| A friend of mine with a TT recently had to replace a piston as well as two valves that were damaged when his engine consumed something its not designed to eat. > 
Apparently it fell into the plenum where it stayed for almost a year. We had rebuilt this engine last January. It finally found its way into the intake of cylinder #5 and got beat around on the intake valves until the little screw came out. Then that piece entered the cylinder.. Caution: These pictures are painful to look at. 
The damage from this little piece of shit was amazing. I dont have a picture of the spark plug, but one of the key indicators that something was in there was the fact that a nice circular impression was made in the collar of the tip of the plug - the flat area where the curved electrode attaches to. It was an impression of the top of the screw head where the edge is slightly raised. Anywho, this engine came out and he took the head off. He replaced the piston, exhaust valves, head gasket and plug and put it all back together. Once everything was running, it wasn't running right. And then it was soon evident that the head gasket was not sealing AND cylinder #5 had low compression. But the head gasket wasn't sealing on cylinder #1, at the other end of the head. Well, here's what happened: he got the short bolt in the wrong hole. A long head bolt in the short hole will bottom out before you can get the head of the bolt down to the surface of the cylinder head. So - it never applies any holding force on the head. The short bolt was only partially threaded and he didn't even torque it all the way down because he said it started feeling "weak". On top of that, he didn't lap in the new valves. So, I get involved. We pull the engine, properly lap in the valves, clean up the threads on the head bolts and the block's threads and reassemble. Goes together - tits. So we take a break and I tell him to check the coolant and oil. We get it burped and we take it out for a spin. He gets on it pretty good and its pulling hard and running well. We take it back to the garage. We pop the hood and the first thing I note is the sound of a rod knocking. We start pulling coil pack wires and find that cylinder #3 is knocking. So I'm scratching my head on this one - those bearings only had like 10K miles on them. So I go over and just check the oil to be sure. Nothing. "Uhhhh, dude, did you check the oil???!" him: "Uh, no. I put 4 quarts in and I never drained the oil - it was new." So we jack the car up and drain the oil. There was only 2 quarts in the SOB. So we pull the plugs to check compression and what do we find? A wonderful autolite plug in cylinder #3, and its whiter than casper. He didn't know where one of the NGK's were, so he used that plug. I told him to park it, dont drive it. We'll do the rod bearings. So bringing us up to this point. I arranged to get the car over to Fred's shop so we can get it on a lift and do the bearings from the underside. We started at 11AM or so. We dropped the cross member, steering rack and the oil pan. I fished new bearings in, all one grade up from the stock grade. I plastiguaged everything and it was at 0.0015", which is well within spec. That one particular bearing journal, #3, was actually in near perfect shape. The bearing was hating life. Check this out. >> 
You can see in the first picture that it is well beyond the nice soft lead material and well into the copper substrate. The amazing part is that the cranks are very hard forged steel and copper doesn't stand a chance up against it. The part that lost: the bearing. The crank was still nice and smooth. This is probably do mostly to the fact that once I noticed the faint sound of knock, we shut it down and didn't drive it thereafter. You can see in the bearing on the far left (damaged one) how the stop tab has completely been pushed to the same curvature of the rest of the bearing. This bearing was just about ready to spin. Had the other bearing's tab slipped too, it would certainly have been an awful death. In the second picture you can see how the heat permanently deformed the bearing too. We put it back together and had her running at 5PM. Oil pressure has gone up an average of 10psi and the engine is holding together very well. We suspect the combination of low oil and a bullshit plug causing detonation is what led to the demise of this bearing. All the other bearings were still in relatively decent shape, but I replaced them all while I was in there. It was suprisingly easy to do this too. Afterwards, I got a case of beer and we proceeded to install my sway bars. Man those things are easy to install. We had it done in literally 30 minutes (on a lift).
[ ashleypowers.com ]
[ agpowers@bellsouth.net ] [ Zemulator Information Sheet ] When pigs dance, you better get it on video... "You never really learn to swear until you learn to drive."
-George Carlin
|
Rod bearing replacement this weekend >>> - 
