JD 8650 next problem. Valves?

[sunnyblueskies]

Ok, so we move on from the Turbo question to the next.

The engine has a light knocking sound, we replaced all injectors, just to freshen things up a bit. It's a new to us tractor, it blows black smoke on start up and at acceleration. Haven't started it yet since the new injectors were put in, because I also wanted to change the valve cover gasket, seemed damaged because it leaked some oil.

Took the cover off, things look clean, but what do I know. So out of curiosity I tried to 'wiggle' the rocker arms, all are tight, except one. I can rock it back and forth, the push rod is just 'rattling' loose and the valve/spring is just sitting there.

What is going on there? What could have caused this?
How do we fix it?

 

[Jim.ME]

Ok, so we move on from the Turbo question to the next.

The engine has a light knocking sound, we replaced all injectors, just to freshen things up a bit. It's a new to us tractor, it blows black smoke on start up and at acceleration. Haven't started it yet since the new injectors were put in, because I also wanted to change the valve cover gasket, seemed damaged because it leaked some oil.

Took the cover off, things look clean, but what do I know. So out of curiosity I tried to 'wiggle' the rocker arms, all are tight, except one. I can rock it back and forth, the push rod is just 'rattling' loose and the valve/spring is just sitting there.

What is going on there? What could have caused this?
How do we fix it?

I would pull the push rod and see if it bent. Compare the adjuster screw in the rocker to see if it looks backed off compared to the others. Also see if it turns easy, it or the rocker might have lost the fit, allowing it to back off.

 

[wore out]

Ok, so we move on from the Turbo question to the next.

The engine has a light knocking sound, we replaced all injectors, just to freshen things up a bit. It's a new to us tractor, it blows black smoke on start up and at acceleration. Haven't started it yet since the new injectors were put in, because I also wanted to change the valve cover gasket, seemed damaged because it leaked some oil.

Took the cover off, things look clean, but what do I know. So out of curiosity I tried to 'wiggle' the rocker arms, all are tight, except one. I can rock it back and forth, the push rod is just 'rattling' loose and the valve/spring is just sitting there.

What is going on there? What could have caused this?
How do we fix it?

Spin/twirl the pushrod, you should be able to see if it's badly bent with it still in place. If it's NOT bent you may very well have a "flat camshaft" and failed cam follower.

 

[sunnyblueskies]

We pulled the rod out, it does not seem bent.
The adjuster screw for the rocker was tight and comparable in/out to the other adjuster screws.
Whatever loosened this specific rocker arm 'gave' enough space for the cap, sitting on the end of the valve stem against the rocker arm, to fall off. It was laying in the housing.
We adjusted the screw now enough for the rocker arm to be tight again, have to adjust for the correct spacing tomorrow, didn't have enough time for that today.
Anything else we can check or do to figure out what the problem is before it becomes a bigger tear apart job?

 

[wore out]

We pulled the rod out, it does not seem bent.
The adjuster screw for the rocker was tight and comparable in/out to the other adjuster screws.
Whatever loosened this specific rocker arm 'gave' enough space for the cap, sitting on the end of the valve stem against the rocker arm, to fall off. It was laying in the housing.
We adjusted the screw now enough for the rocker arm to be tight again, have to adjust for the correct spacing tomorrow, didn't have enough time for that today.
Anything else we can check or do to figure out what the problem is before it becomes a bigger tear apart job?

Do you have the engine barring tool, I would check the lift of all the valves with a dial indicator to rule out camshaft failure before attempting to run it.

 

[used red MN]

Do you have the engine barring tool, I would check the lift of all the valves with a dial indicator to rule out camshaft failure before attempting to run it.

I agree with wo, buy a barring tool and check the cam lift. Here is one on eBay, it’s a bit cheaper hopefully it is fair quality. As long as the gear teeth don’t strip off it should be fine.
eBay JDG820 barring tool
I hate to say this but “camshaft city” seems have some pot holes in its streets in that motor.

 

[sunnyblueskies]

Do you have the engine barring tool, I would check the lift of all the valves with a dial indicator to rule out camshaft failure before attempting to run it.

No we don't have a 'engine barring tool'. But that's our plan now, look a bit closer at the whole picture.
Have to wait for the long weekend to be over to be able to get all the stuff we need to go further.

 

[Harry in Ky]

Why be afraid to start it? You drove it in there the way it was didn't you? You can bump it over a little at a time with the starter without starting it to watch the rocker action.

 

[sunnyblueskies]

Why be afraid to start it? You drove it in there the way it was didn't you? You can bump it over a little at a time with the starter without starting it to watch the rocker action.

You are right, I just don't want to jinx myself and have doomsday lurking over it. LOL It's not like the tractor broke down during seeding or whatever, so we can take our time and check things out.

 

[Janicholson]

With that much motion, the easiest measurement is from the head casting to the underside of the rocker adjacent to the adjuster. compare it to others. it is not a specification, but it sure shouls be within .025" of the others. if that is way off, the cam may be worn as well as the lifter.
Also check the others after rotating the engine to see if other valves are also loose when they are not being opened. Barring it is most accurate, but it can be done using the starter. When an opposing valve is part way through its opening or closing, the 1st valve should show clearance. Not that much though!! Jim

 

[wore out]

Why be afraid to start it? You drove it in there the way it was didn't you? You can bump it over a little at a time with the starter without starting it to watch the rocker action.

If there IS cam damage there will be metal in the oil and running it won't make it any better.

To me it makes sense to get to the bottom of what's going on before running it any more.