Perkins 4108 Run Away and attempts at fixing - help please!

[Cadence]

Originally Posted by zeehag

mine played runaway diesel in 2013, hence the thread bearing name ka lunk. read it.. enjoy it. and enjoy your rebuild.

Did he have a true run away or just a failure to stop? There is a difference.

[zeehag]

Originally Posted by Cadence

Did he have a true run away or just a failure to stop? There is a difference.

exactly. innards of a true runaway no longer look like engine--they look like an erector set town after it was run over by the freight train....

[Cadence]

Originally Posted by zeehag

exactly. innards of a true runaway no longer look like engine--they look like an erector set town after it was run over by the freight train....

The only true runaway I've seen, stopped when a rod came through the block. Hopefully he was lucky, it sound like he was?

[zeehag]

my true runaway was ka lunk.
yes i hope his was not so. they are freaking scary

[captlloyd]

Originally Posted by rmlarson1098

A bit off topic maybe, but as I understand it a true 'runaway' diesel will not stop by shutting off the fuel supply. (?) We carry - but have never used - a 'plug' for the engine air intake. As it was explained to me, in runaway mode the diesel will burn up its own engine oil and destroy itself if not stopped, even after shutting off the fuel supply. A fire is another real possibility. So eliminating air for combustion would be the last solution for getting the beast stopped.
Any motorheads out there want to chime in? Thanks.

“ eliminating air for combustion would be the last solution for getting the beast stopped “. I am thinking first solution.

[Marathon1150]

We have a Perkins 4.108 and it has not run away but we have had a year of interesting experience with injector cleaning/setting and the high pressure pump setting. Much useful info has been provided in the various posts above and I will identify the things that have been important to us. These engines are a "system" and all system components need to be in good running order for the system as a whole to run well.

A number of years ago the high pressure pump failed and filled the bilge with diesel. It was removed by a local mechanic (Vancouver, Canada) and rebuilt in a shop that does these things. It was reinstalled by the same mechanic who botched so many things that I needed to hire a second mechanic to get everything right - including starting the 4108. It then ran well but smoked a bit under load - not unusual when all the diesel doesn't get burned during the compression stroke. It did not occur to me that there might be an issue with the newly rebuilt pump even though the idiot mechanic couldn't get it reinstalled correctly.

While preparing the boat for a Pacific crossing I pulled the injectors and they were sent to a shop in La Paz, Mexico where we were located. They cleaned and adjusted them and they were reinstalled. The engine ran but not as well as previously - basically, it would not run up to the normal maximum RPM underway, particularly into the wind. Unfortunately, we had also swapped the propellor at the same time from a two blade to a Campbell Sailor 3 bladed prop.

Identifying the source of the loss of power problem took a really long time. We started a long series of trial and error approaches to identify the problem - was the new prop over-pitched or was there an issue with the injectors and/or the high pressure pump that was limiting maximum engine power and hence RPM under load?

Ultimately it turned out that:

i. the prop was slightly over-pitched. The supplier in Canada made the necessary adjustments;
ii. pump timing was off because the shop that did the timing assumed the injectors were set correctly, but they weren't; and
iii. the people that did the injectors assumed that the pump timing was correct but it wasn't as a result of the work done in Vancouver 8 or so years earlier.

What we learned:

i. bleeding a 4108 is essential anytime work is done on any component in the fuel system, even changing the secondary filter (the Racor 500 primary is dealt with using a small electric fuel pump to fill it after a filter change);
ii. the relationship between the pump and the injectors is important and each needs to be correct for the engine to work normally and achieve full power;
iii. a well maintained 4108 though somewhat primitive by modern standards (ours is a 1985) is remarkable - it starts instantly even when cold, runs reliably, super smoothly and uses only modest amounts of fuel at the RPM that we normally run at (approx. 1800).

[Compass790]

Originally Posted by skipperpete

The highest vacuum pressure possible is -14.7 psi and depending on the hand I guess that's possible but my engineers kangaroo paws remain intact after several runaway interventions over the years. It takes a leap of faith to do it and I definitely don't suggest you try it but once way back in the days of old time mechanics it was common practice to " palm of hand" choke petrol engines to get them going. I have no idea how much vacuum a runaway engine actually pulls but I know for sure I can stop a 4JH Yanmar at around 4000rpm.

I stopped a turbo equipped front end loader once by putting my hand over air intake that was just idling. It first sucked down a rubber cap on an emergency air intake pipe ( dunno what that did to the turbo) but it felt like my hands were going to go down the air intakes. Had a red ring on both palms, wouldn't have liked to try it at max rpm. Might well be ok but I'd rather use a block of wood.
Would have no hesistation of trying it on our naturally aspirated YSM8 should it decide to runaway

[stewie]

If the correct seals were not used on the injectors, it will leak diesel into the oil

[StoneCrab]

Great thread.
SkipperPete, you did a nice job on the bleed instructions. I have the same engine and hate that manual fuel pump. Since it is attached to the side of the engine, I always wondered if the fuel could get into the block if that diaphragm broke.
I have some heavy equipment with a Deutz engine which is self priming and self bleeding. I run out of fuel a couple of times a year. Fill up the tank and hit the starter and its running. After praying to the 4.108 a few times, I grown to hate that system for bleeding.
It just will not start until it does and most of the time, it doesn't look any different before success than it does before the failed attempts.

[skipperpete]

Originally Posted by StoneCrab

Great thread.

SkipperPete, you did a nice job on the bleed instructions. I have the same engine and hate that manual fuel pump. Since it is attached to the side of the engine, I always wondered if the fuel could get into the block if that diaphragm broke.

I have some heavy equipment with a Deutz engine which is self priming and self bleeding. I run out of fuel a couple of times a year. Fill up the tank and hit the starter and its running. After praying to the 4.108 a few times, I grown to hate that system for bleeding.

It just will not start until it does and most of the time, it doesn't look any different before success than it does before the failed attempts.

If your lift pump diaphragm fails it will definitely allow fuel to leak into the crankcase and contaminate the engine oil but in my experience it happens quite rarely. The pump fitted to the 4-108 has a pesky valve and vane pump at the fuel inlet point that raises the internal case pressure to a level that forces the opposed plungers on the rotary head apart and if that valve or vane pump are a bit tired and worn it makes for a longer cranking period before the start, occasionally a much longer cranking period. Your direct injection Deutz does away with all that and the permanent bleed to tank gives it a huge advantage in the "starting stakes"

[LAGOM]

Don't forget that prolonged or repeated starting attempts can fill your waterlift muffler with water. That water can back into the cylinders.



-Sven

[Ya Ubetcha]

Had the same problem. Luckily we got it shut off quickly. A close examination revealed the rotating fuel shutoff lever was raised up higher than normal. Apparently that allowed ungoverned fuel to flow underneath it. I was able to push it down into place and very nervously travel three hours to a place at a dock where I could remove the fuel injection pump and have it fixed. Expensive fix $750. They replaced worn parts, and assisted in installing it. They say the shaft lever was bent. Now the engine runs much better. Unfortunately that ruined my excuse to remove the engine and replace it with electric drive.

[Sojourner]

Don't have much to add except we bought and carry a CO2 extinguisher for this purpose, to choke a runaway. Think I'll make up a plug for the intake as well, altho it would be a bit scary to hop into the engine room and fish around to plug it during a runaway....

[HNS4vr]

replaced that first, wasn't that. Still working the problem

[oldcal46skipper]

Well 40+ years ago when attending "Marine Diesel Engine Repair" school, all students were required to carry ping pong paddle shaped piece of wood with a rubber pad glued to it. The purpose was to prevent run aways by placing it over the air intake, thus stopping oxygen flow into the engine. We practiced this procedure on running Detroit Diesels, Volvos, Perkins and Mercedes. It works!


As a Fire Fighter for over 30 years, we stopped running diesel engines in damaged vehicles by spraying CO2 into the air intakes of cars, trucks and rail engines. It works!