Quote:
Originally Posted by volvo-express
Thanks for replying.
Has anyone done it without taking off the head. I'm thinking about supporting the valves so it dosnt drop into the cylinder. Is it enough to have the engine on tdc on each cylinder to change seals?
I've seen other people putting rope into the cylinder to do this.
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Yes, sorry, I meant but failed to note in my earlier reply of course the removal of the keepers, retainers, and valve springs as well.
Yes, with these engines, due to the very limited clearance of valves to piston crowns at TDC it is no problem at all to use the pistons to hold the valves in position when you disassemble the valvetrain. I have used that method several times. Usually not specifically for valve stem seal replacement though -- the times I have had to do this is on PD TDI engines which have a tendency to wear holes in the tops of the followers due to excessively narrow cam lobes, and then the follower self-destructs and sends shrapnel down into the bottom of the follower bore that can only be fully cleaned up by taking off the spring/retainer/keeper assembly. D24T engines of course don't have this issue, but the method will work equally well for them.
Compressed shop air fed into the combustion chamber via the injector or glow plug opening (using a compression tester adapter) also works very well to keep the valves up, although then it involves even more labor to disassemble and reassemble those systems as well. Using the top of the piston is easier, as long as you are working carefully and don't lose track of what's going on inside the engine. You can make paint marks on the front crank pulley exactly 120 degrees apart so you don't have to guess about where the pistons are, and then do the six cylinders' valvetrain disassembly in three pairs working the crankshaft in the normal clockwise direction of rotation: 1/6, 2/5, 3/4, then return to #1/6 TDC to reassemble.
Again though, the big question is, are you certain these seals need to be replaced? This is a lot of effort and demands very careful attention to do it successfully, even without taking the head off. Lots of opportunity for risk and error too.
Only worth it if you are sure it's necessary.
And if what it really needs is valve guides replaced also, then the head will have to come off regardless so you may as well do it that way. Valve stem seal leakage is fairly rare on these engines (though of course possible), but valve guide wear is quite typical.