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I was asked to post about my valve stem seal replacement, so here it is.
NOTICE:
- I am not a mechanic
- I had my intake manifold off, but having it on and being able to use my distributor as a reference would have made things easier.
Special items I needed before I started:
- Air compressor
- air line to spark plug thread adapter
- Spring compressor
- magnet on a stick
Steps completed before this story begins:
- set engine to Top Dead Center on #1 cylinder
- removed valve covers
- removed all spark plugs
- supplied compressed air to the #1 cylinder
- removed the rocker arms on the #1 cylinder
What I did:
I started by using a socket roughly the diameter of the spring and a hammer to strike the spring in order to make sure it would easily separate from the valve stem and loosen the keepers:
Next, I attached the spring compressor and began compressing the spring while using moderate downward pressure. At some point the spring (and compressor) would drop to the cylinder head and the keepers would be exposed.
With the keepers exposed, I used a magnet on a stick to carefully remove the keepers, using the spring assembly to help contain one while removing the other.
With both keepers removed and carefully put aside, I then removed the spring and compressor and put them aside as a unit. It often took quite a lot of force to remove the spring, and wiggeling the compressor while cussing seemed to be required. There were a few times where I wondered if I was going to break something and just end up buying new heads. Other times the spring would lift out without effort.
- side note: I had a intake manifold gasket failure that was dumping coolant into the oil pan. That is why the oil looks like milk chocolate and the intake is removed in these photos.
I would then remove the small O-ring at the top of the valve stem seal. It would usually break apart from age and I had to be careful to catch all the pieces.
With the spring removed, I used a small screw driver to pry the valve stem seal loose.
I then lubricated the new seal (motor oil) and slid it into place by hand.
After the new seal was in rough position, I fully seated it using a deep well socket and a small extension. I could feel a bump/notch that the seal would slide over to become fully seated in most cases.
I would lubricate the new O-ring (motor oil ) and install them into the groove in the valve stem.
I then re-installed the valve spring/compressor assembly and began (but did not finish) to un-compress the spring. I then re-installed the keepers, again using the spring to hold the one in pace while I installed the other. With the keepers back in place, I removed the spring compressor and then gave the valve spring a whack with a hammer to give everything a chance to seat itself. Because of the compressed air in the cylinder, this would make a "POP" sound that can be quite loud (especially if your doing an intake valve with no intake manifold in place).
I then applied motor oil to the contact points of the rocker arm, the end of the push rod and the end of the valve stem.
I then reinstalled the rocker and rocker nut. I did not tighten the nut significantly as that is part of setting the valve lash after all valve stem seals have been replaced.
After I finished this valve I proceeded to the other valve in this cylinder. When both valves were done, I removed the air pressure, move the air line to the next cylinder in the firing sequence, turned the engine by hand to top dead center for that cylinder, applied air pressure, and began the process again. This was done for each cylinder.
A note about setting the valve lash:
This processed was detailed in the GM repair manual I used as a reference. I would look up and follow the official process if I were to do this again. It has a sequence to set the valve lash (rocker arm nut tightening) that involved setting the engine to Top Dead Center on the #1 cylinder, setting half the valves, then turning the engine 1 revolution back to the 0 degree mark, and doing the other valves(It tells you which valves to do on each turn). It worked well and was well worth the time to look up.
I did have one tiny problem with your procedure. My valve stem seals came with a small plastic sleeve to put over the end of the valve to protect the seal from the sharp edges of the keeper groove. You apparently did not use this sleeve (at least you did not mention it and I do not see it in the relevant picture).
Nice write up. One thing I would suggest is wiggling the valve stems after the springs are removed. The maximum valve guide clearance is .003. Because the length of the valve stem is approximately twice as long above valve guide as the length below the guide, a dial indicator reading of anything around .006 or more will indicate excessive valve girdle wear and the heads should be pulled and reworked. The C6Z06 427 motors had premature valve guide wear issues. I checked my LS7 heads this way and they had excessive wear. The heads were replaced by GM. The official name for this test is called the "wiggle test". Excessive guide wear is one reason seals can't keep the oil from moving past the valve guides and it is very easily checked when the springs are off.
I did have one tiny problem with your procedure. My valve stem seals came with a small plastic sleeve to put over the end of the valve to protect the seal from the sharp edges of the keeper groove. You apparently did not use this sleeve (at least you did not mention it and I do not see it in the relevant picture).
My apologies. You are correct. I did the work in February and just did the write up last night, so things have already started to slide from memory a bit.
Looks like your getting water (coolant) in your oil. From the pictures of the oil puddled in the head and rocker arms, it's milky looking.
Yes, I had a breech in the front water passage on the driver side, intake to cylinder head gasket, and that was dumping coolant into the oil pan. That is why the intake is off in the photos and I was actually doing the valve stem seals as a "While you are in there" side project.
use the small plastic sleeve over the valve stem to prevent the groove in the stem from cutting the seal as you push it down the stem.
I would also recommend that shop rags be placed on the head on both sides of the valve stem. If you have a keeper pop off, the rags will help you from loosing it.
I borrowed the spring compressor and the adapter to put air pressure in the cylinders from my brother in law. However, I did a quick search and I would say this is pretty close to what I used:
Good job.
The spring compressor used can be a pain but it works well. The one pictured is much easier to use. It pivots on the rocker stud.
Piston on TDC is always a good thing. If you loose air pressure and the valve falls down you can recover. Not easy if the piston is in the bottom of the hole. Use an install tool always because a socket can distort the seal as it fits on the valve guide.
Replacing seals are a good fix for the "cold start " blue smoke in the morning, but it will not stop excessive oil consumption due to worn valve guides. Chevy small blocks with iron heads eat exhaust guides.
12-02-2014, 11:20 PM
My Valve Stem Seal replacement
...Thanks for posting ..WW
use the small plastic sleeve over the valve stem to prevent the groove in the stem from cutting the seal as you push it down the stem.
