Liquid oil in the exhaust.... and other oddities

[maytag]

Hey y'all;
I need some help, and it seems I've diluted my AOS topic enough that this specific issue hasn't attracted any attention. Either that or nobody has an opinion.... which is hard to imagine, haha.

In my "AOS, what breaks first" thread, I've described the situation surrounding this specific question, but to nutshell: I've got oil in the exhaust. I still seem to have good compression in all cylinders, and no obvious signs of intermix. This could be simple catastrophic AOS failure, but there's still one issue nagging at me, keeping me from diving in:

Note the photos below. Large cam plug on the front of intake cam on the left bank is MISSING. Both small cam plugs on the back of the same bank are canted/ crooked. I can't account for this. It's almost as if they've been pressurized and blown out. I've been trying to imagine ways that crankcase pressure could reach those levels, and none of my imaginings are pleasant. None of these areas show obvious signs of oil dripping from those holes, but there is signs of weeping, and the foam sound insulator opposite the missing plug is saturated.

Can y'all please help me with your experience here?

What could have caused this?

Thanks.



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[truegearhead]

I can’t speak to the left side but once had a cam plug fall out of the right side of the motor and it pumped quarts of oil out in a matter of seconds. Odd that you can run without them. That being said if they popes out it’s more than likely a pressure problem which points to the AOS. Id replace the AOS and the plugs (MAKE SURE they are well hammered in, not like your photo) and then send it.

[MaxD]

Are you sure the engine didn't spin the wrong way as a result of the car spinning and then traveling backwards?

Something caused a lot of pressure to build up.

[maytag]

Originally Posted by MaxD

Are you sure the engine didn't spin the wrong way as a result of the car spinning and then traveling backwards?

Something caused a lot of pressure to build up.

No, I'm not certain. The car died when I spun. That may be from what you describe. It happened pretty fast, as it was precipitated by the oil left by our friend in the Ford. :: sigh::
Don't get me wrong.... I blame only myself for the spin, but the conditions leading to it have to be acknowledged too, haha.

So, if the motor spun backwards, what's the biggest fear here?




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[JFP in PA]

Originally Posted by maytag

So, if the motor spun backwards, what's the biggest fear here?

Bent valves....

[maytag]

Originally Posted by JFP in PA

Bent valves....

Right, but that's assuming cam timing changed, which could've happened forward or backward, yeah? (Or is there another way to bend those valves that I'm not considering? )
But I'm still pushing healthy compression numbers in all cylinders.

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[Deserion]

As far as what fails in the AOS, it seems to be the rubber diaphragm that splits.

[The Radium King]

slack in chains.

[maytag]

Originally Posted by The Radium King

slack in chains.

seriously?
Is this something you've seen? or are you postulating?
Shouldn't the chain tensioners be working regardless of direction of rotation?

[JFP in PA]

Originally Posted by maytag

seriously?
Is this something you've seen? or are you postulating?
Shouldn't the chain tensioners be working regardless of direction of rotation?

The chain tensioners function off oil pressure, when the engine is turning backwards, the oil pump is sucking the oil out of them..………..

[The Radium King]

it can happen in older engines due to stretched chains. recall that on our cars we get chain slap on start up due to low oil pressure and the tensioners, like lifters, require oil to inflate, so without oil pressure there is some slack in chains.

[911monty]

While the pic attached is of a 5 chain engine and yours is a 3 chain the mechanicals similarities should be evident.

On these engines the chains have a "driven"(under tension) and a slack side that the tensioners control. The vario cams can move ~23 degrees in relation to the crank and you see how short they are. How many degrees backward does the crank move before all the slack is pulled out of the crank to IMS chain and the camshaft drive chains on the slack side? JFP might know but it would be considerable. Obviously enough to interfere with piston travel.

[maytag]

aaaahhhhhhh..... Bach. ($5 to anyone who recognizes that reference, haha)

Okay. thanks to Radium King, JFP and 911Monty, My eyes have been opened. YEah, I can see it now... makes total sense. that ALSO leads me to understand what MaxD was getting at, about the engine turning backwards....

y'all are a wealth of knowledge here.

now, excuse me while I back-up a little bit, as I take a long look at the way Porsche engineers designed that entire system, and shake my head in wonder. (as in: I wonder why in hell they still had jobs after that mess?)

Of course, I've seen worse, because I've owned Jaguars, RangeRovers and Maseratis.

[911monty]

Originally Posted by maytag

aaaahhhhhhh..... Bach. ($5 to anyone who recognizes that reference, haha)

Okay. thanks to Radium King, JFP and 911Monty, My eyes have been opened. YEah, I can see it now... makes total sense. that ALSO leads me to understand what MaxD was getting at, about the engine turning backwards....

y'all are a wealth of knowledge here.

now, excuse me while I back-up a little bit, as I take a long look at the way Porsche engineers designed that entire system, and shake my head in wonder. (as in: I wonder why in hell they still had jobs after that mess?)

Of course, I've seen worse, because I've owned Jaguars, RangeRovers and Maseratis.

In your previous thread, Post #12, I asked if you got the clutch released before going backwards in your spin when I asked about the scavenge pumps. Have you checked their condition? The sources for pressure in these engines come from compression/combustion, thermal/ water, and mechanical/ oil pump. Since you don't have water in the oil there is really only 2 sources you need to evaluate for pressure in the valve covers. The AOS is a source of vacuum not pressure. It is basically a regulator between the intake vacuum and the crankcase.

[maytag]

Originally Posted by 911monty

In your previous thread, Post #12, I asked if you got the clutch released before going backwards in your spin when I asked about the scavenge pumps. Have you checked their condition? The sources for pressure in these engines come from compression/combustion, thermal/ water, and mechanical/ oil pump. Since you don't have water in the oil there is really only 2 sources you need to evaluate for pressure in the valve covers. The AOS is a source of vacuum not pressure. It is basically a regulator between the intake vacuum and the crankcase.

Thanks Monty. I had to go back and look, because I didn't remember you asking about the motor spinning backwards. Shonuff: you asked. I may not have seen it, as it is a "PS" at the bottom, which I might've dismissed as a sig-line. Either way: I appreciate that you were looking ahead for me. :-)

No, I haven't yet inspected the scavenge pumps. Any second now. haha.

Seriously, I haven't really had any time to do much of anything yet. I've got too much else distracting me right now. When I find a minute to work on the porsche, it's usually just that: a minute.

Hopefully after my business-related fires, my son's wedding, my daughter's Missionary-departure (we're Mormons over here :-) ) and my wife's various and sundry honey-do's... (that's Wife's, not Wives'... even though we're Mormons over here, haha).....

I'll get to it sooner or later.

[Deserion]

Originally Posted by maytag

aaaahhhhhhh..... Bach. ($5 to anyone who recognizes that reference, haha)

Well that's just a mash-up of where it could have come from.

[maytag]

Originally Posted by Deserion

Well that's just a mash-up of where it could have come from.

haha, good man.
Where am I sending your $5?

[maytag]

Borescope:
See the photo below. Honestly, with 150k miles on it (only about 3000 of those by me) I wouldn't have expected to see somebody's sharpie scribbles on my piston top still.

Otherwise, absolutely nothing odd in the initial view.

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[maytag]

Scavenge pumps;
Left side was full of oil when it came out. Turns smoothly, seems to be in good working order. The key was oriented correctly when it came out, so no concerns in my mind.

Ditto the right side, except that it was NOT full of oil. Not "dry", per se, but didn't drip at all when I unseated it.

What's "normal" ?



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[911monty]

Originally Posted by maytag

Scavenge pumps;
Left side was full of oil when it came out. Turns smoothly, seems to be in good working order. The key was oriented correctly when it came out, so no concerns in my mind.

Ditto the right side, except that it was NOT full of oil. Not "dry", per se, but didn't drip at all when I unseated it.

What's "normal" ?



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So to clarify, the left (bank 2?) cam plugs have been blown out and the scavenge pump is possibly not moving oil? Is this also the bank that the camshaft plug may have blown out on? These are not positive displacement pumps. They are rotor. gear pumps. Possible pump damage or blockage downstream at de aerators to sump? Bank 1 (right) could be dry due to AOS directly attached there and most/all oil going to intake?