TGRich

Well this is the second time I'm typing this as apparently using the back, then forward button erases all of your g#dd##n text!

While searching on how to change the cap and rotor, I realized there isn't a whole lot of info on the site for this. This is one of the easiest things you can do to restore lost power in your engine. To see how this part of your ignition system works, go here:
http://auto.howstuffworks.com/ignition-system4.htm

Over time, the high voltage arcing from the rotor to the cap wears down the metal contacts. This causes loss of power.
These are the parts you will need (Toyota part numbers):

Cap: 19101-70020 ($10.50 price quote from Carson Toyota)
Rotor: 19102-46011 ($3.49 price quote from Carson Toyota)
Dielectric grease (My lexus dealer threw in a big tube for free)

Hardware involved:
3 screws to hold the cap on.
2 screws to hold the rotor on.

This is where the distributor is located:

TGRich

The first step is to remove the negative battery terminal. I dont know if this is necessasy, but since we are working on the electircal system, it can't hurt. Then remove the spark plug connectors (6), ignition coil connector (1), and other connector (1) from the cap (7 total). This is done by simply sliding a standard screw driver underneath the tab for each connection and giving it a little tug to come off. Don't worry about remember what connector goes where b/c they are all labeled on the wires as well as the new cap.
When you are finished, it should look like this:

Also, don't forget to remove the connector on the upper right hand of the cap (shown still attached in pic) This can be done with just your hand. It may not be necessary, but it takes two seconds and is better off out of the way.

TGRich

There are three screws that hold the cap one.They are located at approximately the 1,4, and 10 o'clock positions. I used a standard screwdriver to get these off, but a socket (8mm I think) with and extension is also a good idea. Once these 3 screws are off, slide the screwdriver in between and give a small pry to get the cap off. There is an o-ring in there so be a little careful not to break that. You could use a new o-ring, but the one I had in there was still in good shape.

Notice the worn out old rotor. There are 2 screws holding the rotor on. I used a standard scewdriver for these too. They are a little tough to get at with the angle, but still manageable.
TIP: Take a long wrench with a 22mm socket and turn the crank pulley bolt clockwise to rotate the rotor into a better position to remove the scews. This helps A LOT.

TGRich

Remove the rotor after removing the 2 screws. It wil pull right off. Put the new rotor on (lining up the screw holes) in the same position. Be careful not to touch the new rotor's electrical surface at the top when handling it.

Install the two screws to hold the rotor on. You can turn the crank pulley for better positioning again if it makes it easier for you.

After the new rotor is on, put the new cap on. There are 3 screw holes to align. Keep turning it, there is only one way for them to match up so you can't get this wrong.
Install the 3 screws that hold the cap on.

Take the connector and attach it.

Take the other 7 connectors (6 spark plug wires and 1 ignition wire) and wipe off the old grease around the metal and the boot. Take the dielectric grease on spread some of that stuff on.
Reinstall the connectors by matching up the numbers one the wires and the numbers on the cap. The ignition coil wire goes in the middle.

This is a comparison of the old and new rotors:


Here is a comparison of the old vs. new rotor.

TGRich

Reconnect your negative battery terminal.

Congratulations! You have successfully changed your cap and rotor. Now get in your car and take a drive to feel your power that has been restored.

I noticed a difference, did you?

Here is a pic of the finsihed product.

adidosc

very impressive writeup...however, do you think while you are doing that it would be a good idea to upgrade the spark plug wires as well? just a thought...

TGRich

Thanks,

That would be a good idea, although that would require more work. I know for that you would need to remove the timing belt cover and maybe even the throttle body. I know the TB needs to be removed for the plug change, but I don't know if you could get all the wires changed w/out removing that.

adidosc

After I posted that I thought about it more, and now that I think about it, if I go ahead and follow your write-up and then also change the wires, might as well upgrade to iridium spark plugs too while i'm at it. or is there a better setup that could be worked in?

TGRich

I have heard good things about the Iridium plugs. I think I remember seeing a thread here about some plugs called Torquemasters? being good too.

As far as the wires go... some people say that stock is best, but I don't know about that. Too much gimmicky stuff from other companies to make an informed decision.

TGRich

Speaking of the iridium plugs, does anyone know if the ones on ebay are any good?

aliga

iTrader: (147)

From what I have read, the stock ones are the best!

Cloud9

iTrader: (2)

THREAD REVIVED!

I just changed my rotor and distributor cap and took my SC300 around the block....WOW! The car idled much smoother and acceleration was smooth and linear and had more ooph.

It took about 30 minutes to change everything and required basic tools. I bought Bosch cap and rotor from rockauto.com for less than $20. I don't think they have been changed ever...110k miles. The rotor looked like TGRich's. This a must-do for people who hasn't done it before

I am going to change the spark plugs tomorrow to NGK Platinum.

DIYsquirre

Kind of off topic, but since the Intake manifold needs to be removed to change out the plugs do you also need to get a new gasket for it?

dejacky

iTrader: (2)

Just to clarify something. The intake manifold does not need to be removed to change the spark plugs. Only the throttle body needs to be seperated to replace the spark plugs.

sc.Fred

I'm reviving this thread again because it's a great write up!

anyway, i found out that our SC uses 5mm for stock plug wires which i found weird because i used to work on honda's that were like 7-8mm is it because of how the engine is made?