another dead boxster @#$%!

[Jake Raby]

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".

[Jake Raby]

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..

[Jake Raby]

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.

[Jake Raby]

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...

[JTP]

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.

[Jake Raby]

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.

[seningen]

Originally Posted by Jake Raby

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.

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

[seningen]

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

Originally Posted by Jake Raby

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...