540i P1346 and P1347 cyl 3 misfire after timing chain guides + vanos

[StRaNgEdAyS]

Check your clearances between the cam lobes and the buckets at #3 TDC compression.
If you have a bent exhaust valve you'll probably have more clearance at the damaged valve because it isn't closing fully

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[joekitch]

Turn the engine so all 4 of the #3 valves are closed. Then connect some air pressure to the sparkplug hole.
If you hear it blowing out of the throttle body (intake tube disconnected and butterfly open) then you have a problem with the intake valves. As you know you can see them with the manifold off the engine.
If the exhaust valves are borked (GG term) the air will be blowing out the exhaust.
Good luck.

oh, that's....a much better way of doing this, actually.
now to find an attachment to shoot compressed air down the spark plug hole..i suppose i could get the hose that comes with the compression tester and blow air in it from my actual lungs
edit: nope that didn't work and isn't what i want anyway, i have a leakdown tester on the way now
double edit: realized a leakdown tester wouldn't be able to tell the difference between a bent valve and a stuck valve, but a better borescope with a 90 degree mirror would, so i went with that instead

[JimLev]

Get one of those air guns that have a rubber cone tip on them. Push it into the plug hole and let her rip.

[joekitch]

ok so, im even less sure of what's going on now...

got one of those air valve holder tools, screwed it into the spark plug hole and blew into it (with the valves closed) with my lungs, didnt taste great but man i can see why its zero compression, it was quite easy to blown in there.
thing is, i held the throttle flap open and didn't really hear anything through it?
i also set my phone to record next to the tail pipe, and it picked up......no noise ?,

to be fair using actual compressed air would probably make more noise...

Anyway, next thing was to do was to do a lot of borescoping of cylinder 3, and cylinder 2 as a reference.
However....that wasn't very conclusive either. the image quality wasn't great and the mirror attachment for this borescope had some INCREDIBLE flashback
https://youtu.be/_Yi9J17Bx1o?t=53
https://youtu.be/IFHD6PSzpGc?t=60


i mean it looks like the valves are sealing fine? but that doesn't make any sense, how are they leaking so bad if thats the case?
i will say the cylinder looks really gross but the cap full of oil i put in there earlier has not drained a drop so i think the piston rings are fine...

can someone else with eagle eyes spot something wrong with the valves?

[Mach540]

Try blowing a big lung full of cigar smoke thru it

[JimLev]

About the only thing I could figure out is it looks like your all set to start a colonoscopy practice. J/K
Try the cigar smoke, it's gotta go somewhere.
Use the compressor to blow 10-15 PSI in #3.
You should also do the same on #2 so you can use it for a reference.

[joekitch]

question is, how do i distinguish between a stuck valve and a bent valve?
should i just put everything back together and run some rislone through it for a while, then spray some seafoam past the MAF? if there's a stuck valve that should def loosen it up

[joekitch]

oh that reminds me, a particular bit of information i noticed days ago but forgot to mention:

when i pulled the valve cover to check the valvetrain behavior i noticed this white coloration on the inside of the valve cover...i haven't pulled the bank 2 valve cover to see if that side has it too but i'm wondering if this is the kind of stuff you see with a bad head gasket?


IMG_20171229_154355.jpg

[philly98540]

Likely condensation.

Blow compressed air into it. You'll hear where it's leaking.

[Mach540]

Yeah..... looks normal to me. Especially with the cold weather.

[joekitch]

cold is putting it lightly, it hasn't been above 20 degrees in a week and at night it's below 10, sometimes below zero.
this morning at 7 was negative 20 after wind chill, dayum.

anyway i'm editing together a video which shores borescoping cylinder 3, 2, and 1 all at TDC, and then doing a leakdown (sadly, i could hear air coming out the exhaust, meaning exhaust valve issue on cylinder 3 for sure)

[joekitch]

Video is done.
Air sound did come out of the exhaust
visually it seems like one of the exhaust valves is SLIGHTLY open compared to the other cylinders but doesn't look like it's bent.
any chance this is still just some kind of sludge or obstruction holding the valve open a bit or should i just start pulling the head?

skip to 1:55 for a shot of the cyl 3 exhaust valves
skip to 7:13 for the smoking gun

[Mach540]

Well, that was mildly entertaining.... :0
I'd start with just the cams. Very small chance that something else is holding the exhaust valve open. Seems strange that it is just one cylinder if it is valve damage. Did you get a good pic of the piston dome to see if there were any contact marks?
I believe it is the exhaust valve that generally gets slammed if there is interference. At least it is on bank one..... a little easier access if that is any consolation.

[joekitch]

what would contact marks look like though in this case?
there are already cutouts for the valves, would i be seeing some divots WITHIN the cutouts?

[Mach540]

Someone posted a pic recently of two little shiny spots on the tops of their pistons.... Can't find it now.
But it should be self evident if they exist. All the oil you've put in might have obscured them by now.
Kinda irrelevant since you've pretty much narrowed it down to the valve not seating.

[joekitch]

well a valve not seating has two outcomes:
bent valve, gotta pull the head which is a huge pain in the butt
or
stuck/dirty valve which is just some rinslone and seaform

the more i can narrow those two options the better because i really don't want to pull the head and put it all back together and do a valve job ;_;
i'll try sucking oil out then drying it...somehow. what would be a good way to get the cylinder nice and dry?

[StRaNgEdAyS]

What would you see if you put the piston at TDC comp and put the little right angle mirror on the scope in the plug hole and looked around?

Would you have just enough room to see the valves in the head I wonder?

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[joekitch]

What would you see if you put the piston at TDC comp and put the little right angle mirror on the scope in the plug hole and looked around?

Would you have just enough room to see the valves in the head I wonder?

um, yes actually. that's what i've been doing for a while and did for three cylinders in my most recent video
https://www.youtube.com/watch?v=IFJyXh5Nu_Q

[JimLev]

Still can't see or tell much from the video.
With the piston at TDC the top of the piston is slightly above the deck of the block. Can you really see the valves?
StRa mentioned a while back about checking for any play between the cam lobe and the lifter, did you try that? There should be some if the valve is stuck open. Another alternative would be to pull the bank 1 exhaust manifold (pretty easy to do compared to bank 2), that will give you access to the valve stems where carbon builds up. Use some carbon spray cleaner to soften it up and a wooden or plastic pick to scrape it off.

Did the engine run OK before this? Other than it needing chain guides?

[joekitch]

checking for play, as in pushing down on the lifters by hand and see if it wiggles a little or something?
would i compare that play to one of the other exhaust lifters?

also, popping the exhaust manifold to look at the valves, that'd work out well because i could DEFINITELY see if they're bent by looking at the stems with a borescope.
do i need to drop the entire exhaust all the way back to get the heaters off? or can i just unbolt the headers from the head and unbolt the headers from the downpipe and wiggle them out?

[philly98540]

You are certain that you had the engine at TDC on the compression stroke during the air blow in the spark plug test? All the cam lobes should have been facing sort of upwards on that cylinder.

If so, than you already know the exhaust valve is not fully closing. If the engine ran good before you worked on the guides, I doubt the valve is not fully closing due to carbon build up on the stem. It is likely bent. to verify, rotate the engine so the piston is lower down in the compression stroke. The cam lobes will still not be opening the valves. With the more space in there, try to scope again to see if the valve is not seating all the way around. As noted, look for any indication of a strike on the piston or the valve itself. If you strike out here, as mentioned by Jim, drop the exhaust manifold. Shine a bright light in the port. Look again with the scope inside the cylinder. Look for light coming in more on one side of the valve and none at one point. This will indicate its bent. It may be hard to see any bend on the valve stem from inside the exhaust port as a minor bend will not be visable.

[JimLev]

Yes, push/pull on the top of the lifter to see if you have play. Compare it to a good cylinder.
To get the manifold off remove the 2 nuts that hold CAT to the exhaust pipe, unplug the O2 sensor, then remove the 8 nuts that hold the exhaust manifold to the head. That should allow you to drop the manifold down enough to give you access to the exhaust ports.
The valves usually bend right where the stem connects to the back side of the valve which you won't be able to see.

[joekitch]

You are certain that you had the engine at TDC on the compression stroke during the air blow in the spark plug test? All the cam lobes should have been facing sort of upwards on that cylinder..

yes, i specifically showed this as being the case in the video, note the cam lobe positions at 0:19 to 0:30
https://www.youtube.com/watch?v=IFJyXh5Nu_Q
all the borescoping was done in this position

if it does end up being a bent valve, i don't have the equipment to do a valve replacement, is there someone in the MA area who does?
also the fellow who did timing on my engine as part of the TCG procedure has not responded to my texts since friday

[JimLev]

Was it Chris W that did the timing? He knows what he's doing, he's done a lot of timing jobs.
He'll get back to you, sometimes it take him a week or more.

[joekitch]

indeed it was, and that's why i'm so confused about this potentially being a bent valve and why i'm looking for ways to prove it as being anything else. i even left the spark plugs in during the entire time the chain was off so nothing could have gotten into the cylinder to damage it...
there was some dust that settled on the rim of the intake valves when i was doing the valley pan gasket but i cleaned most of that off and that would have damaged the intake valves, which are fine according to the leakdown test