannondales and Gary Fishers.

I would at least try to find a magnet that will fit into the hole where the valve needs to pass through into the cylinder head and try to pull it through ( without the seal in place )

I feel your pain... I am not looking forward to this procedure myself!

I would also try a magnet but not one that could possibly drop into the cylinder.

Well I pressurized the cylinder tonight and even gently rotated the crankshaft, but to no avail. The valve is all the way in the cylinder. When I pressurized it last night, it must have rotated the engine farther than I thought, or else I was a stroke off TDC. The engine won't rotate all the way now, indicating the valve is obstructing the piston movement.

In any event, I called AGA and spoke to a tech today. He said the only other option before pulling the head is to try and reach the valve through the exhaust port after removing the exhaust manifold (which I would be doing anyway). If I can't get it, then the head comes off.

Problem is, now that I can't rotate the engine to TDC, I can't install any of the camshaft tools like this:
BMW N62 and N73 Camshaft Alignment Kit. Is that OK as long as I reinstall it with all the correct tools?

I'm getting in over my head

When an engine is at TDC, only cylinder 1 is at TDC. Unless the cylinder you are currently working on is also at TDC, a valve will quite happily drop all the way down the bore.

Rotating the engine was a dangerous mistake. If the valve was indeed down the bore and free of the valve guide, you could easily bend it, damage a piston crown... Even if the valve had not been completely free of the guide, you risked exactly the same damage if the valve had become jammed in the guide as the piston went through its stroke.

There are no shortcuts here. The head MUST come off.

When doing jobs like valve stem seals in-situ....lets just say there are plenty of traps for the inexperienced. Having adequate air pressure is absolutely essential - and having a compressor that can output adequate volume is equally essential. You WILL leak air through the valve seats to a very small degree if the engine has any wear on it, but you will ALSO leak air through the piston rings. They are not gas-tight - they are simple labyrinth seal.

One of the reasons head removal is a preferred method of dong valve step seals is that the valves and seats can be re-faced at the same time.

Anyway, good luck and hope the head comes off cleanly.

^Yikes... now I am really not looking forward to doing this job. Is there another way to support the valves while working on them other than air pressure? Maybe magnets or even long nosed vise grips wrapped in electric tape or other non-marring material? I guess anything you use would just get in your way while you were trying to replace the valve though... :(

I've pulled and replaced I6 heads (m50, 52, etc) and I really don't want to pull these heads... lol.

Not really, no. You not only need to be able to remove the collet and valve springs, but then you need access to the valve stem in order to remove the seal.

Yeah, figured. Shortly after posting the Sailor Jerry's wore off enough for me to realize I was asking a stupid question...

Well, looks like I might be that much closer to trying the old Lucas additive method and hope the seals swell up. :dunno: :( I don't have a compressor I would trust to supply the necessary air pressure consistently.

I just can't be bothered doing some jobs myself anymore. I'm a qualified mechanic, but have many more enjoyable things I would prefer to do with my time that struggle in a home garage with things like lifting heads, doing timing chains, etc etc.

As much as it hurts the hip pocket, I would prefer to be shooting hoops with my son, or going for a ride with my wife on the motorbike than spending a day under the bonnet of a car.

As a new(ish) father. I can relate to this. I used to spend every weekend in the garage maintaining or modifying the 5 BMW fleet... but now it a rarity for me to get in there and spend any more time than it takes to replace belts or do oil changes.

ants_oz thanks for the reply.

In reading about head removal, the camshaft timing tools are required. But I can't set the engine at TDC since I can't rotate the engine; so do I just leave the crankshaft and cams at their current settings, remove the head, then line it all up with the tools when I'm ready to re-assemble?

When changing the valve stem seals using the AGA tool, you "can" change the valve stem seals without compressed air, and having the valve you work on resting on top of the piston. That is if you know what you're doing, and being 100% sure you're at TDC. At TDC, without compressed air, the valve rests on the piston. With compressed air it will stick out more. I did this job last year, and I haven't used compressed air on quite a few valves, but I also let air in as soon as I needed the valve to stick higher in order to place the retaining collets. When performing this procedure, you have to be very careful. Also, you have to cover everything up that is around the bank you work on. Absolutely no gaps. You will work with some very small parts and you will handle them with magnets. There are also springs, and small parts that can come lose and fly everywhere if not careful. They could land where you leave gaps, and then it's good-bye in the worst case. The repair procedure should NOT be rushed even if you want to have it done quick. Especially the last cylinder on bank1 & bank2 (close to the firewall) are very taxing on the back, and you might feel compelled to finish it off quick. Big mistake. Just take a break, have a beer (it's summer after all), return later. Take extra care and double & triple check that the parts seat correctly after assembly. You might want a helper after all the stem seals are replaced, to very slowly turn the engine over, so you can inspect every cylinder carefully - the valves & valve guides. the engine shouldn't bind, and the valves & roller guides should move smooth. For the cylinders close to the firewall you need a good small mirror for visual. Same for a few other spots. Actually you should take some pics on how the lifters & guides look prior to starting the job to have as reference.

GL

When you tried turning the engine with the valve resting inside, you might have hit the top of the head with that valve. It was probably resting on top of the piston on side, and it was pressing the piston down on that side. the piston isn't true anymore - it probably seats cockeyed in the bore and is wedged with that valve. I can be wrong, but this is what I think happened. Try to find someone that has a snake cam and slide it inside the cylinder to have a visual how things actually are. It might not be that bad. Once you know 100% why the engine is not turning/how the valve is caught, you might listen to the AGA guys and go from underneath without pulling the head. You have to know which way to rotate the engine, if you can remember 100% which was the rotation sense (clockwise or counterclockwise) when the engine seized, so you can try to go the opposite way. You might need a helper and build a small hook out of sturdy wire to pull on the valve to dislodge it. The snake cam and the hook should be able to fit through the hole. the sturdy wire might need a small bend before the hook.

Jmitro, maybe this thread can help you a little. It has some good pictures and descriptions of some procedures. It's a very long thread, but I would take my time and go through it, maybe it will shed some light on what you encounter. It's a different car, but the exact same engine.

Thanks for the info. I have your thread bookmarked as well as another from a 6 (or 7) series. I have rebuilt I6 heads before... but the V8 BMW engines I've only seen it done. It didn't look like fun and so would definitely use the AGA tool rather than pulling the head... and if I can use my snake cam to verify the piston is up on the valves I'm working on negating the need for consistent air... then awesome. That makes me feel a lot better.

BTW, when I do this job... I am going to budget a month for the job so rushing will not be an issue. I'm 6'8" and my back lets me know when I have been hunched over an engine bay for too long. ;)

Yeah. Maybe the valve slid over a bit and is not sitting in the valve relief groove of the piston head, and could be only "slightly" jammed. With that sturdy wire you might be able to pull it so it slides down in the valve relief. Than you might be able to ever so gently guide it back in it's place, while barely moving the crank.

Success!!
Got the valve pulled back up and keepers back in without removing the head. Basically had to pull the exhaust manifold and use mirror, pliers, and extreme body contortioning to feed the valve back up, then slowly rotate the engine to push the piston up which in turn miraculously managed to find the valve guide (after about 15 attempts). The motor rotates freely now without binding. The #2 piston is back up at the top of the compression stroke where it should be.


Anyway, i'm going to read up on removing the camshafts and if it seems easy to do I will change the valve stem seals that way. I am most of the way there, Just need to set the engine to TDC, Remove timing cover, sprockets, and cams. I think that is going to be much easier to change the seals.

Any suggestions "while I'm in there?"

Way to go jmitro!!!

:thumbup::yourock:

I was actually thinking the same thing ( about going the route of removing the cams ) and then using something like this ( Compact Double BMW N62 V8 Valve Spring Compressor | eBay ). or just a standard valve spring compressor. Keep us all posted on how it goes and that is such a huge accomplishment!!!

How have you been able to determine there is no damage to either the piston crown, the bore, or the valve itself?

In short, I have not. if I have valve, piston, or bore damage from a stationary valve falling 3" into a stationary cylinder, this engine is way too delicate. Remember, the engine was NOT running when the valve fell in. Pulling a head just to inspect it even though the valve has been retrieved seems to make a simple problem much more complicated and expensive.

I'm not trying to be a know-it-all (certainly I'm not a trained BMW tech) but the likelihood of a cracked piston, marred bore, bent valve occurring while trying to change valve stem seals.....I would say is practically zero

Fair enough mate, and I acknowledge the engine was not running. But you yourself said that you turned the engine over with the valve in the bore - the point where the engine locked up. This indicates that there was a mechanical jam - the valve locking hard-locked between the piston crown and the head.

Anyway, your call entirely - just asking whether you checked.

There are other options to lifting heads by the way - bore-scopes, or even cheap USB inspection cameras...they can all assist in looking into confined spaces.

I'm glad you managed to get it fixed.

I highly doubt he did any real damage to the piston or combustion chamber. His exact words were " The engine won't rotate all the way now, indicating the valve is obstructing the piston movement." Assuming he was just turning the engine by hand there's not going to be anything more than very minor damage.

I had success with worn seals using this stuff.

http://www.amazon.com/ATP-AT-205-Re-...ct_top?ie=UTF8

http://ecx.images-amazon.com/images/...L._SL1500_.jpg

I would verify the condition of the cylinder, by doing a compression test once the engine is back together or a leakdown test if the compression test shows low compression..

the cylinder now holds pressure at 100psi using the air compressor to hold the valves in place, so I doubt there's anything wrong. I cranked the engine slowly by hand and never put more than about 30 pounds of torque on the bar.

moving on.......

I decided to remove the camshafts and do it the "long" way.

I'll just say that in 1 hour I now have the rest of the #1 bank exhaust valve stem seals completed. Another hour and all valve stem seals of bank #1 will be changed.

I still am using the AGA toolkit to compress the springs and remove/install the keepers, but the small bit of work on the front end to remove the camshafts makes a HUGE difference in time saved by allowing MUCH greater visibility and access to the valve stem seals without the cams in the way.

Interesting, Upallnight. You're brave. Was that success long term?

bank #1 completed!!

Way to go jmitro!!! let's see some pics of bank #2 :)
:thumbup:

Nice recovery! Hope things continue to work out well.

When reinstalling the cams, put the nuts/bolts (not sure which the N62 has as I haven't been into one [furiously knocking on wood]) on a little bit at a time all the way down the cam. This way you have the cam essentially going in straight and not bent due to the pressure of the valve stems/springs pushing up on the cam. I used to do 1/2 turn at a time on the S52 from my old race car. Cracking a cam would really ruin your day...

I'm happy to say the X5 is all buttoned up and I've got over 100 miles on this repair now. It's running perfectly with no CEL or codes. No oil leaks, no coolant leaks, and no blowing smoke!!

It was NOT easy, but I've got the satisfaction of doing it myself, cleaning the engine while I worked, and knowing I didn't lose a single bolt, not, or valve keeper the entire time. Not to mention saving thousands of dollars in labor charges.

Now we need a writeup.

Glad you are enjoying the satisfaction and self esteem contribution from your accomplishment.

Congrats! I bet the sense of accomplishment, and extra heft in the wallet, really contributes to the satisfaction of the repair.

Respect earned.

I may not have the experience of the dealer mechanics or indy shops in doing major mechanical jobs like this, but I'm anal/retentive enough to clean and account for every bolt, nut and Oring that I removed.

I have to give credit to a tech at AGA for talking with me when I dropped the valve into the cylinder; his suggestion to remove the exhaust manifold saved me from having to remove the head.

I also highly recommend anyone contemplating this job to REMOVE the camshafts. Timing is such a minor issue when renting the tools from bimmertoolrental.com, it makes the job so much easier to access the valve stem seals, and the cost was only $60 to rent and return the tools

Congratulations! Last but not least, is to capture your achievements for brevity in the form of documentation of the process. That would be invaluable.:thumbup:

Did you go via the exhaust side as it was an exhaust valve ?
Ive just lost an inlet valve inside and not a clue what to do now :(

Yes, I recovered it via the exhaust outlet.

by the way I now have 14000 miles on this repair; it's been perfect since then

Thats good to know if I can indeed fish it out via the inlet then :)