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Thread Title:

Perkins 4-108; engine life span?

Created On Monday March 31, 2003 20:36

dalger

Posts: 1
Joined: Mar 2003

Monday March 31, 2003 20:36

I have a 4-108 in my 37' sailboat. It is an original installation and is now 20 years old and has accumulated 2,900 hours. I have owned it only for 6 months, there are 2 previous owners. The previous owner had the boat for 15 years and while I would not call him meticulous, he appeared to be fairly diligent about maintenance. The engine is fresh water cooled and has a Racor fuel filter.

In the time I have operated it (about 30 hours) it seems to be running fine and not burning oil. When the temperature is at or near freezing, it is a little hard to start (no glow plugs or pre-heater).

Before I bought the boat, I had the engine inspected by a marine diesel mechanic. He did a cold start and a basic inspection spending about 1 hour. No compression test or other diagnostic involving disassembly etc. He felt the engine was fine and his only recommendation was for an oil analysis and the replacement of a coolant hose. Is the oil analysis a good idea? I have not done it yet.

Aside from the accessories, what should I be concerned about for an engine this old? Is it nearing the end of its useful life? Since it is an auxiliary engine (in theory, sailboats sail!), it does not see a lot of use but I'm careful not to let it "sit" too long. Can I reasonably expect another 1 to 2 thousand hours before having to overhaul the long block? A year from now, we are planning to sail the boat to the South Pacific and will be away for up to 3 years. I expect the trip to add about 1,000 hours to the engine time. Are there some diagnostic checks to the engine I should have completed before such a trip?
Any advice or past experience with these engines would be most appreciated!

-------------------------
Sailboat guy

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Surveyor

Posts: 4
Joined: Aug 2003

Wednesday August 20, 2003 22:27

Aloha,
Did 30K on a 41" ketch with a 4-108, bought the boat with 450 hrs sold it 14 years later with 1600 hrs. Filled the engine with saltwater in LaPaz Mexico from worn out exhaust injection, let it sit to long on the hard in the south pacific and rusted/bent a pushrod. Faithfully changed the oil, strained the fuel and kept the rust down. Had more trouble by not running the thing. Class I took 20 years ago said you could get 15k to 20k hrs before rebuild, that would make me a 100 and something years old and I don't know how many miles on the boat. Run the thing lots and when you get into the tropics put in a vent fan for intake ( engine is spec'd out at 70deg F for max efficeincy, engine room temp in tropics is +140F?) Run it for more than an hour to vaporize the condensation that forms. The power curve will probably never let you get all the HP out of it and it's continuieous duty at 80%. Bring gaskets, Perkins are leakey and noisy but seem to last forever. My wife say's we could a made shorter passages if I would of ran it more, sound proof the thing. So as an ex porsche mechanic, a low tech, sloppy clearance, and iron block engine, I'm sold. Plus, you can get parts everywhere.

-------------------------
Robert J. Dupuis

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scuba

Posts: 2
Joined: Oct 2003

Thursday October 16, 2003 03:55
Good morning, Perkins engines are very reliable i rebuild and sell parts and have been doing so for many years if the engine is looked after you should not have problems. the 4108 is quite easy to get spares for and i carry such parts. see my website at eepottsltd.com regards Eddie ------------------------- eddiepottsltd

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greasyfingers

Posts: 2
Joined: Feb 2004

Friday February 27, 2004 14:17

Dear Sailboat Guy-

I might add my 2 cents worth here, as I thought I had at least 8,000 more hours to go on the Perkins 4.108 that is now seized up in my 38' Seafarer. I offer two things to watch for, as I suffered both, the last of which did it in last week.

1) Be sure your oil lines are in good condition if they run external to the engine to and from the filter. Also- add an automatic shutdown or unmistakable alarm to warn of low oil pressure. When a line blows, you will probably not be looking at the gages, and the pressure is gone in a matter of seconds. I was on my way to the Bahamas when mine blew. The engine slowed a bit and then the cabin sole began jumping up and down with some God-awful pounding before I could get it shut down. The only good part is that I was only 40 miles from home (FL west coast) when it happened and I was able to sail most of the way back. I thought the engine was toast, but when I replaced the oil lines and changed the oil a couple times, the thing seemed to be OK with 60 pounds of pressure and no knocks other than the usual racket.

2) The second episode was due partly to what I consider a design weakness and partly due to my hurried maintenance in preparation for a 5 day trip. The raw water pump on my engine is driven off the end of the camshaft. The end of the pump is directly coupled to the block. The only thing between the inards of the block and the salt water in the pump is a small rubber seal running on the water pump shaft and two sealed bearings. There is a weep hole between the two to supposedly let water out before it gets to the sealed bearings. The sealed bearings MUST be installed with sealant (Permatex #2 or such). The things that got me were:

a) I installed a new Stainless Steel and Rubber seal, but the shaft itself was worn enough that water got by it.
b) I didn't bed the bearings in enough sealant to prevent water getting around them.

The result of all this was that salt water slowly got by the bearings over 4 hours of running until the oil thickened to an almost grease like consistency. I was looking at the oil pressure when it seized. It was normal, but must have been so thick it wasn't going anywhere.

So now I am pondering how to attack the rebuild. I am open to suggestions from others here, as I haven't rebuilt a diesel before and I am contemplating doing it in the boat if the cylinders are OK. I should be able to do the bearings after I get up it out of the bilge and onto the main cabin sole (protected by plywood).

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greasyfingers

Posts: 2
Joined: Feb 2004

Wednesday March 17, 2004 23:29

I thought I would update my last reply to the engine life question. It appears that neither of the previous episodes contributed to my engine's demise, unless it was the pounding that occured when I lost oil pressure on the aborted trip to the Bahamas. After it recently seized, I built a "gallows" in the boat so I could pull the engine up out of it's mounts beneath the cabin sole in my Seafarer 38. I disassembled it in the boat and found the top half of a connecting rod bearing cap in the oil pan. The tapping that I heard about a half hour's running before it seized was the cap flapping until it pounded the bearing enough that it spun and jammed. I thought the tapping noise was valve noise. It was not a knock. The oil in the pan was quite fluid and the other rod bearings are fine. Anyway, I was contemplating just grinding the crank and replacing the bearings, but the big end of the rod is a bit scored up so I may have to pull the head and replace the rod as well. By that time I might as well do all the rings too, and by that time I may just swap in a short block instead. That's where I am now. So one never knows for sure how many hours are left.

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Surveyor

Posts: 4
Joined: Aug 2003

Friday April 02, 2004 19:53
Aloha, If you have not already done it, get the short block and make it easy on yourself. It's an easy engine to do but much easier to just bolt in, unless you want the experience! Perkins, takes a licking and keeps on CLANKING! ------------------------- Robert J. Dupuis

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TengoMar

Posts: 1
Joined: Aug 2004

Friday August 06, 2004 11:01

The 4-108 has a good reputation for long life if properly cared for..... What about a 4-108 that has sat for several years? Is there any hope? Any suggestions for initial start-up after such a long period?

I would start by a complete engine flushing....oil...coolant. Pull the valve cover and make sure everything is free and oiled. Next I would pull all injectors and service. Liberally WD-40 all cylinders. Flush fuel lines, replase filters, flush fuel tank. With injectors removed... manually crank engine a couple revolutions checking valve adjustments. Continue as required to bleed fuel lines, connect injectors and verify operation. If I can find a pressure gauge I'll check cyl pressure. Finally, cross my fingers and see if it will run.

Anything else I should do or check for?

Thanks

Have Ocean...

-------------------------
connections

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joelas

Posts: 3
Joined: Dec 2007

Friday December 21, 2007 20:39

Regarding sieze up, I have had 4 on 2 engines. 2 were the crankshaft pulley coming off due to the bolt coming loose causing over heating. The manual gives 3 different torques for the bolts, all high and hard to do. Besides oil leaks out around the bolt head. So I designed and made a 12 point socket with a flange and slotted holes to fit over the bolt head a bolted it to the pulley. It is a machine shop job, but you only have to take the pulley and bolt to the shop. also I put instant gasket betwen the bolt, washer and pulley to stop leaks. Another, I had added an oil pressure warning switch using brass NPT nipples and a T before the oil pressure sender. The pipe threads broke and I lost the oil. So now I have put the sender switch directly in a galley hole. The other was not tightening the drain plug enough on partial overhaul. Solution obvious. This engine is so easy to overhaul, if you have the factory manual, that you and the usual auto mechanics should be able to do it. Checking wear tolerances and machine work goes out to a specialized shop, the rest is straight forward with carefully reading the manual and care. On one engine I found that a piece of the sea water pump coupling had broken off and went between the timing gears and broke off a tooth, displaced the idler gear and wore the gears substantially, but it was still running OK. I suppose the engines have 1000-2000 hours, Each time for 3, I honed the cylinders lightly and put in new rings and bearings as wear was minimal. The 4th, I let it cool down, put the pulley back, refilled oil and water, started up and has about 500 hours since, although it is slow to start and oil consumption or leaks is high. I suppose I will soon need replace rings as the oil pressure is high. I take the head, flywheel, mounts, and accessories off in place in the boat in the boat to lighten it. Then 4 small men can just lift it right out, take it ashore, and work on it in a convenient shop. I have also had the exhaust gaskets fail on both engines smoking up the whole area. The aluminum surfaces had corroded loosening the seal. They had to be resurfaced in a machine shop. If had had the emergency warnings in place in time they would have saved 3 out 4 tear downs. They should be standard as often the boat is on autopilot and no one watching gauges.

-------------------------
joelas

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