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Automotive Column 36 Engine Has Noise

Automotive Column 36 Engine Has Noise

Syndicated Newspaper Column

If you have noise that only occurs when something is turned on make sure you write down the precise details of the occurrence. This information can be invaluable to a repair shop and save you money.



Daily Car Repair and Advice Tips Question 36 A/C Tensioner Rattle

Dear Motor Medics,
 I really enjoy your radio show which I listen to via iTunes podcast. My wife drives a 2002 Chevrolet Tahoe 2WD with a 4.8 liter Vortec engine and 117k miles. The A/C tensioner pulley on the passenger side front bottom of the engine has been banging on the transmission cooler lines at the bottom of the radiator when the A/C was on and the engine under load. I thought maybe the bearings may be bad so I replaced the assembly but that didn't fix it. The belt is not very old so I don’t suspect that. I recharged the A/C system with refrigerant and the belt still pulls the A/C tensioner down into the transmission cooler lines when under load but only when the A/C is on. Any advice you can give me is greatly appreciated.

Casey T in Huntsville Alabama

Dear Casey,
 Start by checking the A/C compressor by using both high and low pressure gauges. I suspect you may find you have a blown A/C compressor head gasket which causes fluctuations in the low and high pressures resulting in changing loads making the tensioner act this way. I have seen this situation more than a dozen times in our shop. This is often caused by improper charging or a failed fan clutch which has caused A/C system overheating so check the fan clutch as well. When you charge the system adding refrigerant too fast can cause this as well so be careful.

Take care, The Motor Medics
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Advice given by the Motor Medics is for entertainment only. Each problem is different and requires different approaches and answers given here are opinions and just one possibility. Always follow all recommended safety procedures and consult with your own qualified technician before attempting repairs of any kind.

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