engine and drivetrain Stuck Exhaust Valve

[rstclark]

Is you car number matching ?  Meaning the body stamp.  engine block  and the steering wheel cover   Then is the head the correct year casting ?   Should be an e12 with a casting mark for a 75 or late 74

If all those things line up it indicates you have an original car  and may add some value . A different year head is not very significant IMHO  because heads are a soft spot and got replaced  .  If you are a stickler for detail then stay with your head and have it worked on as long as it's repairable  A buyer may not care however about the detail of the head casting 

Shipping and paying for a remanufactured head seems excessive given that  most anything can be addressed by a good machine shop

 

Again ,  pull the head and repair whatever needs to be done   Reinstall the head and be proud of yourself. get help if you need it.

[TobyB]

Take it off.  Unless it's a mess, it's worth fixing.  What comes back as a 'recon' may be a bit short on the 're' and long on the 'con'

 

But again, are you sure it's not a slipped adjuster?

 

t

 

[Boultman]

I can push the valve further into the head if i push on the top of the stem, but it only comes up about 1/3 the way up, unlike the others.  

 

I guess i'll just start pulling everything off.  I liked the idea about pull it off with the manifolds still on.  I could probably rig-up some sort of hoist. 

 

My main concern is getting the timing chain back on, and everything back on just like it should.  This would be new territory for me. I have the Haynes manual, so that will help.  But the photos in those things were taken with some sort of potato from the mid 80's.  

[rstclark]

Go for it 

Take lots of pictures and take your time  Once you have R&Red the head , adjusted the valves  and set the timing you will be a full fledged mechanic

You can do this

['76mintgrün'02]

1 hour ago, Boultman said:

My main concern is getting the timing chain back on, and everything back on just like it should.

 

I have never pulled a head, so this may be of no help... but then again, it might be... so here you go:

 

I pulled the sprocket off the nose of the cam, looking for identifying markings, to determine which cam I have.  I was worried about keeping tension on the chain, so I made this little wooden block, which sits on top of the lower timing chain cover and keeps the chain tight.  

I made a print with a piece of paper set on the lower timing chain cover and cut the block to fit under the gear.  Then unbolted the sprocket and slid it forward, with the block resting on the cover.  It worked great.  Maybe you could do something similar, when pulling the head, so as to avoid slack in the chain?

[TobyB]

Quote

I can push the valve further into the head if i push on the top of the stem

How hard is it to push?  It should take 100+ lbs....  (I'm thinking broken spring, here, and then it bent)

Or the seat's come out, but, dang, I've seen heads with chunks of aluminum missing around the valve seat,

and the seat was still in place.

 

Yes, Tom's wedge is perfect.  Jam it down in to push the adjuster back a bit, and add zip ties to keep the

chain wrapped around the upper sprocket, and you'll be fine.

Bailing wire works great, too.  As long as you TDC the engine, it's no problem at all to get everything back together.

Even if the chain slips, you can almost always get it back up, and retiming the cam's not hard.

 

My preference is to pull the intake, and leave the exhaust, as long as the lower pipe comes off cleanly.

But you can leave the intake if you want to.  It does save messing with the water pipe at the front.

 

t

 

[Boultman]

it is about 100 lb of force.  i was using a flat-head and prying it down... which i'm sure isn't good for the top of the stem, but we are past that...  

 

Since that cylinder looked a lot blacker/oilier with the scope, i'm thinking the valve guide was jacked up and eventually lead to the valve sticking, then bending.  but the engine didn't use oil or smoke..?

 

and damn... it ran and sounded PERFECT.   then i restart the engine after running into a fish market for 10 minutes, and it immediately sounded messed-up.  so odd.  

 

Record breaking heat today here.. once the heat breaks a little in a week or so, i'll start tearing down the ol'girl.   I"ll take photos and try to keep this thread updated.  That's the only way we all learn right?

 

thanks again.

['76mintgrün'02]

I would be happy to send you a wedge.

 

[Boultman]

Alrighty.  Pulled the head.  The exhaust valve is definitely stuck, but i have gotten into the head itself to see why.  That sounds a job for the person that is going to rebuild it for me.  Which leads me to question #1.

 

Who do you guys recommend I ship the head to?  Any advise on what to send, or request?  Upgrades? Should i have them send all the gaskets as well, or purchase those elsewhere (cheaper)?

 

I did not make note of the bolts that hold the upper timing chain cover on.  I'm not 100% which ones were the shorter ones.  i'm sure i could research and find out. 

 

The head doesn't appear to have any cracks or anything.  There are 1-2 weird casting areas, but i'm sure that is normal.  photo below. 

 

Also, the bolts and brackets that hold the timing sprocket on were bent into the bolts looked odd.  The brackets were bent into the bolt heads, like you would a bearing lock washer.  is this normal, or something the last person did and shouldn't have? Photo.

 

The timing chain tensioner has a weird chuck out of the corner of it.  It isn't anywhere near where the chain actually rides (the photo below makes it look close, but that's just because the sprocket and chain are pulled away from cam..).  Issue?

 

lastly, the valve did kiss the top of the piston. which is inevitable i guess.  There is no real damage, just a little gouge, and not very deep.  more like a deep marking.  Photo below.  

Lots of cleaning to do.  I'm mostly concerned about how well i marked the distributor/dizzy and if the timing is going to stay correct when I re-install.  I lined the sprocket up and both of the cam lobes closest to it were facing down, with the cylinder all the

way up.

 

 

[TobyB]

Yeahp, that exhaustive valve do look stucky.   From the amount of goo on the piston tops, I wonder if perhaps

the goo is holding the valve open.  You've got a lotta goo there...

 

Oil, I'd bet- if the bases of the exhaust valves are completely encrusted, the guides and seals will need attention.

You can see the stems easily by looking up the exhaust ports.

If there's goo on the intakes, similar to the exhaust, then the guides and seals are doubly indicted.

The rings could be leaking, perhaps, too.  I can't see the condition of the bores- if there are real gouges in them, that can do it too.

 

It's hard to tell, but #'s 1&4 look like the principal offenders.  

HOWEVER, it could also be carbon from running rich, and you got oil onto the piston tops.  Making the carbon buildup look like oil...

That would explain why 1&4 look the same, and 2&3 look the same.  And if the intakes look a LOT cleaner, that would 

indicate rich running more than oil...

 

The piston damage is probably not a big deal, but the valve's bent for sure.

 

Those cam locking tabs are normal. 

The chunk out of the tensioner slider probably happened on reassembly- but poke at it.  If it crumbles, you'll have to replace the slider. 

The OE one lasts well, but some aftermarket ones got brittle.  I've seen 2, so far, that have done that.

 

And yes, your engine's been apart before.  The head was sanded, and a VR cutting ring gasket was used.  You'll want to have

it lightly decked before reassembly.

 

Ya gotta lotta goo!

 

t

 

[Boultman]

i'll take a look at the valve stem areas tomorrow.  Productivity has ceased for the day, and the intake of pints has begun. 

 

the goo you are seeing is almost definitely carbon build-up from running rich.  There was a decent amount of time when the car ran really rich (playing with carb) and timing was a little off.  The car also had the wrong coil in it (took me a while to diagnose that issue..).  So combustion wasn't great either.  I'm guessing all of these things lead to most of the build-up.  like i said, the car does not burn or leak oil.  If it does, it's not enough to add any between 2,500 mile changes.  I use Kendall 20w-50. 

 

The cylinder walls of 2&3 are perfectly smooth and feel great.  I poked on the slider of the chain tensioner quite a bit, and all seems ok.  

 

Any recommendations on where i should send the head?  are there 2-3 places that most people send their heads?  

 

thanks,

[TobyB]

I've always shopped locally for a machinist.

 

I think most of us do, or at least regionally.

 

I have a vague memory there's someone in your area, but I don't remember who...

 

t

 

[Boultman]

Looks like seat just came loose and stuck. 

 

Anyone know the thread size of the head studs?  I want to get a bottom-tap to run down the block after I flush them out. 

 

[TobyB]

Hmm, look at that- there's a procedure for staking them in... 

Realoem shows oversize ones, even as being available...

 

M12x1.75, I seem to remember, but I don't like running a tap down threaded block holes:  BMW used a tighter "fit class" tap than

you can get generically, so when you run the tap, you take out some metal.  And that just didn't seem like a good idea to me...

 

That shouldn't be too hard to fix, if the rest of the head's ok. 

 

t

 

[Boultman]

i'm not fixing anything on the head, I just wanted to clean up the holes/threads to make sure the studs have enough room to tighten all the way down.  

 

We do this at my shop for industrial repairs all the time.  we like the run taps during refurbishments to just clean things up.