HELP! Perkins 4108 problem

[mikesharp]

Our club boat in NW Spain is having engine problems. Apart from fuel bug problems requiring regular doses of bug killer and filter replacements we have an intermitent uncontrolled reving of the engine. Neither the fuel cut-off not the morse will stop it! until it stops of it's own accord.
Has anyone got any ideas and is the diesel bug anything to do with it?

 

[jfkal]

Seems like a sticky limiter to me. Get a service manual and follow the adjustment instructions.

 

[PaulJ]

I had a similar problem years ago with a Petter 5.5hp which proved to be due to over filling of the oil in the sump - when the boat heeled, somehow the oil was being picked up and found it's way into the cylinder and I'm told the engine was burning the oil as a fuel..... It may sound odd but I reduced the oil level and it was ok thereafter - check the oil level before you do anything more expensive.

 

[oldharry]

Could be a number of causes, and for obvious safety reasons it needs to be tracked down:

There could be various faults in the injector pump - a sticking governor being the first that comes to mind - necessitating strip down and repair. If it is emitting black smoke while revving uncontrollably, then this would point to Pump/injector fault.

Is the revving accompanied by white smoke emissions? A large quantity of white or blue white smoke while it is doing it would indicate a mechanical fault in the engine allowing it to run on the sump oil. Causes: blowby due to stuck or worn rings, damaged piston(s). Further pointers would be that it is more prone to runaway when it has been worked hard. Check for oil being fed via the engine breather into the inlet manifold. If oil is present, run the breather to an empty oil can, to catch the ejected oil. A Perkins Prima I am working on was kept running safely like this for quite a while until the engine could be removed for reboring.

Could any onboard Gas supply be leaking into the engine air intakes? Diesels run away very happily on Calor....

The fact that the fuel cut off doesnt stop the engine suggests it is obtaining some combustible fuel from elsewhere and usually this will be either engine oil or Butane/propane.

Whichever way, it needs sorting before the engine damages itself.

 

[mikesharp]

Thanks for the advice. The news from Spain is that white/blue smoke is evident but a recent report on the cylinders suggests that there is another route for the oil supercharging.
Thanks again.

 

[oldjohnnyb]

I found that the engine on Marabu was behaving as follows.
At 2000 rpm with wind on the nose speed 3.5 Knots.
The boat should do 6.0 knots with no wind and a clean bottom.
Lub. Oil consumption was reasonable. The bottom is covered with rather a good growth because the boat overwintered in Shoreham Harbour and was not scrubbed before heading for Spain.
With the wind on the beam and running at 2000 rpm (governor pulling back diesel consumption) lub. oil consumption very low.
When the revs are set ABOVE 2000 rpm again with the wind on the nose lub. oil consumption is high.
Could faulty piston rings be the reason for lub. oil fueling the engine.
Running the engine at lower revs could minimize the problem.
You thoughts gentlemen.

 

[oldharry]

'fraid it does sound like a rings problem - blowby may not necessarily be caused by wear - sticking rings will have the same effect and often does not show up on compression testing.

Oil consumption figures that you mention seem to point that way too. At low speed, blowby is not a problem, but as engine speed rises, the problem increases out of all proportion.

A Perkins Prima I have recently worked on had the same problem; up to around 3krpm virtually no oil consumption, but at 5krpm it lost a litre in 40 minutes! Compressions were normal, and bore wear within specs. Once stripped we found: rings badly stuck on 2 cylinders, and part sticking on a third, and ring gaps which should not have exceeded .56mm, were in the order of 1.5mm! Yet the engine had started and run perfectly - as long as it did not exceed about 3krpm! At high speed it would run away on lube oil. In this case as bore wear was near the upper limit, we did a rebore as well as new rings. The compression appeared good we think because the rings were not scavenging the lube oil from the bores properly, and was creating a sufficient seal to give a false reading.

Now a question: where is the oil going? Because of the high level of compression, it is unusual for any large quantity of oil to be coming up past the rings because of the high - compression. Instead - and this is a symptom you should check for to confirm Blowby - there is a significant increase in crankcase pressure. If the breather(s) are blocked off in a bad case it can actually stop the engine. Stop off all crankcase breathers for 5 seconds, then see if there is a release of pressure when one is re-opened while the engine is still running. Take care as you can blow the oil seals out if you are over -enthusiastic. If there is, you will find at higher speeds the engine will blow the lube out of the breather. If the breather is connected to the air intake - as most are - then that is the cause of the running away. You may be able to arrange to catch the oil in a can until the boat can be bought home, in which case - with great care to avoid oil starvation - the higher revs could be used. Expensive on oil though!

No easy fix except to strip down and find out whats going on.

One other possible thought - is it turbo charged? If so is the turbo leaking oil into the manifold?

 

[pelissima]

Same engine, same problem two years ago, following a tank treatment !!!
I also heard hair rising stories and advices.
what worked for me was a small cup(espresso) of No 10 oil in the tank.
I guess the tank treatment fluids harms the governor, and some oil sets it back.
Rgds

 

[carannah]

Had the same problem with my 4-107. Seems oldharry may have hit the nail on the head so to speak. My engine would use over a litre of oil in approx 2 miles, another time I could travel 22 miles and not use a drop. Engine started with no probs, but I noticed oil on the water surface as I pulled away from my mooring.

I have now stripped the engine and found the two oil control rings on number three sticking ( not totally which may explain why it would use oil on one occassion and not the next). All measurements are within tolerence using a micrometre, vernier and bore gauges except the piston ring gaps, which had twice the allowable limit. I am now in the process of rebuilding and also having the injector pump and injectors overhauled.

Hope you find the problem soon

 

[oldharry]

Yes, the Prima I wrote about did that too - sometimes it could run all day only pushing half a litre out, next day it could empty itself in a couple of hours running.

I reckoned that if the engine ran at low speed for a few hours the rings tended to free up, but as soon as it was driven hard again the blowby would cause carbon build up, jamming some of the rings again

 

[mikesharp]

Re: Perkins 4108 Notice of retirement

Thanks to all who have offered advice. Just returned from northwest Spain and can report that the 4108 has a blow-by on one cylinder that has pressurised the sump and blown the main seals. Hence the symptoms of massive oil leaks and overrunning (from rocker box pressure via breather pipe into air intake). The same cylinder had blown its injector copper washer/seal).
After some 23 years and in excess of 11000 hours of operation, we have decided to retire our old Perkins and when Marabu has limped home a new engine will be fitted.
Again thanks to everyone who contributed.

 

[chippie]

Re: Perkins 4108 Notice of retirement

Have you decided which engine/model you will fit?

 

[mikesharp]

Re: Perkins 4108 Notice of retirement

We are replacing the 4108 with a marinised ford XLD 1.8 diesel . advantages are: good fit with more or less same footprint, slightly more HP, very cheap spares available everywhere we cruise and a favourite of the local experts (Lancing Marine). We may even end up with a hot water supply in the boat (very decadent but some people expect it these days!)