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 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Apr 2003
Location: Boston, MA
Posts: 132
The good, the bad, and the wierd

I'm tearing down my 90 C2 engine to replace the 4-6 camshaft that was found to have bad wear on the lobes.

Happily a previous owner (not the one I bought the car from though) was thoughtful enough to have the cylinder/heads updated to the graphite head gaskets!!!!!!


Unfortunately, it looks like I need some head work......... 1-3 are like the following, but 4-6 look a nice clean tan..... but that's probably because of a lack of oil on that side.......



I found the following two pieces of flexible rubbery plastic stuck in the narrow end of the oil connector between the chain case, and the cam housing...... I couldn't get a clear picture before the camera batteries died...... It's a 10mm wrench to get an idea of size.....


Is this the cause of my lobe wear? Any ideas what other issues this could cause? Any thoughts on what it could be? Thanks for any ideas.......
-Eric
90 C2
Old 02-18-2006, 12:57 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Apr 2003
Location: Boston, MA
Posts: 132
I removed the rockers on 4-6 and here's what I found......



All 6 look like this, and all the lobes the 4-6 camshaft have a big ridge on the edge.......

The 1-3 cam doesn't have any wear visible.....

Can the worn arms be reground? Or at this stage are they too far gone?

-Eric
Old 02-20-2006, 06:57 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Forced Induction Junkie
 
WERK I's Avatar
 
Join Date: Jan 2003
Location: Wisconsin
Posts: 3,291
Garage
Could it have been caused by improper valve adjustment? If the rocker adjustment was too tight, that is, the rockers riding the cam lobes with zero clearance with the valves closed would cause this. Of course, the valve seats will be carboned, the valve faces will show cracking from excessive heat.
The other possibility is the cam oil spray bars are clogged which would starve the rockers from precious oil lubrication/cooling.
__________________
Dave
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 02-20-2006, 08:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Apr 2003
Location: Boston, MA
Posts: 132
The rockers seemed to be adjusted correctly (I was doing a check when this whole project mushroomed....... bad adjuster foot, bad camshaft..... full tear down..... ugh)

I found little chunks of plastic/hard rubber in the oil tube that runs from the chain housing to the cam housing, so I'm pretty sure it was causing oil starvation...... Now, I have to find out where it came from........ and where else it could have gotten into...........

-Eric

Last edited by ekessel; 02-20-2006 at 08:47 AM..
Old 02-20-2006, 08:45 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
syncroid's Avatar
 
Join Date: Jul 2005
Location: San Jose
Posts: 4,260
You need to check the cam spray bars for debris. It looks like one of them is oil starved. There are three orifices for each cylinder. (spraying both intake and exhaust lobes of the cam)
__________________
Dan
2018 Jeep Compass
2001 Toyota Tacoma 4dr. 4x4
1974 VW Thing (my back burner project)
Old 02-20-2006, 06:09 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
len911's Avatar
 
Join Date: Feb 2002
Location: Central NJ
Posts: 568
I would inspect the chain guides... The guides snap onto the pins that hold them in place (grooved pins) I wonder if the guides broke while they were being installed... I accidentally broke mine while removing them from my current engine and they kind of look like your pieces. A careless mechanic could have just shove the pins into the guides, they snapped and fell to the bottom of the case and the rest is history... Other possibility might be foreign object falling into oil tank... Lou
__________________
'76 911 "Moneypenny" daily driver
'74 911 "JLo" IROC DE Car
'03 CRV, '02 Jeep Grand Cherokee
'03 Holiday Rambler Admiral SE, 30ft, 8.1l, 340HP, 455Ft#
http://www.nicotra4.hpshare.net/BasketCaseMotorsports/
Old 02-20-2006, 06:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered User
 
camgrinder's Avatar
 
Join Date: Feb 2004
Location: California
Posts: 921
I would toss that rocker arm in the trash. From the looks of the rocker I would bet the camshaft is toast.
Take a look at the rocker arms on the left side. How close to the inside of the pad is the wear pattern?
__________________
John Dougherty
Dougherty Racing Cams
Old 02-20-2006, 07:00 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Apr 2003
Location: Boston, MA
Posts: 132
All six of the 4-6 rockers look like the picture, and all the lobes are worn....... oh well, they never said this car was going to be cheap......

There is no visible, feelable wear on the 1-3 cam shaft, and the rockers have an almost imperceptible wear at about the same place as on the bad rockers, but you really have to try to see it..... so i'm hoping they are okay.....

Can anyone explain the oil flow from the pump to the chain cover to the cross over piece, so I can try to figure out where to look for more debris? I'm going to pull the "plug" off the bad cam carrier to see what's inside...... I did check the chain guides, and they look okay. The pieces I found are flexible, much softer than the chain guide plastic......

Thanks for any ideas on this,
-Eric
90 C2 (work in progress)
Old 02-20-2006, 07:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 03:13 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 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.