Perkins 4-108 1981

[Atraxia]

Dear forum members,
I am checking out a Mariner 39' 1981 which has a Perkins 50HP 4-108 engine. Apart from looking a bit neglected on the visual side and wiring it has a pretty load knocking noise when opperated. I am familiar with Yanmar and Volvo engines but don't know a thing about the Perkins. Is this noise acceptable? Is there anything I should pay special attention to? Oh, I forgot to state that the engine is the original and has never been touched (opened) and has some 3000 + hours. Another question - it has bronze seacocks which look ok but the sea water intake and filter look bad and leak and the rest are the boat's original. Should I replace them or just clean them up? Where can I find the seacock with the filter for the engine intake? Thanks in advance to all replyers. Ron

[anjou]

Are there any old aero start cans lurking round the bilge?

Most diesels of this era knock a little when cold but should stop after 10-15 seconds.
Stubborn starters are often adicted to ether once someone has got them hooked and that causes the knocking.

[S/V_Surya]

I have a 4107 and there is no loud knocking. Do not know about seacocks. Mine are brass and I serviced them last year and inspected. In assume they are plug valves. Do they turn easily, have they been lubricated, how do the hose attachments look?