Valve guides. How can they get pushed in too far?

[93rev2sev]

I'm knee deep into a valve stem seal job on an engine that's out of the car.

As I'm going along, I'm noticing that the valve guides seem to be shrinking on the exhaust side. One of them is pushed in so far, there is nothing to seat the valve stem seal on.

So I grabbed one of the heads I have that are stripped and cleaned up. Sure enough, it looks possible that the valve guides in question have somehow moved and are pushed in too far.

What can make this happen? The valve stem seals are not all chewed up at the bottom, like they've been hammering the guide down. Here are comparative pictures.

The only thing I can think of is severe valve float.

Good guide:

Guide pushed in too far:

 

[sperold]

My guess is.... it was like that from day 1.
Try moving them with a press, if it takes the same amount of pressure to move it as all the other heads you have, then the press fit still exists. And they have not moved.

 

[93rev2sev]

The heads are still on the engine and I was hoping to keep it that way, but I can forget that noise, now.

 

[gmorrell]

Wow, how much time on this engine and what were the typical running conditions? What cams? Do you recall the cold valve clearances?

Was this engine previously rebuilt? Do you know what ID the guides were reamed to after installation? I've installed guides in SHO heads, and I bake the heads to about 200F and freeze the guides prior to install so they go in with a little less pounding, but they have to be reamed after install, as the guide compresses a bit, and the ID won't even clear a valve stem. Actually, most guides won't clear a stem even before being installed.

One thing I can think is excessive EGT's may have caused the Aluminum around the guides to overheat and allow the guides to move, or the exhaust stems swelled a bit and dragged the guides. Any evidence this engine has been overheated? Any galling or marks on the exhaust stems?

Edit: If those guides were depressed like that from Day One, that engine must have burned Metric shit-loads of oil.

Oh well, time to get out the head bolt tool.

 

[93rev2sev]

This is Chis Gates' car. He bought it with 40,000 miles or so. To his knowledge, the heads have never been off the car. It now has 180K or so. There is quite a bit of carbon build up and caramelization, but the stem seals were intact, so they couldn't have been pounded from the top unless the seals were replaced at some point after the pounding and the condition was ignored by the mechanic. Edit but that would have been 140,000 miles and 13 years ago...or more Because Chris claims he's never had that kind of work done on it.