Perkins 4108 runaway.

[avazquez]

My 1984 Perkins 4108 low oil pressure alarm went off on idle and after checking the oil and noticing it was "fine" I replaced the sensor. With the new sensor the alarm went away so I figured it was a bad sensor.

The next day as I was leaving the marina when in reverse and with the main sail up suddenly the engine began to accelerate and white smoke came out of the exhaust. It lasted for 5 to ten seconds. I was able to put it in neutral and shut it down. But the boat ended up on a reach sailing into the marina in a channel with slips on both sides and a concrete wall at the end.

By pure coincidence a friend had seen the whole thing and jumped from another sailboat. As I ran to lower the main he steered the boat and my wife looked after the girls. I was able to lower the sail but of course the boat was slowly moving towards the leeward docks full of boats. We decided to turn on the engine and were able to stop the boat and get enough reverse movement to put it in the slip. But it did runaway again for lets say 10 - 20 seconds intermittently. During the event rpms went up to 3000 but it never overheated. There was about a quart of an oil/fuel mix under the engine. Tracing it it seems like the oil came out of the valve cover cap.
After checking everything out I found that the injection pump was leaking badly into the engine through its main shaft. I removed 2.8 gallons of oil/fuel mix from the engine. Don't ask me why I didn't notice the high level oil in the dipstick. I guess there was so much diesel that the dipstick would drain and by the time I looked there was only fuel in the tip.
Bottomline is that after consulting with the guys at TAD and getting a rebuilt pump. I am ready to install it. I've already removed the injectors so they will be serviced, I will open the valve cover to check the valve clearances and install the injection pump. My concern is that oil came out of the valve cover cap. Is there anything else I should check?


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[sartorst]

You were lucky to be able to get out of gear, depends on the trans type ,and to get it shut down ! It sounds like you have it under control now but just to be safe I would have a piece of hard material close by to plug intake to stop another runaway if needed stay close with the plug until engine has reached operating temp for some time then you should be OK. It's when the engine gets warm that the runaway usually occurs
Don't try to use a towel or something soft it will suck it in the intake and you will have more problems
Monitor you oil level closely over the next few hours to make sure it was the injector pump and not the lift pump

[Pelagic]

Wow, that certainly was a pucker moment.....

I had the same happen to me years ago but luckily in open water.

Lesson I learned from that was to inspect oil levels much more carefully by both touch and smell along the dipstick for any internal diesel leaks.

[avazquez]

Originally Posted by sartorst

You were lucky to be able to get out of gear, depends on the trans type ,and to get it shut down ! It sounds like you have it under control now but just to be safe I would have a piece of hard material close by to plug intake to stop another runaway if needed stay close with the plug until engine has reached operating temp for some time then you should be OK. It's when the engine gets warm that the runaway usually occurs
Don't try to use a towel or something soft it will suck it in the intake and you will have more problems
Monitor you oil level closely over the next few hours to make sure it was the injector pump and not the lift pump

The first thing I checked was the lift pump. It is less than a year old and after disassembly it looked perfect. When I removed the injection pump it was leaking a lot through the main shaft. But I will definitely follow your advice.

[avazquez]

Yes a close oil level inspection every time you go to the boat.

[sartorst]

Because of this very reason when I change oil I fill the oil level to the top line exactly an d afterwards check to make sure it is not (making) oil

[capt-couillon]

All's well that ends well.... Doesn't hurt to send the engine oil off for analyses every now and again. Can warn of impending doom before it all goes pear shaped. Leaking lift pump diaphragm is another good point for fuel to end up in the crankcase.

Just overfilling the crankcase with straight oil can also cause a "runaway" on occasion... Thats what happened with this old Rapp 24 Hp on startup. Ride 'em cowboy!

https://www.youtube.com/watch?v=AG1MnXkHhlM

[Lepke]

It's not uncommon for the injector pump shaft seal to fail and allow fuel into the oil. They fail because of age, dirty oil and water in the fuel or oil. Many pump shafts are mild steel and tend to get rust pits where the seal rubs when exposed to water over time.
Rags in the intake slow the engine to a stop and I've never seen rag damage other than cleaning it out of the intake. An abrupt stop can cause the seals or head gasket to be damaged. I went to a school that had a engine setup to run away. Rags were said to be preferred because as the cloth compressed, over a couple seconds, it slowly stopped the engine. It was undamaged and had run away for many classes. But even when you're prepared for it, it's scary.

[Cheechako]

making oil:
-Lift pump diaphagm? leaking into the sump
-Stuck injector?- spraying raw fuel which goes into sump
-bent pushrod, or pushrod off the rocker?
-Injection pump seal leak?


I have had a pushrod off the rocker and a stuck injector before. It put about 1-1.5 quarts of oil in the sump in 8 hours running.

[avazquez]

Update - I have installed the rebuilt TAD fuel injection pump and engine runs great except for rpm's under load won't go past 2500 rpm. Clean propeller, freely turning shaft, it won't even smoke under load at full throttle. In neutral it revs up to 3800 rpm. In the past with the old pump under the same conditions it would rev up to 3000 rpm under load tied to the dock and black smoke would come out of the exhaust. Any ideas?


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[KrazySailing]

Had the same problem of a runaway 4-108. Local "expert" said bad injector pump. Had the injector pump rebuilt, same problem. Had the injectors tested, one was injecting too much fuel. The UN-burnt fuel was draining into the engine oil (lubricating) sump. This thinned the oil and allowed it splash up into the cylinders and add to the injected fuel causing the engine to runaway.

[avazquez]

Well in my case the pump was leaking a lot from the shaft seal. Now the rebuilt pump wont rev up above 2500 rpm under load.


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[Bill Seal]

Talk to the pump rebuilder, ask them how to increase the max fuel flow or pressure.
When in doubt ask the experts, not some internet keyboard jockys with anecdotal experience (like me).

[avazquez]

Already did. So far only advice was to advance timing. It runs smooth and without smoke but the rpm under loading still persists. Believe it or not this forum has solved many issues in the past.


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[avazquez]

Problem Solved. It was the stop lever. The spring pulling it to the open position was a bit loose. Causing the solenoid cable to pull the lever a bit to the close position. It caused low rpm due to lack of fuel. Thanks Everyone for the valuable input. Lesson: always go after the simple things first. I guess!


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