Engine problem.

Allan

Allan

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A chap at our club has an engine problem with a Mercruiser D1.7L DTI Alpha diesel engine. A couple of weeks ago it was started and after running for a short while it started to rev madly.Pressing the stop button did nothing. Sump oil was spraying around the front of the engine, After a short time the engine stopped. There was almost no oil left in the sump and now the engine won't start. It turns over OK and there is no apparent pressure in the sump. Mercruiser don't seem too helpfull. Has anyone here have any ideas?
Allan
 
Allan said:
A chap at our club has an engine problem with a Mercruiser D1.7L DTI Alpha diesel engine. A couple of weeks ago it was started and after running for a short while it started to rev madly.Pressing the stop button did nothing. Sump oil was spraying around the front of the engine, After a short time the engine stopped. There was almost no oil left in the sump and now the engine won't start. It turns over OK and there is no apparent pressure in the sump. Mercruiser don't seem too helpfull. Has anyone here have any ideas?
Allan
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I repaired a Ford Transit engine once that allowed the breather to suck all the sump oil through the air filter. This allowed combustion to take place and the engine could not be stopped with the key-it just ran on at high RPM. The hand brake was applied, third gear selected and it was stalled by engaging the clutch. IIRC a diaphragm had ruptured in the breather valve allowing manifold depression to suck the sump oil in. We topped up the oil and fixed the breather with a crisp packet. No spare parts in the old East Germany.......
 
Thanks very much, I had thought of something like that but had a quick look today and could not see a breather. As the air intake is at the back of the engine and the oil seemed to be at the front I don't think it was the case. I've not had much experience with turbos and intercoolers so wondered if this might be where the problem lies.
Allan
 
They may have used diesel treatment but it would probably been Marine 16. I will check. I feel sure it was running off the engine oil somehow, we can't find where from.
Allan
 
Not sure about the fuel pump arrangement on this engine but sometimes a faulty unit can allow fuel to escape into the sump filling it up until the high oil/fuel levels allow overrun. Have you checked if there is any fuel in what remains of the sump oil?
 
This what happens on a diesel lube ran away: http://www.youtube.com/watch?v=5zx3qKX_Pno

Incredible the engine is still running at the end of the vid!

I had a diesel Sherpa with badly worn bores, crankcase pressure would blow oil out through the crankcase breather, which was connected to the air intake. Run it too hard and enough oil would get in to the manifold for the engine to run away for about 15 - 20 seconds. We kept it running by feeding the breather tube to an oil can, then every hour or so, we would just put the oil back in the sump. The engine was near knackered anyway, so we reckoned it didnt matter. Kept the bus on the road for another year though, as it started and ran just fine othewise.!
 
Oil spraying out of the front of the engine suggests that pressure is building in the crankcase. Perhaps a piston or rings have broken allowing gases to pass from the combustion chamber into the crankcase. This in turn could force oil into the other cylinders causing the engine to run away. Perhaps your friend was fortunate that most of the oil sprayed out of the engine thus cutting off the unwanted fuel supply before the engine did any more damage.

I had a piston break in a car engine years ago and the pressure was enough to blow the dipstick out.
 
These engines have a habit of the wastegate getting stuck and over boosting the engine resulting in a hole in one of the pistons - Sadly this is not the only problem these engines suffer from as your friend has found out!
 
I posted on here a while ago about an almost identical problem--except mine didnt run on but dumped the oil, but could be a similar scenario. It turned out to be a blocked air intake--air filter-- this could cause that problem if it damaged the breather seal then it would suck the oil direct to the inlet manifold and run on. I put another independant breather from the rocker cover to a seperate pot to collect any oil that may escape, plus modified the intake, but so far no more trouble. Wish you luck.
 
Allan said:
They may have used diesel treatment but it would probably been Marine 16. I will check. I feel sure it was running off the engine oil somehow, we can't find where from.
Allan
Click to expand...

Possibly from one of the head oilways. I had a similar problem with a Defender which happily roared away burning sump oil with the diesel pump shut down. When I got the head off ther head gasket had completely disintegrated around an oilway allowing oil to be sucked into the chamber.
Luckily the engine ran out of sump oil before it seized.
 
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