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MG MGB Technical - Double Valve Springs - how to remove?

Hi guys,

I'm trying to remove the valve springs so that I can replace the valve stem seals as the car is blowing a lot of smoke when you pull away from idle (great for James Bond enthusiasts, but less great for the cars behind me). It's a double valve spring setup in the car.

The head is on the car, and I've done some reading. I've got an overhead valve spring compressor tool, same as I've seen on a few YouTube videos. I've attached it to the spring, compressed it as far as it'll go, and that's about it. I've pushed it down, but the valve spring cap is still solidly in place with the two collets unmoved. There is no circlip, just the two collets.

Is it a case of applying more brute force, or am I missing a trick?

Huge thanks in advance,

Grant

PS: Yes, I know it COULD be a lot worse than just the seals, but they're a cheap test and if that solves it hurrah! If not, I'll probably send the head to Pete Burgess for a tweak and swap a piper 285 for my 270 magnum if I've got to swap the piston rings and dismantle the engine.

G Hudson

Grant

I’ve seen some of these methods described but never tried them. The ones I’ve seen rely on either feeding rope in via the spark plug hole or using compressed air via an adaptor in place of the spark plug to hold the valve in place. Your picture shows you’re using neither of these, how were you planning to stop the valve moving down when you compressed the spring?

The collets can get stuck and take a large force to break the initial seal, I normally put a socket over the top and strike it with a hammer this breaks the initial seal and makes them easier to remove. The first time I was shown the socket trick by an old mechanic he hit it quite hard and the collets just jumped out.

Bob
R.A Davis

Grant, If it's smoking when you are pulling away, i.e., under power, the problem won't be valve stem oil seal. Smoking on "over-run", i.e., a trailing throttle is when valve stem and oil seal wear shows up. Under power smoke is more likely bore and ring wear.
Allan Reeling

Pulling away after idling a while will blow oil smoke from oil leaking past the valve stems. Likewise on the overrun its usually when opening the throttle again that you see the smoke. If it smokes WHILE you are on the overrun the leak is very bad, and oil consumption would be high.

And you do definitely need some method of holding the valve up when the collets are removed, probably a good job they didn't come away! They can need a whack to shift them, once the pressure of the springs has been removed.
paulh4

Bob et al,

Thanks. Knew I was missing something. I'll fire up my compressor and give that a go.

When driving it's fine, just when I slow down and stop at traffic lights it's fine, but pulling away it's a thick cloud that goes after about 50-100 yards.

Cheers,

Grant
G Hudson

Paul, Oil is pulled down the valve stems when the throttles are closed, i.e., big vacuum when the valves are open, with air and oil pulled from the rocker cover. Wear doesn't have to be that bad. When pulling away the throttles are open and the vacuum goes to pull fuel and air, i.e., the easier route.
Allan Reeling

Grant Hi
Looks as though you have the rocker gear off already
You need to cover the top of the head with rags
If you drop a collett and it's uncovered you know where it's going to go--down a hole
method
Air pressure into the cylinder
Give the valve cap a little tap-doesn't need much-The colletts are tapered and just need enough to unlock them from the taper
Fit your valve spring compressor and compress the spring
it will only do the outer spring and you will have to push down on the tool enough to compress the inner spring- then remove the colletts -A stick magnet is good for this job---then lift off the springs
Clean out the old seal from the cap or valve ,wherever it ended up
Now-the next bit you can do on your own but if you have a willing helper it's a whole lot easier
--Refit the springs and cap to the head--push down on the tool to compress the inner spring,while holding it down, stretch the seal over the stem to down below where the colletts go and refit the colletts, release the hand pressure on the tool to get the cap to come up against the O ring and colletts and then unwind the tool
next valve is waiting
good luck
willy

If it does happen to have a broken ring you will probably hear extra air bypassing in that cylinder
Also are you sure it's not the breather sucking oil
William Revit

As Bob said you need to hit the top of the valves with a mallet, if you are going to get a adapter to fit in the plug hole to pressurise the cylinders, to hold the valves up, you could always do a cylinder leak test first, then that way you will know if you are wasting your time fitting some valve seals, what are your oil consumption figures by the way.A.T
Andy Tilney

Don't use the original style O rings in the cap - get the improved seals which push over the guide.
Chris at Octarine Services

"Oil is pulled down the valve stems when the throttles are closed"

Yes, but in my experience that is revealed when opening the throttle again. BT, DT. YMMV.
paulh4

Worn valve guides allow some oil into the cylinders while idling usually not very much - this usually only gets partially burnt giving a little blue smoke, on pulling away any oil settled on the piston crown gets burnt as well and you get a puff of blue smoke.

However, if the breather system is pulling oil under idling vacuum it tends to settle in the manifold and not reach the cylinders until you pull away - then you get a big cloud of smoke.

Same applies to accelerating after the overrun in both cases.

So blue smoke is not a good indicator of cause - it could be either.
Chris at Octarine Services

to answer your question, it looks you need more brute force but from you photo it is difficult to tell.

if the head were off, a valve spring compressor will compress the springs enough to view pretty much the whole collet. Just went to my garage and tried it.
it does appear that your spring is insufficiently compressed.

G
Graham Moore

And you only need the seals on the intake valve stems.
Art Pearse

Art
possibly but
There is actually vac at the exhaust valve as well
As the slug of exhaust passes through and then the valve there is a depression and oil 'can' be sucked down the guide
If Grant is having smoking problems I would suggest he do the 8 of them to eliminate possibilities
willy
William Revit

This thread was discussed between 30/03/2017 and 04/04/2017

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