Went to the strip! Kind of... ok not really. WJ vs XJ!

[Bryan C.]

Ok, you're gunna have to help explain this to me cause I'm as you say, "a complete moron".

Can you tell me what happens when oil drips (from the VALVE SEAL) onto the back of a hot valve?

Oil doesn't drip from the seal onto the valve. There is this thing called a "valve guide."

 

[igotanxj]

If it leaks past the valve seal, it will eventually work its way down the valve guide and onto the back of the valve. It can also work its way past the valve while its open and burn from the combustion. :banghead:

What you're thinking of is valve seats. You can loose compression from bad seats, and also slightly change compression by moving the valve in or out of the valve seat, which is basically making the combustion chamber slightly smaller or bigger.

 

[Talyn]

Ok, you're gunna have to help explain this to me cause I'm as you say, "a complete moron".

Can you tell me what happens when oil drips (from the VALVE SEAL) onto the back of a hot valve?

For starters it doesn't cause the cylinder to lose compression.

Do you by any chance have a cousin and/or a brother in Alabama? I know someone that is so similar to you... doesn't have a clue what they are talking about and contradicts themselves. He works for NASA too.

 

[PurpleCherokee]

Oil leaks (through the VALVE SEAL) and ends up getting burnt on the back of the valve, which builds up deposits that prevent the valve from sealing like it should, which causes COMPRESSION LOSS. Simple as that.

Other than the fact that you're all dead wrong about valve seals not causing low compression and making yourselves look like a bunch of tools, you're proving what huge losers you all are for dedicating so many minutes of your life to ridiculing me. You guys REALLY need to grow up.

 

[igotanxj]

Valve seals don't directly cause low compression.

Eventually, if a valve seal leaks, and enough oil finds its way down the valve, (some oil down the vavle guide is needed for lubrication) and enough oil gets to burns on the back of the valve, then the engine burns dirty enough for carbon to stick on the back of the valve, after a few years of neglect you might get some carbon build-up. After a few more years, you might be lucky enough for that carbon to keep the valve from closing all the way.... but were talking a huge buildup of carbon here.

When I took apart the heads to my 66 mustang's 289, there was an ungodly amount of carbon on the back of the valves, but not enough to cause it to stick open. I think it had about 90K miles. Keep in mind, that was an old motor with old technology, old seals, old crappy oil etc.

My jeep has 165,000 miles on it right now. When I swapped my intake manifold for a 99 unit, i saw the back of all of my valves. They looked spotless.... like 10K miles spotless.

So, eventually bad valve seals have the potential to cause low compression but I wouldn't say they DO cause low compression... And plus, this is obviously not what your original post was referring to.

 

[PurpleCherokee]

So your old mustang and your 4.0 have what to do with the 4.7? They all have valves?

I understand what you're saying but what you're not understanding is that just like with every motor, the 4.7 has a few design flaws and the valve seals are one of them.

 

[Talyn]

I'll sum up the few key words and phrases here for you since you also lack basic reading compression: "eventually" "after a few years", "after a few more years", "huge build up of carbon", "old motor with old technology, old seals, old crappy oil etc", "eventually"

And my favorite:

And plus, this is obviously not what your original post was referring to.

See, you also didn't say, hint or even think that the oil leaking past the valve seals could eventually in several years create carbon build up, which would lead to a compression loss. Please see my sig if you have forgotten what you said already.

Oh, and if your buddy actually had that much carbon built up on the back of the valves to cause your mythical compression loss, changing the seals wouldn't remove the carbon build up that is already there. Just give it up.

 

[alex22]

Have you done a leak down test or check the exhaust port for vacuum when the valve is closed on the 4.7 or are you just assuming that to be the case.

As much fun as I have had reading this thread I do have to say one thing on purple's behalf, The Factory valve job on the 4.7 heads is garbage, form day one when it left the factory. the valve seats are not concentric at all. If you remove the heads, take it to a good machine shop, have a proper valve job done and replace all the valves with good ones and use a good Viton seal for the VALVE GUIDE SEAL it will keep exes oil out of the valve guide.
The factory "fix" for the 4.7 heads is just to replace the exhaust valves. One of our customers had a real valve job done on a set of those heads and the mechanic said that the car had never run smoother and had a little bit more power.


~Alex

 

[Talyn]

As much fun as I have had reading this thread I do have to say one thing on purple's behalf, The Factory valve job on the 4.7 heads is garbage, form day one when it left the factory. the valve seats are not concentric at all. If you remove the heads, take it to a good machine shop, have a proper valve job done and replace all the valves with good ones and use a good Viton seal for the VALVE GUIDE SEAL it will keep exes oil out of the valve guide.

While that is true I doubt that purple or his friend know that nor had any machine work done to correct it.

 

[Mc2KXJ]

His only redeeming quality is the fact that he IS a dumbass and is so easy to destroy. That is what he is here for. It clearly is not to add anything of use to off road tech; it's purely for our amuzement.