Here's the Eng Compress. results from earlier video

[bimerguycw]

I thought I would start a continuation thread from my previous to update those so helpful in the past thread please read and comment for help needed.

After getting time to perform the compression and vacuum testing here's the results and I appreciate your addition advice on locating actual problem for repairs:

Vacuum:

At idle 650 rpm = 8.5 inHG steady
At 1000 rpm = 10 inHG and steady
I held the RPM's at several levels and the vacuum increased with rpm's and held steady in each case with no fluctuations at each rpm.

Compression:
1 cyl failed...
Tested each cyl 2 times to verify repeatability and values after 4-5 strokes.

7 cylinders = 175-180 psi
1 cylinder = 88 psi (Cylinders on pass side at front of head where noise the loudest.

Any and all advice appreciated now that we have some real numbers to work with, right?

Can we determine if this 1 year old bottom rebuild is okay and it's in the top-end only or what?

Thanks.

[bimerguycw]

the compression number look like the other 7 cylinders. I understand this means the cylinder is the leak...either piston ring or cyl wall...crap!

I wonder what caused this 1 cyl to go bad if the btm-end was rebuilt about 1 year ago?

Any ideas out there and how much repair I'm looking at? Can I have the head pulled and ring replaced on this 1 cyl from the top if thats all that was failing or should I suspect more problems and do more repairs to avoid another similar problem?

[aston_jag_tech]

Wow! a piston ring fail, ver would have guessed that was the problem....

Good for you in tracking it down...

As you mentioned, go an investigate why it failed and then expand on what else could fail and could cause the fail...

[BillionPa]

slick 50 oil treatment would have caused a ring failure.

[bimerguycw]

20-50W oil at startup according to the Prev Owner that rebuilt it. Then I waited until 1500 miles or so and put 0-40 Mobil syn in it.

Is it possible the prev owner's rebuild could have been faulty and that is just now showing up?

What about the sound on my video, does that add up with this type of failure?

[bill g]

I had this happen on a Jag XJ6 engine years ago - recent rebuild including re-sleeved cylinders - piston slap due to excessive wear in 1 cylinder after only a few thousand miles.
Compression leakage can be caused by excessive wear (abrasive particles in the cylinder), scored bore, rings installed incorrectly, for example upside down or with incorrect end gaps or end gaps next to each other instead of staggered.

Bill G

[BillionPa]

i would suspect a problem with the rebuild rather than wear due to operating conditions.

[bimerguycw]

I think I've read that a piston/ring can be repaired without an entire engine removal and dis-assembly. Is this possible since I appear to have only 1 cyl with compression issues.

[bimerguycw]

So what did you do to repair and did your car have a similar sound and symptom with this problem?

[bimerguycw]

When I first got the car I did a compression test 1st thing and all 8 where in spec with readings of 180 psi +/-5 psi.

But over the year I've had it I have noticed the plugs burning with what appears to be oil. The 2 rears with the most and the other 6 with slight brown/black coloration. I expect the 2 rear were the known valve cover seepage due to the fact that the plug chamber had small puddles above the plug holes each time but suprised about this since it was rebuilt and had new valve cover gaskets. I will take picture of the plugs for comments.

With the year long plug burning with this brownish/blackish coloration I switched to NGK and same issue, so I wondered what was causing the oil into the chamber and thought the PCV plate as it was not replaced with the btm-end rebuild.

[E34-520iSE]

I have zero experience of your type of engine, but the usual way to remove & replace the pistons is to remove the head, drain and drop the sump, remove the big end bearing cap on the defective piston (mark it with tipp-ex if you like, for easy re-assembly) and push the piston from below out through the top of the cylinder. Have a helper look out for bits of broken ring falling out. You really don't want them falling down a bore. As I say, this is just general advice.

HTH,

Shaun M

[bimerguycw]

Thanks for the reply.

That's sounds reasonable if It's just a bad ring or installed wrong but it's still alot of labor to remove head I expect. And if I remove the head I'm tempted to go ahead and have them re-conditioned if the btm-end is sound.

When removing the head(s) what should I watch-out for besides the Bentley manual info?

[Jr ///M5]

Bring the #1 cylinder up to TDC. Place your air chuck into the spark plug hole. Charge the cylinder with air, the leaking air will tell you where the problem is located.

If the air blows out the intake, it's the intake valve. If the air blows out the exhaust, it's the exhaust valve. If the air blows into your crankcase, it's your rings or piston.

It's worth doing this test to determine exactly where the problem lies. It could very well be a bent valve too.

Good luck,
JR

[632 Regal]

with all that engine noise *excessive* engine noise I doubt it is simply a ring. Pull the valve cover on that side and take pics so we can look at all the broken parts.

The valve cover should take about a half hour to pull.

[bimerguycw]

I agree about the valve-train like noise vs. the ring but the oil in plug test is supposed to be a next step in top-end vs. btm-end problem unless the sure fire was is only with a leak-down test I'll do both.

[bimerguycw]

I'm wondering what caused the failure and if valve-train, what else can be checked with valve cover off? Is there anything that could cause this 1 cyl to fail compression test that can be inspected tested under valve cover?

Thanks fo rall the response guy and Merry Christmas to you all.

I'll do these test and take pics and psot soon after Christmas.

[632 Regal]

not really but it is another step in the right direction. I might guess a broken valve spring and the valve was hammering on the top of the piston, maybe parts busting up in the cylinder busted a ring land.

Is there anything that could cause this 1 cyl to fail compression test that can be inspected tested under valve cover?

[bill g]

If you do the air pressure test suggested by JR just make sure you have it at TDC on the compression stroke, not at the end of the exhaust stroke, or air will be escaping everywhere.
Jeff mentioned busted ring land as a possibility - this reminds me of another way someone can stuff up a rebuild - that is if there is a substantial wear ridge in the bore at top of ring travel which is not removed then it is possible for new top ring to slam into that and break.
When I removed pistons with engine insitu in the XJ6 I had to remove the front suspension cross member and engine mounts to get sump off - this meant engine had to be supported from above by chains from a large piece of timber laid across the mudguards.
If putting oil in the cylinder causes compression to come up near to that of other cylinders this would normally point to a ring, piston or cylinder bore problem. I have had bent valves and broken valve springs and these were accompanied by bad misfiring.
A bent valve does not seat properly so will result in excessive valve/tappet gap and loud tapping noise - you could check the valve clearances when cover is off.

Bill G

[bimerguycw]

As for TDC I expect that to be piston at top most position as seen through the plug hole.

I am looking into the pressure leak-down tool also and maybe a rental of a boroscope to seen valves.

Thanks for the info.

[Jon K]

You can also actually set the motor at TDC by lining the crank wheel up with TDC on the timing cover.

I am with JR - his advice is solid. Fill that bitch with air and see where it escapes. The only problem will be listening for the air escaping in the exhaust - you may or may not feel it and an air compressor is going to be relatively loud. The crankcase you should feel, as well as the intake. Hold the throttle body open when you do this because most factory gapped TBs aren't open enough to leak air (hence our IAC valve).

[bimerguycw]

I got the valve cover off of the cyl 1-4 of the noisey v8 and the front-most cylinder #1 had the 90osi compression and went to 180 when re-tested with oil in cyl but noise still seems like valvetrain vs. ping ring or cyl problem.

With the valve cover off I inspected the cam and cam followers per Bentley and no slack at all in the followers when at lobe pointing-up. What are we looking for with the photos and what to check on the valvetrain nw that it's exposed. Should I turn it over few cycles to find the sound and minimize the oil slinging?

Here's the photos link and the Video with sound again for your review and experienced comments.

Photos:
http://cw332.photosite.com/BMWValvetrainphotos/

Video:
http://www.youtube.com/watch?v=m54s5SmC25k


Thanks again for the continued feedback and advice...I need it to make a rash decision on the repairs needed with 1 cyl compression low and valvetrain noisey.

[632 Regal]

well... that sucks but is good, no obviously broken parts. I wonder if a lifter gave up the ghost. When are you going to take a peek down into the cylinder? Hopefully there isn't any damage in there either.
With the cam pointing away from the lifters can you push the lifters down at all?

[bimerguycw]

I pressed about 20 lbs of weight on each cam follower when the lobe was pointing up(least amount of spring tension) and there was no perceivable movement.

What else can I inspect in the valvetrain that amkes sense?

[632 Regal]

I cant make any sence of it at all at this point. Look down the hole would be the next thing to do. Sounds so damn bad I cant believe its an invisible problem.


What else can I inspect in the valvetrain that amkes sense?

[bimerguycw]

that's why I asked about the other items to verify with the valve train exposed.
I wonder where I can rent a bore scope to look into the cyl and valves?

[632 Regal]

wow! those things arent cheap

[BlueM60]

i agree, its time too look down in the cylinder. The valve train visually looks great. I had one car at work with a very similar sound. What had happened is a previous shop had just done intake gaskets a few weeks before. Cyl 8 had like 20psi comp. pulled the plug and a 10mm nut had completely destroyed the upper part of the piston and bent the rod. I hope your case isnt this bad but i would def look into the cylinder. You may not need a scope if you have a good flashlight. Couple questions tho:
Where was the engine "rebuilt"
Did they install all new bearing and seals or do you mean it had an Alusil swap? Im interested to see what the problem is and its nice to see someone so through with pics and vids to help others diagnose the problem. Im sorry for your trouble though and I think no matter what it may end up being a pricey repair.

-Ben

[632 Regal]

yep, wasn't a cheap sound to me...
Im sorry for your trouble though and I think no matter what it may end up being a pricey repair.

-Ben

[bimerguycw]

Do you guys think a stretched timing chain could have happened and cause these symptoms?

I can chekc the TDC and camshaft lobe positions, right? I'm not really sure what Bentley is telling me about the proper camshaft to timing gear positions to check this possible chain skipping a tooth.

Any comment on this?

[632 Regal]

if the chain jumped you have some serious probs. the stock chains should last at least 300k miles. perhaps the bolts loosened up and the timing retarded? that happened on one of my drag engines but it trashed the valves across the board and dropped one valve head. with your compression being so close I doubt this happened but who knows. Something happened in number one...take a bright flashlight and look into the plug hole and see whats up. turn the engine so you can see difft parts of the pistons looking for shiney spots.

[bimerguycw]

Which bolts are you referring to that make have come loose and retard. How do I insure the crank to camshaft position to check the timing. Bentley manual is a little vague to me when it says Cyl lobe will be facing each other, etc.

I'm concerned that I have 2 problems and not just the one since my vacuum is so low(8 in HG at 650 rpm idle) and my intake has oil puddles around it like maybe the PCV has been clogged with oil vacuumed into it, etc.

Thanks for continuing to follow-up with my situation. I wish we had some kinda tool loaner pool for the bore light, etc. I really have had a problem looking into the plug hole even with a slender LED light into the plug hole...I need a fiber scope.

I'd share my Peake tools and others.

[bill g]

Seems like you do have more than one problem. Your vacuum readings suggest late valve timing but this does not account for the compression values/behaviour. If both the intake and exhaust valve on one cylinder were leaking badly (such as if valves bent or burnt) I suppose it would struggle to build up vacuum but your compression readings do not support this possibility.

Bill G

[bimerguycw]

compression reading staken recently. That's why I expect to have to replace the PCV plate and all intake related seals/gaskets.

I want to find the lack of power problem and wonder if it's PCV related because I and others have had a non-firing cyl and not have this much loss of power(approx. 50-60%) but couldn't a bad vacuum and/or bent valve have this symptom?

[632 Regal]

I wouldnt call it non-firing, somethings really messed up and can cause ALL of these symptoms. The drop in power can clearly be caused from 1 bad cylinder pumping crap back into the intake.
Right now I wouldnt even consider replacing anything before you get to the cause. Ill guess something fell into that cylinder, a bolt or something from the rebuild or its hanging up under the valve periodicly...what a mess. if this was a chevy or something id say pull the head but its a bit more work on the m60.



compression reading staken recently. That's why I expect to have to replace the PCV plate and all intake related seals/gaskets.

I want to find the lack of power problem and wonder if it's PCV related because I and others have had a non-firing cyl and not have this much loss of power(approx. 50-60%) but couldn't a bad vacuum and/or bent valve have this symptom?

[BlueM60]

So, hows the injured M60? Any luck with looking down the bore?

-Ben

[bimerguycw]

I plan to check timing chain position and may just buy a Pro Vision fiber scope but have talked to a couple of local BMW indys and they will check my video and photos next week after the New Year's and give their estimates or if I need to bring it in for better diags.

[BlueM60]

Its hard to diagnose without being there but I would seriously doubt that its a timing issue. If you had a slipped timing chain, you would have at least 4 cylinders affected, you said you had low compression on 1 cylinder. I would really concentrate on the 1 problem sylinder. Youll have to have cam blocks and a tool to go into the crank to set timing. Im not saying your wrong in going that direction, but thats alot of trouble to go through for such a longshot.

-Ben

[bimerguycw]

I expect I need to look into the cyl and check valves and cyl wall, but don't expect to see anything about the ring with them in the cyl compressed against the wall.

How much work am I looking at with potential ring replacement and cyl re-surface, etc.? I also expect head work too, right? I don't mind doing the work myself since I have the time but don't want to compromise the workmanship if it's too specialized and there are special tool and procedures that are not in my Bentley and TIS CD info.

Any thoughts on this estimate of the work and level of expertise required?

[BlueM60]

I would'nt attempt any engine work that major outside of a specific engine shop. owuld be very hard to get all the correct close tolerances these engines utilize without all kinds of special tools. Im not saying it wouldnt be possible, but you want an engine thats just a smooth and reliable as from the factory. Hard to do that kind of work in your garage. If I were to go that far I would just source a known good used engine with a warranty from a reputable parts yard, or even EBAY. You could probably find a good used M60 for less than 1000 bucks.
You said earlier this was a "rebuilt" engine- you may be possibly feeling the effects of another shop's shoddy workmanship.

-Ben

[Kalevera]

Listening to that clip, I can't believe you're letting the engine run with that kind of noise. That kind of noise usually results in this kind of damage:

http://img.photobucket.com/albums/v736/suzpectx/7692b55b.jpg

http://img.photobucket.com/albums/v736/suzpectx/bdae4f06.jpg


If you end up needing it, I have a complete Alusil 4.0 drop in replacement available for sale -- see http://www.bimmer.info/forum/showthread.php?t=28780

[bimerguycw]

It has the same look as the other 7 cyl as seen from the plug hole and a mini light down the plug hole, but still need a better look at the cyl around and valves above with a bore scope. That will be next week if I order the flex scope.