Small Block 305 Bottom end clacking (sounds like small diesel engine)

[81GMCSierra1500]

Another question... Engine ran super hot today (30 minute highway drive (110km/h), checked the oil, was well below the "add" mark. immediately went to get more oil and topped up. But even before this, the engine has always had a mechanical clacking noise come from the bottom end of the motor (most audible from directly under the oil pan). Wondering if this is anything to worry about? The motor is otherwise strong, very little smoke, fires right up, even when cold... just wondering 1. can a low oil level cause damage, and 2. is the clacking a serious issue needing dealing with?

Thanks again!

'81

[bdiamond]

Timing issue?

[81GMCSierra1500]

Timing has been checked, apparently the actual part the timing mark is on (harmonic balancer) has slipped, so what's "correct" is not... I don'y honestly care much, it just makes a weird noise... I am concerned about the low oil level/hot temperature possibly causing damage internally... I'm sure everything is fine, but just thought I'd ask on here...

[NJ C10 Guy]

Disclaimer: I am not a mechanic, just talking from my own recent experience.

Have you noticed any drops in your oil pressure while driving? Is the noise there all the time or does it go away? You could always change the oil, cut the filter and look for metal if you're concerned about internal damage. A low level can cause damage if there isn't enough in the pan to reach the pickup.

I had a similar problem where mine was making noise but it seemed like it was coming from the top end. My oil pressure would drop and the noise would get way worse, then it would go back to normal and the noise would cut out. Cut the filter open and bingo...metal particles everywhere. So I picked up a donor motor

[Dead Parrot]

To answer your questions:
1. Yes. Low oil can lead to damage. On a normal SBC with stock pan, pump and pickup, somewhere around 3 quarts remaining is the danger zone. Normal full level is 5 quarts. If gauge, did it ever go the zero, if light, did the oil light ever come on?
2. The noise is harder to tell. Some motors will last a 100's of thousands of miles with a clacking or knocking noise. Other die fast without hardly a peep. I second the notion of opening the filter and checking for bits of metal. Installing a magnetic pan plug is a 2nd option.

To answer the unasked question, a bad overheat can kill one as well. Might be time to check/replace the thermostat.

[81GMCSierra1500]

On the topic of the low oil. When I did check the oil, it was just below the "add" line, but had some small bubbles on the tip of the dipstick. It has been quite hot lately (I on't think that helped much, but the engine needed a full quart (the small bottle is a quart, right?) and a half... So there was definitely oil in the engine... I'm gonna take it for a drive today and see if it does anything weird (it is due for an oil & lube too, so I'll get them to check everything with a fine-toothed comb... She seemed okay otherwise though... When you get paranoid, every little noise is amplified to worse than it actually is, too Thanks for all the input, guys!

[bdiamond]

A litre is just shy of a quart.

[Jake1971]

A 305 sbc engine? Making noise? My suggestion: (free shipping!)http://www.jegs.com/p/Chevrolet-Perf...52506/10002/-1

[81GMCSierra1500]

UPDATE:

Running fine, took it into a shop to take a peek, they said the overheat issue was because of a bad thermostat (no idea how old the one in it now is), and I had just put a full tank of not so great fuel into it, so the hot running temp, low-ish oil level and ****ty fuel all combined to create this nasty situation. I will be installing the new thermostat with some fresh daylight tomorrow, and see what happens...