Both exhaust valve stems on drivers side head are strikingly white. The other bank is a pretty normal brown. See pics below.

Research on this board revealed contradictory schools of opinion. One states that the white is caused by fuel entering the exhaust manifold (weak spring "fluttering" or too much lash). The other attributes white residue to a lean AFM (like spark plugs).

Given these theories, and since the gap (lash) is within spec for both white valves. it's reasonable to suspect that either: both injectors on the driver side are failing or the spring assembly on that side is weak.

I'd appreciate some other opinions.

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I'd lean towards a lean condition. But i'm no T4 expert ...

Here's the other three: (cylinders 2,3,4)
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The white valves are the two driver-side exhaust valves and the brown are from the passenger side.

I know the white is ash, that it's typically the sign of hot combustion and not necessarily a problem, but the valves in the other head look very different and that gives me some concern.

Sometimes it has felt as though that side (the "white" side) of the engine is running little hotter than the other, but I wasn't sure until now.

Thanks Andy, and I share your opinion, BTW.

The HP water-cooled people I've talked to say its a good thing or at least don't think it's a problem, but the engines they are used to run very high compression compared to T-4. I'm speculating that the white ash might mean there's too much heat in an AC valve train. Don't know why I think so, just my uneducated feeling.

If it's an over lean condition then the exhaust temps should vary. Take an IR therm and take the exhaust temps close to the head after the engine is warmed and stablized.

That makes sense, thanks. I'll do it. Any general thoughts on valve color for the type 4 engine?
( My four-year old asked me to add this emoticon)

Thanks again.

I'm no expert, but thought I would mention this in case anyone else has thoughts on it....
I've heard that white deposits on valves can be from excess oil getting in the combustion chamber (rings? valve guides?)

Don't know if it applies, but I figure any possibility is good for discussion.

Didn't think about oil. I'll check the compression too.

Surely the condition of these valves as shown by pics is meaningful.

About to install new H/E and like to know whether I should stop and pull the motor, order a few injectors, or nothing.

Anyone else?

Please.

pull the upper tin off that side and see if there is a mouse house there.

Since both valves are on the same side, and that is a sign of a lean condition, the induction system needs to be checked.

If you're running dual carbs, you likely have a problem on that side. It could be as simple as the carb on the OPPOSITE side is leading this one = linkage needs to be synced. Could have a vacuum leak at the manifold = lean. Clogged jets = lean.

If you have EFI, check for vacuum leaks at the manifold on that side (and everywhere for that matter). Could have injectors that are clogged and it's limiting spray patterns = lean.

I would also check your valve adjustment on all valves to be sure those valves are closing fully. It could be that your valves are just not fully seating and therefore getting really hot (they only cool by contacting the seat for that brief moment between opening).

Did you put it there? I wonder why it never caught fire? Last spring I saw a snake crawl into the passenger side heater vent. Now I know what it was looking for. I won't talk about how I made my wife look for it the next day.

so did you find a bunch of stuff on that cylinder under the tin?

maybe that was cause high temps and lean burn on the cylinder?

Are you kidding? There was a mouse apartment complex on top of the driver's side of the motor. Mostly yellow fiberglass insulation. Cozy. Found one of the old spark plug grommets that'd been chewed through. I've no doubt that caused HT on that side -- couldn't have been much air flowing. That car sat in a barn from 1988-2011, I'm glad you thought of it. Thanks.