Replacing valve seals without an air compressor

[rgriffiths]

I am planning to replace some valve seals on a Beta engine. I don't own a air compressor to blow air into the cylinder to keep the valve from dropping when removing each spring and I don't want to take the head off.

 

I wonder if anyone has any clever tips?

Edited December 31, 2019 by rgriffiths

[Tony Brooks]

Personally I can't see how a spring compressor will stop the valve dropping once the collets are out, it will just make getting the collets off easier. On my Bukh I simply set each piston to TDC so the valve could only drop a few thou but I did use a suitable spring compressor, I think it was usually used for some Ford engines. However with modern  light valve springs manual compression using a ring spanner and a helper to lift the collets out with pin nosed pliers  may well be fairly easy.

[rgriffiths]

Sorry Tony - edited the question to make it clearer. The air compressor blows into the cylinder via the injector hole to create a pressure to hold up the valve. The spring compressor is an overhead valve compressor like this:

 

[Mike Hurley]

2 hammer shafts, or similar, pushing on the spring, 1 other person needed to pop the collets off. Another way is a socket placed over the valve and a swift whack with a hammer, just be careful where the collets end up. Used this system many times when on my own, works for me but 2 people make it easier.

 

[Tony Brooks]

11 minutes ago, rgriffiths said:

Sorry Tony - edited the question to make it clearer. The air compressor blows into the cylinder via the injector hole to create a pressure to hold up the valve. The spring compressor is an overhead valve compressor like this:

 

 

Well, on a diesel I don't think you need one as long as the piston is at TDC and the spring compressor  can compress the spring enough to allow it to drop a little.  On the Lister LR and SR series of engines the bump clearance (between piston & cylinder head) is between 0.025" and 0.0.038" so the valve can't drop far. I have no data for the Beta/Kubota but it won't be that much different. Be aware there may be valve recesses in the pistons so the valve may drop a little further.

 

As an aside you don't need it on most petrol engines as long as you stuff the combustion chamber full of hairy string/light rope via the plug hole but make sure you leave a tail hanging out so you can remove it. Don't try that on a Beta (indirect injection) because it won't work, you just fill the    pre-combustion chamber.

Edited December 31, 2019 by Tony Brooks

[Boater Sam]

I use a forked bar under a bolt or shaft support pillar and put a neodymium magnet on the collet ring to catch them.  

[Troyboy]

I seem to recall being told many years ago that on a petrol engine you could remove the spark plug and feed rope into the cylinder and then compress that up onto the valves . I've never tried it and on a diesel engine the rope would be harder to insert through the injector hole but would probably work OK. 

[Mike Hurley]

6 minutes ago, Boater Sam said:

I use a forked bar under a bolt or shaft support pillar and put a neodymium magnet on the collet ring to catch them.  

Another good way.

[rgriffiths]

All good advice. Thanks. 

[Tony Brooks]

2 hours ago, Troyboy said:

I seem to recall being told many years ago that on a petrol engine you could remove the spark plug and feed rope into the cylinder and then compress that up onto the valves . I've never tried it and on a diesel engine the rope would be harder to insert through the injector hole but would probably work OK. 

Almost certainly not on an indirect injection engine like a Beta because both the glow plug and injector go into the small spherical pre-combustion chamber. With good light and a lot of patience & luck you just might be able to fed the rope through the throat into the cylinder but I very much doubt it. That should work on a direct injection engine but, as I said, the piston is so close to the valves at TDC I doubt its necessary.