Perkins 4-107 - Loud Knocking

[seafarer74]

I have a Perkings 4-107 in a 1974 Seafarer Ketch. The Perkins, while noisy and leaky, has always started on the first turn of the crank, doesn't overheat, and is very fuel efficient. The oil line that runs down to below the injector pump recent burst, spewing oil every where. Engine still had oil pressure, but I heard a knocking so killed engine and discovered problem.

Replaced the oil line and oil, but engine didn't start right up: took 4-5 seconds to start, very unusual for it. After a few seconds, knocking stopped, but then redeveloped 10 minutes later. Killed engine, checked everything, and restarted: same thing, it took a bit to start. It then seemed to idle rough and then died at normal idle speed. Ran for a few minutes and a very loud knock developed. Haven't run since.

My question, is the knock the engine or the injector pump? I've rebuilt many car engines, but never had any experience with an injector pump. I don't think the engine was without oil, even though pressure was very low, but line to below injector pump was not delivering oil, whichever direction it goes.

[bobfnbw]

Could be a injector

[Chief Engineer]

Or the injection pump got starved of lube oil and locked up.

[seafarer74]

I did the injector test of cracking each nozzle. Knock did not stop or change. Only result was engine didn't idle as well. Tried it at each injector. Am now pretty sure it is a rod bearing. Will raise engine, drop pan and find out.

[Finalee]

Blew the same line. I know this is an old thread but wondering how it turned out.

[Lepke]

The injector test doesn't always confirm a bad injector. If the rod bearing spun and got hot enough or banged long enough to distort the rod end, it will knock with the injector disabled.
When doing the test, you need to confirm the same amount of fuel is leaving each tube. If the injector pump is damaged, it may not be sending fuel to all the injectors. If with a new oil tube, the engine oil pressure is normal, the engine is probably ok. I'd bet on the pump.