How long does the poly V belt last?
I have a 1998 E430.
There appears to be no cracks but I was curious as to how long these belts last and if I should change it preventively.

thanks.

I don't know much about the V-8, but on a 103 engine, I last replaced mine on Wednesday, Oct 20th 1993 (according to my maintenance/repair records)

Mine was replaced after 8 years, still looking good; the only reason I replaced it then was I was replacing the water pump anyway.

The maintenance manual has a good description of what to look for. No need to prophylactically replace the belt -- just do the visual inspection as detailed in the maintenance manual, and you should pick up any signs of wear long before it breaks.

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Steve
'93 400E

These belts are very long lived. Degradation is a function of time at temperature, so lots of low speed traffic in hot weather probably means less life than highway speed in cool weather.

The maintenance schedule for my car calls for an inspection at the 30K maintenance interval, but no specified change interval. It's good until it fails inspection. I ordered the belt replaced just before 50K miles circa 1992 when the water pump was replaced on warranty (only cost me the part), and I'm still on that replacement belt, which still looks new.

During my annual belt inspection I also try to wiggle all the pulleys to check the various bearings because if a pulley picks up a wobble or misalignment due to a failing bearing, it could take out the belt. On M103s the belt tensioner pulley is known to fail and take out the belt. One friend had a belt tensioner pulley fail, which took out the belt and the belt took out either the power steering or auto trans cooling lines, which made a huge mess including taking out the hood pad with a combination of belt slapping and oil saturation.

It pays to inspect the belt and pulleys frequently!

I may just go ahead and replace the belt apriori at 90K if I haven't changed it before then. At my current rate of mileage accumulation it will take me between five and ten years to hit 90K.

Duke

I usually get about 60-75k miles on a serpentine belt before I replace it. I replace based on its physical appearance. When it starts to dry out and develop numerous cracks on the ribs, that's what I use to gauge replacement. Being in Florida with the heat in summer probably shortens belt life for me a ilttle bit.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

I use belt conditioner every time I change the oil. Seems to work very well.

My friends E300D got 7 years and 148k out of the original belt. It probably still had a few thousand miles of life in it, but it was starting to crack.

I would say every 100k or 5 years is a safe replacement schedual. They are only about $30-$40.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Thanks for all the responses.