what kind of valve problem is this pic?

[mazing3]

Hi folks,

Just took off my SSIs to make way for the new headers. The engine only has 500 miles on it since I rebuilt it into a 3.2ss. Spent some time looking around after getting everything off and found this on the #1 valve. It's the only one of the 6 that looks like this. I am referring to the cleaned off looking portion right there at the end of the valve near the seat. The different color black right in the middle that doesn't look covered in soot like the rest. the part that looks scuffy white above it is just where I tried to clean it for a better look with a carb cleaner soaked q-tip. I have been getting the blue smoke on start up as well as generally being a crop duster as I break this motor in. I just thought it had more to do with a few oil drips I needed to address until seeing this.

Though I built this motor, the trans and pretty much the entire car, I don't know much about assembling valves as I have never done it. I'm not certain on the terminology either. I know there is a valve guide, a valve seat, then of course springs etc. I just don't know which is the guide and which is the seat and most importantly--which one crapped out on me in this pic. I figured something must be causing the valve to move out of axis enough to scuff that one up. Thanks for any help you can give me here.

few engine details if it is relevant... stock 3.2 heads, 46PMOs, dc40s, 98JEs..

Thanks again.

[Lapkritis]

The valve appears open. The shiny part is the valve stem. The cone it protrudes from is the guide. The seat is the surface of the head (normally insert of harder metal) where the valve rests against up near the large part in the photo when the valve is closed. Judging by the smudge marks on the wall of the port and guide, something has been in there (finger, screw driver, chunk of engine exiting) that removed some of the carbon/soot. Did you check the side to side play in the valve with the engine apart? If the valve wiggled side to side in the guide then you may have a bigger problem.

[mreid]

That's an awful lot of deposits for 500 miles. Who rebuilt the heads?

[mazing3]

Good information, thanks guys. This lead me to linking some other dots together from it's history...

I did actually have something clanging around in the muffler but while shaking it around to get it out I missed where it went, or what it was. My son had just dumped one of my parts bins so it could be anything. Going to look for sooty things. Everything looked fine inside the muffler but now I realize I definitely heard it.

So assuming I can find this thing the valve is probably fine?

The heads actually have 1600 miles on them but only 500 on this version of the motor and I didn't spend much time cleaning the exhaust port side.

Thanks again

[irobertson]

Have you removed the valve spring and then checked the movement of the stem in the guide?
Is it fetching up a bit when the valve is nearly closed?
How about compression test or leak down?
Perhaps you inadvertently bent the valve while timing your cams or at some other point during assembly.
I say this because I touched my #1 exhaust with a piston while timing my cams. If the chain jumps a tooth, you can easily get out of time enough for things to contact.

[mazing3]

No but those are good ideas of where to look. I'd rather avoid doing a top end tear down if I could. That's why I'm hoping this is just a washer or something I dropped in there banging around. Going to take a much closer look to see what fell out of that muffler.

[mazing3]

I found what was in there. It appears to be the top half of a rectangular speed nut. I thought I was really careful with keeping the ports taped off to prevent something fromo dropping in but perhaps not. I'm starting to think my 16month old son might have dropped it into the SSI when it was on the groun. I had the engine upside down in the stand putting them on and it could have fell in.

My only concern is the fact that there is only half of it. And it does look like something violent happened to take the other half off. It's long enough to have been wedged in between the exuast port wall and valve stem to make the marks on both we see in the pic but wondering if it could take enough of a beating there to break off.

The other scenario would be that it came from the combustion chamber and got beat to hell on its way out via the exuast port. I really don't want to do a top end tear down for this unless I have to so can you guys think of any way I can diagnose any real collateral damage without doing that? And would a compression test reveal that?

I was planning on doing a valve adjustment anyway while waiting for my headers so maybe I can push that exhaust vale in enough to get a good look around with an endoscope.

Thanks again and let me know what you think.

[Lapkritis]

Bore-o-scope

[mazing3]

I really need to get one. I work in surgical device sales do have a fun little alternative... 4mm diameter rigid endoscope that can change the view angle from 0 to 90degrees with 360 rotation. A 10k scope we normally use in sinus surgery may be a tad overkill but it works.

[afterburn 549]

The guide appears to have been butchered ! ( on the out side on install ? ).....Not sure what the bore looks like .Gouge marks on vale stem?
i am not finding fault, you asked..and pics alone can be deceiving

[mazing3]

No offense taken, I didn't build the heads. Im going to clean it up a bit and see if the marks are more than just abraded carbon deposits. Thanks again for the input. The car is in the air in limbo for a few days anyway so might as well.

[Eagledriver]

There is probably nothing wrong. If you are worried about it you can do a leak down test on it or have it done somewhere if you don't know how. No reason to tear down the motor unless something is broken.

-Andy

[afterburn 549]

The valve stem should represent a new valve . It does not, not sure if it is size marks, grind marks, but looks like a foreign attack at installation.
The valve is open , now has to close dragging those imperfections up the guide.
Not a good thing

[Lapkritis]

What we're arriving at is likely a guide that is severely worn. This would allow deposits to form on the surface that is normally clean where the valve stem and valve guide contact. The picture indicates a hotdog down a hallway.

[afterburn 549]

Did you check or have checked guide to stem wear whilst apart ?

[911pcars]

Does the engine run?

What are the symptoms, if any?

Compression test performed?

Sherwood

[mazing3]

Hey guys, sorry I have been away from all of this a few days but wanted to answer back on a few things...

It was more of a "what the hell made those marks in there" kind of a thing as i thought maybe the valve was rubbing on the something through it's range of motion. I did find something in the muffler that looks like it could have done it and was content with that being that and just doing a compression test to be sure there weren't any major concerns.

But all of this other speculation from you guys got me to thinking about this even more....

Sherwood, you asked me about symptoms...Car runs great, very strong. There really weren't any problems other than being a rolling smoke machine on start up and on WOT. I was attributing that to not yet spending any real time getting my PMOs dialed in and a few little nagging oil drips (lower valve covers) that needed some attention.

Unless there is anything else glaring wrong here I think I am going to just get the headers on when they arrive and do a compression test just to be certain there is nothing really wrong. Thanks again.

[Lapkritis]

If the guides are very loose you could have valve stem seals leaking very quickly. For comparison, I consider the top end job I just completed that does not smoke at all even during break-in. My engine was also has PMO carbs that required tuning.

[mazing3]

Ugh. I was fearful about that. This might now be turning into a thread about arming me with info to have a discussion with the trusted source I got these heads from.

So it's the valve stem seals that are ultimately the root (or a root) of the smoking? What can cause that to fail assuming they were all new before I put these heads on the motor only 1600 miles ago?

One answer to that may bring me full circle to one of the reasons I was replacing the SSIs with headers to begin with...

I had read some things indicating that the SSIs can wind up actually becoming a bottle neck of flow and be a restriction when the motor gets to a certain level of build. Makes considering my configuration on this build so I figured I exhausted the limit of the SSIs. Someone on this thread had commented on how it looked like there was an excessive amount of carbon built up in there with so few miles and I'm wondering if there is a connection here. Is it possible that things could have been getting "too" hot in there thus contributing to the excessive build up as well causing the seals to fail? I'm connecting dots here that I'm not certain actually connect.

I have to admit, it is kind of embarrassing having the rest of this car at the cosmetic and otherwise mechanical level it is at from bumper to bumper but looking like a crop duster when I lay on the throttle-or just start it up.

I really appreciate all this guys! Having a balls out fast 38 year old 911 is one thing but all that sense of pride goes out the window when it looks like a smoky menace to society.

[johnman001]

For what it's worth, I don't think that the picture posted is showing a stock 3.2 head.

All the 3.2 heads I have looked at have recesses where the factory heat exchangers actually extend slightly into the exhaust port to help protect the exhaust gaskets and to insure a good seal.

I could be wrong as I am no expert and am limited to the relatively few 3.2's that I have actually worked on (84-87 engines).

In any event, I too, think that the exhaust guide looks a bit beat-up and shouldn't appear that way.

just my $0.02