Here's a little write-up on how to change the inner oil seal of your distributor that has no internal coil.
This involves stripping down the distributor and therefore, one has to adjust the ignition timing again upon installation.
Applies to the following engines (there may be others but these are confirmed):
Distributor (Small).jpg 83.87KB 0 downloads
New internal oil seal
New external oil seal
Parts like the rotor, cap and dust seal can normally be re-used but depends on the condition.
Tools required for this job:
-arbor press with <3mm press pin and something to support the distributor "engagement gear"
-straight punch (<6mm)
-timing light and paperclip
Start with removing all HT leads and plug from the cap. Mark up the approximate position of the distributor in relation to the engine, undo the retaining bolts and pull the distributor out.
Remove distributor cap complete with dust seal and rotor. LEAVE THE 4 SCREWS IN THE PICKUP PLATE FOR NOW. It does say don't remove after all.
Mark the "engagement gear" using a center punch to the shaft so it's clear in which way it needs to be re-installed.
Using an arbor press, carefully press out the metal retaining pin. DO NOT USE A PUNCH AND HAMMER FOR THIS STEP AS YOU WILL BREAK THE INTERNAL MAGNETS!
Now that the retaining pin is out the "engagement gear" can be removed.
Measure the height of the shaft against the housing, you will need this to re-install everything in the correct position later.
Now use the press to take out the shaft completely.
Once the shaft is out, remove the 4 screws and the pickup plate. There might be some sealant around the connector. Take it easy and carefully remove the complete plate with magnets & connector.
Looking at the distributor housing the bearing should now be visible. Using a straight punch and hammer carefully remove the bearing, taking care not to damage the walls of the bore.
Once the bearing is out, the inner oil seal is finally visible. Remove this using punch and hammer. Again, taking care not to damage the walls of the bore.
Remove outer O- ring.
Give all parts a good clean while everything is out and ensure none of the bores have any damage from the removal. If so, remove any sharp edges and smooth the bores without removing any material.
Slightly lube the oil seal and press it in the machined pocket making sure it's lip seal is facing towards the cap end.
Once the oil seal has bottomed out it's time to install the bearing. Lube the outside slightly and using a suitable tool press it in until it bottoms out. The size of the tool should be slightly smaller then the bearing outer diameter.
Install the pickup plate and insert the 4 screws. Use a bit of sealant around the plug if you require. DO NOT TIGHTEN THE SCREWS YET.
Check the shaft of the distributor for any burrs or damage and smooth out if needed. Slightly lube the shaft and press it about 1/2 into the distributor. Once the tooth gear reaches the pickups it's important to keep sufficient clearance. Hold the plate centered while pressing in the shaft completely. As it's magnetic the plate will try and touch the toothed gear. Press the shaft in until you measure the same distance from the end of the shaft to the distributor housing as noted down in the removal step.
Using some feeler gauges center the pickup plate in such a way that the gap between the teeth on the gear and the pickup is 0.2 to 0.4mm. I found it easiest to insert 2 gauges between 2 pickups at a time, tighten the 4 screws and then check the remaining pickup. Distribute the gaps as evenly as possible. This step should not be skipped as you risk running the gears into the pickup and damaging one or the other, or most likely, both.
Taking note of the identification marks, install the "engagement gear" onto the shaft and press the retaining pin back in. The "gear" should have some play on the shaft and the pin should be centered at all times.
Re-install rotor, dust seal and cap.
Lube and install new outer O-ring.
Lube the shaft and bore using some oil in the V groove pockets between the outer O-ring and "engagement gear"
Re-install the distributor to the car in the same position as removed or as close as possible. Re-connect all HT leads and plug. Start the car and once the engine is at nominal temperature & revs, set the timing as per Toyota's instructions using a paperclip to bridge terminals T1 and E in the diagnosis connector. Adjust timing by turning the distributor slightly. Once timing is correct tighten the distributor retaining bolts.
Disclaimer: I take no liability for any damage done to your car. Use this guide at your own risk.
Pictures are of a 4A-GE 20V distributor but the same method applies to the other models listed at the start of this post.