TireSmoke.org

wxo wrote:While putzing today, I decided use a flashlight to take a look inside the right side valve cover through the oil filler hole. What a great surprise! It is immaculate in there after 103k miles.IMG_3865.JPG

My second C4 is almost the exact opposite of this! There is oil caking, radiator fluid, and surface rust on the valvetrain parts. I'll be changing the oil filter with some frequency for a while.

I wonder how much Sea Foam in the oil had to do with it.

I removed #8 spark plug today. Remember that this is the one I struggled with for hours to replace. This tells me that I didn't get it tightened properly. This is the other side of itI would be surprised if, once I get this plug back in and tightened properly, the mysterious noise isn't gone. Before I put it back in, though, I plan to borrow Maverick's endoscope and take a peek inside that cylinder to see how things look. I'll post a picture if I can.

Here's a photo from the endoscope looking into the #8 spark plug hole. I can't make out the detail of the threads, but they appear OK. There appears to be an open valve in view. I wasn't able to position the camera to get a better look at anything else.

Next up is clearing a path for my hand to get this plug in straight and tightened.

This update is about this plug, a new ACDELCO 6 that I removed from #8 cylinder. It was removed because, when I removed the injector connector from #8, the mysterious noise went away. From the picture you can see that there was significant leakage around most of the seating area. My first thought was that I had not tightened it sufficiently because of the difficulty getting access to it. This time I removed the metal bracket to which the 7 & 8 spark plug wire looms are attached. This gave me the ability to just get my hand down in there and touch the tip of the plug with my finger tips. Which turns out to be just enough.
I decided to clean up this plug and reinstall it in hopes of a quick solution to the mysterious noise. Maverick and I got the plug installed and we fired up the engine and nothing much had changed. The noise was still there and there was still a very small stumble just off idle. This time I was very confident I had installed the plug tightly enough, so I decided to remove it again to see what it looked like. I was surprised to see witness marks where it had contacted the seat, but not over the entire circumference of the seat. There was still a portion of the seat where it was still leaking. Now this had me scratching my head, so I got one of the old original plugs and cleaned it up and covered the seat with black magic marker to see what would happen if I install it. The answer is that there was no leaking. The whole seat had been cleaned off by contacting the head.
I believe the new AcDelco plug was defective in manufacturing where it had a seating surface that was not parallel to the head. The part of the defective seat closest to the head as it goes in, contacts the head first and just stops there, unable to rotate in any more at the tightening torque.
These plugs are called "ACDELCO 6" and are a replacement for the original plugs {ACDELCO 41-943}. And...I learned that ACDELCO now manufactures their plugs in China. After my experience with the considerable rust on the ACDELCO fuel pump hanger (made in China), I decided to order up some NGK's to replace all the plugs. Amazon promised them tomorrow. The beat goes on...

For reference purposes:
Standard plug for LT1/LT4 is ACDELCO 41-943 or GM 5614244 (from Owners Manual). It is a platinum plug.
I am replacing the "ACDELCO 6" plugs (made in China) with NGK 3186 aka TR5GP (G-Power) also platinum

Unfortunate- but Murphy’s Law is why it got installed in cylinder #8

I might be inclined to find an easy to remove plug that you know works and stick it in
the #8 hole and put the one from #8 in there and see what happens. It would be a
guarantee that your theory is correct. Just a thought. It wouldn’t cost anything
but your time.

GM

The only tangible evidence is the witness marks around the seat. Switching to another plug and seeing that it seals correctly is proof enough for me.
If you are thinking about the mysterious noise issue, I'm not sure it is coming from the leaking #8 plug. I wouldn't be surprised if it is still there once all the spark plugs are changed.

Oh, one more thing. I didn't mention this, but I went back and looked at the seating surfaces of all the original plugs, and their seating surfaces were fine.

I finished replacing all the plugs today. I'm confident I have them right. I gapped them at .044, tightened them per specs and made sure the boots clicked into place. When I fired her up, I noticed that the "mysterious noise" was not as obvious at startup as it was before and disappears over time.
The off-idle stutter is unfortunately not gone as I thought it was. I checked the vacuum at idle and it is 18 inches. I'm not sure what is normal for this engine. On the other hand, Silvia accelerates like crazy. Really fun to drive.
I took it out on Interstate 540 for a run. She has a snatch in the driveline at 70mph and also a vibration (kind of a buzz). I won't be able to tolerate that for long. It's on the list.
An all black late model Mustang came up along side me as we were running about 75mph. Very, very tempting, but I kept my head and let him go.

It's time to catch up on a week of work on Silvia. In summary, I worked on flushing the cooling system for five days, yesterday Randi and I took a test drive and ended up riding home in the cab of a roll-back.

The cooling system sub-project touched several systems, so it was not all that straight forward. First to mention are the knock sensors. On this car they are the drain plugs for the block. On the right side, the connector was partially broken and difficult to remove from the sensor. This will come into play later. To get to the knock sensors, one must first remove protective metal shields on each side, disconnect them and use a combination of a 7/8 socket, breaker bars and ratchets to unscrew them. Once you've done it once and have all the tools handy, it's not so bad. If you remember, I had added cooling system cleaner a month or so ago to help clean up the mess caused by someone mixing regular antifreeze with the DexCool (orange stuff). After draining the system for the first time, I replaced one rad hose and the engine temperature sensor which came with the car and was broken, but functional. Too bad the one I had ordered a month ago from Amazon was the wrong one. This started my relationship with NAPA (at Andy's suggestion). With the parts replaced, I started the flushing process. I drained, filled with water and ran the engine four times before it looked clear enough to move on, which took me several days with normal life interruptions.

In the mean time, since coolant flows through it, I had also planned to remove the throttle body and do a thorough cleaning of it. I had cleaned it on the car a few months ago, but in the back of my mind I was wondering if it might be the cause of this off-idle hesitation I've been working on for months. It turned out to be another mess.

So now I had the cooling system flushed four times and sitting empty. Time to button it up and fill it with new DexCool. Installing the Knock Sensors, I noticed that the one of them had a wiggle in the center contact post where some of the surrounding plastic had broken. RATS! Back to NAPA again. I decided to do this right and get not only two new sensors, but the connectors as well. Another day goes by and now I have what I need to do the final fill. By now I'm quite adept at scooting on my back in and out from under this wonderful vehicle for 5 days in a row. I guess I shouldn't complain because it keeps me young and agile.

From here, things begin moving to the final objective.
-New Knock sensors are in and torqued
-Throttle body is cleaned and installed.
-Coolant flow is rerouted to bypass the throttle body. (tip from the Corvette forum which also allowed me to use an original coolant hose assembly that would have been expensive to replace)
-Filled with DexCool

I turned the key and she fired immediately and the throttle response off-idle was much improved. It was now too late in the evening for a test drive so the next afternoon, I decided to offer Randi a nice top down ride in the 75°Raleigh weather. The engine was running well and I wound it out as much as Randi would tolerate (which wasn't much) but it felt real good...until I noticed the "Check engine light"...P00300 on my Ultra-Gauge. It is some non specific "Random/Multiple cylinder misfire detected". My thought was to head home and check it out, but Randi wanted to stop for a couple of items at the grocery store so I did. When it was time to go, I turned the key and the starting action suddenly stopped. My first thought was hydro-lock. Then I noticed a strong smell of gasoline. Looking all around the engine compartment and under the car, I saw no evidence of a gas leak. Then on a hunch, I took a look at the oil dipstick. It showed a noticeable overfill past full. I also noticed my fuel pressure gauge was showing no pressure when I turn the key to "on". This should pressurize the fuel rail to 58 psi.

Time to call East Coast Towing. Nothing more I can do. It took them about 1.5 hours for them to arrive and Silvia is now back in my garage waiting for the next adventure in wrenching.

With this car's fuel system history, my first thought is an injector blocked open. It seems that the fuel filter should catch residual debris that would cause that, but diagnostic thoughts are welcome. (Just don't ask me to pull the spark plugs)

does the oil smell like gasoline?

Seems the likely case

I smelled the dip stick while waiting for the tow truck. I wasn't sure it it did smell of gas because the smell of gasoline was strong all around the engine. I was reluctant to taste it like Derek does on Vice Grip Garage . I certainly plan to change the oil and filter and change the fuel filter and cut it open to see what it caught. I also plan to lift the fuel rail and prime it to see if any of the injectors are leaking.

well the fuel pump should support them being largely open when running at WOT so having a hard time believing one that is stuck open is causing 0 pressure. maybe it would - only troubleshooting will tell.

my experience with oil levels rising is water in the oil not gasoline. Seems unlikely in this case

Maverick came over this afternoon and we did some testing. I lifted the fuel rail and then pressurized it. None of the injectors sprayed or dripped fuel. We also energized each one in succession and observed the spray pattern and then they shut off as they should. We also noticed the fuel pressure bleeding off quickly. Still trying to solve this one.

it could be leaking back through the pump. has to be that or the regulator