[Zed]

Gents,

Looks like we are going around in circles here. To avoid confusing viewers of this forum I would suggest that we take further discussions off line. Feel free to PM.

1. I have made it clear that im only referring to the topic on hand - i.e engine overheating in a scorpio on account of condenser fan failure. I have no comments regarding issues related to the Indica, zen and accent.

2. @ 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. Although the maximum heat output of the engine is normally at Max power rpm, the ram air effect on account oh higher road speeds (in every gear) neutralizes the situation - hence max torque is the worst case scenario. Im being specific with regards to the Crde engine on the 2005 scorpio.

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.

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. i.e radiator fins are clogged (beyond reasonable levels) or coolant level is low or there is a malfunctioning coolant pump or thermostat.

Any M&M engineers to back me up please ?

[anupmathur]

Originally Posted by Zed

....
2. @ AnupMathur - Contrary to popular perception - ....

Zed, mine is not 'popular' perception; I happen to be a retired Marine engineer!
The point about max torque rpm is true, of course, but not encountered by most of us for any length of time in the real world.
Stop start traffic is an exceptional circumstance for the cooling system and is encountered quite frequently in our cities. The ambient air is very warm due to the heat from all the surrounding traffic; and the engine driven radiator fan is working at its lowest rpm!
There is no mechanism in the Scorpio to detect 'last mile' failure of the condenser fan; i.e. if the connector on the fan motor is burnt out the system 'thinks' everything is still normal and the compressor will NOT cut off. In such a scenario I suspect the engine coolant temperature could begin to rise beyond 'normal'.

At highway speeds the vehicle is unlikely to have any heating problem due to the ram air effect and the fact that the engine driven fan is also working at high revs.

[SS-Traveller]

Originally Posted by Zed

...if the condenser fan fails - the AC compressor gets cut off.

No, it does not. Circuit diagram doesn't indicate that the compressor clutch will release if the condenser fan fuse blows.

Originally Posted by anupmathur

There is no mechanism in the Scorpio to detect 'last mile' failure of the condenser fan; i.e. if the connector on the fan motor is burnt out the system 'thinks' everything is still normal and the compressor will NOT cut off.

True.

[Sutripta]

Originally Posted by 4x4addict

@SS & S

I suppose the S refers to me.

The cooling system has to be designed to control engine temperature without depending on the condensor fan.

You can design (and hopefully implement) anything as long as the laws of physics are not being broken. How do we know what was done?

Do you guys think that Mahindra would design an engine that depended on the condensor fan to control engine temperature?

Your faith will move mountains!

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.

Low pressure protection is left to external circuitry to manage, since the consequences are not potentially dangerous.

Rupture discs, fusible plugs etc because of their use once nature are the last line of defense. Their should be another line of defense before that.

Low pressure means refrigerant has leaked out. Running in such conditions lead to compressor seizures.

Originally Posted by anupmathur

Spike, I don't think our cars have any such external control circuit. There is no LP cut-out that I can see. There seems to be no HP cut-out either!

Best to ask the AC vendor.

Originally Posted by SPIKE ARRESTOR

This value is difficult to generalize as it will depend on a no. of factors. Do you know this value as a 'ball park' figure?
Spike

Eyeball the setup. Work out ratio of cross-sectional areas. Factor in the airflow - pressure drop characteristics of both condenser and radiator. And you'll have a ballpark figure.

[Sutripta]

Mods: Back to back posts, but please do not merge.

Originally Posted by SS-Traveller

And finally, we still haven't arrived at a definite YES or NO answer to Tini's question:

My simple minded reasoning says that failure of the condenser fan while the AC compressor is on will lead to the engine running at a higher temp. Whether that is severe enough to be overheating, or minor enough to be unnoticeable, one cannot armchair theorize without huge amounts of data. Thus my suggestion of experimenting and posting ones observations.

Regards
Sutripta

PS. I don't have a Scorpio. So don't say why don't you do it and let us know!

PPS

WHY can be answered by the automobile engineers among us.

Sorry for gatecrashing!

[SPIKE ARRESTOR]

Originally Posted by SS-Traveller

No, it does not. Circuit diagram doesn't indicate that the compressor clutch will release if the condenser fan fuse blows.

Share please.

Originally Posted by Sutripta

Eyeball the setup. Work out ratio of cross-sectional areas. Factor in the airflow - pressure drop characteristics of both condenser and radiator. And you'll have a ballpark figure.

^^ All those are banal and known facts, this will lead to a figure specific to one vehicle.

I think your question was this vv

Originally Posted by Sutripta

What percentage of air pulled by the mechanical fan does not pass through the condenser?

For a generic figure a lot of samples will need to be considered.

Spike

[Sutripta]

^^^
??
Scorpio specific.

Regards
Sutripta

[SS-Traveller]

Originally Posted by SPIKE ARRESTOR

Share please.

You don't need it, Spike! You consider it to be otherwise?

Also, why sidestep the moot question...?

Originally Posted by SS-Traveller

And finally, we still haven't arrived at a definite YES or NO answer to Tini's question:

Let's hear it from the horse's... err...

M&M engineers

mouth!

[vsun]

Hi All,
My new Mhawk (Run only 1500km till now) is making a screeching sound on initial start up every day. The sound comes for 5 minutes and then goes away (But some times I am noticing the sound is coming (with low intensity) even after 10km drive). The sound resembles the sound coming from an anklet. Day before yesterday I have taken my scorp to authorized dealer workshop and they removed the engine belt and refitted it in reverse direction (As per them, the belt can be fitted in any direction) and assured me that the sound will go away. But there is no difference and the sound is still persisting. I have no other issues with my scorp and the running is smooth and fine. Now I am worried about the sound. Is this a indication for an upcoming Problem? Do I need to go to workshop again and ask them to replace the belt? or wait till first service? any inputs

[SS-Traveller]

Originally Posted by vsun

My new Mhawk (Run only 1500km till now) is making a screeching sound on initial start up every day.
But some times I am noticing the sound is coming (with low intensity) even after 10km drive...
... Is this a indication for an upcoming Problem? Do I need to go to workshop again and ask them to replace the belt? or wait till first service? any inputs

Can be belt / idler pulley bearing failure / automatic belt tensioner not working. Unusual in a new mHawk. Please have this checked out ASAP.

[n.devdath]

Originally Posted by vsun

Hi All,
My new Mhawk (Run only 1500km till now) is making a screeching sound on initial start up every day. The sound comes for 5 minutes and then goes away (But some times I am noticing the sound is coming (with low intensity) even after 10km drive). The sound resembles the sound coming from an anklet. Day before yesterday I have taken my scorp to authorized dealer workshop and they removed the engine belt and refitted it in reverse direction (As per them, the belt can be fitted in any direction) and assured me that the sound will go away. But there is no difference and the sound is still persisting.

Seems to be a belt issue to me at the first sight. Did the ASC check the auto tensioner functioning and the belt condition before fitting it the other way round?

[Aroy]

Originally Posted by SS-Traveller

Can be belt / idler pulley bearing failure / automatic belt tensioner not working. Unusual in a new mHawk. Please have this checked out ASAP.

But the major culprit is normally a slipping belt, especially if the sound goes off after some time. What ever the case, sit on their head and get it rectified as soon as possible.

Never heard of a belt usable after reversing. Curious to know what sort of belt it is, if it is true.

[vsun]

I thank you all (SS-Traveller, n.devdath, Aroy) for your fast inputs.

Originally Posted by SS-Traveller

Can be belt / idler pulley bearing failure / automatic belt tensioner not working. Unusual in a new mHawk. Please have this checked out ASAP.

I will visit ASC within 2 or 3 days.

Originally Posted by n.devdath

Seems to be a belt issue to me at the first sight. Did the ASC check the auto tensioner functioning and the belt condition before fitting it the other way round?

I did not asked this things. ASC guy asked me to wait in the customer lounge and after the work completed, they called me and assured me that the problem is solved. I will ask them to check tensioner and belt condition when I visit ASC again.

[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.

[rjstyles69]

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.

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.