Effect of Timing Systems on Engine Wear

[Passport1]

There are generally two types of engine timing systems on modern engines, cam belt and chain drives. Each has its virtues and vices. There have been gear driven and other exotica but not mainstream now. So the question is this;

1. cam belt timing systems are completely external to the reciprocating parts of the engine. So in theory this system can't contribute to the normal wear processes going on internally.

2. The chain drive system is virtually maintainence free but does contribute to oil degradation and internal wear. Chains and sprockets shed ferrous particles and shear oil. They may also add frictional heat to the engine.

What is gained or lost by these two common systems?

 

[rijndael]

I don't agree that chains are 'virtually maintenance free'. Too many cars now need phasers (GM 3.6 - Ford Ecoboost) and ends up getting a whole new timing set.

Belts are quieter.

 

[Johnny248]

I don't agree that chains are 'virtually maintenance free'. Too many cars now need phasers (GM 3.6 - Ford Ecoboost) and ends up getting a whole new timing set.

Belts are quieter.

Agreed. Timing components are becoming a common issue. I blame the VVT more than the chain itself? Not sure if that is true, but it sure seems like *pick a manufacturer* are constantly having cam phaser issues. In an ideal world I prefer chains because they last forever, but belts because replacement is usually much less time consuming.

 

[KGMtech]

I am told that timing belts are quieter, but I would not be able to tell given my hearing impairment. So many examples of chains stretching due to maintenance neglect, or wrong oil, or chain not designed correctly at OEM that to say these are lifetime parts is often wishful thinking. IF there was a easy DIY change process with some room for people with XL hands, then I would prefer belt.

 

[SC Maintenance]

The only true answer is it depends on who is implementing the chain / belt.

The Oem's went to chains for more advanced control or the "need" for more complex chain drive systems - not for maintenance reasons which they have never cared about IMHO.

In the end If your afraid of your chain causing oil problems, shorten your OCI.

 

[fdcg27]

There is no doubt that chains dump more metal into the oil.
There is also no doubt that belts require replacement, but that's usually not too difficult or costly, at least with old-school dry belts.

 

[Skippy722]

I don't agree that chains are 'virtually maintenance free'. Too many cars now need phasers (GM 3.6 - Ford Ecoboost) and ends up getting a whole new timing set.

Belts are quieter.

I have never been able to hear the difference between a belt driven and chain driven timing system.

 

[BMWTurboDzl]

There are generally two types of engine timing systems on modern engines, cam belt and chain drives. Each has its virtues and vices. There have been gear driven and other exotica but not mainstream now. So the question is this;

1. cam belt timing systems are completely external to the reciprocating parts of the engine. So in theory this system can't contribute to the normal wear processes going on internally.

2. The chain drive system is virtually maintainence free but does contribute to oil degradation and internal wear. Chains and sprockets shed ferrous particles and shear oil. They may also add frictional heat to the engine.

What is gained or lost by these two common systems?

Wet belts deteriorate and the pieces will block the screen in the oil pickup tube and starve the engine of oil

 

[Exhaustgases]

There are generally two types of engine timing systems on modern engines, cam belt and chain drives.

Not true ! Since you did not specify any particular usage for the Modern Engines. I know of many that do not use chains or belts.

Now if it is just the normal cheap die cast throw away small highway vehicle engines then yeah.

 

[barryh]

If duplex chains were engineered to last the life of the car like they used to be then maybe chains but given some modern chains are not maintenance free and neither are the VVT sprockets making replacement on an old car prohibitively expensive, I'd go for the simplicity and easier to replace dry belt any day.

 

[RedSpider]

I'm probably being a bit pedantic here, but I think we are using "maintenance" and "repair" as interchangeable concepts and I dont think it fits. I have had to maintain timing belt systems, by replacing the belt and tensioner and whatever pulleys at the prescribed interval, but I've never had an engine that prescribed replacing the chain and/or guides or phasers or whatever at any specific interval as maintenance. Not saying there arent any, but I'm certainly not aware of any.

Of all the cars I've ever owned with chains over multiple decades, I have only had to deal with one, my 1992 Nissan with the 2.4l KA24DE, the top chain guide broke and was ratting around. Nissan didnt even sell that guide anymore, they simply remove it if it breaks or if its exposed during any other procedure, because it did nothing (other than break off it's bracket and rattle against the valve cover). My understanding is that the later versions of this engine didnt even come with this guide from the factory, even though the bolt holes for the bracket are in there.

Either way, back on point.... whatever my point is.... timing belts are intended as maintenance items, same as plugs, filters, and fluids are. Chains are intended as life of the engine components, same as the crank, rods, pistons, and cams.

 

[rijndael]

Chains are intended as life of the engine components, same as the crank, rods, pistons, and cams.

I'd liken a chain's replacement interval to something closer to a water pump or AC compressor, not a core engine component like a crank or rods.

In the end, it seems like a distinction without a difference. They're something people have to pay for to keep the car in good working order. My wallet wouldn't know the difference between a repair and maintenance item.

 

[JimPghPA]

Wet belts deteriorate and the pieces will block the screen in the oil pickup tube and starve the engine of oil

And wet belt particles can build up in very small passages like the oil lub and cooling of turbos, and caus the turbo to fail.

The filter in bypass on cold stairs let's enough through that eventually enough gets to those areas when an old wet belt is shedding pieces.

 

[Opelman]

A rubber belt has a healthy amount of tension constantly pulling against the cam and crank bearings. Depending on the engine design a chain not as much. I'm not a belt fan as I saw far too many VW bunny diesels with destroyed cams and heads from a broken belt. On the other hand, the Ford pull the motor to repair chain at the back with crap guides is a massive fail too. Truly not a one size fits all kind of thing.

 

[dbias]

I prefer dry belt over timing chain even though belts need replacing as a maintenance matter. I’ve replaced three VW belts and of course the water pumps and pulleys and this is like resetting the engine for another 100k miles. Chains usually last longer but are more labor intensive when they are needed.
As to the question of the post. Chains do contribute to fine material in the oil but good oil and filters and appropriate oci are the answer to that.

 

[dogememe]

I’d rather have a chain. If designed and manufactured properly, assuming acceptable oil change maintenance, it will last forever.

While a belt you are guaranteed to have to change it eventually.

 

[SilentType]

If I had an interference engine definitely would not want a timing belt. Had a belt snap on me while driving a 1987 Escort. Tow truck and new belt later I was back on the road.

 

[rijndael]

Belts in the 1980s aren't comparable to today's belts. EPDM was a significant change.

In addition, old belt systems were at the mercy of the installer to set the tension properly. That's no longer the case.