Perkins 4.108

[cburger]

I have a used Perkins 4.108 that has 5000 hours on it. Came out of a Beneteau sailboat. The engine appeared to be running fine when I purchased it. I actually sea trialed the engine by steaming around with the owner for about an hour in Newport Harbor. With the exception of a couple of issues the motor seemed to run well. I have the motor with an experienced diesel mechanic and wish to have it gone over completely prior to going throught the expense and trouble of installing in my boat in order to insure it runs trouble free for as long as possible. I would appreciate if some of the members can suggest what should be done to service this motor, (Ideally experienced Perkins people). I am planning on doing the the usual: adjust valves, clean heat exchanger tubes, change all filters, new gaskets as required, replace front and rear main seals, new water pump impeller, test and service injectors, bench run motor and perform appropriate diagnostics.

[svHyLyte]

Frankly, if it's already out of the boat, I would go for a complete rebuild as the parts aren't that expensive--bearings, rings, seals, etc and have the head reconditioned etc. If it were going into our boat I'd also replace the injector nozzles--Perkins refer's to them as "atomizers"--have the injection pump rebuilt and sealed, replace the lift pump and water pump's (unless they've been replaced already in recent past--saving the old as spares), replace the mixing elbow (discard the old) check and possibly replace the damper plate, have the starter reconditioned, replace all the hoses and the bellows on the heat exchanger (new thermostat of course).

With the foregoing you'll have an essentially new engine that is very reliable for not all that much money.

FWIW...

s/v HyLyte

PS: With your new installation, I'd also add duel, selectable, Racor FG500 fuel filters and, maybe, a Walker Air-Step. Also ensure that you're pushing enough air into your engine compartment--we have a good sized blower for that together with three 4" dia. flexible exhaust hoses to allow hot air from the "pressurized" engine compartment to escape.

[Tellie]

I'd favour a rebuild as well with a competant rebuilder that will "really" rebuild it and not just bolt in the new parts. It's a few grand well spent.

[SkiprJohn]

If you are the rebuilder I would favor doing a rebuild but if you are going to hire a mechanic to rebuild I'd trade it in for a Yanmar because you'll have a rebuilt leaky, noisy and heavy engine with a rebuilt Perkins.
I personally would do what you suggested in your first post and just install it. It'll last another 10 years or more if you take good care of it and just use it when needed.
Kind regards,
JohnL

[never monday]

Originally Posted by svHyLyte

Frankly, if it's already out of the boat, I would go for a complete rebuild as the parts aren't that expensive--bearings, rings, seals, etc and have the head reconditioned etc. If it were going into our boat I'd also replace the injector nozzles--Perkins refer's to them as "atomizers"--have the injection pump rebuilt and sealed, replace the lift pump and water pump's (unless they've been replaced already in recent past--saving the old as spares), replace the mixing elbow (discard the old) check and possibly replace the damper plate, have the starter reconditioned, replace all the hoses and the bellows on the heat exchanger (new thermostat of course).

With the foregoing you'll have an essentially new engine that is very reliable for not all that much money.

FWIW...

s/v HyLyte

PS: With your new installation, I'd also add duel, selectable, Racor FG500 fuel filters and, maybe, a Walker Air-Step. Also ensure that you're pushing enough air into your engine compartment--we have a good sized blower for that together with three 4" dia. flexible exhaust hoses to allow hot air from the "pressurized" engine compartment to escape.

with 5000hrs on the clock I'd have to agree with the above.
If you choose not to rebuild. Plastigauge the main and rod bearings and replace as necessary. I'd try to leave the head on and pistons in if I could. You have already established it runs well. There for the compression is probably in spec. How easily did it start?

[Stillraining]

cant argue with any of the advice above.

My 2 cents worth...they dont build em like Perkins built them any more..not unheard of to get 10 12K out of them if taken care of.

In my case 4-154 though.( discontinued ).. I could re power for what a complete rebuild would cost..your in a tough spot decition wise..I hate thoes times myself

[funsailthekeys]

TAD can supply a remanfactured 4-108 for around $4500.00 with a warranty. Good price.

[Tellie]

Cburger can always drop it in and do the few minor things he says and cross his fingers and might get lucky and have an engine that runs forever, Perkins 4.108 are great engines. But being penny wise and pound foolish never seems to work in most cases. I'd weigh the installation cost against the rebuild cost. I'd be a bit more than disappointed after going to all the expense of a install just to find out the 2K I saved a month ago just disappeared with having to do it right the second time instead of the first. It's a used engine with no history.

[Boracay]

It only would take one error by your mechanic to cost you many boat bucks.

If you can get a rebuild from a reputable company who specialises in Perkins 4108s then I'd go that way.

Don't forget to milk them dry for all the installation advice that you can get...

[cburger]

I have heard that the 4.108 was originally designed for power generation and rated for 15000 hours before a rebuild was required. The leaking that these engines are renowned for are due to loose tolerances, in theory contributing to the long life of the power plant. That said the motor ran well and started easily, the question was not about anyone's "Opinion" regarding to rebuild or re-power, but was about what individuals who had "Direct experience" with these engines think should be some of the basic issues that are problematic to this motor that should be checked out prior to re-installing.

[Stillraining]

What you said you were going to do to it is about all you can do to it then..as said I have the 4 154 same concept

[Bloodhound]

If this is a replacement for the 4.108 you already have in your W32 then unless the engine in your boat is already kaput, it sounds like you have plenty of time to do a rebuild on the "new" one and have a great engine to swap in when the time comes. But if your current engine is near death then you can swap out now and rebuild the original at your leisure. Great to have a spare engine just waiting to instal.

[sabray]

I had a 4-154 that still runs great and is for sale. I repowered and here is why. To remove the engine in my case requires the disassembling of the edison steering post, removal of the cockpit sole. These both needed rebuilding. Because the bilges were souch a mess from the leaking of the engine the engine had to come out for a rebuild or replacement.I read numerous reports of engines being rebuilt only to leak again. The wiring on the engine and nearby was a mess. Conditions matter and in my case I prefered to have everything new. I bought a cummins from T.A.D.. The cummins was near in profile to the perkins. I performed the work myself which is a consideration but condidering the costs of a yard doing this work the extra costs and the time labor to perform all extras it made sense to me to have an engine with 0 hours brand new. hoses wiring panel etc.. and i know i did not quite answer your question but I faced the same choice and that was my decision. given the cost and labor to rebuild/ remove an engine its nice having the new Cummins very satisfied.

[SkiprJohn]

Aloha CBurger,
My old ketch had a 4-107 (just about exactly the same as a 4-108). It ran fine but there were two problems. The old metal exhaust stack finally gave out and I had it rebuilt for a case of beer and the alternator bracket broke and was not generating appropriate amps until I found the problem (another case of beer). I stalled it twice. Once when a jib sheet wrapped the prop and once when I sucked a fuel tank down to the grit in the bottom. It was almost 20 years old when I sold the boat but still going strong. I would install the engine you have acquired and just be especially careful about clean fuel and clean oil and make certain your exhaust is in good working order and for heavens sake don't over prop it.
Kind regards,
JohnL