[Styler]

Originally Posted by Sutripta

What happened if you turned the "ignition" back on?

Regards
Sutripta

If you turn it back on, the rpm and sound becomes like it is normal idling.
My mechanic's theory here is that the solenoid switch contracts and does not stop the flow of diesel completely.
I was worried because this behavior also happens when the Turbo is leaking oil and this regularly happened before my engine run-away incident and it completely broke down. The difference is that at that time it was happening in Delhi.
I got my turbo checked and there was no oil leak, and this time the phenomena happens only at high altitude and the moment we come down to under 2000 Mtrs everything becomes normal.

[1100D]

Originally Posted by Styler

If you turn it back on, the rpm and sound becomes like it is normal idling.
My mechanic's theory here is that the solenoid switch contracts and does not stop the flow of diesel completely.
I was worried because this behavior also happens when the Turbo is leaking oil and this regularly happened before my engine run-away incident and it completely broke down. The difference is that at that time it was happening in Delhi.
I got my turbo checked and there was no oil leak, and this time the phenomena happens only at high altitude and the moment we come down to under 2000 Mtrs everything becomes normal.

Is there an Ambient temperature aspect to it, rather than the Altitude? Am trying to divert thought towards the injectors.

[Sutripta]

Wondering if something to do with crankcase ventilation. Can't quite figure out the chain of events wrt role of altitude.

Regards
Sutripta

[wrongturn]

Originally Posted by Styler

If you turn it back on, the rpm and sound becomes like it is normal idling.
My mechanic's theory here is that the solenoid switch contracts and does not stop the flow of diesel completely.

The only logical reason I can think of this problem is that at higher altitudes the air is considerably lighter, and the diesel engine only needs fuel and air to run, and the mechanism to switch it off is to block the air supply. Maybe air leaks through the vacuum at higher altitudes and that's what keeps the engine running.

[dhanushs]

Originally Posted by wrongturn

.. and the mechanism to switch it off is to block the air supply. ..

Diesel engine switched off by cutting fuel supply. Not air.

Originally Posted by Styler

...
My mechanic's theory here is that the solenoid switch contracts and does not stop the flow of diesel completely.....

Next time when this happens, try removing the injector lines, any one of them, and see if there is diesel pumped. That way, we can figure out, if this is an engine problem or fuel pump problem.

[wrongturn]

Originally Posted by dhanushs

Diesel engine switched off by cutting fuel supply. Not air.

My mistake, I was trying to relate air and high altitude together as a problem, should have mentioned fuel too. But since the problem occurs at high altitudes only could only think about air density and how that could be related with the issue.
Another couple of views with respect to air density and high altitudes, since this engine was recently rebuilt.

1. In many vehicles, a crankcase breather pipe feeds into the air intake to vent the crankcase. On a highly worn engine, gases can blow past the sides of the pistons and into the crankcase, then carry oil mist from the crankcase into the air intake via the breather.The engine will run on this oil mist, since engine oil has the same energy content as diesel fuel. The engine revolutions increase as this extra fuel is taken in. As a result of increased revolutions more oil mist is forced out of the crankcase and into the engine, and a vicious cycle is created. But this is less likely as it was just rebuilt and let's hope everything is in it's proper place.

2. Engine could have a bad fuel solenoid or bad rings/pvc system. There is a problem with the air pumps for the brake booster with internal leaks keeping oil and vapors in the intake system, allowing run-on.

Just trying to assume that the problem is related to a vacuum leaks, from one component or another which feeds the engine some sort of fuel to keep purring, bearing in mind high altitudes and lighter air density.

[dhanushs]

Originally Posted by wrongturn

.. There is a problem with the air pumps for the brake booster with internal leaks keeping oil and vapors in the intake system, allowing run-on..

Again, in a diesel engine (Scorpio), the brake booster vacuum is generated by a vacuum pump in the alternator, not the intake manifold vacuum like in petrols.

[wrongturn]

Originally Posted by dhanushs

Again, in a diesel engine (Scorpio), the brake booster vacuum is generated by a vacuum pump in the alternator, not the intake manifold vacuum like in petrols.

I stand corrected again. Thanks.
Does that version of Scorpio comes with a High Altitude Compensator. About mHawk I know that ECU has different variables set for different altitudes. But no knowledge about HAC.

Also, as you mentioned about checking the injectors, in what way the functioning of injectors related to variable altitudes. Could you elaborate.

[dhanushs]

Originally Posted by wrongturn

Also, as you mentioned about checking the injectors, in what way the functioning of injectors related to variable altitudes. Could you elaborate.

Removing the injector lines, not injectors, will show if any diesel is being pumped when this condition occurs. That way, one can finalise which part (engine or pump) the problem is. Or its the oil or diesel that is being burnt for the engine to run.

[anupmathur]

Originally Posted by dhanushs

Removing the injector lines, not injectors, will show if any diesel is being pumped when this condition occurs. That way, one can finalise which part (engine or pump) the problem is. Or its the oil or diesel that is being burnt for the engine to run.

You mean removing/opening up high pressure fuel lines while the engine is still idling?!

[Sutripta]

Originally Posted by wrongturn

and the mechanism to switch it off is to block the air supply.

Any examples?

Maybe air leaks through the vacuum

Can't get what is meant

Originally Posted by anupmathur

You mean removing/opening up high pressure fuel lines while the engine is still idling?!

Sure. Done all the time with jerk/ rotary (ie. non CR systems) FIPs.

Regards
Sutripta

[shashanka]

Originally Posted by Styler

If you turn it back on, the rpm and sound becomes like it is normal idling.
My mechanic's theory here is that the solenoid switch contracts and does not stop the flow of diesel completely.
I was worried because this behavior also happens when the Turbo is leaking oil and this regularly happened before my engine run-away incident and it completely broke down. The difference is that at that time it was happening in Delhi.
I got my turbo checked and there was no oil leak, and this time the phenomena happens only at high altitude and the moment we come down to under 2000 Mtrs everything becomes normal.

Your mechanic could well be right, Styler. You have mentioned that you renewed the fuel cut-off solenoid v/v at the time of the engine rebuild. Solenoid v/v issues are too common to dwell on (impurity caught between v/v & seat & not getting cleared with fuel flow, solenoid core not returning to rest position, etc) & it maybe a good idea to get the unit (solenoid & v/v) checked. As we all know an engine does not run on fresh air & love alone! For some reason fuel is reaching the jerk pump & then to the injectors even after switching off. Also as you have clarified the issue is not the same as your earlier experience with a runaway engine (God forbid!), with engine oil reaching the combustion space. So eliminate one source, the solenoid fuel cut-off valve first.

I have my fingers crossed that the problem & its solution is as simple as I'm hoping and not something more profound. Like you, I too belong to the pre-CRDE Scorpio era & love my Bucephalus as much!

[Styler]

Originally Posted by shashanka

Your mechanic could well be right, Styler. You have mentioned that you renewed the fuel cut-off solenoid v/v at the time of the engine rebuild. Solenoid v/v issues are too common to dwell on (impurity caught between v/v & seat & not getting cleared with fuel flow, solenoid core not returning to rest position, etc) & it maybe a good idea to get the unit (solenoid & v/v) checked. As we all know an engine does not run on fresh air & love alone! For some reason fuel is reaching the jerk pump & then to the injectors even after switching off. Also as you have clarified the issue is not the same as your earlier experience with a runaway engine (God forbid!), with engine oil reaching the combustion space. So eliminate one source, the solenoid fuel cut-off valve first.

I have my fingers crossed that the problem & its solution is as simple as I'm hoping and not something more profound. Like you, I too belong to the pre-CRDE Scorpio era & love my Bucephalus as much!

Before my engine runaway this was happening in Delhi and a few days before the engine runaway the Mahindra Authorized Workshop had told me during service that the Turbo was leaking oil. That time it was surely the leaking oil from the Turbo which caused the run-away.

The issue that you miss is that now it is happening only at high altitudes over 2000 mtrs not. As soon as we come down the engine shuts off normally, so it is not the impurity in the solenoid as that would make it happen in Delhi too. There is no way for us to check in Delhi. As a precaution I have got the Turbo checked and it is not leaking oil. Moreover HVK has reported the same has been happening to his scorpio at high altitude without any damaging consequences. I am just not bothering about it too much as long as it is not happening here in Delhi. It's just a few days in the year that I might be at high altitudes anyways.

Styler.

[shashanka]

Originally Posted by Styler

Before my engine runaway this was happening in Delhi and a few days before the engine runaway the Mahindra Authorized Workshop had told me during service that the Turbo was leaking oil. That time it was surely the leaking oil from the Turbo which caused the run-away.
The issue that you miss is that now it is happening only at high altitudes over 2000 mtrs not. As soon as we come down the engine shuts off normally, so it is not the impurity in the solenoid as that would make it happen in Delhi too. There is no way for us to check in Delhi. As a precaution I have got the Turbo checked and it is not leaking oil. Moreover HVK has reported the same has been happening to his scorpio at high altitude without any damaging consequences. I am just not bothering about it too much as long as it is not happening here in Delhi. It's just a few days in the year that I might be at high altitudes anyways.
Styler.

You are right of course - so it is a bigger headache than anticipated. And I'm relieved that it is restricted to high alt. and disappears when you return to Delhi. Gives you more time to work around the problem. I'm going to give it some thought too & ask around - there are a few similar vintage Scorpios here in Lucknow too - & see if any one else has experienced similar symptoms.
Regards,
Shashanka

[shashanka]

Hello Styler, I took the liberty of writing to mahindra's customer care (without any serious expectations, mind you! ) and surprisingly got a very prompt reply. I did not know how to proceed further, so am attaching both - my mail and M&M's reply, in the hope that it just might be of some help in solving the problem you are facing.
Regards,
Shashanka
-------------------------------

Shashanka Choudhury shashach@gmail.com
to: customercare@mahindra.com
date: Sun, Aug 13, 2017 at 12:38 PM
subject: Engine does not shut down after switching off ignition at altitudes above 2000 meters.

Hello,
The above problem is occurring in my friend's 2003 model Scorpio when travelling at above 2000 m altitude (in the hills of HP & UK). When the vehicle returns to the plains, the problem disappears & and the engine stops normally on switching off the ignition.
Would be grateful for advice / suggestion in solving issue.
Regards,
Shashanka Choudhury


CUSTOMERCARE
8:18 AM (5 hours ago)
to me

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