I own a 1992 Crown Vic w/ a 4.6L built 5/92 with 140K miles, I know, its not a truck, but I'm having a hard time finding a forum for help!. Nevertheless, the problem began when I noticed a cold start knock for a few weeks. Should have known something was wrong because the other day the engine "broke" and made a noise that would make you think a rod was ready to blow through the block. Needless to say, I prayed that it would make it home and it did, about 20 miles. The sound did not necessarily correspond to RPM, and was more of a metal to metal clanking sporadic noise. It seemed to idle fine at stops. When I got home, I removed the valve cover from the side the noies was coming from and didnt notice any problem with the valves. Sound is coming from below. Anyway, my neighbor believes its a crank/connecting rod bearing? The car is in good overall shape, inside and out. Should I consider a used engine for $600, a rebuilt for $2000, or try and rebuild myself? I know these are all personal opinions.. Or should I take it into a reputable service center to get a thorough diagnosis. Thanks for the help...

 

Welcome to the forum

It could be a rod bearing. Have you checked the oil pressure to see how it is?

 

Before I had the problem, I had noticed the oil pressure varied. At times, it would read very low, and then it would come back to normal. I would check the oil level to ensure it was okay and it was. This vehicle would burn about a quart every 2000 miles. Thanks for the response.

 

Could have a clogged up screen on the oil pump pick-up, but now that it is knocking to get out of the block, it would at least need a crank kit now.

 

Since the problem I have not checked the oil pressure. I was reading my Haynes Repair Manual and it indicated checking TDC pressure to identify which cyliner is the problem? I'm trying to diagnos myself, but may be better off taking it to a reputable shop.. that is if I can find a reputable shop?

 

Would I be better off finding a good used motor than rebuilding with a crank kit?

 

You said that the knock didn't correspond to RPM, and was more of a metal to metal clanking sporadic noise. My friend has an 80s Chevy truck with a 350 and a Turbo 350 tranny that the knock didn't correspond to the RPM. So we thought it was motor that was knocking, pulled the motor and tranny. Tranny had been slipping and we rebuilt that first. We noticed there were clutches missing in the clutch packs also a bad pump. Well we rebuilt it put it back in without touching the motor and there was no more knock