Who has 100k and NO top end rebuild??
02-08-2011, 12:07 PM
#107
how would i know if the previous owner had a top end rebuild if i bought the porsche from a little mom and pop shop. The car pulls strong, even the rims were cleaned completely all the time, no scratches, engine bay super clean. I say these things because the previous owner must have been **** and probably did it. Is there any way that i can find out?
02-08-2011, 06:00 PM
#108
Instructor
Just went over 100K. I've had it since 70K. Uses about a quart every 2000 miles. No rebuild. Only trouble so far at all was recent. Alternator went out at 99K in the middle of nowhere on I-77 on New Years Day. Closest town was Harmoney, NC. No plane, no train, no bus from Harmony. Cab ride to Charlotte for public transportation was $135. Got lucky with the mechanic who towed in in, though. Good guy. Knowledgeable and reasonable. Believe it or not he owned a 996. The joke in my office was that he had it since the last yankee with Porsche' trouble rode through.
02-08-2011, 07:11 PM
#109
Rennlist Member
111k and car runs great. Really have not monitored the oil (Brad Penn) consumption. SAI/CEL issues but I have been able to pass California smog by clearing the fault codes and following the readiness flag resetting routine until enough are set. Might try SAI flush if can't pass smog next time(2012). No immediate need for top end job at this point--runs TOO STRONG! I guess I do not understand the idea that these cars require a top end job at 100k.
Phil
Phil
02-21-2011, 12:30 PM
#113
Race Car
02-21-2011, 04:14 PM
#116
Rennlist Member
I got no skin in this game but wanted to add what I know. When my motor was torn apart at 29k to upgrade the rods the guides were worn out. By catching it early the valves and seats were saved.
When a guide wears out the valve is no longer guided into it's seat correctly. It now gets guided into place by the valve seat and valve face. This leads to premature wear of the valve and valve seat.
I don't think oil consumption is a good gauge because the valve seals can mask the worn guides. I also don't think that compression tests are helpful because the valve gets guided into place by the taper of the valve and seat. It's only when the worn guide damages the valve and seat the problem starts to show in to form of misfires or lost compression.
Conclusion?? I bet most guides are shot by 50k. I also think the motor will not show symptoms for quite sometime after that. As many have stated they have run over 100k without issues. So what's the proper approach? Great question. Would I tear the motor apart just to change the guides to save the valves and seats. Most likely not. If I was one of those people that dropped the motor for something else then I would strongly consider doing it.
When a guide wears out the valve is no longer guided into it's seat correctly. It now gets guided into place by the valve seat and valve face. This leads to premature wear of the valve and valve seat.
I don't think oil consumption is a good gauge because the valve seals can mask the worn guides. I also don't think that compression tests are helpful because the valve gets guided into place by the taper of the valve and seat. It's only when the worn guide damages the valve and seat the problem starts to show in to form of misfires or lost compression.
Conclusion?? I bet most guides are shot by 50k. I also think the motor will not show symptoms for quite sometime after that. As many have stated they have run over 100k without issues. So what's the proper approach? Great question. Would I tear the motor apart just to change the guides to save the valves and seats. Most likely not. If I was one of those people that dropped the motor for something else then I would strongly consider doing it.
02-21-2011, 04:57 PM
#118
Rennlist Member
Yes and no. Most of the 911 engines I've been into have had a prior "valve job." These would have been done at relatively low mileage as part of a puked chain tensioner repair. So I'd get into them with another 70-100K (120-150K total), and there was rarely an instance a seat would need replacement. Actually, with all the inventory I had around it was easier to find a decent head versus seat replacement. Same with valves. Rare would there be one that couldn't take a second cut. Borderline knife edge? Sure. Mainly it was about stem taper on the intakes though.
In some respects I wish the 3.6L engines weren't so bulletproof. The data we could share back and forth in today's age. Back then how often did you run into another shop owner? At the track maybe a few times a year. Or in one of the monthly magazines with tech articles. (By Bruce Anderson, gasp!)
In some respects I wish the 3.6L engines weren't so bulletproof. The data we could share back and forth in today's age. Back then how often did you run into another shop owner? At the track maybe a few times a year. Or in one of the monthly magazines with tech articles. (By Bruce Anderson, gasp!)
02-22-2011, 03:41 PM
#120
Rennlist Member
No Top End...No Engine work...(I did an SAI flush)
97k on mine and have owned since 40k... so close to 100k, no whammies, no whammies....
use 15-50 Mobil 1 quart per 2600mi...I like to keep oil level at the mid point...
Clutch at roughly 70k
(btw, my alternator went on new years 2010...have been noticing alot of guys losing their alts on new years...?? new thread??)
97k on mine and have owned since 40k... so close to 100k, no whammies, no whammies....
use 15-50 Mobil 1 quart per 2600mi...I like to keep oil level at the mid point...
Clutch at roughly 70k
(btw, my alternator went on new years 2010...have been noticing alot of guys losing their alts on new years...?? new thread??)