I had a nasty oil leak coming from my Auto transmission on my toyota camry.
Engine: 5S-FE
Transmission: A140E
Model: SXV20, XV20.
I didn't know where exactly it was coming from until I had spotted the top of the transmission, drenched in a puddle of oil.
The previous owner had thought that the head gasket had gone (On a 5S-FE engine? Really?), which isn't far off because the entire side of the engine was covered in oil. I put some on my finger and smelt it and sure enough the unmistakable smell of transmission oil came back to me, it wasn't engine oil, the headgasket is fine. Sure enough the loss of drive when on hills or flats was attributed to a low transmission fluid level and I topped it up, which fixed the problem.
Its a simple matter of getting some black silicone sealant from your auto shop and remaking a new seal around the old O-ring on the top of the speedo sensor.
Tools required:
Can of Degreaser (Keep the plastic cap)
Spray bottle full of tap of water
Paper towel or tissue paper
Black silicone sealant (suitable for autos or marine)
Phillips head screwdriver (One that looks like a star)
Prep work:
Put a piece of paper towel or tissue paper inside the cap of degreaser (this is to put the speedo sensors ball bearing (only one of them) and a spring in a safe area.
Step 1:
Remove the speedo sensor plug by squeezing it, Remove the speedo sensor from the top of the transmission using a 10mm socket, it goes out straight up, the plastic gear will get stuck on the transmission housing if you don't take it out going straight up.
Step 2:
Remove off the lid of the speedo sensor by using the screwdriver, if you find that the screws are seized in place then simply tighten the screw (Clockwise) and then undo the screw (Counter-Clockwise) (it should break the corrosion on the thread and let you undo it.)
Step 3:
Grab the ball bearing which may catch onto the magnet of the speedo sensor shaft and put it into the cap. Remove the spring from the center of the speedo sensor and put that into the cap too. Don't lose them.
Grab the rubber O-ring which lives inside of the lid and put it into the degreaser can cap too.
Step 4:
Get your degreaser and spray clean the plastic speedo sensor lid clean and the speedo sensor itself, drain and mop up any transmission fluid that comes out of it.
Get the rubber O-ring and degrease it, then dry it down with paper towel/tissues.
Step 5:
This is where you remove any residue from the parts which was put on there by the degreaser, we need a clean surface, no residue, so the silicone adheres.
Get the water spray bottle and clean down the speedo cap and base, mop up any water with the tissues/paper towel.
Make sure the O-Ring is clean aswell with the water.
Make sure all surfaces are nice and dry, use tissues to dry them with.
Important:
Clean down your hands with the spray bottle full of water, and use paper towel to dry your hands after.
For step 6 to work properly your hands need to be free of any oil residue.
Step 6:
Get your tube of black silicone sealant and the O-ring, put some silicone on a finger and thumb and rub the rubber O-ring between your fingers in the silicone, you don't need much just enough to make a decent seal.
if it doesn't seal properly repeat this step with slightly more silicone than before.
You may need to fill the trough where the gasket sits with black silicone working from the inside out with the screwdriver in hand, I recommend using a small flat screwdriver, ensure you don't get any on the magnet which sits in the center of the speedo sensor.
Clean off the silicone from your hands once your done.
Step 7:
Put the O-ring inside the base of the speedo sensor where it came from, if you want you can add some silicone sealant to the top and bottom of the surfaces to "make sure" its not going to leak but don't add too much, make sure you keep it off the center shaft magnet as that rotates.
Step 8:
Put the spring back into the hole in the center of the shaft and the single ball bearing sits ontop of the spring, keep the shaft of the speedo sensor vertical at all times until Step 9 is completed to prevent losing the ball bearing.
Step 9:
Center the black plastic speedo sensor cap onto the metal base of the speedo and insert 1 screw into one of the holes, screw down but not tight.
Re-insert all 3 screws, making sure not to move the cap around too much while you do this as you could end up pinching the O-ring underneath, if this happens then clean off the silicone and redo it again from step 6.
Tighten down the 3 screws and reinstall the speedo sensor into your transmission.
Step 10:
Put the speedo sensor down into the transmission, ensuring the hole for the 10mm bolt matches up to the hole in the transmission, tighten down the bolt until firm.
Plug the connector back in, degrease it if you want.
Step 11:
Drive the car to the petrol station, bring a flashlight, and check to see if it continues to leak from the top, if it doesn't, re-check it again in a day or two.
Doing this saved me about $110.