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One of those things that you have to stifle hurling when you see it. Sorry. What are you going to do? That engine could be fixed, did the head get hurt? Whatever you do is going to be expensive.
Here is a picture of the head for cylinders 1-3 (broken piston is on #1)
#1 valves and head appear OK mechanically but what does the lighter color on #1 tell you? Intake and exhaust valves on #1 are white compared to others.
No misfire codes were showing in Durametric?!?
Will post next update after I "split the case" and get piston out of cylinder.
I’m guessing that cylinder was running lean.... which in turn increases the combustion temps and burns off all the carbon deposits, leaving the white color. Probably a bad fuel injector. But I would have thought you’d get a code or symptoms(detonation etc) before the cylinder cracked.
Could also be an air leak for just that cylinder(which also causes a lean condition). But judging by the color of those valves it’s been an issue for a while and not something that just happened.
That whole engine was running a very lean fuel mixture.. Which promotes detonation.
Do you have any pics of valves/heads with a good mixture?
The one is obviously lean but the others didn’t look too terribly bad to me. (Then again I’ve never opened a Porsche engine before, and wasn’t paying attention to his cars mileage etc).
ADDITIONAL INFO THAT I REALIZE IS NOW RELEVANT: PREVIOUS OWNER reported check engine light came on at 21,000 miles
Code P1128 -> oxygen sensing range 2 Cylinder (1-3)
Code P1130 -> oxygen sensing range 2 Cylinder (4-6)
Dealer told PO “OK to drive the car as long as check engine light is orange”; no additional diagnostics or repairs completed by PO
I BOUGHT CAR at 24,400 miles & drove cross-country back home
Confirmed codes P1128 & P1130 still relevant using Durametric
Confirmed all fuel trims were high (car running lean) was causing check engine light:
Range 2, cylinder 1-3 (FRA) = 1.29
Range 2, cylinder 4-6 (FRA 2) = 1.29
Range 1, cylinder 1-3 (TRA) = 0.13
Range 1, cylinder 4-6 (TRA 2) = 0.16
Confirmed no intake or exhaust leak; confirmed fuel pressure at rail; replaced MAF sensor at 27,400 miles -> engine operated for 6,400 miles at lean condition
Check engine light off; no codes per Durametric; all specs for DME setpoint in limits per factory manual; passed SMOG
ENGINE SEIZED at 28,500 miles --> Moral of the story...don't ignore your check engine light!
That side looks worse then the other side.
So what are your plans moving forward?
And any idea what was causing it to run lean to begin with?
Good luck with everything. I hope you rebuild it and put 100k miles on it.
Do you have any pics of valves/heads with a good mixture?
The one is obviously lean but the others didn’t look too terribly bad to me. (Then again I’ve never opened a Porsche engine before, and wasn’t paying attention to his cars mileage etc).
Here's a pic of a Boxster head and its combustion chambers. The head is off due to broken valve spring. The chamber with the missing valve is the cylinder with the broken spring. But the engine was healthy before the valve spring broke. The driver, a woman, suspected something was wrong -- I don't recall the symptoms the tech told me she reported now -- she brought the car in pronto.
The tan color in Macster's photo is what your valves should look like. Your engine, as I remember, is very low mileage. Pulling the heads, for me, is the scary part, So in for a dime, in for a dollar, I'd go ahead and at least rebuild that bank. Unless there's massive scoring, you might be able to just replace the broken piston with a new one in standard size. I would want to have those valves checked for burned seats, and have that corrected as needed. My guess would be your lean condition was because of faulty O2 sensors. Obviously something you should take care of immediately. I know they are expensive, but I would suggest OEM.sensors.
Nice if the scoring isn't bad, you might could get by with just honing.
ADDITIONAL INFO THAT I REALIZE IS NOW RELEVANT: PREVIOUS OWNER reported check engine light came on at 21,000 miles
Code P1128 -> oxygen sensing range 2 Cylinder (1-3)
Code P1130 -> oxygen sensing range 2 Cylinder (4-6)
Dealer told PO “OK to drive the car as long as check engine light is orange”; no additional diagnostics or repairs completed by PO
I BOUGHT CAR at 24,400 miles & drove cross-country back home
Confirmed codes P1128 & P1130 still relevant using Durametric
Confirmed all fuel trims were high (car running lean) was causing check engine light:
Range 2, cylinder 1-3 (FRA) = 1.29
Range 2, cylinder 4-6 (FRA 2) = 1.29
Range 1, cylinder 1-3 (TRA) = 0.13
Range 1, cylinder 4-6 (TRA 2) = 0.16
Confirmed no intake or exhaust leak; confirmed fuel pressure at rail; replaced MAF sensor at 27,400 miles -> engine operated for 6,400 miles at lean condition
Check engine light off; no codes per Durametric; all specs for DME setpoint in limits per factory manual; passed SMOG
ENGINE SEIZED at 28,500 miles --> Moral of the story...don't ignore your check engine light!
What's you next steps OP? You seem like a very competent owner. Most people would not know how to disassemble the engine to examine the problem as you have. I hope you'll continue to get this one back on the road. Good luck!
Wow.
The system was screaming that the car had a problem.
The oxygen sensing was showing a very lean condition. Note that this is not a code for an “oxygen sensor” but a code for the oxygen being sensed.
Those readings are off the chart. Usually when l see fuel trim maxxed out, the car is losing a fuel pump, and is therefore going very lean. The engine will still run fine, but just be lean. Since “lean is mean” a lean engine can actually make better power than an engine running at a proper AFR.
This is a classic. When you repair this engine, replace the fuel pump- else you’ll do this all over again. Keep an eye on the fuel trim, and make sure you carry out a system- reset before starting the engine up after repair. If not, the system will default to the prior adaptations.
Whomever said to ignore the CEL needs their *** beat. l could have looked at that data, and in 10 seconds would have told you the engine is lean. Just like l did when looking at the pieces of the disassembled engine.
UPDATE Feb 24 Car: 1999 Boxster 2.5L; 28,500 miles (very low mileage!) Status: Engine teardown complete (case split and bearing housing removed)
for affected cylinder (#1) removed connecting rod bolts so that bearing housing could be removed since piston is jammed in cylinder
#1 cylinder sleeve is slipped -> is this the now infamous workaround for late '98 to early '99 cars that is well documented? (cosmetic damage visible on edge is likely from my repositioning the bearing housing during removal)
#1 piston cannot be removed from the cylinder
Goals: reliable daily driver; not going to track this car; not interested in increasing displacement/"upgrading" to a larger engine
Options:
rebuild engine reusing some "good parts" from existing -> piston rings alone would be $1,200 ($200 each for genuine Porsche!)
replace entire engine with used -> light "refresh" for external items recently replaced on current car (e.g. AOS, intake seals)
replace entire engine with professionally rebuilt ($$)
Choice 4 is gonna be just give it away, your return will be lucky to hit $3000. For a very low use chassis and a bunch of engine parts. I wouldn't do that.
#3 is the best answer, but it would be frightfully expensive. It would restore all of the value to your beautiful car!
#2 Is a crapshoot. I would buy a used engine from Woody. Or 20th Street Auto in Phoenix (done business with them and they are up&up) I got my engine from a guy on Ebay who sent me a nice engine for a good price--he's a breaker in LA. If the used engine worked out it would restore most of the value to your car. A decent used engine would probably be around $3 grand. Finding a very low mileage unit would be difficult and cost more. Mine had around 60,000 miles on it.
#1 I would never do. I've rebuilt more engines than I can remember in my life and the Porsche flat 6 engines terrify me. It would cost you at least $3000 in parts, machine shop work, and put together time.
I would choose strategy #2. Going to probably have decent out come and contains costs. It's what I did on my 01.
02-18-2019, 10:27 AM
