1996 Collector Edition Corvette

[GMJohnny]

We had a small diesel motor at my old job that had some filings in
it. I watched one of our mechanics use a shop vac with a piece of
steel brake line taped to the hose to get in small areas to try to
suck them out. It could be worth a try depending on the angles and
space you have to work with. I would try a magnet wherever I could
also. Whatever you use, my vote would be to clean it up as best you
can and bolt it up. I think your problem would’ve been way worse if
the bearing exploded, but fortunately you caught it in time! Also,
many times I’ve replaced open sided bearings with sealed bearings.
I’ve always done this on machinery (lawn mower spindles, branch chipper
shafts, etc.) but a sealed bearing is basically a “lubed until it fails” bearing.
I’m not sure if it’s good or bad in you application because of heat and
whatever else the bearing is subject to in the engine, but it would
provide you a lubricated bearing. My guess though is that bearing is
getting lubed from the motor somehow and that if you put it in, it’ll
be fine.

GM

[wxo]

GM,
To begin with, I tried to look into the hole with a flashlight, but couldn't see much. Then I poked a magnet through the hole and moved it around but it did not pick up a thing. Besides, it just kept sticking to the block. After that, I used a video camera that Maverick had given me. It turns out that the resolution was not good enough to detect the tiny chips.

Then I started out with the idea of flushing out the filings by dumping a quart of oil through the bearing hole in the front of the block. Since the open side of the bearing faced into the lifter galley, I figured that the chips and filings would drop straight down and would be carried to the oil drain hole back into the oil pan. So I cleaned out the oil pan and positioned it under the engine block and proceeded to dump the oil in. My plan was to scientifically collect the oil and then examine it for the filings and chips. So I dumped in the oil and when I looked under the car, there was oil all over the floor. A lot of oil missed the oil pan and I had a big mess to clean up. So much for the scientific method. When I finally got to looking in the oil pan, I was able to identify about three examples of the filings. Of course there may have been other bits of evidence that ended up on my garage floor.

The only alternative to assess the situation first hand is to pull the intake manifold again. To tell the truth, I just do not want to disturb the work I had already done in that area. I think it is reasonable to let the oil carry the debris into the oil pan and the oil filter. Theoretically, it should work.

Reading through many forum postings, the one warning I read was not to replace the open bearing with a sealed one. It seems reasonable to assume that this bearing lasted for 103K miles, it should outlast me. Plus, whatever the system of lubrication, it, too, seems to work. I plan to soak it with oil as a pre-lube and move on to the next chapter.

[wxo]

My decision to replace the timing chain on this motor had potential pitfalls and I believe I've hit every one of them. The new timing set would have been a slam dunk if it had not been for the requirement to change the gear on the water pump driveshaft. To change the gear, a bearing on the end of it needs to come off first. The bearing on that driveshaft has been a nightmare and I've learned a ton dealing with it. The bearing is pressed onto the driveshaft and the outer race is pressed into the block. If not done correctly either or both of the pressing operations can destroy the bearing. In my case, I believe this caused the startup noise and filings in the oil pan.

The water pump driveshaft is driven off teeth on the back side of the cam sprocket so the relationship between the two are critical. The location of the bearing on the shaft determines the spacing between the water pump gear and the timing sprocket and chain.

Well, with Maverick's help yesterday we learned that, on the second (and last) trip to the machine shop, he did not press on the replacement bearing on the right place on the shaft. There is a ledge built into the shaft and this appears to be the right location for the bearing on the shaft. The new bearing was not pressed all the way to the ledge. This resulted in a water pump drive gear on the shaft to be positioned too far out toward the front of the engine. Then when I assembled the timing set, the timing chain/cam sprocket was jammed big time against the water pump gear. It requires at least .020 inch between the two.

So Maverick and I decided verify our observations. We used my shop vise to press the now damaged bearing all the way to the shoulder and then pressed it into the block to check the clearance. Then we bolted on the cam sprocket and chain to check the clearance. It looked right this time. So, now I have another new bearing on order and my plan is to press it on myself with my shop vise so that I know it will be right. Then, theoretically, I should be on my way again.

[wxo]

I corrected an error in my May 7th post.

[wxo]

I now have a new bearing on the water pump driveshaft and the driveshaft installed into the block. All is looking good for moving forward now. Maverick came over yesterday and we struggled a bit, but got the timing chain and sprockets on and positioned correctly. The timing cover is on and I'm back to the point where, several months ago, I first looked at the timing cover and thought "I'm in this deep, I may as well pull the cover and see what's inside".

The next order of business is to get the oil pan back on. After that, the next milestone I'm working toward is to start the LT4 without water pump or coolant to verify that it still runs and the noise is fixed. By the way, I'm convinced now that the bearing was originally damaged by removing the driveshaft from the block. The outer race of the bearing is pressed into the block face. The only way to remove it is to pull it out by the shaft which means pulling it by the inner race which is attached to the shaft. I can't see how a bearing can withstand this without some damage. The practical result of this is that any time the shaft is removed, the bearing must be replaced. It was a hard lesson to learn.

[wxo]

It was a bit of a struggle, but I got the oil pan bolted in place yesterday. It seemed easier the first time I did it. I still need to check the torque on all the bolts, then install the starter and other miscellaneous hookups under there. So far, so good.

[wxo]

This afternoon, I finished all the bottom side hookups (starter, knock sensors, brackets, etc) and put away the engine crane (now stored in the new garage). It feels good to be done with all that work under the car. I'm looking forward to a startup attempt probably next week some time.

[wxo]

Hoping to get a test run of the LT4, I spent several hours in the garage today. Once I installed the new Opti-Spark, I began all the hookups and everything went well until I got to the the last thing, the Opti-Spark ventilation system. It's purpose is to provide a flow of air through the distributor to prevent moisture buildup. It takes in filtered outside air from a hose just behind the MAF sensor and runs it to the Opti-Spark. Another hose from the Opti-Spark is attached to intake manifold vacuum to complete the system. From my reading, I learned that ignition misfires can be caused by blockage in this circuit preventing a free flow of air through the system. To provide just the right flow of air, a .012" diameter restrictor orifice is placed in the hose going to the intake. It took some study to learn that I could shine a light through the orifice to verify that the hole is not plugged. With the light behind and using a magnifying glass to get a clear view, I saw that mine looked just fine. Once I was satisfied that the components were good, I found that routing the hoses was a problem because I had to consider where they would run with the water pump installed. Everything on the front of this engine is packed tightly. I had to get the new water pump out and put it into place to see where I could run the vacuum lines. The lines that I put in place now needed to be moved. When this proved to be difficult, and with the day winding down, I decided to quit and wait for another day to finish.

[Maverick]

Good work!! I saw where the Opti-Spark ventilation system is an annual service item. How often do you suppose THAT happens?

[wxo]

Maybe once every 103K miles.

[GMJohnny]

Maybe once every 103K miles.

Whether it needs it or not!

GM

[wxo]

I forgot to mention yesterday that I have decided to go all the way in this ignition system and replace the coil and Ignition Control Module. I have both ACDelco parts coming from Amazon. I can't help thinking about BP's problems with ICM's. I could run into the same issue.

[wxo]

Started up the engine this afternoon. It is still noisy. As I see it, I have only one option at this point and that's to bolt on the water pump and fill it with antifreeze . My hope is that the empty water jacket and missing water pump may be funneling normal engine noise out the front of the engine.

[wxo]

I installed the water pump and filled the system with antifreeze, but I didn't install the fans yet. At the startup, the noise was the same, very loud, but it wasn't long before it abated. It looked to me like the noise quieted as the oil circulated around to whatever is causing it. I would say the noise is 75% less than it was at startup, but still there. I suspect the timing chain is making the noise. Also, for some reason it threw two codes, P0100 (MAF sensor) and P0336 (crank sensor). I pulled each of the connectors and reseated them, but the codes continued. I have no idea what that is about.

In the short term, I have two things to do. Fix the codes and drain the oil and open and inspect the filter.

[wxo]

Today's update:
I was able to spray the MAF and Crank Sensor connectors with quick drying electronics cleaner to get rid of the respective engine codes. The engine starts instantly and idles smoothly. I set the fuel pressure at the stock setting ~45psi. The off idle bog is still there with both the Opti-Spark and the coil/Ignition modules replaced with new Delco items. I'm not sure is this is a problem or not if I can raise the pressure to fix the bog.

The screeching noise as I mentioned before is still there. There are definitely steel particles in the oil pan. The new news as of this afternoon is that I'm backing off on my statement about aluminum particles being in there, too. With a very close examination, I can't definitely identify aluminum particles. Cutting open the oil filter showed slightly more particles than before, but still remarkably few. Apparently most of the larger, visible particles did not get sucked up into the oil pump. I ran a small magnet in between the folds of the filter and it picked up very small amounts of minute steel particles. It looks like so far, the engine is being protected by the oil filter.

I called Cloyes tech support again this afternoon and spoke to the head support tech. He was willing to discuss the problem, but in the end, he wanted me to get back to him with the details on what I find when I take the dive back in to inspect the timing chain for the third time. Since I was able to run the engine longer, perhaps there will be more visible witness marks inside the timing cover this time.

This last foray inside the timing cover did have one benefit. I found a definite problem with the water pump driveshaft bearing that may have been overlooked if this problem had not occurred. Stay tuned...