Perkins 4-108, any comments, opinions, or things to watch out for?

Aug 22, 2017
1,608
Hunter 26.5 West Palm Beach
I'm thinking of buying a boat that has a 4-108 engine in it. The motor looks poorly kept, but is said to run. I hope to test run her tomorrow. Is there anything I should watch for? Does this motor have known issues? Are parts readily available at reasonable prices?
 
Jan 5, 2017
2,170
Beneteau First 38 Lyall Harbour Saturna Island
I have had two boats.with the 4-108 in them. Currently rebuilding an Onan gen set powered by a 4-108. I have never had trouble getting parts and have not needed very many. Both current engines have over 6000 hrs. And run fine.
 
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Jan 7, 2014
254
Beneteau 45F5 51551 Port Jefferson
Mine runs fine, no problems around 2300 hours. The only think is it leaks oil, probably from the rear oil seal. About a half a quart or less per 15-20 hours. The rear oil seal seems to be a common problem. There is an aftermarket seal claims to works better than the OEM. I will fix it eventually. For now, I check my oil regularly at least the leak keeps it clean.
You may want to get an oil analysis done.
 
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Oct 22, 2014
16,087
CAL 35 Cruiser moored EVERETT WA
The Perkins engine is a little engine that could and it did. There is a reason the Perkins 4107 and 4108 have been in use for so long. They just work. Not pretty. No super chargers. Just 4 cylinders Banging away. Abused. Ignored. Feed them fuel, oil, and a battery charge they ask no questions they just run.

On a boat it is important that the cooling system is working properly Keeping the engine between 155 and 180 F. The alternator needs to be properly charging the batteries. The engine powers smoothly up and down. That engine is not spewing smoke, diesel, or oil out the exhaust. The fuel system is clean. That there are two fuel filters the primary in a place that can be easily checked and changed, and a secondary on the engine. No fuel leaks. No coolant leaks.

When I talked with my fisherman cousin about the Perkins engine he sang the praises of the engine. Said they had a 4107 on a tractor. The tractor had sat for 4-5 years in the corner of a field. It was covered with black berries and gorse. He sent his son with a weed wacker to cut the tractor out of the brambles. Two days later he went down with 2 gallons of diesel, a battery and a quart of oil. Said he fed the tractor fuel, gave it the oil, Hooked the battery up to the starter, then turned the key. It turned over a couple of times and suddenly fired up.

On my sea trial I ran the engine at 60 to 70% till warm then I tested wide open throttle, in both forward and 70% in reverse. I tested emergency stops. All the time watching the RPM, Oil Pressure, and Temp gauges to see how the engine reacted. I also watched the water exhaust for volume as rpm increased and any smoke from such demands.
just a few ideas.
good luck.
 
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Aug 22, 2017
1,608
Hunter 26.5 West Palm Beach
I had a bid in, & thought that I had an agreement, then the seller brought in other perspective buyers, hoping for a higher bid. I withdrew my offer & walked away. The motor has yet to run. There are other fish in the sea.

Thank you again for the constructive responses I received here. The information about the rear engine seal was particularly helpful, as the bilge has a fair amount of oil in it.
 
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