Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
One Dead Cylinder

I have an '85 930 that I got about a year ago with 68k miles. This car is all stock and appears that it has never had the motor out (very limited records came with it). The care was in great condition, but had been driven very little over the past 10 years or so. I had a PPI done that showed it was pretty solid, but did have some gremlins that the previous owner(s) probably didn't care about fixing since they only drove an average of 800 miles/year. I drove it all summer and fall and did a bunch of DIY projects to get things sorted and reliable (CV boots, switches, shift linkage bushings, removed aftermarket alarm, etc). By the end of the summer, after a couple thousand miles of reliable and enthusiastic driving, it was leaving a few decent size puddles of oil on the garage floor. I also noticed that it was smoking more on start up and starting to consume more oil than was landing on the garage floor.

So, last fall, I decided to take it down to my buddy's house for winter storage and to tinker on it with him (he is an accomplished mechanic on all sorts of equipment from big rigs to now being a partner in a motorcycle shop).

We decided to pull the motor and do a full re-seal, replace the oil return tubes as they were leaking heavily, and replace lots of other suspect seals. Along the way, we decided to do a leak-down check and this is where the fun begins:

First leak down test
#1 = 18% Acceptable
#2 = 98% BAD - leaking through exhaust.
#3 = 14% Acceptable
#4 = 15% Acceptable
#5 = 19% Acceptable
#6 = 18% Acceptable

We then adjusted all valves. All were pretty close. Two intake and two exhaust valves loose and one exhaust valve tight.

Re-tested #2 and improved marginally to 95%. Then put a little oil in the cylinder and tested again. This time improved to 90%. Still not acceptable, and still leaking heavily through the exhaust. One thing that may have contributed to this issue is that the motor got pretty hot a few times during low speed driving last summer due to crimped/crushed oil lines to the front oil cooler - could this have damaged the exhaust valve or seat? I'm assuming the replacement/repair of the front oil cooler lines will help thing immensely.

Given that this test was performed on a cold engine, I would say all, but cylinder #2, are in good working order. This leaves the question of, do you only make repair to that cylinder? Or all 1-3 cylinders. Then, do you leave the other side alone?

I really like this as a stock car and expect to drive up to 5k miles/year. Any insight from the Pelican gurus on how far into this you would go?




Old 05-06-2013, 04:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Feb 2008
Location: Bayside Wi
Posts: 2,760
I had a similar problem, years ago, with a valve guide on my 1978 turbo. The shop just replaced the guides in the bad cylinder. that was 8000 miles ago and it still is fine.So just head work ( if that is the problem ) should keep it going for awhile. Of course I could have had a complete redo as it had 54K miles on it then, however I left it stock afterwards. If you are thinking of adding 20% or more hp well that could be a game changer "another issue" depending on your time of reference. Nice color, is that Renrot Color code #867?
__________________
Anthony @ Voitureltd Bayside WI.

Last edited by voitureltd; 05-06-2013 at 04:58 PM..
Old 05-06-2013, 04:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 3,405
When I got my PPI (motor had a fresh top-end rebuild), all cylinders read 3-5% cold.

I was told "anything less than 10% cold is just fine".

When I asked what they did if any showed more than 10%, reply was "repeat the test hot - over 10% hot is NOT good".

Sorry, 19% cold doesn't sound great to me. I wouldn't think your oil temps in traffic have anything to do with this problem - unless they're outrageously high....

Personally, I wouldn't rebuild half the motor - although I might fix an issue with a single cylinder. But it makes little sense to fix one when you're going to be "right there" anyway.

P&Cs are almost certainly fine, might have broken rings, great opportunity to fit ARP rod bolts for safety and do the heads right; likely guides, maybe a set of valves.
__________________
'77 S with '78 930 power and a few other things.
Old 05-06-2013, 05:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
Voiture, it is Garnet Red, LM3Y/822. At 70k miles, I am teetering on the edge of the band aid (possible guide) vs. doing it right as Spuggy mentions. Spuggy, I was thinking the hot temps were from the crimped/crushed lines to the front oil cooler. Thanks for the input guys.
Old 05-06-2013, 05:54 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Feb 2008
Location: Bayside Wi
Posts: 2,760
Quote:
Originally Posted by aerochip View Post
Voiture, it is Garnet Red, LM3Y/822. At 70k miles, I am teetering on the edge of the band aid (possible guide) vs. doing it right as Spuggy mentions. Spuggy, I was thinking the hot temps were from the crimped/crushed lines to the front oil cooler. Thanks for the input guys.

My job was done by a shop that does lots of race support so it was a quick fix with just a partial disasembly of the motor as the other cylinders were fine at that time. I think the complete repair was around $1800. They thought it was a isolated incedent due to overheating in the cylinder that is known for that problem. still runs great. Well at 70 K you are much closer to a complete redo depending on the abuse from last 70K miles, I was @ 54K and pretty much pampered miles with good maintinance from new.
__________________
Anthony @ Voitureltd Bayside WI.

Last edited by voitureltd; 05-06-2013 at 06:21 PM..
Old 05-06-2013, 06:16 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 3,405
Quote:
Originally Posted by aerochip View Post
Spuggy, I was thinking the hot temps were from the crimped/crushed lines to the front oil cooler.
Well, probably didn't help... If it was very restricted (does the cooler get hot?), you'll reduce the effective oil capacity (making what's left work harder) and reduce the effectiveness of the cooler as a heat sink as well.

What oil temps did you see?

I have a big-ass front-mount oil cooler.. Works extremely well when moving - but doesn't do jack when the car is stationary (see temps of ~220 idling in traffic - but rarely see more than 210 on the track.) If you don't have a fan on your cooler, it'll behave much the same way in traffic - even if the oil line is open...

Holding 2000 RPM moves more air over the engine cooler. But you won't drop it more than 10 degrees or so, solution is to start moving or otherwise get out of traffic
__________________
'77 S with '78 930 power and a few other things.
Old 05-07-2013, 07:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Jiu Jitsu Grappler
 
Rodsrsr's Avatar
 
Join Date: Jul 2006
Posts: 4,570
Garage
18% leakdown is hardly acceptable for a Porsche motor. These are very precision engines ...not small block Chevys. 5% or less is where you should be.
__________________
Jiu Jitsu Grappler
Know Gi / No Gi

1976 Turbo Coupe 3.2
2009 Carerra S 997.2 (SOLD)
Old 05-08-2013, 08:35 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 13,433
did it run ok before the removal?
you may have dislodged some carbon and it is now blocking the E valve. if that one was lose, i would consider this even more.

those numbers are a bit high. if you did not have the bad cylinder and the engine was still in the car, i would say drive it. since it is out and if you have to do one cylinder, i would re-ring all 6, do the heads a rockers and put SC cams in it.
the bad thing is, you could pull the pistons and they be out of spec, then your bill just doubled.
if they are a OK, you have a great motor for another 120-150k.
__________________
86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 05-08-2013, 10:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Jiu Jitsu Grappler
 
Rodsrsr's Avatar
 
Join Date: Jul 2006
Posts: 4,570
Garage
Thats ture...new rings on out of spec ring lands will just exacerbate the problem and eventually break the new rings. I would bet that the motor just needs a complete top end...valve job, guides, chains, ect. The bottom ends are fairly robust and you may not even need to touch it.
__________________
Jiu Jitsu Grappler
Know Gi / No Gi

1976 Turbo Coupe 3.2
2009 Carerra S 997.2 (SOLD)
Old 05-08-2013, 03:14 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 3,405
Quote:
Originally Posted by Rodsrsr View Post
The bottom ends are fairly robust and you may not even need to touch it.
Factory rod bolts are probably the weakest link in the stock 3,2/3,3 bottom end. They stretch if you over-rev. And then they're not under tension and just come undone.

Sometimes, they do this even if you don't over-rev. 3,2 bolts do this as well. Because they're the same bolts. Week after my 3,3 did it, 3,2 was in the same shop because it threw a bolt on the same rod (#6). 160,000 mile car, same owner for the last 15 years or so. Shop owner said "they just do that; sometimes. I can guarantee the owner didn't over-rev it".


That will cost a rod, guaranteed. Probably a crank journal. And you may find (like I did) that a good used std/std crank with matched rods is almost the same price as a set of undersize big end bearings - and you avoid a crank regrind/re-hardening (which apparently is not as good as the original). But you're still splitting the cases either way.

ARP rod bolts are an investment/cheap insurance if you're lifting the cylinders anyway; no real need to split the cases just to fit them. Although you have to go by torque if you don't - and measured stretch is arguably better (and manufacturer preferred/recommended).

That's just the very top of the slippery slope....
__________________
'77 S with '78 930 power and a few other things.
Old 05-08-2013, 04:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Rocket Scientist
 
Join Date: Jun 2008
Location: Detroit
Posts: 938
At 95% leak down cyl 2 should be acting like a dead miss. Is it running poorly? I would think you would notice something like that.

Being a flat engine, it is not unusual to have some carbon fall down and get between the valve and seat, especially with all that hand turning to get the pistons at tdc. Maybe you should give it another chance?
Old 05-08-2013, 06:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
Voiture, thanks for the feedback. A couple of builders/wrenches have also suggested that scenario along with rapping on the rocker to perhaps loosen up some carbon build-up. What were your symptoms when you did the guide?

Spuggy, on a few occasions last summer it got as hot as a needle width above the 2/3 line (I forget what the little numbers say on the way outside and they are in C on this Euro car). I rarely drive in any traffic, but we have some fun, long, windy, 1st, 2nd, 3rd gear uphills here in Utah and that is where I would see the temps. This is a stock, fun, weekend car that gets me out of the house and in the garage; I like tinkering but I would like to avoid the slippery slope, for now at least.

Speedy, it was not running poorly, quite the opposite in fact. We are going to take another look at things this weekend and come up with a plan.

I really appreciate everyone's input and advice!
Old 05-09-2013, 07:42 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Turbo Hooligan
 
Join Date: Sep 2007
Location: Greensboro NC
Posts: 1,246
since its a stock Euro Car, it could be possible for the mechanic to have accidentally moved the crank pulley to the advance timing mark instead of the 120 mark...then bam wide open valve on #2. if you have 98% leak down on #2 its a dead miss. you could pull the spark plug lead and it not make a change.
__________________
www.d-zug.com
blog.d-zug.com

All these guys do is drive too fast, work on cars, chase ******* and drink.. really no fun at all...
Old 05-09-2013, 05:51 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,634
Yeah, make sure you didn't accidentally miss-timed the crank when doing leak-down. Either that or there is a big hole somewhere. Also, try to do it when engine is somewhat warm.
__________________
Thank you for your time,
Old 05-11-2013, 11:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
This weekend was revealing. With heads off, we now know that this top end was very tired. 5 out of 6 cylinders had broken rings, with #2 (the suspect cylinder) having a shattered ring in a dozen or so pieces and also a very wet exhaust valve. All pistons and heads have a pretty good build up of soot/oil and piston skirts have evidence of blow-by. A quick inspection didn't reveal any tell-tale cylinder damage but we have not yet inspected the pistons and ring seats to see what kind of shape they are in. So, for now, I am definitely in for lots of head work, new head studs, and some cylinder work and rings (at least).

A couple of questions come to mind. I have no idea what condition the cams are in and some guys talk about the merits of SC vs. 964 vs. Stock - can somebody enlighten me to the differences keeping in mind that I intend to keep this as a stock car? What exactly are the new tensioners (current are hydraulic is there something newer)? What is the latest consensus on ARP vs. Supertec head studs?

More to come, but some iPhone pics for now:

Bank 1,2,3 with heavy build up on pistons:


Head 1,2,3 with heavy build up and especially dirty on #2:


Broken ring on #2:


Wet exhaust port on #2:
Old 05-20-2013, 06:50 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
beepbeep's Avatar
 
Join Date: Jun 2001
Location: Sweden
Posts: 5,634
It doesn't look too bad/tired to me. Clean it up, re-ring, measure for wear an re-assemble if OK

P.S. You might want to check injector on #2. Rings got shattered by knock, injector might be flowing badly.
__________________
Thank you for your time,
Old 05-20-2013, 12:11 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
Hey BeepBeep, thanks for the injector suggestion, with the motor out, I'll be checking out the other systems to make sure they are in order.

I'm researching good / reasonable machine shops to do the head work - any suggestions out there?
Old 05-20-2013, 01:11 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
Update on project:
Engine top end completely torn down. Heads sent to Supertec and new guides and exhaust valves installed. Heads received a clean bill of health otherwise. Cylinders and pistons are getting cleaned up and new rings installed. Supertec head studs, a gizillion gaskets and other consumables are being replaced. I hope to have all parts here next week to begin the build back in earnest. I think I have all pertinent parts (who knows), but do have a question about this tube that connects to the crankcase breather. I don't think my photoshop capabilities are very good, but the pipe I am talking about is the metal pipe with the heavy weld line that has a a fitting with braided hose that connects the engine breather. My question is: is this a stock piece? If so, what is the part number - I can't find it anywhere? Thanks for the help!



Old 06-01-2013, 12:55 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
 
Banned
 
Join Date: Nov 2007
Location: Rockwall, Texas
Posts: 8,760
Here is the big money breather hose/pipe. The picture/drawing on the Pelican listing is wrong - I got the part number from the Porsche PET, page 36, with the correct drawing.


Pelican Parts - Product Information: 930-107-397-01-OEM

What most people do with that breather pipe, if the hose section is leaking, is carefully cut the crimped metal part so you can remove the short section of hose and then install a new section and simply fasten it with hose clamps - works great as only oily vapor passes through it.
Old 06-01-2013, 04:40 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Registered User
 
Join Date: Jul 2012
Location: Park City, UT
Posts: 81
Garage
Awesome, thank you Ronnie!

Old 06-01-2013, 05:47 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:48 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.