[m_upreti]

Originally Posted by sach.sri

hi,

In my Scorpio mHawk (OCt 2010) - i am getting a rattling kind of sound when i stop the vehicle on red lights- basically if i stop the vehicle after running for sometime and also when the clutch is depressed partially.
The ASC people say that this is because of the Start/stop sensor and it makes the engine RPM dip which causes this rattling noise.
They say that this is common for at least 99% mhawks? Is this correct - any of the mHawk owners face this issue?
I personally dont agree with this explanation.

Not a chance. Write to M&M customer care and quote what you have been told by the A.S.S.

[sach.sri]

Originally Posted by rjstyles69

Please ask them if they have been smoking something obnoxiously sedative.I haven't heard of such a thing and never experienced it on my Mhawk.

So i thought - so what can this be?
Anyone - any ideas?

[n.devdath]

Originally Posted by sach.sri

In my Scorpio mHawk (OCt 2010) - i am getting a rattling kind of sound when i stop the vehicle on red lights- basically if i stop the vehicle after running for sometime and also when the clutch is depressed partially.

From what you say, the sound is caused by something rattling at idle rpm/close to idle rpm when the engine vibrations are at their most. It is certainly not the sensor or the engine rattling else it would have fallen off by now.

It sounds like a plastic part somewhere in the cabin or loose end of a metal plate pretty thin. Could you be slightly more specific about:

Where does the sound seem to emanate from?
Does it go away if you rev the engine slightly above idling?
Does it come if the vehicle is moving with the engine off? It should if you go on a bumpy road for a short distance.
Has it increased or decreased over time?

OT: I would recommend you go to Koncept, Noida since I ve been there and they are good bunch of people. If you want a reference, PM me and I will give it to you.

[sach.sri]

Pls see responses inline below.

Originally Posted by n.devdath

From what you say, the sound is caused by something rattling at idle rpm/close to idle rpm when the engine vibrations are at their most. It is certainly not the sensor or the engine rattling else it would have fallen off by now.

It sounds like a plastic part somewhere in the cabin or loose end of a metal plate pretty thin. Could you be slightly more specific about:

Where does the sound seem to emanate from?
>> Cant really say, it does look to be coming from the engine compartment.

Does it go away if you rev the engine slightly above idling?

>>Well, it goes away in 1 or 2 secs, even if the engine is not revved and the car is standing still

Does it come if the vehicle is moving with the engine off? It should if you go on a bumpy road for a short distance.

>> to the best of my knowledge, it does not happen due to bumpy roads, when the car is in motion, i have never observed this noise. Never tested with engine off.

Has it increased or decreased over time?

>> No. It has been the same.

OT: I would recommend you go to Koncept, Noida since I ve been there and they are good bunch of people. If you want a reference, PM me and I will give it to you.

>> I might, if the sterling guys in Gurgaon cannot fix it, only thing is living in Gurgaon, Noida is a long distance off. Will give you a PM if i am taking the case to Koncept. Thanks.

[sudheermenon]

The tyres in my scorpio are MRF Wanderer and I have recently filled Nitrogen in it. The scorpio manual recommends 32 psi on all tyres. But while at the tyre shop one of the guys suggested to reduce the pressure to 30psi. Can anybody suggest what is the optimum air pressure? Its mostly me alone(almost 80%) and rest is with my family of 4 people.

[Styler]

Originally Posted by 4x4addict

@Aroy:

My question is how will the Scorpio Engine overheat due to the condensor fan not working. I understand the issues with the AC, but this whole discussion is about the engine over heating due to condensor fan not working not problems with AC.

I have a 2003 Non-CRDE Scorpio done 85,000 kms. I recall there was only one occasion in the life of my Scorpio when the temperature shot up. It was mid june in Delhi in very high temperatures and stop go traffic. I found out that the Electric Condenser Fan was not working, and had completely jammed.
I turned off the AC and the temp got back to normal.
I remember the ASC quoted 11,000 for the AC Condenser Fan (I could buy a 1 Ton room AC for that money). I just got it replaced from outside and it costed 2000. The problem of heating with AC did not reoccur after that.

I don't know the reasons, but from practical experience I am sure that the Condenser fan failure causes the Engine temperature to rise.

And I can confirm that when the Condenser fan failed the AC did not get cut off automatically.

Styler

[anjan_c2007]

Originally Posted by sudheermenon

The tyres in my scorpio are MRF Wanderer and I have recently filled Nitrogen in it. The scorpio manual recommends 32 psi on all tyres. But while at the tyre shop one of the guys suggested to reduce the pressure to 30psi. Can anybody suggest what is the optimum air pressure? Its mostly me alone(almost 80%) and rest is with my family of 4 people.

I always make it 32 psi for all the tyres.Thats I believe the recommended pressure on the owner's manual.

[shankar.balan]

30PSI is cool when you're mostly alone. you get a slightly softer ride and the tyres bite better on the tarmac.
when driving with a full load of either people or luggage, 32 is best.
the Scorpio behaves very much better under full load conditions - when the load is extremely light it tends to skitter about especially over rumble strips and uneven road surfaces, especially at speeds.

Originally Posted by anjan_c2007

I always make it 32 psi for all the tyres.Thats I believe the recommended pressure on the owner's manual.

[sudheermenon]

Thanks Anjan & Balan.

I think wanderer being very stiff makes the Scorp skitter more. I will try with 30 psi and see how good it is.

[sudheermenon]

Friends, I need the experts help and advise on more topic.

I am planning for a long(very lonnnnng!!) trip from Cochin-Delhi-Amritsar-Rajasthan-Cochin next month. Its a 15 day trip. I need your advise on the following

1. What all precautions should be taken on such long drives for Scorpio?
2. My scorpio has done almost 12000kms and I dont think it would be ready for the 15K service by the time I start my trip. I plan to give the car for service one week before my trip. What all checkups should be done before the trip?

Please help. If any one of you has a check list for scorpio for such drives please let me have it.

Thanks

[moinakg]

Originally Posted by sach.sri

So i thought - so what can this be?
Anyone - any ideas?

Do you see a drop in RPM to below 1K ?
If yes then get your clutch switch checked/replaced. I had a similar issue at 5K Kms just before first service without the rattle though. The engine RPM would momentarily drop below 1K RPM upon depressing the clutch and it would vibrate before settling down. I also had problems with the start/stop mechanism behaving weirdly occasionally. ASC found the clutch switch defective and replaced it under warranty during first service and all is well now.

Originally Posted by sach.sri

hi,
The ASC people say that this is because of the Start/stop sensor and it makes the engine RPM dip which causes this rattling noise.
They say that this is common for at least 99% mhawks? Is this correct - any of the mHawk owners face this issue?
I personally dont agree with this explanation.

They are speaking Bull.

[SPIKE ARRESTOR]

Originally Posted by Zed

1. The coolant will not overheat on account of the electric fan not working (or failing) since the visco fan takes care of airflow through radiator.

Not necessary, depends on the prevailing "conditions" (external as well as internal).

2. Therefore the AC compressor 'cut-out' would be the first noticeable effect (in stop go traffic) if there is an electric fan failure since the AC condenser will be dependant on the electric fan on account of nil ram air.

Compressor will cut off and cut in due to the change in pressure within the AC circuit.

Originally Posted by SS-Traveller

That there's no way a car can overheat if the electric fan does not work?

There are chances it will overheat, all depends on the "conditions".

Originally Posted by Zed

Most R-WD vehicles - Sumo, Scorpio, Xylo, Qualis, Innova (and also some of the premium SUVs ) have an engine powered fan normally with a viscous coupling to regulate fan speeds. In any of these vehicles you can take the electric fan out and even at max ambient limit ( 45 Deg C ) the engine will not overheat - as long as the cooling system components are in working order (thermostat, coolant pump, no cavitation \ fin damage in raditor and correct coolant level).

To make my point clearer - the Innova has no electric fan. The visco fan also doubles up as the condenser fan - this is achieved by a combining radiator design \ layout with an appropriate fan diameter and visco clutch setting.

Point valid up to an extent but not necessary.

Originally Posted by 4x4addict

Electric fan is not redundant, but as Zed points out it is for cooling the condenser/AC gas and not for the engine per se. As you can see many people are running Thar CRDe with condenser without the additional electric fan for the condenser without any heating issues. AC will be more effective with the electric condenser fan.

Ok, you got a point.

In one of earlier SUV which was black in color, I felt the AC was ineffective on very hot days. On diagnosis, I found that the wiring harness for the dual condensor fans had shorted and the condensor fan was not working. Only the radiator fan was working. I never had any heating issues, but only less efficient cooling of Ac.

Ok.

There is absolutely direct heat exhange between the AC cooling system and engine cooling system. AC compressor adds some more load on the engine, but that additional load of the AC compressor shouldn't cause the engine to heat in modern powerful engines. This may have been the case for older wheezier diesel engines.

Agree, but not necessary.

Originally Posted by 4x4addict

@spike:

Query is "If condenser fan fails, will the Scorpio engine over heat?"

You were referring specifically to Scorpio, which I missed in my earlier post and interpreted it as a generic query. The answer cannot be a simple 'Yes' or 'No'.

Originally Posted by Aroy

. Extra load of AC on the engine, when you are stationary
. Heat leaking from condenser to radiator. but normally with a fan coupled to the engine, the fan is also rotating slower thus pumping in less air, and that coupled with extra heat load passed on by the condenser will present a higher load on the radiator,

These are some of the conditions. ^^

Originally Posted by Zed

The radiator fan has to clear the cooling requirements of a given vehicle - which is basically the vehicle running at max operating ambient, with full load (perhaps even an overload factor) and the engine running continuously at the max torque and max power rpms.

What air speeds (general) are we looking at when we compare Radiator and Condenser fans?

If the AC condenser fan malfunctions, the AC compressor gets disengaged and hence the question of the AC condenser reaching inordinately high temperatures does not arise.

Are you sure on this?

Originally Posted by SPIKE ARRESTOR

No

Depending on the "conditions". I should have elaborated more on why 'No' and when "Yes'.

Originally Posted by 4x4addict

@SS & S

Do you guys think that Mahindra would design an engine that depended on the condensor fan to control engine temperature? The cooling system has to be designed to control engine temperature without depending on the condensor fan.

Lol, thinking about what all I have seen, this had me laughing.

Originally Posted by anupmathur

AFAIK, every AC compressor has an internal high pressure protection built in. This could be a pressure relief valve or a bursting disc. In the event of impermissible pressure being built up the discharge port is shorted to the suction port or the crankcase.
It is industry practice to not depend on external wiring and circuitry to prevent dangerously high pressures.

There is a twist to this, I am eagerly awaiting to see the Compressor drawings before commenting on this any further. Will update once I get concrete info.

Originally Posted by Zed

Remember that the temp gauge has a dead zone - ie from starting point to about 60 or 65 deg - the sensitivity \ accuracy is very low and from 80 - 100 the sensitivity is high. This is by design.

Hmm. You know this, good.

Originally Posted by SS-Traveller

I wonder if Spike would be so forthright with his answer to Tini's question...

Well if you ask a generic question it will be 'No' but if it is specific to Scorpio it will have a tendency to overheat / go beyond normal operating temperatures at certain conditions, otherwise it will be operating in safe zone despite condenser failure.

I was talking to one of my friends who is also a Vehicle Test Engineer (Cooling system specialist). He has tested some of these in India and abroad. He tells me that newer ones behave satisfactorily even with a disconnected / removed Condenser fan, only when the ambient is severe the problems begin to arise. The ambient he is referring to is ~ 55 found in regions of Rajasthan (where these vehicles are mostly tested for cooling performance in India).

Originally Posted by Zed

T

The condenser fan is responsible for reacting to cooling demand from the HVAC system and keeps the condenser at the right temperature. It is certainly not redundant. However it does not play a role in the engine thermal management loop.

Yes,

Originally Posted by Zed

@ AnupMathur - Contrary to popular perception - Start stop traffic (even at high ambient) does not represent the worst case scenario for engine cooling. The worst case scenario is when the engine runs at max torque rpm, with max load at maximum operating ambient temperature. Im being specific with regards to the Crde engine on the 2005 scorpio.

Why 2005 Crde Scorpio only?

It is the job of the primary radiator cooling fan to keep the coolant temperature within a certain 'rise over ambient' limit during the cooling trials (Part of vehicle validation). The cooling trial involves not just the vehicle under full load but also a second vehicle (wiht its brakes partly depressed) to create the 'max torque' situation. The AC condenser fan plays no role in the cooling test.

You seem to know a few things about cooling trials. It would be great if you could share something on Cooling system performance tests like what all tests are done, what is the acceptance criteria etc. I am asking you specifically because the importance of the words in bold (above) are mostly known to people who have either conducted or witnessed the cooling 'trials'.

Just to repeat what was mentioned in an earlier post - if the condenser fan fails - the AC compressor gets cut off. There is no way a scorpio can overheat on account of a condenser fan failure - UNLESS the cooling system is not in good shape in the vehicle we are talking about.

Well, actually there is a way. What if the Compressor is still engaged (cut in / cut off happening due to pressure surge)?

Any M&M engineers to back me up please ?

Not one, but agree to some of the things mentioned by you (especially that word, which brought back some old memories).

Originally Posted by Sutripta

^^^
??
Scorpio specific.

Don't have that data, but can manipulate from things available with me. Not needed here anyway.

Originally Posted by SS-Traveller

Also, why sidestep the moot question...?

No sidestepping. I prefer to stay away when posts turn towards 'impugning' route. I was also away (literally) for some time.

Originally Posted by Styler

I have a 2003 Non-CRDE Scorpio done 85,000 kms. ------

Interesting point but things have come a long way since 2003. Right from Radiator, Pump, Condenser, Lubricants, Fans, Instrument gauges etc.

So, to sum it up-

Will any car overheat if condenser fan fails? No / Yes (depending on the prevailing conditions and vehicle configuration)

Will Scorpio overheat if condenser fan fails? No (favorable conditions) / Yes (severe ambient conditions and Compressor in action for prolonged times).

I hope this makes things clearer.

Spike

[Zed]

@ Spike Arrestor
I was only trying to clear the misunderstanding that the condenser fan plays some part in radiator (engine) cooling. I kept referring to the 05' scorpio as some of the replies meandered into indica vistas and other pascar overheating scenarios and I wanted to keep my replies specific as my understanding of pascar engine cooling is limited.
I was under the impression a failed condenser fan resulting in ineffective cooling of the condenser would trigger the compressor to shut off. If this is not the case and the condenser continued to run the additional heat load would certainly add a few degrees to the engine coolant since the high air off condenser temp would hinder radiator cooling. At the same time the scorpios radiator system is pressurized (close to about 1 bar if I recall ) and the coolant will not 'boil' upto 110 deg C or so.

Hence with the increase thermal load on account of a kaput condenser fan & the resultant rise in the coolant temp being 10 - 15 deg C over normal (around 85 -90 deg C as far as I recall) , the engine will run just fine even if the temp gauge is in the red zone. I guess things start to go bad between 115 - 120 Deg C with the hoses and other accessories.

I was involved in the technical side of the automotive business but at a certain point in my career realized that dealing with people was equally or perhaps more challenging than dealing with machines. While machines can have a mind of their own atleast they dont have an opinion or talk back ... well with the advent of SIRI theyve already started I suppose. I crossed over to the dark side and am now in the sales & marketing domain.

[n.devdath]

Originally Posted by sudheermenon

I am planning for a long(very lonnnnng!!) trip from Cochin-Delhi-Amritsar-Rajasthan-Cochin next month. Its a 15 day trip. I need your advise on the following

1. What all precautions should be taken on such long drives for Scorpio?
2. My scorpio has done almost 12000kms and I dont think it would be ready for the 15K service by the time I start my trip. I plan to give the car for service one week before my trip. What all checkups should be done before the trip?

A small list of things that I would recommend to keep in your truck are:
1. A set of spare fuses.
2. A set of spare bulbs.
3. A set of belts.
4. Some new engine oil, say about a liter.
5. A bottle of coolant.
6. A tow rope with shackles.
7. An effective puncture repair kit, a foot/electric pump and a good tire lever and jack.
8. All vehicle papers and your DL in original and a couple of photocopies at different places.
9. A strip of yellow tape on your right headlamp's right corner running from top to bottom of the headlight.
10. A diesel can, funnel and pipe about a metre long.

You will end up using none of what I ve mentioned yet, if required these things are of immense help at times.

Your car is new so you need not worry about anything in it as long as there are no niggling issues already. Get your regular service done, get your wheels aligned, balanced since it will increase tire life, check all fluids and drive off.

You will reach your destination and back home before you know it.
Bon Voyage.

OT: I am driving from Blore to Delhi on the 25th so we might catch up in Delhi or elsewhere if you are in those parts in the initial December weeks.

[sudheermenon]

@n.devdath, thanks a lot for your response.

I would be starting from Cochin only by 18th and reaching Delhi only by 22nd. If you would be available in Delhi at that time we can meet for sure. Anyways wish you both good luck.