Stuck Inlet Valve on Cylinder Head - Assistance requested

[StuF]

I have been trying to setup my tappets this eve and have noticed that one of the pushrods kept popping out of engagement with the rocker
Upon removing the rocker and inspecting the spring loaded inlet valve it appears to be stuck in the depressed/compressed position (see pic) and the exhaust valve is open as it should be
This is unknown ground for me - anyone have any ideas how to remedy the situation and free off the stuck spring?

Any help greatly appreciated

 

[sparkywig]

Stuck valves are usually a sign of worn valve guides, Stu.
Has the bus been running OK previously?
What cylinder is the stuck valve on?

Turn the engine by hand until the relevant cylinder is at Bottom Dead Center (farthest away from the valves), then tap the stem of the valve with a plastic or brass hammer, or piece of wood between a normal hammer and the valve stem/spring retainer. You might be lucky and it may pop back up.
Turn the engine over by hand a few times to see if it sticks again.

 

[beef]

If, as it looks, the spring is compressed, then unfortunately it looks as though you have problems. As sparkywig says, probably a damaged valve guide. Another possiblity is something physically under the valve head, but that's extremely unlikely if the engine was running fine. My advice is to remove the head. A sticking valve isn't too hard to remedy one the head is off, and it will eventually need fixing anyway. Left alone, it won't do the engine any good.

 

[StuF]

Cheers for the advice - have rotated the engine a few times and given it a good whack without any success.
Engine is nearly out as I didn't want to mess about - looks like it might be a bent valve and have no idea how long it's been running like it to be honest
It's on the rhs cylinder head - exactly where the stud sheared when replacing the push rod tubes so maybe more issues ahead.
Never removed this section of the engine before and nothing like a deadline to focus the mind.
Thanks again and will post more when it's out and stripped!

Best I cancel Friday's rolling road session! :lol:

 

[sparkywig]

That's one way of getting out of buying lunch.

 

[ozziedog]

Hi Stu, Wish there was an easy answer, but you won`t be able to do it `nice` without popping the head off. Like the guys have already said, buggered guide, bent valve, a chunk under the valve face, if it`s a smashed up valve face I reckon you might of noticed that. Did you pop the plug out to make sure it`s still all in one piece mate ?

Ozziedog,,,,,,,,,,,,,,,,,, Good luck bud,, and hurry up, I got beers chillin :lol: :mrgreen:

 

[StuF]

Well engine is out and I am done for the night - I can see some more cash being spent to get us back rolling for next weekend
Think I identified an issue that may have caused the stuck valve, the HT lead attached to the spark plug was damaged so it may have been running on 3 cylinders for some time!
Not sure what damage that would have caused over the period of time its been like that, will get it stripped down further tomorrow after work and get the head off.

Any pointers on how it comes off? Have removed the 4 nuts inside the head itself but other than that I imagine its remove some tinware, sparkplug and some other nuts to free it off?
More progress tomorrow! Bed is calling

 

[rlepecha]

To get the head of you will need to remove the fanshroud (don't forget to disconnect the thermostat first!) And then remove the tin that is over the head.

There are four more nuts under the tin, once you have them removed it should just pull off.

I can't imagine the engine running on three cylinders for a while would cause damage like that, it would seem more likely that something may have fallen down the carb throat and ended up lodged behind the valve or the guides were worn to the point that the valve could become stuck.
The only other possibility I can think of is the valve seat has broken away from the head and is now holding the valve open.


Its quite amazing how well these engines run on only 3 cylinders, its very difficult to tell by the sound or that's what I have found anyway!

Good luck with it


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[StuF]

Cheers for the tips - after 5 hours sleep I am up and off to work, fingers crossed I can get an early stack and crack on getting the cylinder head off.
Pic of the offending HT lead and will post more once the head is inspected

 

[67westy]

That's one way of getting out of buying lunch.

I'm treating it as a default victory so fully expecting my lunch still

 

[StuF]

Piss off Adam :lol:

 

[georgeyv]

Not sure how far away you are but there's a guy just up by Doncaster in Bentley called Headmasters - He's a complete wizard with head work and last time I had something done I remember wondering if he's had a price increase in the last 20 years, absolute peanuts compared to the other firms local to me.

Worth a phonecall to see if he can point you in the right direction!

 

[StuF]

Cheers for the info George - have managed to get the cylinder head off now and released the stuck inlet valve
Got a spring compressor and removed the offending article!

It was pretty bent!!

Some pics



Stuck open



Other side



Pistons are fine thankfully and no scoring inside the bore



Removed the valve and guide - you can see how bent it is



Garage chaos!!





Bloody glad it didnt snap off and make a mess of the pistons or other valve!!

Awaiting parts now and should be rolling again by Sunday if the postie is kind!

 

[rlepecha]

Is the valve and guide significantly worn? Are you planning to check all the other valves and guides while you have it in bits? If one is worn its likely the rest are too!

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[StuF]

Checked the rest of the valves for smooth operation by carefully depressing each of them and checking for any resistance or movement - all were smooth and tight.
I think this issue was caused by the lack of spark from the broken HT lead
Will give the engine a good inspection before its refitted

 

[georgeyv]

Good work - Also, cheers for the PM about the gauges - going to order some bits and get sorted!

 

[sparkywig]

That's one way of getting out of buying lunch.

I'm treating it as a default victory so fully expecting my lunch still

Piss off Adam :lol:

:lol:


Stu, if I were you I'd whip the other head off and replace all the valves and guides, give the heads a clean up and refit. Just for piece of mind, and to maybe not give Baz any ammunition.

 

[jonboylaw]

^ what sparky says, replace the guides and valves whilst you have chance. Ideally get an 8mm reamer and ream the guides after fitting. Then lap the valves to the seats and clean thoroughly before re assembly.


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[jonboylaw]

And whilst the engine is out, replace the clutch plate, cover, CRB and do the main oil seal and flywheel o-ring and check the end float. Then make sure the barrel cooling fins and heads are clear of debris.


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