Okay, guys who've done a lot of engine work, don't raise your hands.

What is wrong with this picture? (aside from too much flash)



More detailed pictures will be posted after a few people have tried or succeeded in guessing the answer.

- Eric

 

Now that looks like the head on my old rod, mine is much better now that my new wife flushes out the fluids after she drives it.

 

The two center cylinders look like they are running lean(hot) other than that I'm stumped....Tedd

 

Is there a chunk of carbon or something stuck between the valves on the second from right cyl ?

 

Each cylinder is burning differently

 

No hits so far.

The cylinders are burning a bit differently from one another, but that's not unusual, given the different lengths of the intake and exhaust tracts, and differing amounts of compression in each cylinder after years of use.

The second cylinder from the right (which is #4) does not have anything stuck in it - that's a cast-in oval depression.

- Eric

 

Are the 2 center cylinders running hot and burned the exhaust valves? Possibly head gasket failure there and burning coolant as the spark plugs look white too.

 

Still no winner.

The center two exhaust valves are lighter, but I think that the picture makes them look whiter than they really are.

- Eric

 

Ooh, ooh, I know, I know, I know, call on me, call on me, call on me!


It's upside down. It's supposed to look like this:

 

There's a wise guy in every class.

Go sit in the corner.

I'd hate to have to go to assigned seating...

- Eric

 

Valve/piston contact on the first cylinder exhaust? I see something there

 

Whose first? Mine or Jaunty's?

I'll kind of figure you mean the leftmost cylinder in my picture, which is #8.

Which valve? Where?

- Eric

 

Oh, wait, you said exhaust.

What do you see there?

- Eric

 

Yes left most cylinder exhaust valve on the edge near the divide between the 2 valves in your picture. You can see the gray spot of the valve and a small black line there. My guess is contact from probably a stuck valve?

 

That's the right place.

Not exactly the problem, but you've recognized that there's something wrong there.

- Eric

 

Looks like a small ding on the second one in from the flipped pic on from the right.

 

Ok then I am going to go back to the burnt valve idea but on the valve I described as there is no carbon residue at that area. If not then I am stumped

 

DING DING DING DING DING!!

We have a winner.







This didn't look like much at a glance, but it is important to be able to recognize something like this so as not to think it's fine and put it back together.

More details to follow...

- Eric

 

Magna's lucky I didn't see this thread in time. I totally would have won. I mean if I had gotten those bifocals the doc prescribed....and I had more experience......and I was smarter
Eric, is this off your vert?

 

At first I was going to ask if the head gasket was on upside down. Aren't the ridges supposed to go toward the head?
To be honest the pictures were too small for these old eyes/

 

This is one of those lessons for us all:

Check everything.


Somewhere over a year ago, I bought a used engine from a guy I've dealt with before.
I consider him to be honest, and I don't think he was intentionally hiding anything.
I wanted a motor I could use in my car for a while, until I get around to building a 425 that I've got lying around, and just wanted something that was running reasonably well, was likely to continue to do so, and was cheap.

The guy I got it from has a few cars, and was very happy to hang out, talk cars, and show me all of his stuff. This engine came out of his '68 Cutlass. He said it ran well, was all original, but it was now extra because he'd put an LS motor in the car. He showed me the car and it was a nice, clean installation and ran great. Kinda tempting, actually...

The motor was on a dolly in his garage, complete, as removed.
I looked in the cylinders with a borescope (all of them) to check for Bad Things and to make sure it had the high compression pistons.
I got it for $350, pan to air cleaner, including A/C compressor, alternator, P/S pump, etc., obviously with no guarantee, and obviously without hearing it run.

When I got it home, I began cleaning it up to paint, etc.
Inside it was used, but clean, with no accumulated gunk.
I did not do a cold compression test on the engine stand, though I really should have.
I pulled the pan, checked the bearings, found one rod bearing that was too loose, changed the mains and that rod bearing, and let it be (all of the bearings had normal wear, but looked good, same for the journals).

I did not pull the heads, because I didn't want to mess with the factory head gaskets.
This was my second mistake, the more so because the year before I had bought a set of recently rebuilt #6 heads for $75 at a flea market - they had maybe few thousand miles on them, and had new valves, seats, guides, springs, rockers, and bridges (oh, and valve covers, to. I've got a lot of those now).
My third mistake (OK, maybe my first, chronologically) was that I didn't cc these heads when I first got them - I just checked them over and put them in the corner.

So, I clean up the motor, change some bearing shells, drop in a HV oil pump that I had lying around (to make up for any bearing "problems" I might have missed), shimmed for 60psi, new timing chain and gears, a slightly improved cam from Mark, clean, paint, new gaskets, rebuilt carb (carb and distributor are original, distributor was set up with a Crane electronic sensor when I got it, had new wires, Blue Streak cap and rotor, and came with a near-new Blue Streak set of points and condenser in a baggie when I got it, as well), put it all together, drop it in the car, break in the cam, and drive it.
I set up the timing right, with springs and an adjustable vacuum pot, and it runs great, good power, smooth, but the idle is just a little bit rougher than an Olds should be.

I do a compression test (Hmmmmmm... maybe should have done that before as a matter of routine) and find all is well, pressures from about 150 to 170, with the #8 cylinder showing about 90psi (by memory - I've got the darned piece of paper I wrote it on somewhere). Oil doesn't change it. Do a leakdown test, and it's leaking through the right exhaust pipe.

Well, it runs well, so I put that on my "list" to get to "sometime."

Time goes by, and I finally get around to cc'ing those other heads.
They measure out to about 60cc and 63cc (if I recall - I have to recheck them when it stops raining), with the lower one being measurably thinner than the higher one.
They've been decked.
Which means there's no need to lose sleep thinking about factory head gaskets, as they will almost definitely require thicker ones (pending final measurement of piston depth).

So, "sometime" finally arrived yesterday, and I pulled the offending head (darned rain - the other should come off tomorrow), and this is what I found:










This, gentlemen, is a burned valve.

Left to its own devices, in addition to robbing smoothness, power, and economy, it would eventually have broken, sending shrapnel throughout Creation.

If you look closely, you can see how the area of the cracks, as well as the area leading away from it, is a different color, because it got hot enough to burn off all of the deposits that were on it.
It is a classic pattern.

Also note the seat - it should be straight, but is instead concave, as here:



If you ever run into a seating surface like that, you have a problem, even if it looks nice and clean.


Here's a more obvious one from someone else:




And another one from the same person (what did he do to his engine? ):

100_0923.jpg

You will note that in this second shot, the exhaust valve has also receded.
Now, looking back, you will note that my exhaust valve did NOT recede, in spite of 106,000 miles and some hard use (sporty Cutlass 2-door, which I think was a convertible), and non-hardened valve seats.
This is why many of us say, "Don't waste your time with lead substitutes."


Incidentally, I haven't tried to measure it, but the ridge is minimal and identical in all cylinders.


To sum up:
I didn't check the compression when I got it.
I didn't cc the new heads when I got them.
I didn't pull the heads to check the valves, though, if I had known that the new heads were already milled, I would have.
No big deal, I drove the car for a season and had fun with it, but it's more of a PIA to change the heads in the car than on the engine stand, and it'll cost me a second intake gasket.


If you've read this far and are still interested, here are a couple of articles on the subject, a discussion of valve failure, and a photo essay on burned valves.

Happy motoring!

- Eric

 

I still think my answer was better.

 

Yup.


No head gasket in the picture, just the residual pattern from the factory gasket.

And I'm not sure about WinDOS machines, but on a Mac, I just press "Command-+" (probably "Control-+" on a PC), and the screen gets bigger.

- Eric

 

Back to your corner!

- Eric

 

Thank you for the quick lesson Eric! I haven't built an engine so now this is in my tool chest waiting for use.

 

You're welcome - that was kind of the idea.

It's good to post up anomalies when we find them, to let the others know what stuff looks like in the real world.

- Eric

 

What causes something like that? Nice clear pics too thanks

 

Often it's due to valve stem and guide wear, which causes misalignment and poor sealing,
In this case, there is definitely more play than there should be - somewhere between a 32nd and a 16th of an inch without actually measuring it - so that's probably the problem.

Once you have an exhaust valve that has poor contact at one point (such as because of poor alignment due to a sloppy stem), that area gets hotter than it should, because ¾ of a valve's heat is sucked away by the seat every time it closes, and that area doesn't make contact when the valve is closed.
Over time, that hot area begins to warp and to be eroded, and gets bigger, which makes it hotter (especially at the center), which accelerates the process.

After a while: Bye bye, valve.

- Eric

 

Lol...... Ya I had it nailed down at the get go but I didn't want to spoil all the fun

 

Yes, it is Ctrl - + to zoom in, and Ctrl - - (Ctrl plus the "minus" key to zoom out). But the screen doesn't get bigger (at least mine doesn't). It stays the same 24-inch monitor it always is.

It's what's on the screen that gets magnified. However, zooming in doesn't do a whole lot because the image is enlarged at the same resolution, so it becomes slightly more out of focus with each zoom-in increment. I'm guessing it's the same on those magical, can-do-no-wrong Macs, too.

 

Okay, here's another one (boy, I'm just full of these this week aren't I?):

There's something off in this picture, other than the usual signs of a used engine.
What happened here at some point in the past?



- Eric

 

Cyl#2 got too hot?

 

Nope.

By the way, you are looking at cylinders 8, 6, 4, and 2, in that order, and #8 did have a bad exhaust valve, which led to lower compression and incomplete combustion, causing the deposits to be thinner, but more tenacious.

- Eric

 

Okee dokee, I'm gonna say Head Gasket failure
That and the pushrods have fallen out....

 

Nope. Original head gasket was great. None of the corrosion between cylinders that you sometimes see.

And those pesky pushrods, yeah, they keep rattling around.

The evidence is distinctive, but subtle.

- Eric

 

Have pistons been replaced in cyl 8 and 6? Only reason I ask is the diectional notch in the pistons look different than those in 4 and 2? Or am I backwards on that? Could be just the angle as well. Also #2 cylinder wall looks like it has a line in it or something.

 

2 of the head bolts (or something) broke above the 8 and 4 cylinders?

 

Nope, all of the pistons are 350ci 6cc high compression pistons, as installed by the factory in 1968.

The line in #2 is a reflection - I couldn't get a perfect picture considering all of the variables, including light, shadows, reflections, camera angle, and piston positions.

- Eric

 

Nope. Those are the locating pins for the head gaskets and heads. There are always two pins and three tabs, for some reason.

This is kinda fun.

- Eric

 

Someone had the intake off in the past and didn't replace that baffle that bolts in below the lifters? I think "fun" has a different meaning in my dictionary. It translates to 'sadistic' in yours. JK - I'm kinda enjoying this too.