4108 injection pump question???

[EagleSailTwo]

The Perkins 4108 in my sail boat is original (1977) and with 3400 hours on it, according to it's clock, the engine starts easily and runs very well.

I would like to know if the injection pump on this engine is self lubricating type, or do you need to change it's own oil???

[Alan Wheeler]

Diesel pumps are lubricated and cooled via the fuel flowing through them. So no, there is no other oil in them to change. The bottom end drive of the pump that is connected to the engine is lubricated from the engine oil system.

[Alan Wheeler]

I should add, at 3400hrs, the injectors and pump probably need a service. But as the old saying goes, "if it ain't broke, don't fix it". So unless you are experiancing any issues, I would leave well alone.

[Jon D]

I would actually counter the leave it alone above. Have a 4.236 with about 3000 hours on it. Was running fine before we pulled the injectors and high pressure pump. At the service center they found the pump was failing and would have totally failed shorty and the injectors were not in great shape either. Since the change fuel burn is down and engine runs even better.

[CSY Man]

I get about 500 hours on the injectors from the 4-108.

They are the old fashioned type and can't go 800 to 1000 hours like modern injectors.
Or so they say.

Never had a problem with the injection pump, but I understand an overhaul can be quite expensive.
Crossing meh fingers that it will last a long time.

[ssullivan]

CSYman - what did the injector overhaul cost last time you did it? My 4-108 runs flawlessly (other than a few oil drips around a gasket here or there). I'm not sure where to begin doing any maintenance to it, other than routine stuff. I was going along the lines of what Wheels said - if it ain't broke, don't fix it.

[Jon D]

Sean

Injector overhauls should run about $100 per. the pump overhaul was expensive I don't remember how much. That is a every 2000 hour or so job the injectors should be looked at every 500-1000 depending on who you beleive.

[btrayfors]

Injector pump rebuilds are very expensive, and require very expensive equipment.

I had my 4-108 pump rebuilt in St. Thomas in 1998 by Diesel Power and Injection for $775.78. They did a very nice job, and a very quick one. Met me at the Red Hook Ferry, drove to shop, rebuilt the pump, drove me back to Ferry in the afternoon. Nice folks.

Bill

[CSY Man]

what did the injector overhaul cost last time you did it?

In May this year I paid $60.00 a piece.
Then found them leaking around the big nut (body).
All 4 of them leaked.

Took 'em back to the shop, they tested them and found all 4 to be defective, dripping and drooling instead of a fine spray pattern. (Only 30 hours since last service/overhaul)

Turned out a rookie mechanic had done a bad job on my injectors. After the second servive, which I personally watched, they were good. No smoke, no leak, starts right up, etc.

As for preventive maintenace on the 4-108....

Well, here is what I have done:
Took the starter out and had it overhauled. The shop said I did it in the nick of time as the forward bearing was coming loose.

Also adjusted the valves, found a little slack here and there. I think the book says every 1000 hours...?

I do the 2 zinks every year or so.

Boiled the heat exchanger in acid a couple of times.

Rinsed the cooling system and replaced every hose and hose clamp.
Replaced the thermostat.
Replaced exhaust hose and clamps.
Impeller.
Installed an electric fuel pump. (As a back-up for the lift pump and a "go home" pump, and also for ease of bleeding the engine)
Installed a Racor Vacuum gauge.
New temp transmitter and gauge.

Probably done some more stuff, but the above is what I can remember for now.

Giving lots TLC to my 27 year old engine. To my knowledge is has never been overhauled and needs all the help it can get to reach a really ripe old age and still put out smoke free horsepower.

[Alan Wheeler]

Starting and Smoke are the biggest sign to injector service. But it is surprising just how much of a fuel savign and power increase can also be had from a service,(providing the injectors are worn ofcourse)
A sign of bad injector operation can be hard starting when hot, Black smoke, excessive combustion noise. Signs of a worn pump can be hard starting cold, lack of power. But a worn pump is not always noticable till it fails. The major wear item is the cam. In an inline pump, the cam is much like the engine cam and can be subject to a lot of wear. The other major point is recalibration. The reapir of a pump is not so bad, it ios the calibration that requires special equipment and is what creates the cost. An injector should cost about $80-$120 each to service and calibrate, dependign on what needs to be done. Simple is a clean, and calibration, extreme is a new tip, seat and needle.
The injector system should be considered the "spark plugs" of the Diesel engine and as Spark plugs adn points, they do need servicing at some point.

[EagleSailTwo]

I have never worked on the 4108 engines but know some Mercedes diesels pretty well. I don't know who makes, or made, the injectors for the 4108, but rebuild kits, usually include tip and nozzle, from Bosch are almost always made in India and are inferior to the original German Bosch parts now almost impossible to find!

As a result of inferior Indian injector replacement parts, rebuilds, even from factory, or a knowledged service personnel, rarely function properly, or anywhere near when the injectors were new. Correct pop test pressure (balanced set) and good spray pattern, atomization, are essential for a smooth and easily started diesel.

The lower end of the injection pump on a Ford Leman 120 does need oil changed periodically so I am told, and yes, the diesel fuel will lube the upper end. I use RedLine diesel fuel cetane boost and ip lube in my 300D and now also in the boat and as a result, the cladar clader and or nailing, is minimized and there is more power.

Anybody try bio diesel yet?

[never monday]

Originally Posted by EagleSailTwo

Anybody try bio diesel yet?

I've tried it, I advoate it everywhere I can. BUT don't do it in a boat. We have too much natural rubber in our marine fuel systems.

[SkiprJohn]

Eagle Sail,
Lots of bio diesel articles in "Good Old Boat."
I used to have a 4-107. Lots of hours on it but it ran great, didn't smoke and started everytime.
The only time it was down was when I started messing with the fuel injection pump and I took out one of the screws on the side. It was not a bleed screw and I had a devil of a time rethreading it properly and then had to bleed the whole system.
My best advice is to keep changing oil at the proper times. Check all your hoses, change your fuel filters, keep it clean and don't mess with it until you see symptoms requiring attention. The last Perkins I worked on had a radial fuel injection pump, not an inline.
If you are concerned about a fuel injection pump failing, buy a used one and keep it as a spare.
Last time I had pump rebuilt it was over $800 but it was a Mercedes Bosch.
Kind Regards,
JohnL