2001 Expy Knock on acceleration

[VictorDuwon]

So far, I've disconnected the heater hoses, but I can't seem to get the wiring harness bracket disconnected from the valve cover bolts. Its plastic, and I can't seem to get it up without breaking it. Is there a special tool or technique for this?


Edit:

Nevermind, I figured it out. So far so good. Is there a logical reason some of the bolts have the shaft and others are just a 8mm bolt?

 

[VictorDuwon]

Got it off and doing the source of my knock. Broken valve spring.

 

[JamaicaJoe]

Well indeed, there's your problem!

That was your original thump most likely.

Was the valve keeper still in place?

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[JamaicaJoe]

Now I am nervous.

I have an 01, 4.6 L with half the miles. But a while back, I took it to AutoZone to have the alternator tested and the "tech" over revved my engine to the point I am sure the valves were floating. No problems so far, good oil test results, but the valve train is is the weak point in these engines,.

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[VictorDuwon]

JamaicaJoe, is the valve keeper this thing:

 

[Trainmaster]

but the valve train is is the weak point in these engines,

Worry not. I don't think they are Jamaica. The right head gasket and exhaust manifold studs are...

 

[JamaicaJoe]

JamaicaJoe, is the valve keeper this thing:View attachment 40064

It's a pair of small semicircular bits that hold that cap onto the valve stem. If all your spring parts were loose without the keepers, the valve would drop into the cylinder. Did that happen?

See bottom center, those bits.

https://s.yimg.com/lo/api/res/1.2/w.../images/prod/xlarge/TFS-2500500_xl.jpg.cf.jpg

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[VictorDuwon]

I didn't see anything like that. I'll feel around there with a magnet this morning and see if I can find anything.

I'm trying to find a replacement spring also. Will I be able to replace this without removing the shaft? I can see how the rocker arm and spring fit beneath the cam, but now that you mention missing pieces, I'm not so sure.

 

[VictorDuwon]

I didn't find anything in the wells, but where the timing chain is I did see what looked like a partially ground up piece of curved metal. One of the keepers I think. I went for it with my magnet, but lost it.

The valve seal does seem to be intact however.

 

[JamaicaJoe]

So the valve did not drop? Try to find all the metal bits. An oil and filter change will be on the list.

I can't advise the best way to proceed. These are wear parts, at that mileage, you may need to replace all the springs and followers. Otherwise you could change what's broken and keep your fingers crossed.

There is an identical recent thread on broken cam followers on this board. In that case the follower roller siezed up, scored the cam.

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