Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

Engine Knock

Thread Tools
 
Search this Thread
 
Old Jan 31, 2021 | 01:14 AM
  #1  
PaulCarrera's Avatar
PaulCarrera
Thread Starter
Instructor
 
Joined: Oct 2015
Posts: 145
Likes: 10
From: Sunshine Coast, queensland, Australia
Default Engine Knock

Hi everyone
84 S2 euro
Did a little work yesterday, new thermostat and checked the cam gear bolts and then decided to pressure wash the engine.
after that when I eventually started it after drying the air box out there is a bit of a knocking sound ( not a rod sound ) and wondering if maybe I have gotten moisture into a knock sensor plug or something
does anyone have any ideas?
I have only had it idling at this stage
Reply
Old Jan 31, 2021 | 01:19 AM
  #2  
The Forgotten On's Avatar
The Forgotten On
Nordschleife Master
10 Year Member
 
Joined: May 2012
Posts: 5,216
Likes: 431
From: Thousand Oaks California
Default

Most likely a lifter that just needs to be pumped up from the car sitting. Pretty common and the fix is to drive the car.
Reply
Old Jan 31, 2021 | 06:53 AM
  #3  
gazfish's Avatar
gazfish
Rennlist Member
10 Year Member
 
Joined: Feb 2016
Posts: 1,246
Likes: 271
From: Dublin, Ireland
Default

Originally Posted by PaulCarrera
Hi everyone
84 S2 euro
Did a little work yesterday, new thermostat and checked the cam gear bolts and then decided to pressure wash the engine.
after that when I eventually started it after drying the air box out there is a bit of a knocking sound ( not a rod sound ) and wondering if maybe I have gotten moisture into a knock sensor plug or something
does anyone have any ideas?
I have only had it idling at this stage
Unless its been heavily modified for Australia, there is no knock sensor. Did you counter-hold the cam gear with another wrench when you checked the bolt?
Reply
Old Jan 31, 2021 | 07:39 AM
  #4  
Petza914's Avatar
Petza914
RL Community Team
Rennlist Member
15 Year Member
 
Joined: Oct 2007
Posts: 28,530
Likes: 8,342
From: Clemson, SC
Default

Both pressure washing and steam cleaning engines are not great choices, especially on cars with electrical plugs and harnesses as old as ours can be. The force of the water from a pressure washer can pass the rubber seals on waterproof electrical connectors as can steam molecules because of the speed at rhixh they're moving in steam, then once they cool down they just become water inside the connector. I wouldn't clean an engine with anything greater than garden hose pressure and even then, cover the brakes sensors on the master cylinder as they can fill with water and then throw a warning light and need to be replaced (AMHIK).
Reply
Old Jan 31, 2021 | 07:56 AM
  #5  
Speedtoys's Avatar
Speedtoys
Addict
Rennlist Member
15 Year Member
 
Joined: Sep 2010
Posts: 13,583
Likes: 1,044
From: Boulder Creek, CA
Default

Originally Posted by Petza914
Both pressure washing and steam cleaning engines are not great choices, especially on cars with electrical plugs and harnesses as old as ours can be. The force of the water from a pressure washer can pass the rubber seals on waterproof electrical connectors as can steam molecules because of the speed at rhixh they're moving in steam, then once they cool down they just become water inside the connector. I wouldn't clean an engine with anything greater than garden hose pressure and even then, cover the brakes sensors on the master cylinder as they can fill with water and then throw a warning light and need to be replaced (AMHIK).
But note..that a proper steam cleaning facility can do miracles on the bay itself..and the front of the block where oil and time can be interesting.

Just have your man be aware of what not to point at.

If you have one you can FIND, prep the car. Take out the undertrays, wheel well liners and rear plastic pieces, show with with a friend and a pair of electric tools to remove the tires once in the air so as not to waste their time..

Of all places, and the industrial level ugly that comes off cars/truck/paving equipment that they do..we have one in the heart of DT San Jose Kalifirnia.
Reply
Old Jan 31, 2021 | 12:29 PM
  #6  
Mrmerlin's Avatar
Mrmerlin
Team Owner
20 Year Member
 
Joined: May 2004
Posts: 31,162
Likes: 4,161
From: Philly PA
Default

If you have not already done this i would suggest that you check the torque of the cam pulley bolts ,
if necessary remove the bolts and add a drop of blue loctite to the threads and retorque , NOTE its common to find the bolts loose.
NOTE if you do find a loose bolt then it would be wise to remove the pulley,
and resurface the mating areas with 400 grit paper to remove and work hardened areas .
At this point get a new flat washer and new bolt so all the surfaces are fresh and will have max grip
NOTE its not a good idea to wash the engine as the TPS unit can be damaged from water ingress.
most of the components have small holes and if the water is forced into them then they can be damaged.
Your car doesnt have knock sensors but it does have a CPS

Last edited by Mrmerlin; Jan 31, 2021 at 12:32 PM.
Reply




All times are GMT -3. The time now is 07:52 AM.