Paul L

When you do the compressor job for replacing the valve stem seals, what if the air pressure drops down below optimal and the valves drop. Can they be pumped back up with higher pressure?

Pete79L82

Not they cannot. The valve would be open and you could not pump air into the cylinder fast enough to build pressure.

Paul L

Thanks, Pete. That is what I was afraid of. I cannot see putting these Crane seals on to the valve guides - however well oiled - without pushing the stems down despite 100psi.

Sorry, I will edit the large photo.




[Modified by paul79, 7:53 PM 2/26/2002]


[Modified by paul79, 8:01 PM 2/26/2002]

Pete79L82

Paul;

I put some of those on an old El Camino I used to have. After I put air to the cylinder I took a pair of needlenose vise grips and wrapped some duct tape around each of the jaws. After I removed the spring I GENTLY clamped the visegrips to the valve while I pushed the seal onto the stem.

Worked good for me.

MikeC

Paul, I did the seals on my truck's 350. I don't think the valves would fall unless your pressure got really low. My engine has so much blowby that the compressor was switching on every 3 or 4 minutes. I put very similar valve seals on my trucks engine with no problem. I think I had my regulator set to around70 or 80 punds too, so I wasn't even pressurizing the cylinders to the amount I could.

If this still bothers you, pull the sparkplug out, get the engine up to almost TDC push a length of rope into the cylinder and bring the piston up to TDC and the valves will not be able to move at all.

The air pressure will work though. You have 2.02 inch intakes and 1.60 inch exhaust valves, air at 90 PSI will exert 288lbs and 180lbs of force on the valve. that means you would have to stand on the valve stem to get the valve to fall into the cylinder!

Paul L

Mike, that sounds reassuring. Pete, not sure about the duct tape??? for some reason but I am sure that it works. Just have visions of a Bill Cosby "Whoops" during the surgery. Hope someone has a long enough memory to recall that track on vinyl.

Larry B.

I did the job by putting coiled up slick nylon rope into the cylinder and turning the engine by hand,compressing the rope to hold the valves up. No risk of dropping the valve. Worked for me. Twice. :yesnod:

faster69

Paul, Many people get away with the compressor trick . however, if the valve drops then you have to pull the head. What I do is pull the spark plug and fill the cylinder with 1/4 nylon rope. just keep pushing the rope in until the cylinder is full. I also turn over the engine by hand till it stops against the rope. no way can the valves fall in. Hope this helps. Rick

Paul L

Somehow that low-tech solution makes sense. Simplicity is the essence of design!

john's '81 mouse

Another advantage of using the rope is that you won't get water standing in you cylinders like you might get if you use compressed air, unless you have a water filter on your air compresssor. I used compressed air when installing my valve stem seals, until I found a cylinder that leaked air at the intake valve and then had to remove the head and found water from condensation in the compressed air in the cylinders I'd already done. Note, I did find the leaky intake valve as a result of using the compressed air method, and had I used the rope method, I'd never have discovered this condition.

Metal Wulf

and here i thought you HAD to pull the head to do the valve seals....


my car smokes like crazy until it's been running for like 15 mins... If I don't have to pull the heads maybe i'll look into actually fixing them...

:cheers:

GOTVETT

Mind if I take that advice too! I have really bad valve guides on cylinders 3 and 5. What what special tools are required to do the job.