Ok,
Here we go again. Yet another question for those of you that know more about motors than I do. I am rebuilding the top half of my 76's motor (5.9 liter) and I found that the rubber seals around the valve stems (valve cover end) are worn and/or cracked. I know it is not a huge deal at this time because she ran just fine with them in this condition before I took it down. Anyways, can I replace these seals with the heads installed? I need to get this pig re-assembled and I just don't have time to wait on the parts.

 

Make sure the piston under the valve/valves is at it's highest position. Compress your spring with some needle nose type vise grips (will need two of them). Take out the ratainers and top, the spring should come off at this point. Remove your seal then reverse the process.
I did this to a 460 in a F150 while traveling in Mexico. I could not find the needle nose type vise grips, sooooo guess what I ended up useing???? BAILING WIRE!!!! I ran it inside the second to the top and bottom wrap of the valve spring and turned/twisted/tighted it with a regular pair of vise grips until the spring compressed enough to get the retainers out. Then to remove the wire I just cut it with some wire cutters and pulled the access wire out with a pair of pliers.

 

Thread moved to the proper engine forum.



Yes you can, You need the proper tools though.

You also have to have the engine crank in certain positions to avoid having the valve fall into the cylinder.

You can do a search in our tech articles for Changing valve springs as the process is the same

 

Been there, done that.... Take a long length of rope that is small enough to fit into the hole of the spark plug. Pull the plug and fee the rope in, of course leave enough so you don't lose it inside Bring that cylinder piston up to the top and it should hold your valves in place. You can rent a spring compressor tool from the local parts store that colapses the spring. Pull the retainer and remove the tool, replace the seal and reverse your process. I want to say I spent about 2 hours on all 16 seals.

--Mike

 

Remember to remove the chips and bits of the old seal as they can clog the oil return passages and cause leakage later on. The new seals may come with a tool to get them over the valve stem. If they do, it will protect the new seal as you install it. Oil the valve stem before installing the new seal. You may also be able to use a plastic straw on some valve stems if you have problems getting the new seal installed.
tom

 

the easiest way is to charge the cyl with compressed air...you can buy the fitting at most auto parts stores, hook it up to compressed air, and the valves will stay closed...There is a little bar, that lools like a small crow bar, with a hole cut to keep the valve stem exposed...It hooks on to the rocker shaft...A little pull and the spring collapes, remove the keepers..then the spring...switch seals, and reverse the process...only takes a few moments per cyl. I have done this in less than a hour, in the truck...But of course you need a compresser...

The last 390 I did this to, was in such bad shape, the compressor ran non stop because the air was bleeding past the rings......The seals didnt help much..LOL

 

> the compressor ran non stop because the air was bleeding past the rings......

Yea, happened with my truck, I ended up using rope. Then I get the first spring off and find out my valve stem seals do not fit over the stem correctly and are too tight and float with the stem instead of staying at the bottom. I guess some how I have oversized valve stems.

 

That's what they're supposed to do...

 

I'm trying to swap the valve seals on my 390, and I'm having difficulties getting the retainers off... What's the trick?

 

Get a rubber or dead blow hammer and give 'em a couple whack's. I use a piece of wood and a hammer, particularly effective when you've already got the spring compressed.

 

I like a few lite taps from a tac hammer.


That will pop them loose.



-Brandon-

 

I did the rope trick on my 66 2wd, we used two screwdrivers to pry with. I took a old rocker arm set-up and took everything off and put the towers back on, to use as a place to pry. The keepers were stuck petty bad, so with the springs compressed we used a hammer and screwdriver to hit between the keepers to pop them off. Coppressed air would not of worked because of how hard we ended up having to hit them. As it was, some of the valves openned up and pinched the rope and we had to pop them to release the rope. We pulled the oil pan because all the rubber from the seals was down and plugged up the oil pump pick-up.