MGB Valve Stem Seals 77 MGB

[kyreb1862]

How hard would it be to change the valve stem seals on my B with the engine still in the car. I remember doing the job on an old ford I had once but that was about 30+ years ago. I just used a screw in air chuck and air pressure to hold the valves in place.

 

[Stewart]

Your most likely going to have to pull the head which is no big deal in a B. Make sure to get the payen head gasket for the reinstall.

 

[MGZT260]

Actually, if you are replacing the o-ring seals you can do that without removing head, almost just like any other OHV engine.

Key points

1 remove valve cover
2 remove rocker arm assembly
3 remove spark plugs
4. rotate engine so that each pair of valve is closed (work one cylinder at a time)
5 if you trust that piston is at top you can skip installing an adapter to supply low air pressure to keep valves up, otherwise use one
6 with proper tool compress valve spring and remove keeprs
7 remove old o ring, install new - install new deflector if you think necesary or if they look extra worn where close to valve guides
8 reinstall springs and keepers, move on to next cylinder
9 when all four complete reinstall rocker assembly and valve cover
10 recheck vlave clearance when cold as retorquing the rocker assembly may change clearances ever so slightly

Now, if you are doing guides then yes, you need to remove head, take to a machine shop for them to press in, and ream to size.

Or simply switch to 20w50 racing oil and a quart of STP or Marvel Mystery

tech tip link https://www.mossmotors.com/graphics/products/PDF/297-108.pdf