Pay attention to the gauges, subtlety matters.

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Pay attention to the gauges, subtlety matters.

Postby Dan Chambers on Tue Aug 14, 2012 7:29 am

After the phone call, with the diagnosis confirming a complete engine tear-down and reconstruction with (mostly) original parts, I called the cardiologist, then the paramedics, then the loan officer at the bank.

Why the elevated blood pressure and sucking sound from both my circulatory system and my wallet? A slight variation on one of the gauges on my 911 dash: the oil pressure gauge to be specific.

Here's the story: after some extensive re-working to get the car tight and right for legitimate smogging and registering, I got the car back running great. All systems were "go" and I've been planning and prepping for the upcoming TT at WSIR in September, to be followed by a stint to Laguna Seca and Buttonwillow. I've been acquiring goodies to help keep me in the running with a certain red and yellow 911SC co-driven by a couple of hot shoes, and was planning on dancing in the mirrors of a certain silver 911SC piloted by a driver who until now has driven a Porsche with the engine in the wrong place. Well, as Jackson Browne will tell you, "all good things... gotta come to an end."

I noticed a small, almost eccentric little change on one of my gauges shortly after re-fitting my car for smog: the oil pressure light came on at idle and the pressure dropped to about 0.8 bar at idle. If I rev'ed the engine just 100-rpm the light went out and the oil pressure raised to about 1.0 to 1.1 bar. At running speed (2500-rpm to 4500 rpm on the street) the oil pressure was "normal" at around 4 to 4.5-bar - 5 bar above 4000-rpm. Normal for most Porsches, but slightly different from what I was used to with the 3.6 conversion ("perversion"??) under my decklid. My pressure used to read about 20% to 30% higher on the gauge because of the difference between the 3.0 vs 3.6 engines (a gross simplification of the difference. There's too much to mention in this long post).

So I thought "Huh, maybe something in the recently changed vacuum / tubing plumbing has caused a change in the way the pressure sender reads the pressure." When I mentioned the drop the tech expert that prepped the car for smogging he said "Yeah, I noticed that, too. Replace your pressure sending unit (under the intake) and see if that isn't it." So, I thought "Great: a quick sender change-out and I'm back in business." My initial thought was; "This engine is only 2 years old; fresh-built by one of the best in the business - it's a bullet-proof 3.6 - I got nothing to worry about. This engine has another 8 to 10 years of street/track life left in it. It's barely broken in."

Well, after the sending unit was changed the pressure still read low. The mechanic/tech that I talked with (different one now) said, "Not good. There might be something wrong that could lead to real problems. We should drain the oil and look for bits of metal in the bottom of the case. You could have lost a piston oil-squirter, or it could be something worse. Best not to drive the car hard or rev it high until things get looked at." At this statement, my vision blurred and I had an epiphany of 100-dollar bills sprouting wings and flying out of my wallet in a mass migration toward ... infinity. The dream of chasing down a red or silvered 911SC at the track started to become the nightmare of chasing fleeting revenue and long weekends of side-jobs and Top-Ramen Gourmet dinners. "But, it's just a tiny drop in pressure! How bad could it be?"

Draining the oil and finding the tell-tale bits of metal told the story. The phone call from the shop came waaaay tooooo early; I knew I had to be sitting down. There was a glimmer of hope; the shop couldn't tell if it was a squirter - a less-extensive (read: less-expensive) tear-down or a crank plug; a complete tear-down. The afternoon phone call; that's when all the color ran from my face. My head pounded, my ears buzzed with the sound of small rectangular slips of paper - colored green - fluttering into the intake manifold of my 3.6, and being burned like the 100-octane on the front straight of WSIR. My engine had been laid bare on the shop's bench for all to see. The culprit: a crankshaft plug dropped from the crank and resting in pieces in the bottom of the crankcase. Luckily, no severe damage to crank, case or related parts.

There is sunshine to this gloomy story. I'm actually very lucky in one respect: had I ignored the slight drop in pressure and assumed everything was tight and right with my re-built, 2-year old engine, I most certainly would have "grenaded" the engine into itty-bitty parts either on the mountain roads of East County, or most certainly at WSIR in September. My "A-R" tendencies toward having a perfectly running engine / car saved me from making a critical error in judgement and destroying the parts that make up my engine. The cost of replacing the entire engine would be much more than the cost of the "tear-down and rebuild with same parts" fix that I will ultimately have to deal with. Just about everything that came off the engine will go back in.

"It was just a very small, slight reduction in pressure." Wrong. It was a tell-tale warning sign that something was seriously wrong and needed to be addressed before catastrophic damage occurred.

So, next time you look at your gauges and something seems to be amiss, park it! Get it checked out... thoroughly. What seems like a tiny change from the norm could be the difference between pulse ... and no pulse ... for your air-cooled Porsche engine.

Trust your gut.

:beerchug:
Dan Chambers
"It's just a "well prepared" street car ... or a very, very well-mannered track car." :burnout:
1983 SC #91 3.6L, "Black Pearl" Livery
1987 944 (gone but not forgotten)
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Re: Pay attention to the gauges, subtlety matters.

Postby Jad on Tue Aug 14, 2012 2:04 pm

:cry:
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Re: Pay attention to the gauges, subtlety matters.

Postby Gary Burch on Tue Aug 14, 2012 6:01 pm

ouch
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Re: Pay attention to the gauges, subtlety matters.

Postby Rsylvestri on Sun Aug 26, 2012 8:18 am

WOW!
Great catch by you and the techs, sorry to hear about that Dan.
Maybe Buttonwillow??
'76 Carrera 3.0 #418 CC07
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Re: Pay attention to the gauges, subtlety matters.

Postby Dan Chambers on Sun Sep 09, 2012 10:21 am

Update: First; thanks all for the condolences. Nothing quite like seeing in your racer/street-car in the ER. :grr:

Now for the good news: After the tear-down it was found that no damage occurred internally. :D Case, pistons/cylinders/rings, heads/valves, intermediate shaft/oil pump, timing chains and gears, etc., etc., - all  :bowdown: OK! Phew! dodged a $-bullet there! Now on to even better news:
-found a crank and rods that will work just fine. 8) Old crank and rods are fine for resale to a street-car home (not advised for a racer :nono: ).
-the re-build is coming along carefully, slowly, nicely.
-Willow Springs TT is out, but the Big Bear Tour is in for break-in. :beerchug:
-Buttonwillow TT is a real possibility; with Car #1 and Car #98 clearly in my windshield and cross-hares. :twisted:

Big thanks to the individuals and shops in town who've helped out, stepped in, and rescued me from selling the car. You all know who you are, and I'm grateful beyond words.

Look for the "new and improved" Black Pearl motoring (pun intended) down the road by month's end. :burnout:
Dan Chambers
"It's just a "well prepared" street car ... or a very, very well-mannered track car." :burnout:
1983 SC #91 3.6L, "Black Pearl" Livery
1987 944 (gone but not forgotten)
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Re: Pay attention to the gauges, subtlety matters.

Postby mrondeau on Mon Sep 10, 2012 8:55 am

Great news!!! :beerchug: Can't wait to get out and play with the Black Pearl. Hopefully, I won't be too far behind you at the track. We'll see how it goes at Big Willow.
Mark Rondeau - Retired from club duties
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