Amazing engine NON-failure and repair questions - Toyota Nation Forum : Toyota Car and Truck Forums

Just2Bizee · 07-14-2007, 09:37 PM

Anyone ever see or hear of this happening? My wife's '97 4cyl automatic had an oil leak coming from the pan. No big deal. I dropped the pan and was scraping off the old gasket when I noticed a few chunks of metal in the bottom. Turns out the head of one of her connecting rod bolts sheared off and and apparantly took a piece of the piston skirt with it. There's never been any indication (noise, pinging, shavings in the oil, etc) that anything was wrong.
http://farm2.static.flickr.com/1250/...7f2c68.jpg?v=0
http://farm2.static.flickr.com/1062/...321a1f.jpg?v=0

I'm planning on replacing the 2 affected connecting rod bolts and the bearings. I'm not worried about the piston as it appears fine other than the little chip out of the skirt. It's gonna have to sit for a few days while I order two new connecting rods and new bearings, but I'm just shocked that the engine didn't fail when it happened. Anyone ever hear of this? Any suggestions for doing the repair? This is the first time I've been into this particular engine. Thanks for any feedback!

dc_98_cam · 07-15-2007, 02:37 AM

I think the big question is whether you can retract the piston from the cylinder to the point that you can get the piston pin out, and not free the piston rings. .... That is, normally, you install the piston, piston rings, and connecting rod from the top of the engine block using a ring compression tool, with the cylinder head removed. ... However, if you have enough working space, and just don't pull the piston too far out from underneath, you might be able to do it. ....Before you proceed with the replacements, note the orientation of the pistons with respect to the front of the engines, make a scratch mark inside the piston skirts if necessary. Also inspect the connecting rods for any particular orientation ... Have never tried to install the entire piston length and rings from the underside of the engine block .... wouldn't think it would work. .... Maybe if you're just careful and don't pull the piston out too far. ... Squirt plenty of engine oil on the cylinder walls before you start moving the pistons.

Blackhawk3D · 07-15-2007, 02:27 PM

You need to replace that piston, that's a failure waiting to happen and more $$$ down the road than you want to deal with. Anytime metal gets an imperfection that large in it the whole piece is compromised.

ghettosled · 07-16-2007, 07:14 AM

thats a first for me. im surprised it hasnt caused any more problems.

Just2Bizee · 07-17-2007, 09:53 AM

My gut tells me rare catastrophe, but with that oil leak, I can't be 100% sure the wife was checking her oil at every fill up like I told her to. It could have run low at some point during the past 2 years. We were in an apartment, parking on asphalt, in a different place every day, so I didn't know how bad the leak was until we moved into our house a month ago. Poor car care on my part.

masteryota1 · 07-17-2007, 12:02 PM

wow man, you know how to do all that, and live in atlanta, i need to swing by and watch some of this repair work lol

jrcrum · 07-17-2007, 02:14 PM

That is amazing -- I would have expected it to throw the rod! It's possible that the bolt just failed because it was defective, or over-torqued, and when the bolt head turned loose it rattled around and hit the piston, knocking the piece out of it, and the engine may run fine for a long time that way. But if it was mine, I would pull the head and replace that piston.

And if you do pull the head, I would replace the rings and the other rod bearings, as well as all of the rod bolts (in case any others may be thinking about turning loose, too).