Damage to spark Plug

I think it's too much of a coincidence that it happened on #3. I'm no expert but I think it might have leaned #3 just like those with the STS before him but not to the extent of cylinder or piston damage. I think the plug electrode got hot enough that it either curled or pressure caused it to close (somehow). If it was a piece of carbon, a pressure check will tell you cylinder and valve condition. The tap you hear could be the carbon stuck to the valve seat. Just some thoughts.
 
FlyingLow said:
Is this something easy to do or do I have to pull parts of the engine off?
Click to expand...

It's pretty simple. Get the engine warm, just let it idle for a while. Take 1 plug out a time and screw in the flexible rubber fitting (metal ends) to where the plug goes. Disconnect fire to the plugs. You do NOT want to run the engine with the compression gauge attached.

Used to be, you'd just pull the coil wire, that obviously isn't the case on this engine. I am scrambling to get out of town, otherwise I'd go look at my truck on how to do this, I'm sure someone else will chime in on how to do this.

Have someone crank the engine (without firing) with the gauge attached to each cylinder. Make sure the throttle body butterflies are held wide open while cranking. Write down the numbers. They should be withhin 10% of each other.

The idea of a leakdown test is a great idea, but requires other tools. Not too tough, but maybe best left to someone else.

Good luck.
 
SilvrSRT10 said:
I think it's too much of a coincidence that it happened on #3. I'm no expert but I think it might have leaned #3 just like those with the STS before him but not to the extent of cylinder or piston damage. I think the plug electrode got hot enough that it either curled or pressure caused it to close (somehow). If it was a piece of carbon, a pressure check will tell you cylinder and valve condition. The tap you hear could be the carbon stuck to the valve seat. Just some thoughts.
Click to expand...

Cylinder pressure would not bend it. Reason for this is that the pressure is equal on all surfaces of the electrode. Therefore you would not have a positive pressure side to cause the bending.

Make sense?

I'm sure the misfire code was a result of the gap being closed on the plug. When that happened that plug was no longer firing, hence the code.
 
Silverback said:
Cylinder pressure would not bend it. Reason for this is that the pressure is equal on all surfaces of the electrode. Therefore you would not have a positive pressure side to cause the bending.

Make sense?

I'm sure the misfire code was a result of the gap being closed on the plug. When that happened that plug was no longer firing, hence the code.
Click to expand...
Yeah, That makes sense. I'm sure the spark plug misfireing is what threw the code as well. What we are all scratching our heads about is what cause the electrode to bend. Hopefully it's as simple as the carbon thing that is now causing the tap noise. But I'm still concered about it being #3 too. Scotts going to have to dig deeper and let all us couch mechanics know.:D
 
REOMOTORS said:
It's pretty simple. Get the engine warm, just let it idle for a while. Take 1 plug out a time and screw in the flexible rubber fitting (metal ends) to where the plug goes. Disconnect fire to the plugs. You do NOT want to run the engine with the compression gauge attached.

Used to be, you'd just pull the coil wire, that obviously isn't the case on this engine. I am scrambling to get out of town, otherwise I'd go look at my truck on how to do this, I'm sure someone else will chime in on how to do this.

Have someone crank the engine (without firing) with the gauge attached to each cylinder. Make sure the throttle body butterflies are held wide open while cranking. Write down the numbers. They should be withhin 10% of each other.

The idea of a leakdown test is a great idea, but requires other tools. Not too tough, but maybe best left to someone else.

Good luck.
Click to expand...

Go by the instructions when you get the gauge, but I think the right way to run the test (esepcially on our engines because you can't remove the coil wire) is to remove all the spark plugs and check one cylinder at a time. That enables the engine to spin faster and it will keep the engine from starting as well (obvioulsy). You're looking for significant variations between cylinders. Write the readings down and do all 10 cylinders. As I recall, more than a 10% variation is not a good sign.
 
Here you go!

CYLINDER COMPRESSION PRESSURE TEST
The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions.

Ensure the battery is completely charged and the engine starter motor is in good operating condition. Otherwise the indicated compression pressures may not be valid for diagnosis purposes.

1. Check engine oil level and add oil if necessary.

2. Drive the vehicle until engine reaches normal operating temperature. Select a route free from traffic and other forms of congestion, observe all traffic laws, and accelerate through the gears several times briskly.

3. Remove the Auto Shut Down (ASD) relay from the Power Distribution Center (PDC).

4. Disconnect ignition cables from spark plugs.

5. Remove all spark plugs from engine. As spark plugs are being removed, check electrodes for abnormal firing indicators fouled, hot, oily, etc. Record cylinder number of spark plug for future reference.

6. Be sure throttle blade is fully open during the compression check.

7. Insert compression gauge adaptor Special Tool 8116 or the equivalent, into the No. 1 spark plug hole in cylinder head. Connect the 0-500 psi (Blue) pressure transducer (Special Tool CH7059) with cable adaptors to the scan tool.

8. Crank engine until maximum pressure is reached on gauge. Record this pressure as No. 1 cylinder pressure.

9. Repeat the previous step for all remaining cylinders.

10. Compression should not be less than 689 kPa (100 psi) and not vary more than 25 percent from cylinder to cylinder.

11. If one or more cylinders have abnormally low compression pressures, repeat the compression test.

12. If the same cylinder or cylinders repeat an abnormally low reading on the second compression test, it could indicate the existence of a problem in the cylinder in question. The recommended compression pressures are to be used only as a guide to diagnosing engine problems. An engine should not be disassembled to determine the cause of low compression unless some malfunction is present.



Hope this will help. It out the service manual.
 
Well after reading Vipertek's write up I think I will take it to someone to do the test. Who can perform a leak-down down test? Should I take it to the dealer or just to any local shop?
 
Its really not that hard to do. If you change the spark plugs you can do this.

Just remove the auto shut down relay (ASD) this will keep the truck from starting. You can buy a compression tester at the auto parts store for 50 bucks. Screw it in to each cylinder and write down each cylinder pressure. It will be very obvious if one cylinder has a problem. Have one person crank the truck over from the inside and you watch the gauge hooked to the cylinder. Crank the truck for about 6 to 8 seconds per cylinder. If any cylinders are in doubt do the test 2 times. The ASD relay in the PDC under the hood. If you can't find it let me know and I can post a pic.
 
As viprtek said, it's easy to do. Also the less you run it the better off you may be if it is indeed something serious.
 
viprtek said:
The ASD relay in the PDC under the hood. If you can't find it let me know and I can post a pic.
Click to expand...


A pic would be nice cause I don't know what/where that is located. So let me get this straight. I have to remove all the spark plugs and then just hook up the compression checker. Next I just crank it a few times to get the compression. Should I do all of them or just the odd side?
 
FlyingLow said:
A pic would be nice cause I don't know what/where that is located. So let me get this straight. I have to remove all the spark plugs and then just hook up the compression checker. Next I just crank it a few times to get the compression. Should I do all of them or just the odd side?
Click to expand...

Do all of them, and find out what the difference is between them. In reading the thread.. I am guessing that your going to find an issue with #3.
 
FlyingLow said:
A pic would be nice cause I don't know what/where that is located. So let me get this straight. I have to remove all the spark plugs and then just hook up the compression checker. Next I just crank it a few times to get the compression. Should I do all of them or just the odd side?
Click to expand...

Get the screw in type of compression tester. Some just have a rubber tip on them that you have to hold in place, and they are worthless in my opinion. It will screw in just like the plug.
 
Hey Scott! How are things? Sorry I don't have time to check in here too often. I had a moment today to scan some of the thread names and this one caught my eye. And, as you know, I have some experience with these things. I tend to agree with the great ape (How you doing, Magilla? Good to see you're still alive and kickin'.), your luck with STS might have run out.

The compression check is a good first step to let you know if that cylinder is sealing up. On mine, the compression on the normal cylinders was around 122 but #3 was around 70 or so. If you're comfortable changing your own spark plugs, you can do the compression check as well. If not, take it to someone. A leak down test will be more definitive and give you better data but the compression check can give you some good preliminary information. I looked inside mine with a boroscope and it didn't show anything. However, the boroscope can tell you if there is any visible cylinder wall damage (mine was damaged below the piston out of sight of the boroscope) or if there are any chunks on top of the piston in the combustion chamber.

Now about that plug. Sorry to say this but that plug looks just like mine did. We went through all the same theories that have been mentioned here and finally concluded that the plug got very, very hot. There was no carbon on top of the piston, there were no chunks in the compression chamber, there weren't any bent valves, it just got really, really hot. Basically, your #3 cylinder got leaned out. The good news is that if your cylinder compression is still good, your oil is free of metal (check your magnetic oil pan plug too), you're not burning oil (no smoke, not using oil) and there is no oil blow by (my engine bay was covered with oil) it may have simply leaned out under the hard driving conditions, hopefully, causing little or no damage. Chances are that if all of these things check out then you're okay - for the time being. However, this may be a wake up call. You'll note that my truck as back to being N/A.

That knock you mentioned concerns me. Is it a high frequency knock and can you identifiy it as coming from the valvetrain? Or, is it a lower frequency knock that sounds somewhat muted like it is coming from deep inside the engine block? Mine had the latter and my #3 rod bearing was not just spun, it was disintegrated sending all of that metal into the oiling system. A lot of it ended up in the oil pump and wrecked havoc. It chewed up the crank (over $2,200 list price) and annihilated the timing cover where the pump is located ($600 list price. Thanks, Jack! You bailed me out on that one!).

The bottom line is that you have some decisions to make. Do you chance causing further damage and drive it or do you play it safe and pull the head, drop the pan and yank the piston to see for sure what might have happened inside? Again, if all the aforementioned conditions check out, chances are you're okay but then again, how much is peace of mind worth? If it was me, I'd look for and consult an expert(s). I found a great Viper tech in Salt Lake that took care of me. Hopefully there is someone like him near you.
 
Phil thanks for info. First the tick is just barley noticeable. It starts right at start up for a few seconds, then just fades away. I do have some soul searching to do about the STS. I just hate spending the money to get it removed and the truck back to stock. Well not really stock, but drivable.
 
The information that has already been put forth is very good.

As Justin & Phil(BigAsp) and some others have stated a Leak Down test is really what you need to do, or have done.

I can drill a 1/16" hole through the top of the piston crown/dome and it will not show up on a compression test. It will show up when you leak it down.

On the fuel funny car we never do anything but a leak down test as it is the only accurate method of detecting damage.

Detonation will damage (pinch) the ring lands and will bind up the piston rings. This binding will not allow the ring to move freely and a loss of sealing will hapen.

As was also stated it could be a piece of carbon that closed the plug gap, or a piece of piston.

If a leak down test shows normal sealing on all cylinders it is safe to drive. If there is excessive leakage, over 8-10% leakage you have a problem in the engine. Normal leakage on a sound engine is 6% or less.
Leakdown tests should be done with the engine at normal operating temperature.

As a leak down test is done with compressed air injected into each cylinder. You can listen at the crancase breather, exhaust manifold or intake manifold/throttle body (with the butterflys open ) to see where the air is escaping and that will tell you where the problem is. Rings/piston, intake valve, or exhaust valve.
On an engine with piston/ring failure it is common to have leakage at all 3 places.
 
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