NissanTD 27 (Non Turbo): Repair or Replace?

[gun_slinger88]

Good morning everyone.
I have started restoring an old Nissan pick-up of my father-in-law, specifically a 1991 Nissan Pathfinder 4X4. I had the alternator and wirings replaced, repaired the airconditioning system, small flaws on the body, including under chassis and other suspension parts. Overall, it is now in running condition and I have been using it for 4 months.
I have been observing the engine and although it is still running, starts smoothly and could still give a decent speed, I have to add engine oil to it from time to time because the level goes low after some mileage. It also emitting black smoke if revved up to high especially going uphill. Suspected problem is piston rings, valves and other engine parts. Other issues are sure to come up once the engine is opened. Please note that the engine had never been overhauled in all its 23 years.

My question is should I have the engine repaired or should I just buy a replacement engine? What option would be more cost efficient? I'm still looking forward in being able to use it for the next 3-5 years.

Thank you in advance.

[crazy_boy]

losing oil - wala bang leaks mga seals? check also the PCV valve. baka barado na.

black smoke - when did you last perform PMS? possible barado na din air filter.

before you decide to have it overhauled, do a compression test first. this will determine if you need to overhaul or not.

[gun_slinger88]

losing oil - wala bang leaks mga seals? check also the PCV valve. baka barado na.

black smoke - when did you last perform PMS? possible barado na din air filter.

before you decide to have it overhauled, do a compression test first. this will determine if you need to overhaul or not.

Sir, ikaw din ata kausap ko sa PDVD. hehehe
Anyway, walang tulo so seals are in tact. PMS was December. I also checked replaced air filter and fuel filter as adviced by central diesel pero ganun pa din. Napacalibrate din siya last Nov.