Porsche Parts Catalog Porsche Accessories Catalog Porsche Technical Articles Porsche Tech Forums
 
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Setting Engine at Top Dead Center
 
Bookmark and Share

Pelican Technical Article:

Setting Engine at Top Dead Center

Steve Vernon

Time:

1 hour1 hr

Tab:

$0

Talent:

**

Tools:

15/16-inch or 24mm socket

Applicable Models:

Porsche 944 Turbo (1986-89)

Hot Tip:

Mark the direction of any belts when removing

Performance Gain:

Allows you to perform certain work

Complementary Modification:

Replace belts

There are several jobs on your car that you need to set the engine at Top Dead Center or TDC including changing your timing belt or replacing your head gasket. While it is possible to set the motor at TDC by yourself due to the positioning of the crank reference viewing window, it is easier to get a friend to help.

You will be setting the engine at TDC when the number one cylinder is at the top of its compression stroke. Remember that the crankshaft rotates twice for every single rotation of the camshaft, so if you simply set the crankshaft to TDC without looking at the position of the camshaft, you may actually be at TDC on the exhaust stroke for cylinder #1. So, after you set the crankshaft, double check the camshaft sprocket to make sure the camshaft alignment mark is at the TDC position as well.

You are going to be turning the main crank pulley with a 24mm or 15/1-inch socket to get the engine into the TDC position.
Figure 1

You are going to be turning the main crank pulley with a 24mm or 15/1-inch socket to get the engine into the TDC position. You can remove the under engine tray and access the pulley from the bottom (red arrow). Please see our article on under engine tray removal for additional assistance. This is the easiest way when setting the TDC with a friend since you will need someone above the engine to see the view port on the flywheel. It will save you the work of removing the air box.

You can also remove the air filter box and access the pulley from above (red arrow).
Figure 2

You can also remove the air filter box and access the pulley from above (red arrow). This method is easier when working alone but involves more work to remove the air box; please see our article on air box removal for additional assistance if you follow this route.

Either way you will be placing a 24 mm or 15/16-inch socket on the main crank bolt and turning the engine clockwise (red arrow).
Figure 3

Either way you will be placing a 24 mm or 15/16-inch socket on the main crank bolt and turning the engine clockwise (red arrow).

It is a good idea to remove the spark plug on the number one cylinder and either place a wooden dowel or rubber hose into the cylinder to be able to tell when the cylinder has reached the top of the stroke (red arrow).
Figure 4

It is a good idea to remove the spark plug on the number one cylinder and either place a wooden dowel or rubber hose into the cylinder to be able to tell when the cylinder has reached the top of the stroke (red arrow). Never put something metallic that could scratch the piston or cylinder in the spark plug hole and never put anything shorter than 18-inches in length (you do not want the object to fall into the engine.

There is a viewing port just above the distributor cap in the one o'clock position (red arrow).
Figure 5

There is a viewing port just above the distributor cap in the one o'clock position (red arrow). You can look in through the view port to verify the cam is on the compression stroke but do not use this to lock the motor in the TDC position. Make sure to use the marking on the flywheel for absolute accuracy.

The viewing port to determine TDC on the flywheel is down on the left rear of the engine just beside the speed reference sensor.
Figure 6

The viewing port to determine TDC on the flywheel is down on the left rear of the engine just beside the speed reference sensor. It is buried down behind the oil filler cap. Viewing it while turning the engine is very difficult if not impossible (red arrow). If you are working by yourself, make small adjustments until you are sure the engine is at TDC.

As you are rotating the engine clockwise you will first see the letters OT on the flywheel.
Figure 7

As you are rotating the engine clockwise you will first see the letters OT on the flywheel. Continue turning the engine until the scribe mark (red arrow) on the flywheel lines up with the tab in the other side (green arrow). You may have to stick your finger into the port and clean up the flywheel to see the scribe mark but if you have already checked the cam marking and dowel in the number one cylinder, you should be close so you don't have to clean the whole flywheel. You can now lock the flywheel in place.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Fri 12/9/2016 02:48:37 AM