 Initial Diagnosis, Fritz is hurt... |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
  |
| nine14cats |
  Oct 12 2006, 11:15 AM
Post
#1
|
|
Bill Pickering -- 914-6 GT aka....Leeloo  Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None  |
We just looked at the motor in Fritz. We found the belt in the dual distributor broken and one of the disty caps had evidence of arcing. Leakdown shows cylinders 4 and 5 have 100% leakage. You can hear the air rushing past the exhaust valves! (IMG:style_emoticons/default/barf.gif)
In a word....fuck... (IMG:style_emoticons/default/icon8.gif) (Sorry for the language, I'm a little sad and more than a bit frustrated). It would appear that I either have bent valves in cylinders 4 and 5 or broken rings and / or pistons. Can a distributor failure in one of the two disty's lead to such a top end failure? I was driving very well at Thunderhill when this happened. I did not miss a shift or over rev the motor. The funny thing was that I was actually feeling smooth about everything. I cannot describe how bad I feel. We're having another cup of coffee and the motor will be dropped in about 2 hours. We will tear down the top end over the next few weeks and fix it. Major bummer. Bill P. |
   |
 
|
| J P Stein |
Oct 12 2006, 12:04 PM
Post
#2
|
|
Irrelevant old fart Group: Members Posts: 8,797 Joined: 30-December 02 From: Vancouver, WA Member No.: 45 Region Association: None |
From what I've read, yes. With only one plug firing, you can get detonation.
|
|
|
|
| McMark |
Oct 12 2006, 12:05 PM
Post
#3
|
|
914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
The 'dead' distributor was probably firing one or two cylinders (4 & 5 I'd wager). So you would be getting extreme detonation in those cylinders. I haven't heard of detonation bending valves, but I suppose it's possible. Or the detonation caused the timing chain to skip or stretch to the point where the piston contacted the valves.
If it's just leaking out the exhaust valve, there's a chance your pistons are okay and it'll only need some head rebuilding. :pray: |
|
|
|
| Brad Roberts |
Oct 12 2006, 12:20 PM
Post
#4
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
The second dizzy head ran by the belt runs the bottom plugs. There is something like 5deg timing difference between the two rotors. If the belt breaks.. the computer cannot compensate enough with the timing (knock sensors cant keep up) and you get severe detonation. Porsche has reported MULTIPLE broken cranks!! because of this issue. This is why the updated breather setup from the fan was SOO important. They added a line from the fan shroud to help evacuate what amounted to "ozone" breakdown of the small drive belt.
This SUCKs. This could be worse than thought. B |
|
|
|
| nine14cats |
Oct 12 2006, 12:33 PM
Post
#5
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
QUOTE(Brad Roberts @ Oct 12 2006, 11:20 AM)  The second dizzy head ran by the belt runs the bottom plugs. There is something like 5deg timing difference between the two rotors. If the belt breaks.. the computer cannot compensate enough with the timing (knock sensors cant keep up) and you get severe detonation. Porsche has reported MULTIPLE broken cranks!! because of this issue. This is why the updated breather setup from the fan was SOO important. They added a line from the fan shroud to help evacuate what amounted to "ozone" breakdown of the small drive belt. This SUCKs. This could be worse than thought. B The motor was idling smooth and we just cut open the filter and found not metal. Can I still have a broken crank? Bill P. |
|
|
|
| nine14cats |
Oct 12 2006, 12:35 PM
Post
#6
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
Engine shot...dropped in one hour and 15 minutes....drinking coffee...
Attached image(s) 
|
|
|
|
| nine14cats |
Oct 12 2006, 12:36 PM
Post
#7
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
another engine shot...
Attached image(s) 
|
|
|
|
| nine14cats |
Oct 12 2006, 12:36 PM
Post
#8
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
What the hell...my G50.... (IMG:style_emoticons/default/biggrin.gif)
Attached image(s) 
|
|
|
|
| nine14cats |
Oct 12 2006, 12:40 PM
Post
#9
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
On the plus side, the lightened flywheel and 4 puck clutch setup looks great. No wear issues. Even AXing it all season on top of the track events.
I may put a new 4 puck back in and keep the used one as a spare...you know...DWD... (IMG:style_emoticons/default/happy11.gif) And maybe some solid lifters? More things to think about. Bill P. |
|
|
|
| brant |
Oct 12 2006, 12:40 PM
Post
#10
|
|
914 Wizard Group: Members Posts: 11,618 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
|
dang sorry about that bill.
my understanding of the broken dist belt, is that the detonation often holes a coupld of pistons. on your 100%leakdown test, where was the leaking sound going (intake, exhaust, oil sump?) you can put a rubber disposable glove over the intake/exhaust/vent and easily see where the leak is going. hoping for the best! brant |
 |
|
| nine14cats |
Oct 12 2006, 12:42 PM
Post
#11
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
QUOTE(brant @ Oct 12 2006, 11:40 AM) dang sorry about that bill. my understanding of the broken dist belt, is that the detonation often holes a coupld of pistons. on your 100%leakdown test, where was the leaking sound going (intake, exhaust, oil sump?) you can put a rubber disposable glove over the intake/exhaust/vent and easily see where the leak is going. hoping for the best! brant Hi Brant, It appears to be coming from the exhaust valves on both 4 and 5. I'm hoping it's top end only. So far, finding no metal in the oil or filter is a positive. Bill P. |
|
|
|
| Brad Roberts |
Oct 12 2006, 12:51 PM
Post
#12
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
The engine will run fine on one belt. I know several 993 owners who drove around for years with one broken belt. They always ran premium and never drove the car hard. They ignored the dash light. The computer will log mis-fires.
I dont know how else the valves would have bent unless a piston or 3 came apart and hit the valves. Brant nailed the test with the plastic gloves. Factory techs are trained to use a glove on the oil filler of a Boxster or 996 to check for a broken Air/Oil seperator. If the seperator is broken.. then the glove gets sucked into the oil filler neck! B |
|
|
|
| KenH |
Oct 12 2006, 03:09 PM
Post
#13
|
|
Senior Member Group: Members Posts: 680 Joined: 16-January 03 From: Gilroy, CA Member No.: 156 |
Might consider "Crank-Fire" ingition when you rebuild.
Ken |
|
|
|
| Aaron Cox |
Oct 12 2006, 04:10 PM
Post
#14
|
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
QUOTE(KenH @ Oct 12 2006, 02:09 PM) Might consider "Crank-Fire" ingition when you rebuild. Ken got clewwit on speed dial ? (IMG:style_emoticons/default/smile.gif) sounds like a good idea |
|
|
|
| Brad Roberts |
Oct 12 2006, 04:20 PM
Post
#15
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Cheaper to replace the little belt once a year.
I'm curious now to know whether or not the car has a "check engine light" This would have quickly triggered the light when the belt broke. I'm kinda doubting it had a light since the gauges are probably early 911 and not 993. I suggest a Boxster (IMG:style_emoticons/default/alfred.gif) B |
|
|
|
| nine14cats |
Oct 12 2006, 04:27 PM
Post
#16
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
The tub is a 1980 SC with only oil temp and pressure and tach left. No warning lights.
With my luck regarding race cars, I fully expect to blow the Boxster motor when I start it up to pull it out of the trailer at the first event. Really. Bill P. |
|
|
|
| Series9 |
Oct 12 2006, 04:47 PM
Post
#17
|
|
Lesbians taste like chicken. Group: Members Posts: 5,444 Joined: 22-August 04 From: DeLand, FL Member No.: 2,602 Region Association: South East States |
I'll be watching this.
I have bad dreams about that distributor belt cutting loose on the RS. |
|
|
|
| Randal |
Oct 12 2006, 04:51 PM
Post
#18
|
|
Advanced Member Group: Members Posts: 4,446 Joined: 29-May 03 From: Los Altos, CA Member No.: 750 |
QUOTE(nine14cats @ Oct 12 2006, 03:27 PM) The tub is a 1980 SC with only oil temp and pressure and tach left. No warning lights. With my luck regarding race cars, I fully expect to blow the Boxster motor when I start it up to pull it out of the trailer at the first event. Really. Bill P. No metal in the oil filter is a good sign. If the crank was gone there would have been lots of noise and metal everywhere. Air blowing into the header says a valve is bent, or I guess in the case of extreme detonation part of a valve could be missing? Do you have a scope to look into the cylinder? You might learn a lot. Still hoping it is confined to the top end. |
|
|
|
| nine14cats |
Oct 12 2006, 05:15 PM
Post
#19
|
|
Bill Pickering -- 914-6 GT aka....Leeloo Group: Members Posts: 2,618 Joined: 10-February 03 From: Campbell, CA Member No.: 287 Region Association: None |
QUOTE(Randal @ Oct 12 2006, 03:51 PM) QUOTE(nine14cats @ Oct 12 2006, 03:27 PM) The tub is a 1980 SC with only oil temp and pressure and tach left. No warning lights. With my luck regarding race cars, I fully expect to blow the Boxster motor when I start it up to pull it out of the trailer at the first event. Really. Bill P. No metal in the oil filter is a good sign. If the crank was gone there would have been lots of noise and metal everywhere. Air blowing into the header says a valve is bent, or I guess in the case of extreme detonation part of a valve could be missing? Do you have a scope to look into the cylinder? You might learn a lot. Still hoping it is confined to the top end. Hi Randal, I was going to take it easy this weekend and just pick off the honeydo list before the big build weekend. It looks like we'll pull the motor apart this weekend instead. I'll take pics of our findings. Bill P. |
|
|
|
| sixnotfour |
Oct 12 2006, 07:03 PM
Post
#20
|
|
914 Wizard Group: Members Posts: 10,418 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains
|
QUOTE I dont know how else the valves would have bent unless a piston or 3 came apart and hit the valves. Missed shift =mechanical overrev= bent exhaust valves |
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 3rd May 2024 - 03:18 PM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.