Valve seal replacement

[joecal]

I want to change the valve stem seals in a 305ci without pulling the heads. I'm getting some blue smoke after starting. The compression seems fine and the plugs are all dry so I think it's just the seals are old and probably original. I don't have a air compressor so I was going to try using the rope method. Does anyone have any tips on doing this and what size bolt is on the end of the crankshaft? I still have to order a valve spring compressor, I found one on ebay I might buy, it's just a plate that fastens to the rocker arm bolt to compress the valve. I ordered the seals from RockAuto and they were inexpensive. Anyway, any help is appreciated, it doesn't look like that hard of a job or am I wrong?

 

[BR@NDON]

I did valve stem umbrellas a while back and just remember using the piston to stop the valves. I'm sure that's not the preferred method, but the rope idea seems a little out there to me. The tool is definitely the way to go and will make your life easy.

 

[joecal]

Thanks Brandon, you use the rope to pack the cylinder and then bring the piston up as high as possible so the valve doesn't fall in.

 

[74 Shortbed]

Always bring the piston up to the top, that way you can never drop a valve, there are several ways to keep the valve seated that works, I've always used air since that will always return it if by chance you happen push the valve down.

 

[MikeB]

Always bring the piston up to the top, that way you can never drop a valve, there are several ways to keep the valve seated that works, I've always used air since that will always return it if by chance you happen push the valve down.

Man, that's very good advice. Last time I changed valve springs I used air, as always, but didn't have the piston up quite high enough. I had brain fade and disconnected the air hose, causing a valve to drop just below the top of the guide boss. I couldn't reach it, and a magnet didn't help. I reconnected the air hose, but all it did was blow air past the valve! Heck, it was probably blowing air down on the back of the face. I knew the piston was on the compression stroke, so I turned the crank a few degrees and was able to grab the valve when the piston pushed it up a little. Whew!

Regarding the rope method, I have a buddy who's a former aircraft mechanic, and he swears by it. And it's sometimes easier than trying connect an air hose on an engine with headers.

 

[74 Shortbed]

Man, that's very good advice. Last time I changed valve springs I used air, as always, but didn't have the piston up quite high enough. I had brain fade and disconnected the air hose, causing a valve to drop just below the top of the guide boss. I couldn't reach it, and a magnet didn't help. I reconnected the air hose, but all it did was blow air past the valve! Heck, it was probably blowing air down on the back of the face. I knew the piston was on the compression stroke, so I turned the crank a few degrees and was able to grab the valve when the piston pushed it up a little. Whew!

Regarding the rope method, I have a buddy who's a former aircraft mechanic, and he swears by it. And it's sometimes easier than trying connect an air hose on an engine with headers.

Well, you were lucky I learned the hard way, I had the piston wayyy down like at the bottom, at the time I used a stiff wire which works but it happened to slip off the valve, next thing I heard was this clunk sound, I can still hear it today, lol.....

Rope method works real good, gotta jam it in good though so it's solid otherwise it can be a pain if you happen to push the valve down and it don't spring back all the way up.. I use a short section from a compression gauge to go in the head then hook the air hose to that, works good even with headers that cross in front of the plug..

 

[joecal]

Thanks guys for the advice, I appreciate it. I would prefer using air if I had a compressor. I really don't want to buy one, because I probably won't have a use for it other than airing up tires. So what size socket do I need to turn the crankshaft?

 

[MikeB]

Well, you were lucky I learned the hard way, I had the piston wayyy down like at the bottom, at the time I used a stiff wire which works but it happened to slip off the valve, next thing I heard was this clunk sound, I can still hear it today, lol.....

That's funny! Any nightmares?

 

[RangRayy]

should be a 5/8 bolt. i replaced my seals when my heads were off, i know ideal situation, but even with the tool i could barely push the spring down. figured it was because in 29 years of never being undone before kinda made them freeze and lock the retainers in. i had to tap on the top of the springs to help release the springs allowing them to compress with the tool. hope that doesnt happen to you but just in case it does dont panic. also i used a socket to help push the umbrella seals down made life simpler. good luck sir and buying a compressor isnt as bad as an idea as it sounds, you never know when it will come in handy. even with a 1/4 or 3/8 impact.

 

[Georgeb]

A quick search on the Chicago craigslist turned up a lot of cheap copressors. You will find other uses over time. Or you can sell again after the project.

 

[Georgeb]

One other note. Use a magnet when you remove and install the keepers. They are little and oily. Don't drop one down an oil return hole. Just sayn........

 

[joecal]

Thanks for the information, and the bolt size and about the magnet, I have to get one of those too. You fellas are right about an air compressor but I've read it has to be a decent size one, at least 150 psi I believe. I did look on Craigslist and saw a few and checked out Harbor Freight ones too. I always wanted to learn how to paint cars, I wish I bought a good size air compressor when I was younger. I knew someone that could have taught me too, oh well.
Thanks again, this forum is a big help!

 

[74 Shortbed]

That's funny! Any nightmares?

Yeah, it's funny now but it wasn't then, LOL, no nightmares but it was enough to make me remember to always make sure the piston is at the top, lol..