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MG MGA - Valve Seal Installation Method

What is your methodology to install the stock rubber valve stem seals over the valve stem? Do you have a tool you use? My method requires two thumbs and a second set of hands to pull the last edge over the stem with a screwdriver or finger.

This teardown had 0 miles (never even started, long story) and some of the seals appeared to have some deterioration (the car had sat for 12-18 months). I don't know if that was from our installation or just sitting and other issues.

I'd like to know what your methods are!

Thanks!
J DeRienzo

JDR,
The stock seal is a simple "O" ring. Is this the seal type you are installing.
Better seals are the cup type with a wire coil like an oil seal has. Neither have been hard to install after they have a little oil on them.
Peter.
P. Tilbury

These are the stock type and I did oil them, although it was STP engine additive which is a higher viscosity. I think I've tried 5W-40 in previous attempts with the same issues. These are from Moss and are just stiffer than the dickens. I get them about 3/4 the way over the stem and they pop off.

After breaking the first seal and having to overnight a pack to get the car on the road ASAP, I wanted to see if I was missing a fundamental technique for installing O-rings. Sure sounds simple, but sometimes you miss something!
J DeRienzo

a dental pick type tool is a better bet than a screwdriver, a screwdrivers edges tend to tear or
strecth the o ring too much. with the pick end completely thru the o ring I start that end onto the stem and circle the pick around the stem using my thumb or fingers to stop it from popping off.Hope that helps. Chuck
Charles O'Brien

Chuck, I know the tool you're referencing. I don't have one, but I think I can improvise something that won't compromise the seal and potentially work.

Thanks for the feedback and ideas!
J DeRienzo

Why not put stem seals on the guides?
Art Pearse

The machine shop that reworked my head allowed me to watch its final assembly. They were having trouble installing the valve seals which at the time seemed to have an indersized internal diameter. Like you, I only had 8 seals, and it took us 20 minutes to find the first one that got airborne during its fitting process. I happended to have a golf tee in my pocket and suggested that they give it a try. Turned upside down on top of the valve stem it provided the necessary taper to fit the seal over the end of the valve stem. You might try that. You will probably have to "fit" the golf tee end O.D. to the valve stem. I wish I had had a phone with a camera at the time.
Good Luck!
Don Carlberg
Don Carlberg

I made this tool for my XPAG engine but I presume it would work for the B-series engine, too?

It's a simple tube that fits tight over the valve stem (8 mm?). The well lubricated seal is pushed down by it.

Willem van der Veer

second picture

Willem van der Veer

On re-reading your post I understand you had difficulties with getting the o-ring onto the stem?

With my assembly that went easy by just pressing flat on top of it with my thumb, again, well lubricated and pushing on a valve that is well supported from underneath.
I found it hard to get the ring low enough to fit the cotters properly, so I 'invented' my o-ring fitting tool.
Willem van der Veer

Umbrella seals are much easier to install....A set comes with an "installation tool" , which is nothing more than a thin-walled plastic tube, that fits snugly on the valve stem, the seal slides easily over this tube.....
Umbrella seals are commonly used in 18V engine (MGB) rebuilds....Personally I love them.
For the B engine, small-block Chevrolet seals (available at all auto parts stores), fit perfectly.
They have a nylon insert that slides on the valve stem, and then there is a snap ring at the base, that fits over the guide.
You might check into it for your application. I would not be surprised if the same seal would work for the "A".
Edward
Edward Wesson 52TD

Thanks a lot for all the replies. It sounds like the installation of these seals is different for everyone.

I wound up buying a set of O-ring tools that had two of the 90 degree hook-type picks. I wanted to install the O-rings like the B manual has (above the spring retainer and just under the keepers).

I managed to do this by installing the valve and spring hardware. Then I compressed the springs and hardware and while using my underarm to hold the valve spring compressor steady, I took the two tools opposing each other, placed the seal around the two tips, cocked the tips 45 degrees apart from each other and starting from the bottom lip on the top of the valve stem, wrapped the O-ring up, over, and around the top of the valve stem.

For the cost of the O-rings, I'd encourage anyone doing this to buy two or three sets to account for issues with installation and potential defects of the O-rings themselves. I am glad this is all behind me yet again.
J DeRienzo

This thread was discussed between 15/05/2013 and 21/05/2013

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