Stuck valve

[McSparky]

Hi everyone

So over the weekend I packed up my Series 2a 2.25 petrol and set off for a 4x4 meet. The old girl was cruising beautifully but 15km out of town I hit a steep hill and half way up had to change down to 3rd and suddenly the engine lost power and sounded like a tractor. I pulled over and poked around, checking everything I could but eventually I had to phone a friend to come and tow me back into town. After some more poking I removed the rocker cover and found the #4 cylinder exhaust push-rod bent and the corresponding valve was about a centimetre lower than rest and well and truly stuck. So I popped the head off and inspected the cylinder and there is no obvious impact damage with the valve so I assume its not bent but the valve is very very stuck. My questions are what could have caused this? Can I just replace the valve and do I need the ream anything? Is there anything I can test or check to prevent this happening again in future?

Thanks

Carl

[Adam001]

Is the rocker shaft also stuck down with the valve with the head off? it shouldn't be if the valve is stuck.

I would remove the rocker shaft and see if the valve remains stuck, then procede to remove the spring from the valve and keep dismantling it until you find the problem.

I suspect the valve stem has siezed in the guide somehow, possibly ingress of debris or something has bent, you may have to have the valve and valve guide replaced, or hone out the valve guide and fit a phorshor bronze insert which is often easier and can be performed at most capable repairers

Adam

[McSparky]

Is the rocker shaft also stuck down with the valve with the head off? it shouldn't be if the valve is stuck.

I would remove the rocker shaft and see if the valve remains stuck, then procede to remove the spring from the valve and keep dismantling it until you find the problem.

I suspect the valve stem has siezed in the guide somehow, possibly ingress of debris or something has bent, you may have to have the valve and valve guide replaced, or hone out the valve guide and fit a phorshor bronze insert which is often easier and can be performed at most capable repairers

Adam

Thanks for your reply Adam. I pulled the head and have dismantled pretty much everything except the valves; still waiting on a loaner valve spring compressor. All the rockers move freely but the valve doesn't budge. I'm just amazed that this happened because I completely rebuilt the engine 2 years ago and the it hasn't done much mileage since then; this was actually the first long trip I attempted. I'll have to wait for the spring compressor to dismantle the valve and inspect everything carefully.

[missingsid]

Same thing happened to my V8. It was running fine then started to make a gradually louder knocking noise.

Pulled the rocker cover and found the bent rod and stuck valve.

I got replacement heads.

Marc.

[Adam001]

Did you have any luck with this?

[McSparky]

Did you have any luck with this?

I did eventually I stripped the head and gently tapped out the stuck valve, which came out fairly easily. I then cleaned the head inside out to get rid of anything that might cause a problem in the future. I also checked each valve carefully and found a bit of galling on the one which was stuck; a mechanic friend said it was probably all still a bit tight because the valves and guides were new. So I bunged the valve in the drill press and carefully sanded the stem with 1000 grit sandpaper till the galling was gone and it was well polished. I actually did all of the valves and guides and checked tolerances just to be on the safe side. Then new push rod, new oil, new stem seals and fresh coat of engine enamel while I was waiting for the parts to arrive and she's running better than ever. *Sigh*.. It's a labour of love