The School of Hard Knocks

[sideshowbob]

If a picture says a thousand words, what's a video with sound good for?

Knocking

My bandwidth may not bee too good on the upstream!

What does the noise bring to mind? It appears to be coming from the top somewhere in the center of the head. A stethescope reveals nothing at all. The valves have been adjusted, but they don't stay that way long. Engine gets very low vacuum (10~11) and compression reads 150 across. Peeking through plug holes with my LightOnAWire™ shows no sight of valve to piston impact. And yes, this is pretty much part of the problem I've had for months, but the knocking is louder (or the exhaust quieter?). I've replaced the manifold gasket and gotten nowhere. Ideas? Please don't tell me to get another motor, please? Could this be spark knock? I have no idea how to tell. The only experiences I've had (burnt valve chunks and rod bearings due to oiling failure) didn't sound like this.

[=Enigma=]

What is this LightOnWire tool you are referring to? Is it a fiber optic viewing scope attached to an eyepiece or something like that?

[Fun_in_my_z]

My car dose this untill it is warmed up. But as it idles the valves knock louder and louder.

Im going to have the head rebuilt after i get all the body work done.

[sideshowbob]

What is this LightOnWire tool you are referring to? Is it a fiber optic viewing scope attached to an eyepiece or something like that?

Ummmm. No. It's an LED attached to a resistor and a 9volt battery. For those moments when your flashlight and face want to occupy the same space.

[Nigel1943]

Have you checked for wear in your camshaft tower journals? This would make your cam move around and could be why your tappet clearances dont stay right for long.

[sideshowbob]

No, it seems quite solidly in place and I can percieve no endplay when moving the cam sprocket by hand but I have no dial indicator to thoroughly check.

[LanceM]

I don't have the bandwidth to listen so let's try to define better what you are hearing with works. You say knock, a knock in automotive terms usually means a sound like someone hitting the inside of the block with a hammer pretty hard, Knock knock knock.

A tick is more like the sound of two spoons being struck together.

Are you really hearing a knock?

The reason I ask is to hear a knock in the center of the head would be very unusual, I have only seen this once and it was on a Ford 9N tractor, it wasn't until I pulled the head that I discovered a huge amount of carbon built up on the head in #4 cylinder, the piston was actually pounding the carbon every stroke sounding like a knock in the head. I would find it hard to belive that there could be that kind of build up on a Z engine, they tend to get blown out pretty regular

[mlc240z]

how about a loose or worn valve seat?

[sideshowbob]

In fact, there was tons of carbon on the valve tops, I had thought this might be the cause and ran seafoam through it. It cleaned them up a bit but the noise remaind! On another note: One of the injectors wasn't firing (loose connector) on the number 1. I remedied the situation and now all I'm hearing now noisy tappets and a horrible misfire (lump lump lump).

MLC: Probably likely, that carbon was THICK and may have knocked one for a loop! But again, compression remains the same! I would think that a loose seat would kill compression on a cylinder?

Thanks for the input everyone, looks like I'll have to pull the head soon to find out what's up! Unfortunately it won't be in a parking lot anymore, so no funny stories about whinos On the other hand, they were fairly annoying

[montoya_fan01]

MLC: Probably likely, that carbon was THICK and may have knocked one for a loop! But again, compression remains the same! I would think that a loose seat would kill compression on a cylinder?

it will..............eventually

[sideshowbob]

I went a bit haywire today. I took out the radiator, condenser and set my engine to TDC in preparation to remove largish chunks of it. That's when I discovered that my timing mark reads at 15 degrees BTDC when I'm @ TDC. This could explain a few things. The timing has been set at around 23 or so, this is with the vacuum advance disconnected! (It leaks). Though it still doesn't explain the lowered compression (there are some more unsavory ideas about that!) it explains some of the other ills I've been suffering from. I should have noticed this weeks ago :stupid: .

The noise: Should the lash pads be firmly against the rocker arm when the valve is closed? Mines a bit loose. This is, no doubt, the cause of the remaining noise I'm hearing.

[sideshowbob]

Oh hell, one more thing: I have an N42 head. I have no idea whether or not there are hardened seats in this thing, should I be using additive just in case?