Valve Stems. Can They Be Replaced With Heads On?

[akoz493]

I recently purchased a 99 ES300 from a friend who ran into hard financial times. The car needed some work which I had performed. Among the problems was a misfire in cylinder #2. I replaced the spark plugs and coil pack for the whole motor. The car runs great now BUT, it smokes blue at start up for about 40 seconds after sitting for any long period of time. Lots of smoke. It didn't smoke before I did the work. My mechanic says (and I agree) that the problem is the valve stem seals on cylinder 2. My question to everyone here is this. Can he compress the cylinder to perform the seal replacement? If this can be done, he won't have to remove the cylinder head. That would save me a ton of money. If this isn't enough info, let me know and I'll try to clarify more...Thanks for any help you all can give.

[lenore]

Yes that can be done by a good mechanic, I had that done on a Mercedes 190 e years ago. The mechanic replaced the valve stem seals without removing the head.... It is a matter of turning engine to position the valves closed and then pressurizing the cylinder through the spark plug hole.

[gabep]

Maybe, maybe not. I have a 94 Camry that has a minor valve stem problem. If it was a domestic built car that procedure would work but it is a Japanese built machine so the head has to be removed and run through a machine shop. I would do some deep research before trying it.

Good luck.

[Toysrme]

Yes, but you have to drop the valves down into the chamber, take the stem of through the intake port, put it back on, then the valves pulled back up from the chamber. (they hang upside down and the ports average 1.75"*1.5" and are sliced in half to around 1.25"*1.75 per runner in the siamese head ports.

And no you can't compress the cylinder to hold the valves in place. If you can't REMOVE the valves entierly from the valve guide / stem seal (sits on the bottom of the guide) then you can't remove the seal. It would be like trying to replace a washer on a nut & bolt while the nut was still screwed nto the bolt = aint gunna happen.

So the answer is... Yes. You can do it without taking the heads off. However, it is 5 bazilliondy times easier to do it via taking the heads off the top of the engine. You may aswell take the heads off & re-gasket the entire engine at one time...

(You pressureize the chamber to hold the valves up so you can replace the buckets, shims, retainers springs, etc. not valve stem seals.)

[akoz493]

Thanks for the reply. To clarify, what I need to replace are the valve stem SEALS. I know I missed that in the subject field up top. Does that change anything?????

Yes, but you have to drop the valves down into the chamber, take the stem of through the intake port, put it back on, then the valves pulled back up from the chamber. (they hang upside down and the ports average 1.75"*1.5" and are sliced in half to around 1.25"*1.75 per runner in the siamese head ports.

And no you can't compress the cylinder to hold the valves in place. If you can't REMOVE the valves entierly from the valve guide / stem seal (sits on the bottom of the guide) then you can't remove the seal. It would be like trying to replace a washer on a nut & bolt while the nut was still screwed nto the bolt = aint gunna happen.

So the answer is... Yes. You can do it without taking the heads off. However, it is 5 bazilliondy times easier to do it via taking the heads off the top of the engine. You may aswell take the heads off & re-gasket the entire engine at one time...

(You pressureize the chamber to hold the valves up so you can replace the buckets, shims, retainers springs, etc. not valve stem seals.)

[Toysrme]

No, that's what we're talking about.

The bottom of the head:

From the intake port:

The valve stem seals sit on that guide. Aslong as the valves are installed, the stem seals can NOT be removed. Again, go back to the analogy of a nut, bolt & washer. trying to get the washer off the bolt without removing the nut first. It's impossible.

[akoz493]

Toysrme,

I found a toyota mechanic who did the job WITHOUT taking off the heads! All he did was remove the valve covers and overhead cams (cams come off in one unit!) He told me to tell you about this tool, he said alot of Toyota/Lexus mechs don't even know about it but it's saved his a** a bunch of times. Check out this website. www.toyotool.com

I just thought you might find it interesting. Thank you for your responses.

No, that's what we're talking about.

The bottom of the head:

From the intake port:

The valve stem seals sit on that guide. Aslong as the valves are installed, the stem seals can NOT be removed. Again, go back to the analogy of a nut, bolt & washer. trying to get the washer off the bolt without removing the nut first. It's impossible.

[akoz493]

Toysrme,

I found a toyota mechanic who did the job WITHOUT taking off the heads! All he did was remove the valve covers and overhead cams (cams come off in one unit!) He told me to tell you about this tool, he said alot of Toyota/Lexus mechs don't even know about it but it's saved his a** a bunch of times. Check out this website. www.toyotool.com

I just thought you might find it interesting. Thank you for your responses.

No, that's what we're talking about.

The bottom of the head:

From the intake port:

The valve stem seals sit on that guide. Aslong as the valves are installed, the stem seals can NOT be removed. Again, go back to the analogy of a nut, bolt & washer. trying to get the washer off the bolt without removing the nut first. It's impossible.

[wwest]

No, that's what we're talking about.

The bottom of the head:

From the intake port:

The valve stem seals sit on that guide. Aslong as the valves are installed, the stem seals can NOT be removed. Again, go back to the analogy of a nut, bolt & washer. trying to get the washer off the bolt without removing the nut first. It's impossible.

I think he's talking about the seals inside the valve springs that prevent oil, mostly, from flowing, getting, down into the valve stem area and therefore slowly leaking around the valve guide into the combustion chamber.

[Toysrme]

If the valve remains installed into the valve guide which is pressed into the cycinder head (ie NOT dropped completely out of the guide into the combustion chamber)

Then it is absolutely impossible with any tool to change the valve stem.

This is a valve stem seal

This is where it goes:

The www.toyotool.com tool is not applicable to any DOHC Toyota engine that I know of. It is replacing valve stems that are located on the top of the cylinder head, while I can't name a single DOHC Toyota engine which does that. They're always installed on the bottom of the guide to keep them away from as much heat & prolonged mass oil exposure as possible.

That is the TOP of the cylinder head where the cams are located. Our valve stem seals are located underneath all that hanging upside down in the intake port.