It has been a great while since I posted. If anyone searches my username, you will notice I rebuilt my 2M4's engine. Well, about 350 miles after it was on the road I had to get it towed. It has sat in the back of my garage ever since. Reviewing my old posts, even then it had sat for 6 years. Now it has sat for 4 more! but good news: I'm back into it!! Bad news: Broken connecting rod and hole in the block!
I've got the engine out and on the stand, been just diagnosing, forensic analysis you could say. I know a new engine is the solution, but whatever I screwed up last time, I cannot repeat! [url=http://s1072.photobucket.com/user/Bill_Schwartz/library/][/url]
I am hoping that was an image location. I may have to try again. The image showed a broken connecting rod, specifically the cap end pieces, on the right. In the foreground various peices of the block I collected along the way.
The question is, what is the thingy on the left? Round with a large hole in the center. Six small holes around the periphery. I recall seeing it during the rebuild, but I cannot remember what it is or where it came from!
I'll post this and see if the image shows up. If it doesn't I'll up date later. The day is too nice here to sit at the computer.
It looks to me like it's the camshaft thrust plate that is located behind the cam timing gear. There should be two bolts still in the block that held the thrust plate.
Confirmed! Just looked behind Cam Gear and sure enough, two bolts and the ears which were once part of the thrust plate are still under the bolts.
Forensic analysis isn't coming together. There is the obvious, broken rod and hole in block. But there are also dozens of shavings, which I suspect used to be shims on the crank shaft because I had it turned. filled the space between the crank and the connecting rod. I would say oil pump was working because many of the shavings were right at the pump suction. And now a thrust plate on the cam shaft.
What was the sequence of failure? I would love to say its a 1984 and had one of the bad connecting rods. but I think if it just broke, the shims wouldn't have been to shredded. seems to me the shims shredded, making for a loose connecting rod and then it broke.
Crazy. oh, BTW, the failure occured while climbing a hill. downshifted HARD and then got real noisy. Iu jst shut it off and pulled over.
The sample picture from E-bay shows a Chevrolet part that seems to have a beveled ring in the middle. There is a thread on PFF about that ring, and I can't find it....but it's here somewhere.
Looks like a motor Run without oil if I've ever seen one, and Or serious Over revving, Or BOTH. (and I've seen more than a few). I take it you're just looking at it out of curiosity ?
The beveled ring is a spacer to prevent the timing gear from being pressed too far onto the camshaft. Those thrust plates seem to be almost as brittle as glass. You can press the cam gear on without the spacer but if you go to far you aren't gonna be very happy.
Oh, for sure curiousity first. And surely I don't want a repeat. I am confident the oil was there. The oil pump had at its suction a bunch of shredded metal. The pump gear and pin were intact at disassembly. I can't account for whatever oil went out the hole n the block, though! So now way to say it had x amount of oil the instant before the failure.
To go much of anywhere from here I must climb mountain passes. The hill I was climbing is about a three mile, 8% grade. On the way up, it downshifted hard once. surprised me. I thought, man, I didn't like that. But all seemed well and I continued the climb. Shortly, it did it again, followed by being killed. It started again, but sounded obviously mechanically bad. I still drove it to the top, with very little power and very noisy. I made it to a pull out and got safely off the road. And called for the tow truck. Like I said, about 350 miles on the rebuild. Tragic!
