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-   -   Diesel Engine Runaway - What it is, and how to stop it (https://www.team-bhp.com/forum/technical-stuff/204960-diesel-engine-runaway-what-how-stop-3.html)

Oops, I have an Ecosport which has run 145k kms so far in 5.5 years. It has been drinking up oil like crazy. Filled in 9 litres so far in 8500 kms. I keep checking oil levels after every 1000kms and top it up. Been busy to take it to the workshop yet. Ford SVC said the turbo has to be changed as there is a small leak and they don't repair Turbo chargers.It emits black smoke as soon as I start the car in the morning. Mileage has dropped to 10-12 kmpl in city with AC always. No problem with pick up or driving in 3 digit speeds, as I mostly use them on highways.

Should I inspect the turbo charger for leaks from a FNG or should I replace the Turbo charger itself.

Any inputs from diesel engine gurus, especially with Ford Diesels.

Thanks in advance.

Damaged rings can also cause such oil consumption. So try to repair turbo from a good workshop outside and if the oil consumption persists, overhaul engine by changing rings alone or by changing pistons also.

Thanks for initiating the educative post.
I was not at all aware of such a behavior from the engine.
Its really horrifying to experience it live and that too you had it twice! :Frustrati
I would have immediately sold off the car after the first experience.

https://www.youtube.com/watch?v=SvSWJynQzI8&t=16sRecently, I had come across a video on youtube, but couldn't fathom what was going on.

Thank you @Dhanushs for the article.

Having suffered a partial engine seizure in my 2009 Punto MJD due to a oil seal leak in the Turbo leading to over heating of the engine and eventually 2 cylinders running dry. I had done all my research on Engine Smoke Colors and then all about Turbos and their seals, I still had no clue as to what Engine Runaway was. This is serious hazard and could happen to anyone.

Having the spouse fill your diesel with the right amount of gasoline is another way to cause a runaway. It is also grounds for immediate divorce in North America.

Thanks Dhanush. Very informative indeed, a true eye opener. Rated 5 stars!

I had experienced 'runaways' with 2 stroke bikes back in the day but never imagined a diesel engine could rev itself to death burning only lube oil.

Well, your engine behavior will then match your handle!

Leaking crank seals?

Regards
Sutripta

Nopes, we were experimenting using 93 Octane and 1 grade 'hotter' spark plugs after shaving the head just a tiny bit for higher compression and better performance from those Yamaha 2 stroke engines, very specifically the twin cylinder RD 350 and the smaller RX 100. The spark plug tip remained hot enough to ignite fuel even after ignition was switched off. The best method to stop the engine was to disconnect the fuel pipe from the carburettors or fuel tank.

^^^
You were lucky. The RDs were famous for holing pistons in the hands of overenthusiastic tuners (or incompetent mechs who did not know how to set ignition timing). Took just a couple of seconds.
BTW, why hotter spark plugs?

Regards
Sutripta

Yep, I've seen pistons failing too. As for ignition timing, those breaker points were a proper PITA requiring adjustments ever so frequently.

As I said before..just experimentation. In the 1980s using "seat-of-the-pants dynos" after attempting to increase compression ratios, higher octane fuel & free flow exhausts, main jets etc. One thing that we had to worry about were the poor brakes on the RD 350 which resulted in accidents, some fatal, of friends and acquaintances.

The RD 350 LC or that monster the RD 500 LC ( (LC - liquid cooled) were even more fun to tweak.

On a tricked machine won't that simply lean out the AFR resulting in detonation that could damage the pistons and rings?

Asking as I recall RD people running hotter machines facing a cracked piston due to improper fuel tap's that restricted flow.

:OT Rings were a minor issue, piston blow outs and seizures were the worry. Either way, any engine running beyond its designed parameters via modifications runs the risk of incuring damage howsoever minor. No fuel meant lower than normal lubrication (it's a 2 stroke) although the 2T oil pump continued to function.

I have the same question as JediKnight - why not press the clutch? The engine is done for anyway but pressing the clutch/shifting to neutral at least helps control the vehicle, no?

All electronics and safety checks done in the software running in the ECM are helpless when thermodynamics takes over. A mechanically governed engine and an electronically governed engine are no different when in a runaway state. The latter would have preventive mechanisms, such as intake cut-off valves to starve the engine of air when the ECM senses an uncommanded increase in RPM. But if these mechanisms fail, then the engine is as dangerous as a mechanically governed engine without any gizmos.

By disengaging the clutch, the engine would not have any load, further increasing the RPM. Remember, higher RPM means more suction and a still further increase in RPM. Beyond a certain point, the mechanicals give way and the engine could disintegrate.

I get the feeling that in this case 'car guys' were fooling around with 2strokes! :)

Regards
Sutripta