Yes, you could get an audible rod knock if the bearings are damaged. Also, if you have oil pressure and/or oil temp gauges, watch for substantial changes in their behavior since the "incident".Absolute pressure/temperature readings usually don't mean much, but changes in their behavior can allow you to spot a bearing problem early (greatly reducing the risk of crankshaft damage).I once had an engine that ate a set of brand new rod bearings in just 20 miles. It didn't even knock although the bearings were down to the backing metal in just 20 miles. I tore it down the 2nd time after the bearing job because it felt sluggish and exhibited high oil temps / lowish pressures after the bearing job. Indicating high friction (and likely excessive clearance). I have NO idea why it never knocked, I consider it one of those exceptions every rule seems to have... Turns out the root cause was an oil supply problem. Live and learn But that's beside the point, just an extreme example of gauges being a Good Thing.Don't let me scare you though ; as you say, likely the VW diesel bottom end is very strong.Marcel
Congrats!If you know how to use FTP for uploading, I can set you up some image-space on my webserver.It's not very fast, but for posting a couple pics to this forum it should do just fine. (that's what I use it for anyway, posting pics to various forums)
Jake--with an oil pressure drop like that I would indeed recommend at least taking a look at things. As Marcel said, all would have to happen at once pretty much or else it would not make much sense to do it at all. If the bearings got mashed badly enough to cut your oil pressure in half, chances are the rod upper bearings and the lower crank bearings were both pretty screwed up.
Could it be as simple as the blow-off valve on the oil pump? Rat407 rebuilt his engine and still didn't have oil pressure...I'm not sure if he figured that one out or not.Steve
BTW in many engines it's possible to remove the bearing caps one by one and replace main bearings without removing the whole crankshaft. You need a little trick to push the upper shell out and in, but it can be done. You still don't want to, though.
Which is why I recommend leaving them ALL in if they're allright. If you want to replace the rod bearings only that's fine, but you still need to measure them, so you know whether to look at the mains or not.
Plastigauge is thin wax "wire". Comes in a few thicknesses, at about $1 per ~1ft strip. You take off a bearing cap, clean up, take (cut) about 1/2" of plastigauge, and put it on the crankshaft (when working under the car, you would put it in the bearing cap). It is used across the width of the bearing (parallel to the crankshaft). Put the bearing cap on, torque to spec, remove, and measure how thick the now squished strip has become compared to samples printed on the packaging.If there's a lot of side clearance on the conrod, try to keep it from moving around as you tighten it. Crankshaft orientation does not matter as long as it is fixed in that position, so just pick a convenient position for each measurement. And mind the oil feed hole, you don't need plastigauge in there
The only way to screw up is squishing/smearing the stuff too much by allowing things to move around or putting too much pressure on the bearing cap somehow. The stuff should be squeezed to the exact clearance and no further. This may be what went wrong on mom's car, or there might have been a completely different reason why bearing failure still ended up happening. If in doubt, measure twice and see if your results are consistent. Do not average, the highest reading is best, you can only err to the small side.
