Brian911

Big bummer guys. It's 12:40 out here in Cali and I just got back from lunch when I heard this horrible racket comming from my engine (1980SC)I have heard a slight knock before but now it is just out of control. It sounds like it maybe behind the fan and under the airbox. Yes there is oil in the engine. Maybe someone has an answer or clue as to what it maybe. I commute an hour each way so lets hear.
Thanks to all that respond.
<img src="confused.gif" border="0">

Jeff Curtis

Brian, there's several things that can be, ranging from a broken head stud that has progressively gotten worse...meaning that the original broken stud caused a leak between the head and the cylinder that only gets worse, possibly because the other lower stud to that head/cylinder broke as well, due to the extra stress on it. Of course, as the leak and damage gets worse, so will the noise. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

This could also be a dropped valve and/or timing chain issues.

It's fairly doubtful that an SC motor has bad rod bearings...but it's possible.

My advice, either way - would be to drain the oil and remove the lower valve covers to see if any broken head studs with their mate barrel nuts are "hanging around".

If you can't find broken head studs (my vote, BTW) then pull off your muffler and timing chain covers to see if a tensioner has let go and/or you have some VERY worn items in there, to include chain ramps, cam sprockets loose/worn.

MYSELF, I would just remove and tear down the engine...sounds like you have some major issues...any of the aforementioned issues are big jobs to correct - and will likely require engine removal anyway.

Sean Hamilton

Brian,
Have you diagnosed the knocking yet -
concerned fellow 80SC owner.