Cylinder Valve Stuck Open!!!

[Birdsboat]

I?ve finally got my motor started after 5 years in storage!! I got it up to temperature and set the timing mixture and idle. While running I noticed a tapping noise. I?ve taken the valve covers off and checked all the push rod clearances and have noticed that when #6 is at TDC, the rocker arm is extremely loose which I guess is causing the tapping noise.one of the valves is stuck open. I?ve rotated the engine by hand and the push rod operates but that valve stays down and doesn?t move. Any suggestions for freeing a stuck valve?? What could the reason be why it?s stuck??

 

[Bondo]

Any suggestions for freeing a stuck valve?? What could the reason be why it?s stuck??

Ayuh,.... Pull the heads, drag 'em to a machine shop, 'n get 'em rebuilt,....

Caused by water,... rusted in-place,....

 

[Birdsboat]

Would you suggest to only change the valve stem seals in the rebuild or valves and springs aswell?

 

[Lou C]

This is why manufacturers recommend fogging engines that will be put in storage. If one is stuck, then its going to be best if you have the heads gone through do a good valve job then re-assemble with new marine gaskets. If one stuck, then others may be getting ready to stick.

 

[Grub54891]

Usually the machine shop replaces unusable parts, including seals, the refinish the seats and valves that are usable.

 

[Scott Danforth]

5 years is a long time. usually they recommend removing the rockers to rest the springs if you intend to store for more than 6 months.

As Bondo said, bring it to a machine shop. they will tell you what needs to be done

 

[kenny nunez]

You have 1 shot before pulling the heads. If the valve stuck after the engine started, remove the rocker arm then with a brass punch and a hammer and the piston down in that cylinder try driving the valve down further with some penetrating oil, some times the valve will pop back up from the spring tension, if this starts to happen just keep tapping the valve down until it is coming all the way up. Eyeball the stud to be sure that it has not pulled up, if so drive it back down and re adjust the valve. Some times we get lucky, if not you will pulling some heads as said before.

 

[biggjimm]

Pretty common for valves to stick on one that has sat that long. Unfortunately you may find other things wrong with it after sitting 5 yrs. Like seals & any rubber components drying out & cracking. Check it over real good.

As for backing off the rockers, I bought a 69 Z-28 with a 468 BB. It was a retired drag car with a "blown up" motor. I bought it for $1500 & after having title in hand I popped the valve covers off & tightened & adjusted the valve lash, fired it up & drove that beast home. That guy was pissed. An old drag racer trick is to back the rockers off on those big, solid lift cams to prevent spring damage during the off season.

Good luck with it!
Jim.

 

[Birdsboat]

Thanks for all the advice guys. I will try the penetrating oil but I’m pretty sure the heads will be coming off! I have checked and found the thread on the rocker stud is sitting higher than the rest. Does this need to just be tapped down? I think I’ll do the rebuilds myself. I have rebuilt car heads in the past with grinding valve seats and clearances. I will keep you posted

 

[biggjimm]

If the stud has pulled loose, tapping it back down won't fix it. It will pull again. Sometime. Probably at the worst possible time.

The machine shop you use will be able to fix that for you easy enough.

When you talk about doing it yourself are you talking about actually grinding the valves or "lapping" them in. Big difference between the two. Good idea to have them surfaced while your at it.

Keep us posted.
Jim.

 

[Scott Danforth]

Thanks for all the advice guys. I will try the penetrating oil but I’m pretty sure the heads will be coming off! I have checked and found the thread on the rocker stud is sitting higher than the rest. Does this need to just be tapped down? I think I’ll do the rebuilds myself. I have rebuilt car heads in the past with grinding valve seats and clearances. I will keep you posted

take it to a machine shop or buy new heads

new vortec heads are $500. non-vortec heads are less

 

[Lou C]

The machine shop will go through your heads and check them for cracks & warpage and will also make sure the valves, seats and guides are ok. You'll wind up with rebuilt heads which will give your motor a new lease on life. Make sure to really clean the exterior of the engine before taking it apart and take photos of how the accessories are bolted on. Set the engine at TDC of the compression stroke for #1 (dist rotor pointing at wire #1). Then Mark the position of the rotor on the dist body and also mark the body of the dist relative to the intake manifold. This will all mske re assembly easier. Id also pick up s thread chaser to clean the head bolt threads in the block. Be careful ckeaning off old gaskets. I used a razor blade and vacuumed out all the debris. Clean clean!!

 

[Birdsboat]

I have checked the valve again and it is no longer stuck I let it soak with some penetrating oil and it now seems more free than the rest!!! I?ve pushed down on the stem a number of times and it is returning with no Problems. I now only have to deal with the rocker stud which has pulled out slightly.

If the stud has pulled loose, tapping it back down won't fix it.

Any suggestions how to sort out the rocker stud?

 

[hoowahfun]

I think you can order oversized studs to put in. Or you might just try some locktite or something like that to keep it in place and see how it goes. Could be a cheap fix that lasts for a while or a cheap fix that lasts for 5 minutes. Only a few bucks to try.

 

[Bondo]

Any suggestions how to sort out the rocker stud?

Ayuh,.... Have screw-in studs installed at the machine shop, while they're rebuildin' yer heads,....

Any less is a fool's errand,...

 

[scoflaw]

pinning the stud may be a solution for you

 

[GA_Boater]

The only solution for fixing a pulled stud is in a machine shop while they rebuild your head.

 

[Grub54891]

pinning the stud may be a solution for you

​And how do go about doing that? Never heard about it myself.

 

[Scott Danforth]

Pinned studs fail...and take out tbe stud boss. Tahe heads to machine shop and have converted to screw in studs

 

[Birdsboat]

Where would you suggest for me to source the new screw in studs from? I am living in the UK and all the marine suppliers I have contacted cannot source them.