10 replies to this topic

[Propshaft]

I am about to fit a new rubber half moon seal I presume the higher part goes to the outside? The seal seems to be about 5mm (1/4”) to long do you need to trim it to length or doe it manage to squeeze and loose the 5mm thanking you in anticipation
Ps can’t find anything in the workshop manual regarding this seal

[DeadSquare]

DON'T  cut anything,  the seal is the correct size.

 

It is fitted so that the "flange" is on the outside, to stop it moving into the gear box.  It can't move out of the gear box because the Backplate of the Timing Gear holds it in place.

[DeadSquare]

It is easier to turn the engine upside down and fit the gearbox to the engine than fit the engine to the gearbox.  The gearbox is lighter.

 

Very lightly oil the seal and fit it over the front main bearing.  As you lower the gearbox you can see that the 1/2 round of the gearbox is fitting over the seal and not trapping the "flange".

[Spider]

Yes, the flange of the seal goes to the outside.

In regards to it being too long, there are some solid types I've been supplied over the past 15 years that definitely are too long, you'd break the flanges off the gearbox case before you'd pull them all the way down. While it's been tempting to cut these back a wee bit, cutting them clean and dead square is quite an ask.

 

The Half Moons that I have been fitting though has a ribbed profile, they do sit up but squash down OK when done up. I use an RTV sealant on them (don't forget the blunt ends !) and I find it easier to put these on the engine, and then fit the gearbox to it.

[Propshaft]

Thanks for all your input yes I have the engine upside down the gearbox is definitely lighter than the engine will probably be joining them today thanks

[PeterG]

With the engine and gearbox assembled add RTV to the seal and the end pockets. Push one end in, then push the other end in so it bulges out in the middle. Push the middle and it will compress against the ends and go in. Its a fairly easy  job if you use CAM6548.

[DeadSquare]

Thanks for all your input yes I have the engine upside down the gearbox is definitely lighter than the engine will probably be joining them today thanks

Put a rim of grease in the gearbox casing recess where the "O" ring seals the oil suction, between the block and the gearbox.  It helps to hold the "O" ring in place when the gearbox is inverted.

[gaspen]

Hello

 

I replaced this seal to the rigid one but still has leaking. I've  put some RTV on both ends.

 

I noticed that it can be inserted two ways :

 

A) The outer surface of the seal is flush with the engine block ( or it is "pressed" against the timing plate as you can see on 1st my photo)

     In this case there is a gap beetween the seal and the gearbox casing which could indicate that it is not on its right position (?)

 

B) The inner edge of the seal is pressed against the gearbox case (see 2nd picture*)

 

*Yes it is a flexible seal, I've took this photo for better explanation

 

 

 

 20260504_074707.jpg   51.88K   3 downloads

 20260504_080500.jpg   27.79K   3 downloads

[imack]

I've always fitted the flexible seal and I fit them asper your second photo,with the edge of the seal flush with the gearbox case.
I never shorten the seal.
I always fit the seal to the gearbox case, then lay the gearbox/ sump gaskets onto the gearbox case with sealant applied to the gasket (no sealant on the 1/2 moon seal) with the ends of the gaskets resting on top of the raised ends of the 1/2 moon seal.
I then lower the block with the front timing cover plate already fitted squarely onto the gearbox using my block and tackle.
I find doing it this way it's easy to lower the block in a controlled manner and check that the 1/2 moon seal and sump gaskets are not dislodged during installation.
I've never had one leak.

This is the engine immediately after the engine has been lowered onto the gearbox. The gearbox to block bolts are being installed.

Attached Files

•  Screenshot_20260504_082335_Gallery.jpg   25.31K   2 downloads
•  Screenshot_20260504_082300_Gallery.jpg   35.08K   1 downloads

Edited by imack, 04 May 2026 - 07:28 AM.

[gaspen]

I've always fitted the flexible seal and I fit them asper your second photo,with the edge of the seal flush with the gearbox case.
I never shorten the seal.
I always fit the seal to the gearbox case, then lay the gearbox/ sump gaskets onto the gearbox case with sealant applied to the gasket (no sealant on the 1/2 moon seal) with the ends of the gaskets resting on top of the raised ends of the 1/2 moon seal.
I then lower the block with the front timing cover plate already fitted squarely onto the gearbox using my block and tackle.
I find doing it this way it's easy to lower the block in a controlled manner and check that the 1/2 moon seal and sump gaskets are not dislodged during installation.
I've never had one leak.

This is the engine immediately after the engine has been lowered onto the gearbox. The gearbox to block bolts are being installed.

Thanks.

 

I have to replace it in situ as it is a freshly built engine and i dont want to lift out the whole unit. Also i will not trim the ends of the seal

[gaspen]

It seems that I was on the wrong track. There is leak at the rear tappet covers from where the oil flows on the backside of the timing plate to the lowest point.  I run the engine on increased idle and looked at the bottom of cover/plate : not a drop of oil. Then i stopped it and after a while the oil started to drop. So i put the gaskets to the tappet cover with rtv. I hope it will be okay