Valve seal rope trick

johnnyzoom

johnnyzoom

Well-known member
I tried to replace some valve stem seals on a badly smoking engine using the rope trick.

No matter how much rope I put in, can't keep the stem from sinking.

Do I need to go to compressed air to get enough leverage on the spring to seperate it?

Or is this a sign of something worse?

Engine runs strong, but smokes (blue) like nobody's business. Don't think it's running rich, and don't think it's sucking oil through PCV.

Thanks for any advice.
 
i tryed the rope once n never got it to work ,, i always use air ,, but seals normly only smoke on startup not driving ,, if its going down the road n smokes i would think oil ring ,, do a comp test
 
That rope trick has worked great for me a number of times, maybe you could describe your process and we'll see if we can figure out where things are going wrong.

-ron
 
I used the rope method a couple of months ago. I was surprised to find that in order for it to work I was shoving over 7' of rope in the cylinder. I personally thing the rope method is probably the most fool proof as if you break the "air" seal the valve is gone.

Out of the 12 valves I had two that would drop about 1/2 to 3/4 of an inch and it was no problem.

On my Cougar the only limitation was the ability to rotate the engine. I could not get a wrench on the crank pully as the fan shroud was in the way and fan and I was too lazy to take it apart, so I used an allen wrench on the power steering pully. Not the best but with patience it worked.

SHOVE MORE ROPE IN!
 
Well here's what I was trying:

Removed all spark plugs thinking it'd be easier to turn the engine. Started with #1. Admitedly, I'm just short of TDC, but thought difference was "negligible". In past I've been able to turn engine by pushing on fan, but not this time, belt slips.

Pushed about 5 feet of rope in there, using screwdriver to push it in as compact as possible, can't fit any more. Using 1/4" laundry line type rope, maybe it gives too much and I need nylon?

Using $10 spring compressor from chain store, type that you remove the rocker then bolt down. Get plenty of leverage, fits over spring correctly.

When attempting, the valve sinks about 1/5 of an inch or so, I'm pulling really hard but it looks like the spring is compressed and no joy.

The more I look at this the more I think my problem may be running rich, I get lots of black soot at end of exhaust, so I will pursue that possibility. But I'd really like to successfully change these seals since I already started and it'd be good for the engine (this is a new project, engine has 97k).

Thanks for the help.
 
I used 3/8" nylon, cheap bulk rope from the hardware store, probably about 7 feet of the stuff, make sure to melt the end together so it doesn't fray and don't use black tape because it could 'pull off' as you remove the rope from the cylinder. I rotated the block to the bottom of the stroke, shoved in about 2.5-3ft of rope, then rotate the motor until it stopped. The engine will stop turning over when the rope gets to the top of the cylinder and can't be compressed anymore. The rope should be forced up against the valves by this point also, so your spring compressor should now be able to work as expected. If you experience any engine rotation you may have to find a way of keeping pressure on a wrench on the harmonic balancer, or have a friend/family member hold it.

-ron
 
CoupeBoy is right - put the rope in BEFORE you move the piston towards TDC, and it'll compress - jamming the valves in place.
 
Make sure when you are doing this that you have the rocker arms off or you could bend the valve. Also pulling all the spark plugs will make it easier to turn the motor.
 
Ok, I'll give that a try, rope then turn engine for more pressure.

Thanks for the help. Last night when I couldn't get this, I knew if I posted something on it I'd have a solution within 12 hours.

This board never ceases to amaze me.
 
don't forget to take an appropriate size socket and hammer and smack the top of the retainer. This will loosen the locks and break any varnish seal.

John
 
cobraguy":17rd9zgy said:
If you do lossen then with the socket and hammer method be ready to cath flying parts.
Click to expand...

Good point, on a 200 if one of those retainers made it down a pushrod hole you would no longer need to use the rope trick because you would be pulling the head.
 
lol you guys are funny :D

You don't use a socket to remove the valve springs. You just give it a wack so that the varnish is broken. Then you put the spring compressor on. Failing to do this will sometimes, not always, mean that the valve will try to stay with the spring when it is compressed. It's when you don't do this, and the valve and locks pop up suddenly, that's when the pieces fly :roll:

John
 
Remember, we had to tell Johnny that you do the rope trick with the engine off. :wink:
 
Another way to do it - make an adaptor using a butchered spark plug, an air valve etc. Use compressed on the apaptor air to push the piston to bdc and blow the valves shut but be careful not to break the air seal or it is head off time.
 
Once upon a time I bought a cheap compression tester just to get the spark plug threaded fittings. Then I threaded on an air fitting so that I could do as wagon suggested above. I've never used it.

-ron
 
The compressed air method works better.

And it has the added bonus of helping diagnose burnt/bent valves.

If you pull the rockers off, pressurizing the cylinder, and are getting air out the exhaust or intake - then that valve is leaking.

whack it a few times with a hammer to re-seat it (softly).

If it doesnt go away, you know its a worn out valve/seat.

You can also get a qualitative feel for the state of your rings. If one cyl is leaking WAY more into the crankcase than the others, then you know it's rings have got problems.

Will also help you find blown headgaskets too. Basically, on each cylinder - check for air coming out where it's not supposed to :)
 
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