 Help with Engine Noise, New Overhaul Problem |
|
|
|
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. |
|
|
  |
| Andre914 |
 Jul 6 2005, 10:52 AM
Post
#1
|
|
Newbie  Group: Members Posts: 21 Joined: 23-February 05 From: San Diego, CA Member No.: 3,647  |
I have just finished a complete overhaul of the fuel injected 1.8 liter engine from my 1974 914. I reused the pistons, honed the cylinders, and installed all new rings, bearings, gaskets, and seals. All fits and clearances are within factory limits. The engine is reinstalled and I have set the dwell, timing, and valve clearances. It is running very well except for one thing.
I now have clatter (or a slight mechanical rattle) that ONLY occurs between 2000 and 3000 R.P.M. during deceleration. If I apply any amount of throttle the noise goes away. I have combed the entire engine compartment and undercarriage for sources. Other than the torsion bars for the engine lid and rear trunk lid, which now have rubber hose insulators installed, I can not find anything else moving or hitting other parts. If anyone has a suggestion I would be very grateful. |
   |
 
|
| Jake Raby |
Jul 6 2005, 11:29 AM
Post
#2
|
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Yep... Sounds like a slightly worn lifter bore OR you have wiped the thust on the #3 cam bearing.
Did you double thrust thecam? Were your cam bearings brazilian or German? I'll almost bet the noise is the thrust- Btewen 2-3K the cam is at the poin where it is needing thrust control the most. I have been down this road several times. |
|
|
|
| John |
Jul 6 2005, 11:43 AM
Post
#3
|
||
|
member? what's a member? Group: Members Posts: 3,393 Joined: 30-January 04 From: Evansville, IN (SIRPCA) Member No.: 1,615 Region Association: None |
Jake, Would you please explain? Is this something that you typically do? I would like to know more. Thanks, John |
||
|
|
|
||
| Andre914 |
Jul 7 2005, 12:01 AM
Post
#4
|
|
Newbie Group: Members Posts: 21 Joined: 23-February 05 From: San Diego, CA Member No.: 3,647 |
Jake,
Thanks for your reply. The bearings were the standard German replacements received from Pelican Parts. Thrust is only taken up by one half of the bearing. The cam shaft end play was only .002" or .003" before I mated the cases. Do you think this would be enough to make this noise? I did not replace or regrind either the cam or the lifters this time. Haven't run it enough to wear the thrust surface out yet have I ? |
|
|
|
| Jake Raby |
Jul 7 2005, 12:07 AM
Post
#5
|
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
That means either buying a double thrust cam bearing set (from my store) or buying two sets of stock bearings and removing the thrust bearing from one set to create a "Double thrust" for the #3 cam journal.
This decreases the chances of a bad thrust necessitating a tear down by 1/2.... Were your bearings German or Brazilian? |
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 17th May 2024 - 02:38 PM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.