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Makes me long for the LN bearing update...just turned 19k miles on my '02 3.2
S. |
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We have a trailer load of cars on the way down next week, including another from Chicago that has an engine failure.. On the way the truck will be stopping by Louisville KY to pick up a 996 with intermix.. May as well fill that truck up with cars headed to Flat Six! Hell, we are going to start our own trucking company, just to move cars to and from our facility! |
Jake,
Which transport company do you use and how safe are cars from damage, cosmetic or otherwise to and from, or at your facility? |
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We have full security and surveillance systems with a 24 hour on site (armed) watchman. We don't have problems, period. |
Pat's Boxster just showed up. I'll get it up in the air tomorrow and diagnose it. I'll share the pics if it is a "failure".
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Here are a few pics of Pat's car being diagnosed..
First we drained the oil through a strainer to see what material was found.. Then we dropped the sump plate looking for debris but only found some of the IMS bearing seal. This leads me to believe the IMS bearing is going, but is not the primary cause for the car coming to us with its issues. More in the next post with more pics.. |
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After seeing that the IMS probably is not the primary reason for this episode as the bearing seal is just now being compromised the diagnostic process continues in another direction..
At this point it could be something as minor as a blown Air Oil Separator (AOS).. Then I noted an exhaust flange that was wet with oil on the 1-3 cylinder bank and that was suspicious.. See the pics. The next step in diagnosis is finding out why that one exhaust flange is wet, if the issue is the AOS BOTH of the exhaust flanges would generally be wet with oil, so now I am thinking the engine had a failure on the 1-3 cylinder bank. We have pulled the spark plugs and are in preparation for a borescope inspection, followed by a leakdown and compression test. When the #1 spark plug was pulled that cylinder was full of oil, so looks like we have found the smoking gun... This engine hasn't been written off yet, it could still be nothing more than an AOS, but now I am thinking cylinder/piston failure or a valve failure that busted the piston.. The diagnostics will tell us. Pat did the right thing, he shut the car down at the hint of a problem and did not try to re-start it, neither did we... We assume the worst from the beginning and then work our way out to the simpler things.. Lots of people approach this in an opposite manner, only to waste lots of time and the customer's money. |
Ok, compression and leakdown test results are in.. I have found some trend data that is leading me to believe the engine has a bent connecting rod.
Here are the compression and leak numbers: #1= 270 PSI/ 19% leak down #2= 235 PSI/7% leak down #3= 230 PSI/5% leak down #4= 220 PSI/7% leak down #5= 235 PSI/7% leak down #6= 230 PSI/7% leak down The #1 cylinder was filled with oil when the spark plug was pulled for the tests.. A borescope test showed no signs of piston/ valve failure. The high cylinder pressures of 31 are because the cylinder was pickled in oil, forcing the rings to seal off extremely, which is normal... BUT the high leak down numbers don't make sense as the leak down is entering the crankcase, as if the rings are not sealing.. This leads me to believe the engine had a failed AOS, it filled the #1 cylinder with oil and then hydro-locked thus bending the connecting rod. This would explain why dynamic compression is exceptional but static leak down is horrible. The next course of action is to replace the sump plate, fill the engine with oil, replace the spark plugs and coil packs and then fire it up... If the engine has a rattle, we know its not the IMS bearing, because we know it is at stage 1 failure, but thats just a compromised seal.. If this rattle is found near #1 cylinder with the stethoscope then we can figure that the connecting rod is bent. If the rod is bent, the engine will be issued a Death Certificate as the work to repair this on the 1-3 cylinder bank requires complete disassembly. If this is the case its a classic example of how an AOS can fail and create a secondary failure with enough collateral damage to kill the entire engine... Or the head could have cracked and dumped oil in the cylinder, or the scavenge pump on that bank could have failed, or, or, or.. it could be a new mode of failure we've never seen before. So, after lunch we'll service the engine with oil, fire it up and see what happens... If it doesn't rattle we'll change the AOS then run the engine on the dyno, get it warmed up to burn all the oil out of the cylinders and then run a second compression and leak down test to see if the numbers on cylinder #1 are closer to those of the other 5 cylinders. Hopefully all 5 cylinders will be within allowable tolerances at +/- 10% differential across the board. I'll report back... |
This entire thread is amazing. From breakdown to analysis/diagnosis in Jake's shop within 24 hrs.
Jake, I really appreciate you explaining your thought process and logic rather than just posting your final findings. This allows alot of us with less knowledge and experience to follow closely and understand the process. If only my wife's cardiologist was as competent and forthcoming with information. I feel as if I'm standing next to Jake explaining all this to me personally. A virtual workshop. My totally stock 2000 S is running great at the moment and that can give one a false sense of security but I know this type of failure is a real possibility. I will have to get more proactive in treating my car to some preventative maintenance. |
Can you observe whether the Piston has less travel than the other
cylinders with a hand turn? A hydrolock we had -- bent the connecting rod (effectively shortening it) and the piston travel was shorter than the others -- I don't remember by how much -- but it was visually noticeable. Mike Quote:
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JTP,
Thanks for the kind words... I wanted to take this opportunity to illustrate how these engines should be cared for and examined when they have had potential failures.. The general way a shop attacks a problem like this is by "throwing parts at it" to see what repairs the issue.. This engine also had all the classic examples of a total failure, so many would say "its blown up, replace it" when the reality of it is the engine might not have had much going on at all.. Its too early to say, but I am hopeful that we can have this car repaired within 48 hours from the time it failed... It arrived on the perfect day, we are awaiting parts for every other job in the shop!! Mike, If this rod is bent, it has not been shortened, it has more than likely been twisted in the bore, which is how I have seen these rods deform in the past with hydro-lock. |
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You've got way more datapoint -- the one I saw curled over with a bow -- I'll have to dig it out and see it actually twisted and see if I can determine if the stroke would have been shorter or not. Always trying to gleam some information from every failure to make the next go round easier. As others have said -- thanks for sharing! Mike |
Learning from failures provides exceptional experience.. Thats what we do and have done, even with our own test engines.
Now, the results are in... It appears that Pat dodged a big bullet!! We detached the AOS charge hose to the intake and blocked it off, filled the engine with oil and fired it up.. It smoked like a freight train for 5 minutes and then started clearing up!! There were ZERO mechanical sounds from the engine from start up to full warm up so I feel the issue is the AOS.. I also feel the engine is mechanically sound. Now we will install a new AOS .. I'll then drive it home tonight and put some miles on it under a watchful eye, then tomorrow we'll repeat the compression and leak down tests and compare numbers to ensure the episode didn't hurt anything else. NOW: What people need to learn from this is simple.. IF Pat had cranked this car back up after this extreme episode he would have been in trouble.. The #1 cylinder was half filled with oil, just a bump of the starter would have hydro-locked the engine and created a cylinder/piston/connecting rod failure in short order.. Thats because engine oil can't be compressed to figures as high as the CR of the engine, near 11:1.. Something has to give and something will break. I think this one was just an extreme AOS failure, we know that everything else is fine.. BUT Pat has an IMS bearing thats at a very early stage 1 failure and he has to make up his mind about what to do. With the car at my facility, the wisest decision is to retrofit that puppy and be done with it.. With seal material in the sump, I feel OK test driving it and doing the rest of my work, but I'd do something very soon... I won't be dynoing this car until the IMS bearing is addressed, the liability is too high to stress the engine that hard with seal material in the oil... Pat, go play the lottery... You were lucky today.. BUT you paid attention to the forums and did exactly what you were supposed to do, shut the car down immediately, don't try to re-start it and get it to someone who specializes in the M96 engine. I could be wrong and if I am the test drive will illustrate that later this evening.. Thats why I do things the way I do them. |
Makes me glad I replaced my original AOS at 84k when I put in the new clutch and LN bearing. I thought at the time maybe I was being a bit over cautious. Very interesting stuff and thanks for sharing as well.
Steve |
wow, jake. awesome diagnostic plan. thanks for sharing this; it really does provide insight into the merits of a sound, scientific diagnostic approach versus the shady tree shotgun approach.
as we can all see, it pays dividends, and appears to have done so in this case. nice work! |
I'll post when I get home this evening with news about the test drive...
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As many others have said...thank you. Great thread everyone, especially JR!
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Mine is an '03 base and wonder if it too has a potential problem with RMS. Also has Porsche made a recall on this issue or any class action filed to have Porsche rectify a major issue?
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AlexH, the short answer to your second question is simply No. Porsche is pretty much not going to cover anything having to do with this unless the car is still under warranty...which is why it's an especially big problem...and also why there's Jake Raby with solutions. :cheers: |
A Judge won't keep your engine from failing.. sorry..
I drove Pat's Boxster home tonight.. 43 miles with no issues at all. After the first 10 miles with the new AOS fitted the smoke had completely cleared up and there were no noises or issues at all. We'll re-test for compression and leak down tomorrow to see if the numbers are more consistent after run time to burn all the oil out of the intake/cylinders and etc. This was just a bad AOS, but it could have been much, much worse. |
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