I bought a Hunter Legend 45 with a Yanmar 4JHTE about 2 years ago. There was a lot of diesel fuel in the crankcase. Asked around and was told fuel pump bad (leaking diaphram). I replaced it and everything was fine - until this past week. Fuel back in the crankcase. I called Yanmar dealer and they just say bring it in. Has anyone had recurrent fuel pump problems? Are there new additives in the fuel that eat diaphrams now at alarming rates? Could there be another path that so much fuel ends up in the oil? or was this just a coincidental bad pump? who knows? Its only 10 minutes from slip to ocean, so admittedly we don't use the motor for extended times on a regular basis, and usually only at low rpms. I'll put it through the paces more aggressivly once this problem is solved. Incidently it created a runaway engine situation and I was lucky to shut her down by smothering the intake - thank God! Hope no damage. Dan O'side
Diesel Fuel in the crankcase - again!
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Don't take another chance - you're lucky
If you had a runaway engine, you are lucky the engine did not blow the whole crankcase off and damage the sailboat and potentially sink it. The vapors in the crankcase can explode by compression just like on top of the piston. Get it into the engine people before you crank it again. Diesel engines rely on compression and heat of compression to ignite the fuel vapors. Don't take another chance with running the engine until a mechanic looks at it. My two cents worth.
If you had a runaway engine, you are lucky the engine did not blow the whole crankcase off and damage the sailboat and potentially sink it. The vapors in the crankcase can explode by compression just like on top of the piston. Get it into the engine people before you crank it again. Diesel engines rely on compression and heat of compression to ignite the fuel vapors. Don't take another chance with running the engine until a mechanic looks at it. My two cents worth.
srojoe! & Dan
srojoe while I agree that you could get a run away engine, just exactly how does diesel ignite in the crankcase???? It is under atmospheric pressure so it surly does not get pressure ignited like on the other side of the piston. There are no spark or flames from the combustion cycle as they are sealed by the piston rings. Explain the physics to me. For the record a run away engine normally has bad rings that allow oil to escape from the rings (they are pressure feed at the oil (bottom most) ring and the compression rings scrape all but a molecular layer off on the way down the cylinder) and pass into the combustion chamber OR have so much blow by that it gets into the PVC system and the oil is use via the intake manifold. This oil is then burned via the diesel cycle just like any other fuel. It does make a racket as the "injection timing is not what you would want. This "blow by" could be from bad rings or over filling of the crankcase (oil or fuel). This certainly would not cause an explosion in the crankcase has there is a low O2 environment and no compression there. Also for the record to stop a run away engine just stick a wadded up shirt in the intake manifold or wrap it around the air inlet to restrict the air flow. And don't forget to put the throttle to idle first. Dan The only place where fuel and crankcase meet is the fuel pump and the injector pump. The latter being not very suspect as it would manifest as a cylinder that is not getting fuel and "misses" first and as fuel in the crankcase only after a while. It should be an easy task to determine if the fuel pump is leaking again. Just replace it. 2 nipples on the fuel lines and 2 bolts that connect it to the block. Probably a 15 minute operation to replace the FP and 15 more to bleed the lines. You always wanted to have a backup anyway should that not prove to be the culprit.
srojoe while I agree that you could get a run away engine, just exactly how does diesel ignite in the crankcase???? It is under atmospheric pressure so it surly does not get pressure ignited like on the other side of the piston. There are no spark or flames from the combustion cycle as they are sealed by the piston rings. Explain the physics to me. For the record a run away engine normally has bad rings that allow oil to escape from the rings (they are pressure feed at the oil (bottom most) ring and the compression rings scrape all but a molecular layer off on the way down the cylinder) and pass into the combustion chamber OR have so much blow by that it gets into the PVC system and the oil is use via the intake manifold. This oil is then burned via the diesel cycle just like any other fuel. It does make a racket as the "injection timing is not what you would want. This "blow by" could be from bad rings or over filling of the crankcase (oil or fuel). This certainly would not cause an explosion in the crankcase has there is a low O2 environment and no compression there. Also for the record to stop a run away engine just stick a wadded up shirt in the intake manifold or wrap it around the air inlet to restrict the air flow. And don't forget to put the throttle to idle first. Dan The only place where fuel and crankcase meet is the fuel pump and the injector pump. The latter being not very suspect as it would manifest as a cylinder that is not getting fuel and "misses" first and as fuel in the crankcase only after a while. It should be an easy task to determine if the fuel pump is leaking again. Just replace it. 2 nipples on the fuel lines and 2 bolts that connect it to the block. Probably a 15 minute operation to replace the FP and 15 more to bleed the lines. You always wanted to have a backup anyway should that not prove to be the culprit.
To STOP a
run a way, take your trusty fire extinguisher and point it at the air intake. Pull the trigger. Just like it puts out a fire (takes away O2) it will starve the engine of O2. Keep hands and clothing away from the intake. Vinny
run a way, take your trusty fire extinguisher and point it at the air intake. Pull the trigger. Just like it puts out a fire (takes away O2) it will starve the engine of O2. Keep hands and clothing away from the intake. Vinny
NO!!! NO!!! NO!!!!
The powder will fry the engine. It is like introducing sandpaper to the innards of the engine. You will be looking at a TOTAL ENGINE REBUILD. It would probably be cheaper to just buy a new one once you introduce the powder to the intake manifold. It is not going to "suck you into the seventh level of heck" so just restrict the air flow with what ever is handy. Vinny, I have worked on engines for a few years and have actually seen a runaway. It ain't that big a deal and certainly does not warrant destroying the engine.
The powder will fry the engine. It is like introducing sandpaper to the innards of the engine. You will be looking at a TOTAL ENGINE REBUILD. It would probably be cheaper to just buy a new one once you introduce the powder to the intake manifold. It is not going to "suck you into the seventh level of heck" so just restrict the air flow with what ever is handy. Vinny, I have worked on engines for a few years and have actually seen a runaway. It ain't that big a deal and certainly does not warrant destroying the engine.
Diesels and runaway engines
All diesel engines will run on just about any burnable substance that you can get into their combustion chamber. Even coal dust will work but it has to be a lot of it and REALLY finely granulated (powdered sugar is course by comparison) The oil gets into the combustion chamber by some means and the compression cycle ignites it. It ain't pretty as the timing of the explosion is not correct but it is effective at driving the engine. The engine will (typically) start to run rough and increase speed (first warning sign, increased speed WO increased throttle). As the malfunction continues, and this could go on over the course of several hours, the engine will not throttle down and runs at operating RPM even though the throttle is at idle. At this point the engine is running off the "other fuel". Crankcase oil, fuel in the crankcase, kids squirting olive oil onto the air intake, it don't matter, the engine will be completely uncontrollable with the throttle. The only SAFE way to kill the engine is to cut off the air. A CO2 fire extinguisher is ideal. A powder ABC one is going to leave you with a fried engine. FTR most boats don't carry CO2 fire extinguishers. Anything that can keep air from reaching the engine will work, but some solutions are more costly than others. Sticking your hand over the air intake horn of the air cleaner will work but be prepared to do some first aid as the 14.7 psi pressure differential will raise a mean blood blister!!!!
All diesel engines will run on just about any burnable substance that you can get into their combustion chamber. Even coal dust will work but it has to be a lot of it and REALLY finely granulated (powdered sugar is course by comparison) The oil gets into the combustion chamber by some means and the compression cycle ignites it. It ain't pretty as the timing of the explosion is not correct but it is effective at driving the engine. The engine will (typically) start to run rough and increase speed (first warning sign, increased speed WO increased throttle). As the malfunction continues, and this could go on over the course of several hours, the engine will not throttle down and runs at operating RPM even though the throttle is at idle. At this point the engine is running off the "other fuel". Crankcase oil, fuel in the crankcase, kids squirting olive oil onto the air intake, it don't matter, the engine will be completely uncontrollable with the throttle. The only SAFE way to kill the engine is to cut off the air. A CO2 fire extinguisher is ideal. A powder ABC one is going to leave you with a fried engine. FTR most boats don't carry CO2 fire extinguishers. Anything that can keep air from reaching the engine will work, but some solutions are more costly than others. Sticking your hand over the air intake horn of the air cleaner will work but be prepared to do some first aid as the 14.7 psi pressure differential will raise a mean blood blister!!!!
runaway diesel
On a delivery of a Hunter 54 from Miami to the Chesapeak we had a runaway engine when a turbocharger bearing went bad and the lubricating oil to the bearing was sucked into the engine. Tere was considerable exhaust smoke prior to the runaway. I think it is safe to block the air intake with your hand, but if you have a concern you can keep a block of wood in the engine compartment for cutting off the air.
On a delivery of a Hunter 54 from Miami to the Chesapeak we had a runaway engine when a turbocharger bearing went bad and the lubricating oil to the bearing was sucked into the engine. Tere was considerable exhaust smoke prior to the runaway. I think it is safe to block the air intake with your hand, but if you have a concern you can keep a block of wood in the engine compartment for cutting off the air.
Ed & Bill
Ed Your delivery runaway sounds very much like my situation. Where is that turbo bering's lubrication source - the crankcase? How did you determine that's where it recieved its fuel source? Mine started to tach up suddenly while putting up a sudden huge brownish/black plume of smoke. The smoke didn't last too long, and I was able to smother the intake with a beach towel. The rpms dropped and it finally responded to the fuel shut off plunger. In my panic I never recall pulling back on the throttle, I gave the helm to my wife and said head out to sea. Meanwhile I went below to tear apart the engine compartment lids and see what I could do. The smoke didn't last long, and some speculate that an injector tip may have come off and dumped a sudden amout of fuel in, hence causing the overloaded combustion chamber. There was still plenty of fuel in the crankcase to feed from, so I'm thankful that it just shut down once that burst was over (approx. 2-3 min.) Bill, your description seems very much like what happened here as well. I think there were a couple of issues on mine, 1. fuel in the oil, and 2. I was never able to motor beyond 2000 rpms from the start. This was very unusual for my motor. And even at that there was a small amount of black smoke coming out. This may suggest clogged injectors possibly. Could that cause one to suddenly "blow"? Seems there was no governor control once rpms climbed. Thanks, Dan O'side
Ed Your delivery runaway sounds very much like my situation. Where is that turbo bering's lubrication source - the crankcase? How did you determine that's where it recieved its fuel source? Mine started to tach up suddenly while putting up a sudden huge brownish/black plume of smoke. The smoke didn't last too long, and I was able to smother the intake with a beach towel. The rpms dropped and it finally responded to the fuel shut off plunger. In my panic I never recall pulling back on the throttle, I gave the helm to my wife and said head out to sea. Meanwhile I went below to tear apart the engine compartment lids and see what I could do. The smoke didn't last long, and some speculate that an injector tip may have come off and dumped a sudden amout of fuel in, hence causing the overloaded combustion chamber. There was still plenty of fuel in the crankcase to feed from, so I'm thankful that it just shut down once that burst was over (approx. 2-3 min.) Bill, your description seems very much like what happened here as well. I think there were a couple of issues on mine, 1. fuel in the oil, and 2. I was never able to motor beyond 2000 rpms from the start. This was very unusual for my motor. And even at that there was a small amount of black smoke coming out. This may suggest clogged injectors possibly. Could that cause one to suddenly "blow"? Seems there was no governor control once rpms climbed. Thanks, Dan O'side
Shutting down the runaway
For those of you who have an air intake that is hard to get too, Yanmar says its perfectly safe to shut down a runaway with the decompression lever. Food for thought
For those of you who have an air intake that is hard to get too, Yanmar says its perfectly safe to shut down a runaway with the decompression lever. Food for thought
Fuel during a runaway
The fuel is the motor oil that gets sucked into the engine from the oil leak. You don't have to leak diesel fuel to get a runaway. ANYTHING that can burn and is fine enough and in enough quantity can be used as a fuel for a diesel!!! Blow a gasket and it leaks motor oil into the intake and the compression cycle WILL ignite it. Even a smoky fire can provide fuel for a diesel. All lube oil comes from the engine crankcase. My (admittedly uninformed) opinion is that the fuel pump is bad and leaking through the actuator arm hole into the crankcase. These things are cast iron and pot metal and not made very well for a marine environment. A simple inspection of the pump should tell if it is the problem child.
The fuel is the motor oil that gets sucked into the engine from the oil leak. You don't have to leak diesel fuel to get a runaway. ANYTHING that can burn and is fine enough and in enough quantity can be used as a fuel for a diesel!!! Blow a gasket and it leaks motor oil into the intake and the compression cycle WILL ignite it. Even a smoky fire can provide fuel for a diesel. All lube oil comes from the engine crankcase. My (admittedly uninformed) opinion is that the fuel pump is bad and leaking through the actuator arm hole into the crankcase. These things are cast iron and pot metal and not made very well for a marine environment. A simple inspection of the pump should tell if it is the problem child.
Just my opinion, but -
While I am not a diesel mechanic, I know it is possible for the crankcase oil and fuel blowby past worn or broken piston rings to ignite and cause the engine to accelerate uncontrolled. This is why simply shutting off the normal fuel won't stop a runaway, the blow by gases, fuel, crankcase oil can "fuel" a runaway diesel. At my workplace, we have large diesel engines that have a safety shutdown device that monitors the crankcrase pressure and at 1" water column positive pressure, it will shut the fuel racks to the engine. This will only cut off the normal flow of fuel to the engine. The crankcase can become a volume of "fuel" to the engine and will cause it to run until exhausted. The crankcase may be at atmospheric pressure normally, but, as the pistons stroke, it is possible to draw air into the crankcase to provide the O2 for combustion. When we rebuilt one of our diesel engines, one of the largest concerns was that of a ring to not seat properly and allow gasses to blow into the crankcase and potentially cause a runaway condition. I urge caution and if you ever get fuel into your crankcase, make sure you get a mechanic to look at it and get it fixed pronto. I am going to talk to the diesel engine engineer at my workplace about this to help me understand more.
While I am not a diesel mechanic, I know it is possible for the crankcase oil and fuel blowby past worn or broken piston rings to ignite and cause the engine to accelerate uncontrolled. This is why simply shutting off the normal fuel won't stop a runaway, the blow by gases, fuel, crankcase oil can "fuel" a runaway diesel. At my workplace, we have large diesel engines that have a safety shutdown device that monitors the crankcrase pressure and at 1" water column positive pressure, it will shut the fuel racks to the engine. This will only cut off the normal flow of fuel to the engine. The crankcase can become a volume of "fuel" to the engine and will cause it to run until exhausted. The crankcase may be at atmospheric pressure normally, but, as the pistons stroke, it is possible to draw air into the crankcase to provide the O2 for combustion. When we rebuilt one of our diesel engines, one of the largest concerns was that of a ring to not seat properly and allow gasses to blow into the crankcase and potentially cause a runaway condition. I urge caution and if you ever get fuel into your crankcase, make sure you get a mechanic to look at it and get it fixed pronto. I am going to talk to the diesel engine engineer at my workplace about this to help me understand more.
Dan, please post when you find out cause
Dan, it will be most helpful for all to be informed of what you have to repair to keep the fuel out of the crankcase. This forum is very helpful and educational. I enjoy hearing what others think about the topics.
Dan, it will be most helpful for all to be informed of what you have to repair to keep the fuel out of the crankcase. This forum is very helpful and educational. I enjoy hearing what others think about the topics.
You Bet
I'm meeting with a highly recommended mechanic Thursday so we'll see what he finds. I'll be glad to let you all know. Regards, Dan O'side
I'm meeting with a highly recommended mechanic Thursday so we'll see what he finds. I'll be glad to let you all know. Regards, Dan O'side
update- fuel in the oil - The Good, Bad, & Ugly
H45 with 4JHTE Yanmar Bottom line = inconclusive What was done: 1. siphoned old engine oil - replaced with 15w40 @ 6.5 litres, new filter (no evidence of water/coolant in oil) had diesel fuel about 3 inches past high mark 2. Changed both fuel filters - bled system, (primary had crud in the view bowl bottom) 3. Started engine, cracked each injector one at a time while running listened for engine rpm drop. #1 significant drop, #2 slight drop, #3 significant drop, #4 no drop!! 4. Put in gear, accelerated - wouldn't go past 2000 rpm, oil pressure good 5. Pulled and labeled each injector and sent them for bench test (know in a week) All had tips on (good), all were brownish rusty dirty color - ugly) 6. Ordered new low pressure feed pump ($95) I don't trust old one What I found: 1. No change in performance. will wait to see what lab says about injectors 2. I need to have a shut off fuel valve in the front by the filters (mine is a Stalag 13 tunnel crawl to the deepest part of the boat to shut off at tank -bad) 3. Always fill your fuel filters with fuel before installing to aid bleeding 4. Turbo unit spun freely -had some crankcase oil dripping from it(likely from overfill situation through breather) 5. Air intake clear 6. Can't find engine zinc location (Does it have one?) That's about all for now- 2hours @ $80/hr - Good investment on how to bleed - but how do you stop the bleeding??? Dan O'side
H45 with 4JHTE Yanmar Bottom line = inconclusive What was done: 1. siphoned old engine oil - replaced with 15w40 @ 6.5 litres, new filter (no evidence of water/coolant in oil) had diesel fuel about 3 inches past high mark 2. Changed both fuel filters - bled system, (primary had crud in the view bowl bottom) 3. Started engine, cracked each injector one at a time while running listened for engine rpm drop. #1 significant drop, #2 slight drop, #3 significant drop, #4 no drop!! 4. Put in gear, accelerated - wouldn't go past 2000 rpm, oil pressure good 5. Pulled and labeled each injector and sent them for bench test (know in a week) All had tips on (good), all were brownish rusty dirty color - ugly) 6. Ordered new low pressure feed pump ($95) I don't trust old one What I found: 1. No change in performance. will wait to see what lab says about injectors 2. I need to have a shut off fuel valve in the front by the filters (mine is a Stalag 13 tunnel crawl to the deepest part of the boat to shut off at tank -bad) 3. Always fill your fuel filters with fuel before installing to aid bleeding 4. Turbo unit spun freely -had some crankcase oil dripping from it(likely from overfill situation through breather) 5. Air intake clear 6. Can't find engine zinc location (Does it have one?) That's about all for now- 2hours @ $80/hr - Good investment on how to bleed - but how do you stop the bleeding??? Dan O'side
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