Perkins 4-108 diesel

[Dynamo1181]

Originally Posted by bsankey448

This mechanic is the Perkins mechanic at the service center and has been working on them for years. My yacht surveyor agreed with the mechanic and gave me the names of two more mechanics to question. I'm calling them today. See what they say. Who should I believe? Diesel mechanics or guys talking on the web?

Look at the log. Is it timely? Oil changes at 100 hrs or less? The log should probably show both fresh water and salt water pump rebuilds. You should probably see injector and pump rebuilds at least once in 4000 hrs and probably more. Was starter rebuilt? Heat exchanger cleaned? Valves adjusted? Head re-torqued? All of these items show a prior owner who is conciontious about kjeeping that engine purring.
If your inspector checked compression and the results show not in specs. If he said there is water in oil or oil in water, then the engine has damage. If the guy simply looked at the hrs and said it is at the end of its life, then I would hope you didnt pay for the survey! Do you have a report of a current oil analysis done by the surveyor? Previous owner?
The above info should tell you if the prior owner or the mechanic you hired did their job.
A

[bsankey448]

I haven't seen any oil analysis, won't be here till Tuesday.

[gjordan]

Did the mechanic give you an actual condition report(compression, oil pressure when up to proper temps, oil analysis) or did he just give you an opinion based on hours? He may well be trying to sell you a new engine. On the other hand, that bad opinion is a great bargaining chip for a major price reduction on the boat. If you buy the boat with the present engine, run it for a few monthes and see if it seem reliable. First thing to check is how clean the fuel tanks are. A boat that has been sitting for a while can have things growing in the fuel that will stop any engine, new or old. Good Luck with it, and keep us posted._____Grant.

[Cheechako]

Originally Posted by bsankey448

Just talked to the mechanic who did a survey on the engine. He says that a Perkins with that many hours is just about at the end of it's life span and I will need to do a re power in the not to distant future.

That is probably the safe thing to say when asked. However, it doesnt mean the engine wont go another 4000 hours. You're asking him to throw a dart... he's erring to the safe side. If I was going world cruising with an engine with 4000 hours, it would be a minor worry in the back of my mind the whole time.
Perspective: if the average speed of a car is 45 mph, then 4000 hours of use is 180,000 miles. If a Ford diesel pickup has that mileage on it, I would assume it will go another 50k, maybe more, but I probably wouldnt tow a RV trailer around the country with it.

[Gr8Heart]

Originally Posted by bsankey448

See what they say. Who should I believe? Diesel mechanics or guys talking on the web?

Listen to everyone. (Plans go wrong for lack of advice; many advisers bring success.) Decide for yourself. Discount those who have something to sell you, like a new engine. But don't disregard them. BTW: I'm in the same situation. Perkins 4-108 - rebuild or replace? Not sure yet...

[Barnhard_Marine]

Things to think about. Does it smoke when it's at normal operating temperature? What is it's maximum no load or high idle RPM. That means in neutral at full throttle? What is the maximum engine rpm in forward underway with a clean bottom and a reasonable sea state. Their should no be more than a 10% reduction in RPM between load and no load. Diesel engines have governers
Diesel engines have governors gas engines don't. People that own diesel engines freak out when you race the engine at full rpm in neutral. The engine has a governor to protect it you will never know if your engine is achieving full throttle if you don't check the no load rpm.
Does the engine falter, miss, idle erratically or overheat under load? What is the oil pressure on start up when cold, What is it hot? How is the alternator mounted is it loose is their a belt dust trail on the engine or engine compartment? Does the engine start right up when it's cold? Are their signs of oil and coolant leaks. If you can answer these questions with some degree of certainty you have a good engine if you can't what they people are telling you is most likely true. You'll need to start looking for an engine.

Good Luck

[bsankey448]

OK some time has passed. I bought the boat because things checked out fine with the engine. Now, what is the easiest way to change the oil, how much oil does she take and what kind of filter should I buy?

[lannen]

The first thing you should buy is a shop manual. I used my manual a lot when I still owned the 4-108. They are very easy to fix, parts readily available and the shop manual will answer all of your questions.

Congrats on the purchase, and enjoy the boat!

[bsankey448]

I found a shop manual on line PDF file, but it doesn't tell how to do it that I can find.

[KDH]

Originally Posted by bsankey448

OK some time has passed. I bought the boat because things checked out fine with the engine. Now, what is the easiest way to change the oil, how much oil does she take and what kind of filter should I buy?

From your other post today:You can do the same thing on a 4-108 or at least you can on mine! There is also an old sump entry where once upon a time my engine had a built in pump although it is long gone and capped. I prefer to change through the dipstick. There are a few different models of 4-108 so I suggest you wait until you get there and hopefully the boat will have an owners manual. If you have some pics and want to put them up I'm sure someone on here can help you identify which 4-108 it is. I think it is about 5 qts, could be a bit more ( I always have to look this up in the manual). We use a Fram oil filter, PH2821A. Bought it at Advance Auto parts online but if you are in a rural area (used on tractor engines) they may have it in store.

I also agree you should try to find the workshop manual as I use ours constantly. My copy is from 1968 and even though my boat, and presumably the engine, is mid 1980s the manual seems to correspond with the exception of the heat exchanger.

[SkiprJohn]

Congratulations!
I can't remember how I used to change the oil in my 4-107. It's been such a long time since I had it. Some folks use a pump that has a small tube that goes down the tube where you check the oil. I don't know how effective that is. It seems to me there was a drain plug on the pan but I can't be certain. You want to catch all the oil and not let any go into the bilge if you can help it.
kind regards,

[SkiprJohn]

Did you ever tell us what boat you bought?
kind regards,

[bsankey448]

I bought a 1984 Tayana 37 with 4000 hrs on the engine. Maintenance log looks good. She had excellent care as far as I can tell. I want to change all the fluids just to be sure.

[Irish rambler]

Hi bsankey. The Perkins 4108 is a great engine, parts can be found cheap at any Massey Ferguson tractor dealer. Marinising parts are easy to get from Bowman, UK. If you need spares you can also get them from Parts4engines.com When you have a chance flush out the cooling circuit with a proprietary cleaner and refill with anti-freeze, anti freeze contains a lubricant for the water pump as well as an anti rust agent and will keep the liner seals supple. DON'T let it overheat (over 95/ 100 c )and you can expect it to run for 30 years or more with proper maintainance.
Good luck.

[bsankey448]

I'll try sucking out the oil with my vacuum pump after I heat up the engine. How much oil is going to come out?