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How to: Replace the main seal (flywheel end)

11953 Views 7 Replies 6 Participants Last post by  JLAudioFan
This guide is for the installation of a brand new main seal on the flywheel side of the engine for any 88-91 CRX. If you see evidence of oil leaking out from under the transmission/engine mating surface, this is a likely culprit.

Tools/supplies needed

Sledgehammer/Deadblow hammer
Driver tool or PVC pipe (same diameter as seal)
2 sheet metal screws
Brand new seal (from honda)
Big flathead screwdriver or small pry bar

Removal of old Seal

The document assumes that you have already removed the transmission, clutch, and flywheel from the vehicle. If you have not, please review the other "How to's" on those subjects first.

First, the take your sheet metal screws and screw each into opposite sides of the old main seal. The main seal is only about 3/8 of an inch deep, so don't screw them in too far.

Once you the screws are secure in place, you need to pry on them with a big screw driver or small pry bar. Pry against the end of the crank shaft...not the aluminum block. The crank shaft is hardened steel. The block is soft aluminum and will scratch and gouge easily. Alternate prying between both sheet metal screws. The seal will eventually pop right out. Discard the old seal.

Installation of new seal

Once the old seal is out, clean up the seal surface on the block. It should be clean, dry, and free of any grease or oil.

If you do not have a special driver tool to hammer in the new seal, you will need to go to your local hardware store with the new seal and find a piece of PVC pipe that has the same outer diameter as the new seal. Use this piece of pipe to hammer in the new seal. My PVC pipe was actually a pipe end cap, so I could hammer directly on the end of it. If yours is an open ended pipe, you may need to use a small block of wood over the end of it to evenly distribute each blow of the hammer. Be sure to only exert force on the outside edge of the seal. The inner area is delicate and surrounded by a thin precision spring. Hammer the seal into the block until it bottoms out in the block. Make sure it is evenly seated into the block all the way around the seal.

Clean the spilt oil from the area below the main seal. If you see oil again in this area in the future, you will be able to diagnose the new problem. In addition, the less oil that is sitting around in the clutch/flywheel compartment, the less chance that you will contaminate your clutch with oil.

You're done!
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I had better luck just pulling that plate that the seal in mounted into. The buggered-up seal just would NOT come out through its hole, so we removed the plate and noticed that the seal looks to have been installed from the back (crankshaft) side, and there was a small lip preventing it from coming out that way. A couple taps with a hammer - tapping it INWARD but with the plate off the block - and it was out. New one went in easy as pie, and hasn't had a leak in over 25,000 miles.

More than one way to skin that particular cat...:)

Yup...that's the way I originally planned on doing it until a mechanic friend of mine gave me the sheet metal screw tip. I had the bolts out, and the gasket sealant ready to re-seal the plate once it was off, and he told me to try the other way first. If all else fails, taking the plate off will make easy work of the seal.
The screw trick worked like a charm. My main seal wasn't leaking but I figured now is a better time to replace it then later since I was replacing the clutch. The PVC pipe cap also worked really well. Found the three inch cap at Home Depot for like $3.
Good to hear that it went well for you. Stavros also enlightened me with another trick that you can use in a pinch. If you don't have a piece of PVC pipe that is the right size, as a last resort, you can flip the old seal around backwards and then put a piece of wood over it and use it to drive in the new seal.
I've just used a phillips with electrical tap wrapped around the tip or a microscrewdriver.

The last time I did it I just removed the housing as it makes it easier to clean and install, but also you can clean and put a fresh coat of sealant where the housing meets the block. which is possible to leak from and should be done anyway if you ask me.
Do you have to drop the oil pan for the housing to come off that holds the main seal in a zc sohc?
I forgot to get a pvc pipe cap while i was out running around today so i just used the old seal + deadblow mallet to smack the new one in. The machine screw worked like a charm (make sure they're self tappers!)

Thanks for this howto =)
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