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JustinT · 28-04-2024, 05:26

Quote:

Originally Posted by skipperpete

It could be that the pushrod missed the socket in the follower but more likely is a stuck cam follower, tap it back down after pouring some oil over it…. Tap it gently then roll the engine over to push it up again, and repeat, and repeat, unless its really badly rusted in place you will prevail.

Thank you!

I was going worst case scenario, like one does.

Here is what happened before (just to make this thread a story!)
Gasket in place: https://youtube.com/shorts/cyAgXEdAY...5PRtsx3sdLPY8D
I just removed a tiny bit from the hole that had to go over the collar

Head in place: https://youtube.com/shorts/oE2w1e-FL...TTPHF3QmwDtz0o

**skipperpete** · 28-04-2024, 05:41

Try not to use the pushrod for the procedure, my preference would be a copper or brass rod. Its important to avoid damaging the socket in the follower.

JustinT · 28-04-2024, 05:42

Quote:

Originally Posted by skipperpete

Try not to use the pushrod for the procedure, my preference would be a copper or brass rod. Its important to avoid damaging the socket in the follower.

Good tip, thanks. I've got plenty of rods I can use at home instead.
Am having a hard time turning the engine by hand though.

GrowleyMonster · 28-04-2024, 07:23

Quote:

Originally Posted by JustinT

Good tip, thanks. I've got plenty of rods I can use at home instead.
Am having a hard time turning the engine by hand though.

If you have a valve that is not opening when it should, resistance to cranking would be expected. And just to be very clear on this, you have a valve that remains closed, and is not opening, due to a push rod not coming up? Or is it a valve that remains open, not closing when it should?

With the rocker assembly removed, is the suspect pushrod not going down, or not coming up? At the lowest point of the cam does the pushrod slide up and down easily without the associated rocker arm and valve spring there to push it down onto the cam?

Just to clarify in your mind exactly what is supposed to be happening at the cam shaft,

And here is a youtube: https://www.youtube.com/shorts/sBD5XeCYaFk

JustinT · 28-04-2024, 07:52

The pushrod appears not to be moving at all (with rocker assembly removed)

GrowleyMonster · 28-04-2024, 09:04

Quote:

Originally Posted by JustinT

The pushrod appears not to be moving at all (with rocker assembly removed)

Can you tap it down? It must not be riding in the tappet on the cam. It should slide easily up and down, and as the cam lobe rotates upward is when it should be pushing the rod up. As it rotates back downward the pressure of the valve spring via the rocker arm should push it back down, so it follows the cam's upper surface as the camshaft rotates. Refer to the pic I posted a couple of posts up.

Do you think maybe you have put the rod in a bind with the head gasket? If you have not yet torqued the head down, the gasket is still perfectly good so use it again.

The gasket couldn't by any chance be upside down, could it?

JustinT · 28-04-2024, 10:48

I have torqued the head down but the head gasket isn't binding the rod.
The gasket could be upsidedown but I copied the YouTube video.
I shall have to try to line up the tappet and also see if I can tap it down with a different rod so I don't damage the pushrod.

JustinT · 28-04-2024, 14:20

So this is the bottom of the pushrod. The lifter/tappet/cup/follower. Does anyone know what this looks like and what I am feeling for down that hole? If I move the engine backwards would that more likely get the lifter to line up again? Or is is stuck in the air possibly? I find the info online down the bottom end rather sparse, most help stuff is the head and valves rather than down in the guts. The closest I have found is classic motorbike chat about the pushrod/lifter connection.

**Wotname** · 28-04-2024, 14:59

Most likely 'stuck in the air'. More info soon!

**Wotname** · 28-04-2024, 15:24

My suggestion -

You have 3 valves/pushrod/cam followers working correctly and one that doesn't. My guess is the one that doesn't was also the one didn't work earlier (and had the bent pushrod).

Now remove the top hamper (~~tappets~~ rocker arms, rocker shaft etc) and remove all the pushrods.

Place a long skinny rod into the space where a working pushrod was.

Rotate the engine through 2 revolutions of the crankshaft while applying hand pressure on the skinny rod. You will feel the cam follower (tappet) move up and down once and you can measure the distance traveled. This gives a base line on how it is meant to work and feel.

Do the same with all the other working cam followers. Each one will actuate once during the 2 revolutions of the crankshaft and they will all feel the same and move the same distance.

Now place the skinny rod into the dud spot and very likely it will not move at all. If so, it is 'stuck in the air'. You have to apply just enough pressure to force it back down. You also have to turn the crankshaft while trying to push the cam follower back into position just in case it is sitting on top the cam when you first attempt to push it down. Refer to Skipperpete's posts #150 and #152 for more guidance and hints.

Note the cam followers follow the cam lobes on the camshaft. The camshaft only turns one revolution for every two revolutions of the crankshaft.

**Wotname** · 28-04-2024, 15:41

Another guess

Some time long ago in the past when the engine was shut down, the exhaust valve in the dud position was fully open which means the cam follower was fully raised. It sat this way for a longish time and for whatever reason, the cam follower seized in this position (some rust probably). The next time the engine was rotated (by the starter motor), the camshaft moved as usual but the cam follower did not. Normally the pressure of the valve spring transmitted by the rocker arm and pushrod pushes the cam follower back down.

With the cam follower 'stuck in the air', the push rod held the valve open. As the engine was getting turned by the starter motor, the piston came up to TDC and smacked against the open valve. With the piston trying to smack the valve closed and the cam follower trying to keep the valve open, something had to break or bend. In this instance, it was the pushrod that bent.

If my guess is correct, the original defect was the cam follower getting 'stuck in the air'.

You are getting closer to fixing this engine

JustinT · 28-04-2024, 15:43

Ah, thank you Wotty, brilliant stuff. I'm 100% sure the follower is "stuck in the air" from tests today. The pushrod absolutely does not move and yes, it was the same one as the stuck valve. Tomorrow I shall attempt to loosen it.

GrowleyMonster · 28-04-2024, 16:00

Quote:

Originally Posted by Wotname

Another guess

Some time long ago in the past when the engine was shut down, the exhaust valve in the dud position was fully open which means the cam follower was fully raised. It sat this way for a longish time and for whatever reason, the cam follower seized in this position (some rust probably). The next time the engine was rotated (by the starter motor), the camshaft moved as usual but the cam follower did not. Normally the pressure of the valve spring transmitted by the rocker arm and pushrod pushes the cam follower back down.

With the cam follower 'stuck in the air', the push rod held the valve open. As the engine was getting turned by the starter motor, the piston came up to TDC and smacked against the open valve. With the piston trying to smack the valve closed and the cam follower trying to keep the valve open, something had to break or bend. In this instance, it was the pushrod that bent.

If my guess is correct, the original defect was the cam follower getting 'stuck in the air'.

You are getting closer to fixing this engine

Sounds like a very good analysis, Wot.

GrowleyMonster · 28-04-2024, 16:06

Quote:

Originally Posted by JustinT

Ah, thank you Wotty, brilliant stuff. I'm 100% sure the follower is "stuck in the air" from tests today. The pushrod absolutely does not move and yes, it was the same one as the stuck valve. Tomorrow I shall attempt to loosen it.

Justin, do you have some Marvel Mystery Oil? It is a much loved product for unstucking stuff and getting it going smooth and slick again. A teaspoon down the hole should slick everything up nicely. It won't hurt your engine oil a bit, either. Barring that, a shot of clean new engine oil. You got a lot of the same crud down there that you had in the upper works.