[mooza]

I have noticed that my engine vibration is very less when cold, but increases when it reaches its stabilised operating temperature. Is this normal ? (when checked at standstill, with only engine running). I just changed the engine mounts a couple of months ago.

The above experience is being felt more in summer, when the stabilised temperature is higher (as seen from the needle on the dash). Is it normal for the stabilised temperature value to be higher in summer, considering that the engine temperature is supposed to be controlled by the thermostat at the same value, regardless of ambient temperature ?

Some feedback on this

[n.devdath]

Originally Posted by mooza

The above experience is being felt more in summer, when the stabilised temperature is higher (as seen from the needle on the dash). Is it normal for the stabilised temperature value to be higher in summer, considering that the engine temperature is supposed to be controlled by the thermostat at the same value, regardless of ambient temperature ?

The operating temperature is independent of the ambient temperature since it is controlled internally by the cooling system. There could be small variation in hotter months due to atmospheric effects but anything significantly higher should be looked into. Check if the radiator fins are clean and are receiving sufficient air alongwith the coolant levels.

Regarding the vibrations, you could check if the mounts have been fitted/tightened properly to the recommended torque values. You could also check the gearbox mounting as it could also lead to vibrations especially in the cabin due to the gear lever vibrating more than normal during idling.

[Rahulk76]

Originally Posted by n.devdath

The operating temperature is independent of the ambient temperature since it is controlled internally by the cooling system. There could be small variation in hotter months due to atmospheric effects but anything significantly higher should be looked into. Check if the radiator fins are clean and are receiving sufficient air alongwith the coolant levels.

Regarding the vibrations, you could check if the mounts have been fitted/tightened properly to the recommended torque values. You could also check the gearbox mounting as it could also lead to vibrations especially in the cabin due to the gear lever vibrating more than normal during idling.

Maybe this might help although told already

New testing innovations increase the accuracy and efficiency of torsional vibration analysis

[mooza]

Thanks Devdath & Rahul, for the replies. I will tell the service centre to check the gearbox mounts as well, when I turn in my Scorpio for servicing in a couple of weeks time.

I was also thinking, since even a slight drop in the stabilised operating temperature is having a good effect on the engine vibrations, whether is it possible for service centres to marginally reduce the thermostat setting, to drop the stabilised temperature just a little bit. Of course, this should only be the last recourse I guess, after checking the mounts and other reasons.

I wish they had provided a green band in the temperature gauge, to indicate whether the temperature is within acceptable limits. This is not there in my Scorp

[n.devdath]

Originally Posted by mooza

I wish they had provided a green band in the temperature gauge, to indicate whether the temperature is within acceptable limits. This is not there in my Scorp

Technically, the entire range of the temp meter other than the red is the safe operating range. Changing the thermostat settings alone will not make the engine run any cooler. It is the design, volume and the capacity of the cooling system that determines how cool or hot an engine runs. The thermostat just helps to kick in the coolant and turn on the fan when required and of course, indicate the engine's temperature to the driver.

[narayanang76]

I guess the problem mentioned here in this thread is probing to a wheel balancing issue, before probing any other reasons such as mounting issues etc. On one earlier postthe thread owner had mentioned that after wheel balancing the problem disappears, but returns back in 500 kms run approx.

I would suggest go to a 'PROPER' wheel balancing center, make sure that ALL the wheels are balanced (reading zero) and also that the weights used for balancing are of good quality and holding to rims properly. When problem returns, please take the wheels again for balancing and see if balancing is 'OFF' again (any weights have fallen off etc), correct them again as need be.

From my experience, before anything for such a kind of vibrations, wheel balancing should be checked and corrected.

Please share your observations and experience if you wish to do so

Regards,
narayanang76

[mooza]

Originally Posted by n.devdath

The thermostat just helps to kick in the coolant and turn on the fan when required and of course, indicate the engine's temperature to the driver.

The thermostat turns on the coolant pump and fan whenever the coolant temperature reaches the upper preset value. The coolant pump/fan gets switched off once the coolant temperature comes down to the lower preset value, thus automatically maintaining the temperature between these two preset values. If it is an adjustable thermostat, then the upper preset value can be lowered a little bit, so that the temperature of the engine gets lowered. The result will be that the coolant pump and fan keep getting switched on more often than usual. If the coolant fan and pump run non stop, then it can be assumed that the design limit of the cooling system has been reached. If not, there is scope for adjustment.

If my assumption is wrong, I welcome any feedback on this from all