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Posted by: Series9 Sep 26 2006, 03:43 PM

As many of you are aware, I advised Liz to stop driving her car when I observed exhaust gas venting out of the oil tank on Saturday morning in Moab.

We flat-bedded her home just to be safe.

Looks like it was a good call.

Compression check (cold) reveals:

1. 105
2. 100
3. 105
4. 90
5. -0-
6. 105


The engine has not eaten itself, so we're going in. #4 will receive a check as well.




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Posted by: Series9 Sep 26 2006, 03:44 PM

#5:




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Posted by: Dr. Roger Sep 26 2006, 03:55 PM

ouch.

zero compression is never a good thing. at least rings would show some compression usually. do the 6 engines lose seats too?

i can build you a SBC engine pretty quick if you like. =-)

Posted by: Series9 Sep 26 2006, 03:57 PM

Since exhaust was coming out of the oil tank, I'm pretty sure the valves are fine.


And, bite your tongue about the SBC.

Posted by: Series9 Sep 26 2006, 04:13 PM

I think Liz has the 'hard luck' trophy for next year behind door #5.

Posted by: Ferg Sep 26 2006, 04:18 PM

Uhg, i'll happily pass the "award" along to her after seeing those compression results.

Here's hoping for the best!

Ferg

Posted by: Aaron Cox Sep 26 2006, 04:21 PM

looks super rich in there..... wierd... ZERO not even like 20 or 30?

interesting.....

what are you thinking about it? since its zero.. i doubt its my idea of "oil washed away by excess fuel".. and i bet you are right on a holed/busted piston

Posted by: Brian Mifsud Sep 26 2006, 04:22 PM

My rule of thumb with my Beetle engines was that when more exhaust gas came out of the crankcase ventilator than the exhaust pipe, it was time to rebuild.

After rebuilding, I'd back off the ignition timing and/or enrichen the mixture as this was usually caused the big holes in the pistons

$500 complete performance rebuild and back on the road again....

I'm sure it's just as easy and cheap with a 911

Posted by: Series9 Sep 26 2006, 04:33 PM

I'm pretty sure exhaust was coming out of the oil tank due to a big hole in the piston.
I'm pretty sure it looks 'rich' because there's a big hole in the piston.
I'm pretty sure the compression is zero because there's a BIG HOLE in the piston.

This is all starting to add up.

Posted by: Aaron Cox Sep 26 2006, 04:35 PM

i think you are right....

so what caused it? lean or advance?

Posted by: SirAndy Sep 26 2006, 05:08 PM

PING PING PING

seen it *many* times during my dirt-bike racing days ...
Andy

Posted by: JPB Sep 26 2006, 05:15 PM

Suckorama bro! How do they say, unlucky in cars lucky in love?


This is a situation for shure.

Posted by: Matt Romanowski Sep 26 2006, 05:20 PM

Don't know the motor, but a bunch of things could do it. Too deep of valve reflief pockets. Too lean. Ping (as Andy said) and/or detonation. Timing issue. Weak Piston. On and on....

Sorry to see it. No real telling until you get the piston out. Make sure to pull a couple of other cyclinders off and check the pistons. If it was a lean / timing issue, there could be others ready to go.

You can get Zyglo (or equivalent) at the local Airgas to crack check.

Matt

Posted by: Bleyseng Sep 26 2006, 06:06 PM

'bout time someone else got it as Brad has won it 5 years in a row.

Posted by: jd66921 Sep 26 2006, 06:11 PM

Jeez Liz, I thought you only lost a clutch cable....

Posted by: McMark Sep 26 2006, 06:19 PM

Sounds like you've got something nice for the trophy wall.

Bummer Liz. Time to bump the bore.

Posted by: Series9 Sep 26 2006, 06:19 PM

It's not lean, but I was running it a little advanced.

I'm going with that or straight bad luck.

Posted by: MW 914 Sep 26 2006, 06:25 PM

This should go in the official quotes thread but it is appropriate here as well:

Liz - "I hope the engine isn't shot. I can't afford to put in a 3.2 right now"

As if that was the only option!

Posted by: ThinAir914 Sep 26 2006, 11:01 PM

I dunno Joe... I think it's a hole in the piston. Probably a big one!

Posted by: effutuo101 Sep 26 2006, 11:03 PM

How much is one of those nifty fiber optic camers so we can look inside the engines with out taking them apart? Somebody could probalby make a mint with if they made one with a light so we could poke around our motors with out taking them out.

Posted by: Aaron Cox Sep 26 2006, 11:03 PM

Posted by: hcdmueller Sep 26 2006, 11:24 PM

The decent models are designed for examining aircraft engines and cost about $20K on the low end. I have a couple at work but I am definitely not in the right place to help. They pretty much all come with lights though. Here is a link to some cheap ones if anyone is so inclined. No guarantee on the quality.

http://www.fiberscope.net/servlet/the-Fiberscopes/Categories


Sorry to hear about the engine. That just sucks.

Posted by: messix Sep 27 2006, 12:23 AM

i saw one for about 1,500 a while back.

Posted by: MJHanna Sep 27 2006, 06:12 AM

Posted by: Dr Evil Sep 27 2006, 07:19 AM

Harbor Freight has one for sale for $269

ITEM 91565-2VGA 36" fiber optic scope

Posted by: Bleyseng Sep 27 2006, 07:34 AM

fiber optic camera for $400

http://www.personalarms.com/surveillance/st403.htm


time for some JB Weld on that piston.

Posted by: Brian Mifsud Sep 27 2006, 08:18 AM

Looks like there is no need to look inside.. the 0 compression makes it really clear what they are going to find...

Anyhow, can you buy 1 jug and 1 piston for 911's like you can for a beetle engine?

Posted by: Eric_Shea Sep 27 2006, 08:38 AM

Yes, you can get just one. You can probably get just the needed piston.

This is the "first" time I've ever heard of a 911 engine just plugging along and holing a piston. With zero compression it certianly seems to be the case but wow... I'd love to know what caused that. Those SOB's are T-O-U-G-H. It would take a lot.

Anxiously waiting.

Posted by: Borderline Sep 27 2006, 09:05 AM

I'm curious as to the conditions of how this happened. How fast was she driving? Climbing a hill? My experience is that you need a lot of heat to melt down a piston. Are you concerned about all the in the oil system now? Do you think the filter will take care of all of it? Sorry for your bad luck.

Posted by: Brian Mifsud Sep 27 2006, 09:14 AM

Many a rebuilt engine has been ruined by oil coolers letting particles loose that were accumulated when said engine died. My experience is that the oil cooler and whole system needs to be high pressure flushed with HEATED cleaning solvent. Some of the guck won't cut loose at room temps, but add 150 degrees and particles of "plague" start moving.

It's a good idea to put a coffee filter into your oil drain funnel and try to "rebuild" all the pieces you can find of the aluminum piston that weren't vaporized. This is where a good "bean counter" is handy...

Posted by: Duffster Sep 27 2006, 09:20 AM

Bummer, Liz. You 're obviously in capable hands for the fix.

Posted by: Series9 Sep 27 2006, 10:28 AM

Thanks for all the condolences, but I think she'll be fine.

We were going to pull the engine anyway to fix an oil leak, so it's not really that big a deal. I just want to find the missing piece (hopefully just one) in the sump.

Posted by: Toast Sep 27 2006, 10:53 AM

Sorry Liz! That totaly sucks! And I thought my car problems sucked.

Sounds like its time for a NM "Lets Fix Turtlegirl's Engine" get together.

Posted by: Headrage Sep 27 2006, 12:20 PM

Bummer on the motor guys.



This is gonna be a good thread though...

Posted by: Matt Romanowski Sep 27 2006, 12:25 PM

You won't know till it's apart, but if the piston just cracked and then burnt, there won't be much to find in the sump. From your dexcription, it didn't just grenade.

Matt

Posted by: GTeener Sep 27 2006, 03:22 PM

Wow, that's a buzzkill on a car party weekend.

Hope it's a simple fix that doesn't require an engine rebuild.

Posted by: Series9 Sep 27 2006, 04:46 PM

One hour flat. I think that's a new record for me removing a /6:




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Posted by: Series9 Sep 27 2006, 04:48 PM

Last. I had a look in #5 with a flashlight, but couldn't see any hole.

The leak-down gauge shows 100% bypass.




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Posted by: DNHunt Sep 27 2006, 04:49 PM

Man, that is just a shame. I hope you are lucky and it's just a bunch of time ansd a few parts. I don't think anyone mentioned an oil filter autopsy but, I sure would want to see what's in there. Joe could you hear where the air is escaping to?

Good luck

Dave

Posted by: Series9 Sep 27 2006, 04:54 PM

Definitely into the case.

Posted by: Madswede Sep 27 2006, 05:38 PM

Not a bad idea, that. 'course, Liz doesn't often find time to drown her sorrows much, not having that much time or inclination to get totally wasted ... but this might be the time and the inclination for such a rare occasion. Maybe after she gets it fixed would be the time for a very relieved

I strongly suspect that Joe can fix it without too much fuss and cost - not a new engine, certainly. After all, Joe's pretty handy with a as I can tell you after working on my ex-1997 VW Jetta.

Actually, I thought I'd be the one who developed such a problem, even though my engine is "new" by many of you teeners' standards having been made in 1992 - since I was the jackass that missed a downshift from 5th to 4th trying to put it in 2nd instead. I plead the fifth on the reasons behind that one, and no, Andy, it was well before we started drinking so my brain was still on. More or less. Kinda.

- Jon

Posted by: McMark Sep 27 2006, 11:19 PM

I'm gonna go with my original gut feeling... broken rings/ring lands

Posted by: Aaron Cox Sep 27 2006, 11:21 PM

my original guess was a broken ring due to lack of oil due to fuel washing it away for being rich...

i dunno....

only joe knows.

Posted by: Brian Mifsud Sep 28 2006, 07:54 AM

Are we putting money on our speculations?

Posted by: Eric_Shea Sep 28 2006, 08:06 AM

That was my thinking back in Moab. The only weird thing is zero compression. I'm still inclined to think rings and such.

Posted by: Bleyseng Sep 28 2006, 08:46 AM

I'll try a different guess...

scored cylinder....oily sparkplug, zero compression.....seen it once or twice including a loose wrist pin that scored the shit outta the cylinder cuz the engine builder didn't install a clip.

Posted by: 9146986 Sep 28 2006, 08:50 AM

I'm going to guess either a cracked or burnt piston; or a burnt/bent valve.

Just my guess, it could be a handfull of different things. Those are just the two that I've seen firsthand.

Either way a bummer.

Much less embarassing than the owner dropping a screw down the intake. (not me, a customer)

Posted by: Bleyseng Sep 28 2006, 08:57 AM

btdt--a helper dropped a carb wingnut down a carb (have a ever said how much I hate carbs) and didn't tell me. Drove the car and chipped a small spot in a exhaust valve which when the engine get hot made it have a miss. Only when it was hot, drove me nuts especially when I was told about 2 weeks later about the dropped nut.

Posted by: jsteele22 Sep 28 2006, 09:11 AM

Okay, if this is gonna be a guessing game, my money is on a very small hole in the piston, a hole about the diameter of a ......



























chopstick.

Posted by: Matt Romanowski Sep 28 2006, 10:11 AM

If it's really at -0- compression, it's more than just rings. Think about standard skirt clearances and how much air can get by. It will make compression with bad rings. Leak numbers are a different story.

Shoot, we've run turbo motors with no rings. High RPM race motors only run 1 ring - thin too - about 1mm.

Matt

Posted by: rick 918-S Sep 28 2006, 10:29 AM

Posted by: rick 918-S Sep 28 2006, 10:37 AM

My guess, stem bent, head off, or exhaust seat out of place holding the exhaust valve open, that inturn broke the piston causing a hole. Exhaust is backing up from the other cylinders through the open (damaged ) exhaust valve and holed piston into the crank case, hence the exhaust coming out the oil filler.

What do we get if were right?

Posted by: Eric_Shea Sep 28 2006, 02:19 PM

Watching you from for the lake...???

Posted by: rick 918-S Sep 28 2006, 02:38 PM

Wishin you all were here!




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Posted by: Root_Werks Sep 28 2006, 03:08 PM

Hole in piston.

Posted by: Brian Mifsud Sep 28 2006, 03:20 PM

ahem.... "Wingnuts" used to hold air cleaners on Dual carbs have amazing leveraging properties... split a barrel wide open.... but that didn't happen to me.. no it was a friend's brother...yea, that's the story, yea......

Posted by: Series9 Sep 28 2006, 05:10 PM

We have a winner!

(and it was #2, not #5. I was looking at it backwards)


I'll be looking for more than one piece in the sump.




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Posted by: Aaron Cox Sep 28 2006, 05:14 PM

now the fun part - what was the cause?

nice work joe :salute:

Posted by: GTeener Sep 28 2006, 05:15 PM

Ouch. How do the piston rings break?

Posted by: Aaron Cox Sep 28 2006, 05:18 PM

look closer.. how do RING LANDS break?

Posted by: echocanyons Sep 28 2006, 05:24 PM

How did you take the heads off with the chain box in place?

I agree this is a good time for a bump in displacement and improved bolts

Posted by: sixnotfour Sep 28 2006, 05:48 PM

those are Deves rings , 3 piece oil ring ick, are those Kolbenschimt pistons or Mahle ? measure the ring thickness versus ring groove , chance off wrong rings installed.

Posted by: Brian Mifsud Sep 28 2006, 06:24 PM

clean that piston with acetone or carb cleaner.. the story will become much clearer...

I was just by a Buggy Shop yesterday, and they have all their "best hits" sitting under glass. A screw was sucked into a barrel and made the most PERFECT impressions (multiple times) all over the combustion chambers and piston before they broke. The detail was so perfect, it looks like you are actually looking at the screw itself! You have to study closely to see it's a concave/negative impression.

Posted by: Series9 Sep 28 2006, 06:48 PM

They're Mahle piston/cylinders.

Because it failed the way it did, I'm going with good old fashioned piston failure.

Broken rings are one thing, but this was almost catastrophic. Again, I'm going with a simple piston failure.

Posted by: Headrage Sep 28 2006, 07:03 PM

Yep.

Piston, not rings is the root cause based on the picture...

How's everything else look so far Joe?

Posted by: Heeltoe914 Sep 28 2006, 07:05 PM

I may have an extra piston you can have just pay for ship. Maybe even a cylinder.
Are you going to do the rod bearings on that cylinder?
And how many miles are on that motor?
Just curious.

Posted by: Series9 Sep 28 2006, 07:11 PM

I would take a piston and cylinder if you have a pair.

I'm not doing the bearings.

I don't know how many miles.

Posted by: tracks914 Sep 28 2006, 07:35 PM

LOLOLOLOL Did no one else get the chop stick joke? That must be a classic thread here somewhere??

Posted by: byndbad914 Sep 28 2006, 07:37 PM

small hijack - Matt, you have ran no rings whatsoever? I haven't heard of that before... but agree on the single compression ring thing. Built a 347 Ford for a guy years back that had 30+psi boost, ran a thin oil-control ring and a single 1/16" compression ring to get the crown above the top ring land as thick as possible. They only have a 1.090" compression height to begin with so 3 rings were just too tight and would hammer the top ring land down if he went a little lean..

which brings me to this question for Joe...

Do you see signs of detonation on the top of that piston? Does it look like the top ring land hammered down onto the ring? Detonation can cause that, and once that top ring gets squished, then what you have in your had is what I have seen - just blows all the ring lands to pieces. Won't have a melted piston, just hammered upper...

Your plug is all cruddy, but do the other plugs show detonation? I would worry that there has been long term detonation hammering the crowns on all the other pistons too and that was just the first to let go... proceed with caution. I have really never seen a piston fail "just because" or bad machining/casting tho' truly possible. Just more likely that piston failure was "caused", not "the cause".

Best of luck - always sucks to be taking pictures of internals unless it is during assembly for the first time.

Posted by: McMark Sep 28 2006, 07:44 PM

Were the injectors checked out? Fuel distributor? I'm thinking lean detonation/heat issue. I'd say check the injectors, if you haven't already.

Posted by: Series9 Sep 28 2006, 08:03 PM

Every injector was flowed before we started the car the first time.

It's a new fuel distributor and it's a little rich right now.

All the other plugs look slightly on the rich side of normal.

Posted by: Series9 Sep 28 2006, 08:10 PM

Top ring clearence checks at .003"

The second ring is completely missing.

Posted by: Rider914 Sep 28 2006, 08:41 PM

Can we see a pic of another plug?

I find postmortems fascinating . . .

Posted by: Heeltoe914 Sep 28 2006, 08:50 PM

Joe I really dont have any books handy that till me if this piston and cylinders is what you are looking for. But If thay are its free to you, if no we tryed. Good luck

cylinder part#854/1A piston# 090202 2


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Posted by: sixnotfour Sep 28 2006, 09:06 PM

Its the second ring where there can be a problem. 1.5mm or 1.75mm
2 different ring set P/N's

Check a good one to be sure or for shit and giggles.

Posted by: Series9 Sep 28 2006, 10:58 PM

Well, I REALLY appreciate the attempt, but they are not a match.

The only 'part number' I can find on the piston is: 90L61 or CO21

The cylinder says: 90ZN2W5

I have to assume the '90' in both numbers refers to the diameter of the bore.

In the pictures you sent, the skirt is also clearly different.

Posted by: Series9 Sep 28 2006, 11:06 PM

Once the cam is out and the cam tower is off, you can remove heads and cylinders at will. The chain housing has nothing to do with it once it's apart.

And no, it'll remain a 2.7 unless it decides to eat itself completely.

Posted by: Series9 Sep 28 2006, 11:11 PM

That piston also appears to have a single compression ring.....


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Posted by: So.Cal.914 Sep 28 2006, 11:13 PM

I wonder if it could have been those 12.5 revs. I've never had one of mine blow

the lands, the top.. yes.

Posted by: Series9 Jan 25 2007, 07:15 PM

This came out of the screen:




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Posted by: Cap'n Krusty Jan 25 2007, 07:48 PM

Hope I'm not too late here. If you go with a used piston and cylinder, make SURE you use the same height group as the rest of 'em. Number inside a triangle at the base of the barrel. The Cap'n

Posted by: pffft Jan 25 2007, 08:00 PM

Are you comfortable using the existing oil cooler. I've heard nasty
stories about bits hiding in them after breakage like that.

patrick

Posted by: Series9 Jan 25 2007, 08:44 PM

I don't have a warm fuzzy feeling about any of it, but any bits that might have made it past the scavenge pump would have been caught in the filter on the tank. The on-engine cooler gets oil post-filter.

Now there could be bits in the external cooler, but again, there's a filter between it and the engine inlet.

Posted by: Series9 Jan 25 2007, 08:45 PM

Thanks for the reminder. I'll double check the candidates.

Posted by: Carrera916 Jan 26 2007, 12:41 AM

Umm, Joe,

if i were you, I would tear the engine down as these metal bits, even "metal dust" will wipe the bearings out in no time. No matter what the screen does, these nasty stuff will find it's way and destroy everything that requires lubrication.

yeah, it can be costly but hell, its far cheaper to have the bearings replace and clean out everything in the oil system for once and all...

Just my opinion as i've been there before.....especially when I forgot to put one gawd damn wrist pin clip in.....nasty, nasty, nasty

The ring landings....good chance that the groove has widen over wear and tear, it's enough to break the rings...i've seen it before too many times....

J