bufmatmuslepants

iTrader: (3)

How long from when the knock started until you parked it, and was the crank salvageable? Did it require a polish, a turn, or a trash can? Havnt torn my old motor down yet, don't know if I need a new crank or not, just planning. I noticed mine at a stop sign windows down no music, gingerly drove home 5 miles, listened, then pulled the motor.

Tolley's94z28

iTrader: (4)

You have to tear it apart to fix it right? Might as well take some extra time and inspect everything. Because in many cases you won't know everything until you get in there and look.

SS RRR

iTrader: (2)

you should not plan anything as far as a build is concerned until you know exactly what is wrong with what you have now.

bufmatmuslepants

iTrader: (3)

I have tho whole top end waiting on the bottom end, just havnt torn into it yet, it's in CT and I'm in MD and havnt brought it down yet. Just curious what anyone has seen with rod knock damage.

SS RRR

iTrader: (2)

Only one I have seen is where the knock was bad enough to rock the engine. Head, piston, rod and crank journals were hosed. Really hard to say in your case.

93M6Formula

I pulled apart a 6.2L diesel that my uncle ran low on oil and had a knock. It was soo bad it ground the crank journal 1/8" down and was unsalvagable. Not saying thats what happened to yours but it can either just take a polish or a small grind or it will completely trash the crank.

noice

I think the idea of "rod knock" and "piston rocking/slap" are being confused here. If the rod is loose enough to be heard knocking it is already too late and the motor will spin a rod bearing, main bearing, seize a piston pin, piston damage, cylinder wall damage, camshaft damage.

You can put a timing light on the engine and if the noise happens every time the light flashes, it is probably a valve train issue. If it happens twice for every time the light flashes, you have some lower end damage.

bufmatmuslepants

iTrader: (3)

My oil pressure didnt change and when myself, my dad, and my friends dad whos been a mechanic for 40 years put our ears to it it sounded like the bottom end not valvetrain. The valvetrain looked ok when I pulled the heads but I didn't pull the lifters and didnt really look at anything when I pulled the pan, this all happened 6 years ago. It's been in a bag in my grandmas garage since.

bowtienut

iTrader: (1)

Probably right. The only time I've ever heard a rod knock without doing damage was on a 250k Vortec in my truck. It was a very deep "thunk thunk" that lasted only 2 seconds (till oil pressure quieted it) at cold startup after the truck sat overnight. I had a good mechanic/builder swear to me that there was nothing wrong with it (he never heard it on a cold morning start), but I pulled it anyway and replaced it with a crate engine.
Sure enough, a couple years later when I tore that motor down, the rod bearing clearance was opened up to .004-.005. Replaced with stock rod bearings, and it's running great with no noise in my daughters 3rd Gen.

Piston rock/slap can go on for a couple of minutes after startup on a very cold day.

Good idea; never thought of doing that!

nitrous2fast

iTrader: (2)

I just use a stethoscope. Put it on the valve cover then put it on the oil pan. If a true rod knock, with full oil pressure you will hear it when on the oil pan.

bufmatmuslepants

iTrader: (3)

Next time I'm up in ct I'm going to tear the motor apart and take pictures and bring the pieces home, it's been on a stand for 6 years in a bag in a climate controlled garage. If its toast ill probably just rebuild my current motor since this ones healthy. REALLY trying to not let it snowball, I can get $500 for my running motor, and was going to use that to offset the rebuild on the other one, but if the crank is trashed, by the time I have it cut and rebalanced that will eat my $500, so in that case ill use the healthy motor.