I'm wondering if this sounds like rod or main bearing knock or if it could be something else -
Background - 1996 Fleetwood Bounder 36-foot RV with Vortec MPFI 454 that has 90K miles and seems well taken care of overall - purchased it as a non-running project 3 years ago, tried tinkering with it then to no avail, let it sit for 3 years and now back to tinkering. If I can't get it working, I'll just swap the Flexsteel interior into a trailer, but I'd like to try to get this one to run. It started and ran similar to how it's in the video below when I bought it, then quit starting at all for a while, now it runs for about 5-10 seconds at most. It's been making that knocking noise the entire time I knew this motor and it's been bugging me since day one.

Fuel pressure is 60 psi with key on and does not bleed off with key off. There is a strong spark from the coil and the coil is new. Also new spark plugs, wires, cap, rotor, PCV, fuel filter and air filter. Drained the oil this year, it smelled like gasoline, possibly from all the failed starts. Gasoline in the tank is a few years old now. But I doubt it's that old that it's doing "this". Pulled the distributor out and it has an "upgraded" metal gear with all edges nice and flat (not razor thin) and looks new to me. I believe that distributor was installed correctly when I checked it 3 years ago, but will recheck it now that I've pulled it, just have to refresh my memory on how to use the "bottom" timing mark on the RV (either #5 or #8 at TDC). It was giving a code P1351, I've posted previously a separate thread about it, but it's no longer giving any codes.

Questions:
- does the noise in the video sound like mains or rods?
- is there a possibility of MPFI 454 injectors (not CSFI 350) to be bad and do this?
- any other ideas about what can cause the metal noise in the video or next troubleshooting steps?

 

could be a lot of things i guess, could even be something simple like the flex plate bolts

 

Heard about the torque converter bolts. But would the noise still come from the engine? I know it's hard to tell from the video and can be hard in general to pinpoint the source of a noise in a vehicle, but it seems to me that it's coming from inside the block, which is why I was worried about the main bearings. I've also heard about timing chain stretching and jumping timing. Will pull the distributor again and re-examine all sides of the bottom gear, did some reading, sometimes only part of the gear wears and so I'll look more closely. Will try to see what the camshaft mating gear looks like through the distributor hole. Also going to need to check my cat, as all this unburnt fuel might have killed it, although it wouldn't cause the knock. Any ideas of where I should start? From most likely to least likely cause of the noise?

Anyone knows about the bottom timing mark? Do I just use it with #5 cylinder the same way I would have used the upper timing mark with #1 cylinder at TDC? The top mark is such a pain to get to with a mirror in an RV...

 

you could just craw under it and inspect the bolts

 

Crawled under the RV last night after work, took off the tranny cover, all torque converter bolts look appear to be tight, at least by hand and visibly, I did not try to retorque them. Pulled out the distributor to double check the gear again, it looks like brand new, likely replaced by the previous owner. The camshaft gear looks okay whatever I can see through the hole. Not sure if the distributor was installed correctly and will double check when I install. It appears I can use the lower timing mark (at 5 o'clock) and the #8 cylinder at TDC to set the timing.

Are there any ways to confirm mains without taking the bottom end apart? I'm not sure that there is enough room to pull the oil pan without pulling the engine. Not to mention rolling new ones in.

If I don't find a simpler solution to fix what I got now, then probably just replace the motor, or cut off the front part and make a travel trailer out of it by welding in a hitch.

 

Making an assumption, what does the oil look like?

 

Well, the oil was drained into a dirty pan that might have had some sludge in it already, but what I looked at was quite chunky. Like pretty thick. It also smelled a lot like fuel, which is understandable, as all this unburnt fuel is washing down cylinder walls and getting into crank oil. I do still have the old oil filter up there and it could potentially be hacked apart to see what it caught... Everyone is telling me the engine sounds like it will need to be pulled and rebuilt... In which case I will just replace it probably... Just grasping at straws in hopes someone might tell me that it's not a lost motor somehow...

 

I'd throw an oil change at it first.

 

another one? as in drain the fresh oil and look what's in that? what does anyone here think of a possibility that a timing chain jumped a tooth or few?