[CrackedHead]

I was on my way to the airport yesterday afternoon in my Logan Diesel and was doing 100-120km/hr on a ring road. Total distance - about 25 km and the car was behaving perfectly throughout.

However, as I slowed down and joined slow moving traffic - the engine started knocking (just like what happens if one drives in high gear at low speed). This happened when down shifted to 2nd gear at a speed of 20km/hr.

Stopped the car and got off to catch my flight. There was a crazy amount of smoke as the car was restarted to be driven away and the engine was quite unresponsive. Asked for the car to be stopped and checked the instument cluster:

• There were no warning lights glowing on the instument cluster.
• The temperature gauge was at the normal position

So then I let the car be driven away and went into the airport. The car was checked out at the nearest known mechanic and parked with the engine off for a half hour.

It started and ran properly afterwards. No engine check light as if nothing ever happened .

The car is only 22K km's old and this is the first time its been causing any trouble. Regular service schedules have been adhered too. Please help me figure out whats wrong. I am not in town and need to sort this out remotely.

My first guess was that the had overheated but the coolant level was upto the mark.

[mayankjha1806]

Originally Posted by CrackedHead

There was a crazy amount of smoke as the car was restarted to be driven away and the engine was quite unresponsive. Asked for the car to be stopped and checked the instument cluster:

• There were no warning lights glowing on the instument cluster.
• The temperature gauge was at the normal position

What was the color of the smoke, Black, White or Blue. Black smoke in Diesels is usually due to air filter being dirty and needs cleaning.

There is an excellent thread on this subject and post by DBHPian @Dadu. Please go through this link.

http://www.team-bhp.com/forum/techni...l-engines.html

[CrackedHead]

Originally Posted by mayankjha1806

What was the color of the smoke, Black, White or Blue. Black smoke in Diesels is usually due to air filter being dirty and needs cleaning.

There is an excellent thread on this subject and post by DBHPian @Dadu. Please go through this link.

http://www.team-bhp.com/forum/techni...l-engines.html

Thanks, the smoke was black. And the engine was also knocking.

I don't know if the filter alone would cause both. Also, things were back to normal after the car was parked briefly.

[Randhawa]

I think it was just the air in the system. Was the noise like metallic knock and the noise suddenly increased followed by loss of power?.

If anything like above then you had a air leak on the injectors, there are rubber pipes attached to it and they can come loose(suck air) or you had less fuel in the tank giving way to air in the fuel line.

[nozzlering]

Air in fuel system will not cause black smoke. It will only cause the engine knock. In this case, I feel the air filters need to be cleaned/ changed. In the given situation, lack of scavenge air will cause the engine to knock (lack of power generated) and black smoke (insufficient amount of air to burn the fuel injected). The car might be running OK. But it wont perform well at high speed or at higher loads (high throttle conditions).

[dhanushs]

My guess is that something might have gotten stuck in the intake during the sprint, starving the engine of air. This has happened before, worth checking out.

Other than that, please go through Dadu's points.

[Aroy]

The black smoke coupled with loss in power points to lack of air, so that the mixture was extremely rich. The probable cause is

. The air filter was partially clogged and at high speed due to extra demand for air a piece broke off and clogged the air inlet. Once the car stopped the piece must have dislodged itself, so you are back to normal.

. Though highly unlikely, there may be a temporary fuel leak which fed the fuel into the air intake, can happen if the fuel pump increases pressure to cater to increased demand. This can happen only if a) the fuel pipe passes near the air intake, b) the fuel pump increases pressure with speed, c) The hole closed itself once the pressure and the temparature went down.

. Least probable - Injector failure at high pressure combined with higher temparature. The injector jammed so that it did not close properly.

I would suggest that you first check the air filter and if it is perfect only then trace the fuel pipe (in case it had a hole, there would be a tell tale oil smudge on the pipe. If all else is OK then check the injectors.

[Sutripta]

Originally Posted by dhanushs

My guess is that something might have gotten stuck in the intake during the sprint, starving the engine of air. This has happened before, worth checking out.

Originally Posted by Aroy

. The air filter was partially clogged and at high speed due to extra demand for air a piece broke off and clogged the air inlet. Once the car stopped the piece must have dislodged itself, so you are back to normal.

Hi,
As a possibility, these rank quite high.

Is the plumbing from the air cleaner soft? Could a dirty air cleaner have caused it to collapse, and later spring back into shape?

Regards
Sutripta

[Jaggu]

Check filter first, if so clean or replace it. Also check all the hoses that connect filter to the intake for any leaks/loose clips. Should be fine, if problem re-occurs then you need to check injector and pumps.

[CrackedHead]

Originally Posted by Randhawa

I think it was just the air in the system. Was the noise like metallic knock and the noise suddenly increased followed by loss of power?.

If anything like above then you had a air leak on the injectors, there are rubber pipes attached to it and they can come loose(suck air) or you had less fuel in the tank giving way to air in the fuel line.

I heard the motor knock one time just before I parked the car (I was driving before I got off). So I thought I was trying to move the car in 4th and checked the gear I was in. So basically - I re-slotted it into 2nd and revved it a bit. Yes, there was loss of power. Pulled onto the kerb within ten meters and I got off.

The tank was half full. Could this be a bad diesel filter (or water in the fuel)? Will get the plumbing checked.

Originally Posted by dhanushs

My guess is that something might have gotten stuck in the intake during the sprint, starving the engine of air. This has happened before, worth checking out.

Other than that, please go through Dadu's points.

Thanks, this was checked for. The filter has been checked and found normal. The problem has not re-occurred.

Originally Posted by Aroy

The black smoke coupled with loss in power points to lack of air, so that the mixture was extremely rich. The probable cause is

. The air filter was partially clogged and at high speed due to extra demand for air a piece broke off and clogged the air inlet. Once the car stopped the piece must have dislodged itself, so you are back to normal.

The filter is 100% intact (no broken pieces).

Originally Posted by Aroy

Trace the fuel pipe (in case it had a hole, there would be a tell tale oil smudge on the pipe. If all else is OK then check the injectors.

Will do. How to check the injectors. Wouldn't a bad one throw up and error code and bring on the check engine light?

Originally Posted by Sutripta

Is the plumbing from the air cleaner soft? Could a dirty air cleaner have caused it to collapse, and later spring back into shape?

Nope. Doesn't seem soft enough to have done something like that.

Originally Posted by Jaggu

Check filter first, if so clean or replace it. Also check all the hoses that connect filter to the intake for any leaks/loose clips. Should be fine, if problem re-occurs then you need to check injector and pumps.

Filter was found to be ok and has been fitted back. How do I get the injector and pump checked? The idea of going to the mahindra service station in a small city like Lucknow to have them troubleshoot a precision component doesn't really excite me

[Jaggu]

Originally Posted by CrackedHead

Filter was found to be ok and has been fitted back. How do I get the injector and pump checked? The idea of going to the mahindra service station in a small city like Lucknow to have them troubleshoot a precision component doesn't really excite me

You can try one of the Bosch center's if you have one near to your location. But M&M dealers should be able to handle since Logan is one of the high volume vehicles.