The Stovebolt Site Forums The Shop Area Engine Shop Head-on valve seal replacement

My valve guide seals on my 261 are going out in a bad way, the back three cylinders smoke bad on decel. I'm sick of crop dusting with this thing. It uses a quart every 300 miles. The plugs are clean and all the oil is going right out the tailpipe; compression is fine.

Has anyone installed umbrella seals with the head in-place? I know the general procedure, use air pressure or rope to hold the valves closed, compress spring and pull off keepers, slip new seal on. Does anyone have a recommendation for valve spring compressors or seals? What umbrella seals fit a '62 261?

I have a spare '58 235 848 head I can swap in if needed but I don't want to have to rebuild it. The higher lift 261 cam might make the valve guides die.

If you don`t mind to use F..d parts

Dan pa was sending me a set of the Ford (ouch) umbrella types. He says they work great.

I go put em on my new head when it comes from the machine shop on friday.

Drop Dan Pa a line to get the specs/parts number

Frank

If you're using that much oil, the exhaust guides are worn out. Don't waste time changing seals; swap the head. Putting umbrella seals on would be a very short-term fix, if it workd at all.
Jerry

HRL,

What about the dreaded " I did the head, now the rings are-a-smokin" theory?

Stuart.

When that happens, I think it means that you worked on the wrong part of the engine, not that you stressed a marginal component.

I'm sure I'm leaking some of the oil, too, but maybe the exhaust valve guides are worn out. Is there a way to check without yanking the head?

If I'm going to yank the head then I'm going to pull the whole engine and have the whole mess rebuilt. I don't know how many miles are on this block but it had the original paint job when I got it.

It's possible to remove the valve springs from the top without pulling the head. Be sure the piston is at the top of the stroke to keep the valve from falling into the cylinder. This can be done by watching the operation of the valves. Turn the engine clockwise by turning the fan with the spark plugs removed, until the exhaust valve closes, and the intake just begins to open. mark the crank pulley with chalk, and make one full turn. now you're at the top of the compression stroke with both valves closed.

Pry the valve springs down until you can remove the keepers, and remove the springs. Grab the valve stem at the top and wobble it back and forth. There should be little, if any free movement. If there's a noticeable amount of free play, the guides are worn out. Be SURE the piston is at the top, or the valve can fall into the cylinder, and you'll have to remove the head! Reassemble the springs on the valves, and move on to the next cylinder.
Jerry

Pry the valve springs down sounds a bit crude to me Lincoln.

Spend those $23-$27 and get one of those universal overhead valve spring compressors.

We use it often and with this tool it`s a peace of cake now.

[img]http://www.mytoolstore.com/kd/2078.gif[/img]
http://www.mytoolstore.com/kd/kdengi13.html

[img]http://www.bobstools.net/Store/media/16750clp1x11x11x1.jpg[/img]

http://www.bobstools.net/Store/LS16750.html

Frank

Frank, I've got about a dozen home-fabricated tools dedicated to different engines, that work better than those fit-all tools. i keep forgetting I'm not dealing with a bunch of pro mechanics, so I skip the obvious steps.
Jerry

HRL,

I would think if you aren't dealing with a bunch of pro mechanics, then you would want to INCLUDE the obvious steps.


Stuart.

I wouldn't mess with any of the head-on-engine stuff unless it was an emergency repair to get the truck back in service. This doesn't seem to be the case here, as it is serviceable, albeit smokey. Also, I am lazy and would rather work at the bench than leaning over the engine. Just pull the head and have the guides replaced and the valves replaced or reground as needed. No seals necessary this way. To speed things up, have another head ready to install before doing anything and it will take less time to switch out the head than to mess with doing anything with the head on the engine.

Just my opinion, but if you're not sure about the condition of the rest of the motor, rings, cyl. walls, etc. a head gasket doesn't cost that much. I'd yank the head off and put that sucker on the bench where I could comfortably work on it. Then you can clean the combustion chambers, clean the valves, inspect the guides, I believe the guides should have about .0015" clearence? H.R.L. will correct me if I'm wrong. Then you can take a look at the cyl. walls and get a better idea what's going on. You'll be able to "feel" if the vavles are too sloppy in the guides. Wiggle the valve head side to side, you'll know if it doesn't feel right.

Besides, layin' over top of those big fenders kills my back!

I'm still tall and young and bendable, so I don't mind working over my fenders.

I plan to rebuild this engine with a hot cam and higher compression in a couple of years anyway, so I may not do anything yet.

I've seen guides worn out due to too good a seal! If the umbrella seals are used, then the original O ring below the keeper and the sheet metal shroud under the spring retainer should be left off. (I've worked so many V-8's and 250/292's I don't remember if the 235's have the same arrangement.) It's possible to starve the guides for oil enough to create rapid wear, especially on the exhausts. Once the oil starts to gravity-flow down the exhaust guides, oil consumption increases dramatically. If you're using a quart in 300 miles, umbrella seals will help a little, but not much.
Jerry