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Does a timing chain (as opposed to timing belt) need any specific maintenance? In particular I'm talking about a BMW Z4

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as far as I know they require no maintenance, they just last a lot longer. my understanding is they last 3x longer than timing belts but are ~3x more expensive to replace –  Patrick Mar 7 '11 at 22:07
    
So if an average timing belt is to be changed at 60,000 miles (average) I can expect a chain to snap at 180,000? –  m.edmondson Mar 7 '11 at 22:09
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They also cause 3x the amount of damage when they snap. Flying chains will seriously tear stuff up under the hood! :-) –  Brian Knoblauch Dec 1 '11 at 17:19
    
My Skoda Felicia has chain replacement interval of just 60'000km and both times it was changed at specified times it was noticeably stretched and made rattling noises while running. –  Krom Stern Jun 13 '13 at 7:09
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5 Answers 5

While regular maintenance is not required it is advisable to check how much the chain has stretch, say every few 100K. If the chain stretches too much the tensioner may no longer be able to perform its job. There's also the problem of the pins becoming a bit loose in the side plates.

The chain should also get a visual check whenever the opportunity presents itself to ensure there is no evidence of things like side plates starting to become loose. Rollers should be felt to ensure there is no discernible ply between roller and pin.

Timing chains don't often break but when they do they generally take chunks of engine with them, as well as allowing valves to get too friendly with the pistons on most engines.

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I'm used to timing chains on American V8's, but they will "stretch" over time (think 200k miles) and sometimes on high mileage engines they could "jump" a tooth if they are too stretched out.

But they do not require any maintenance.

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Checking chain stretch is a maintenance item that really needs to be done on them. –  Brian Knoblauch Jun 12 '13 at 12:39
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Regular maintenance is not needed. However, a "rattling" noise that changes with engine RPM may indicate a problem with the chain or timing gears. Usually this isn't an issue until higher mileage (150k +).

Next time you go by your dealership, ask them if they've had any problems in particular with your year model. If you hear of instances of chains commonly being replaced at X miles because of some problem (and you trust your source), then you may want to take preemptive action.

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BMW timing chains are engineered for the life of the engine and never need maintenance or replaced. To prove that point BMW has always performed several long distance tests on its new engines before they are put on the market. Back in the 90s they took a e34 (5 series) and ran it over 2 million miles, just performing the standard maintenance. When they took apart that engine everything measured to spec.

Enjoy your Bimmer and just make sure to get the regular maintenance performed but no need to worry about the timing chain. Now if your a e30 guy like myself your stuck with the single worst decision, sorry second worst (hiring Chris Bangle), Bimmer engineers made and that was to go with a 'quieter' rubber band timing belt. Argghh!!

Chris

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The problem with those high mileage tests is that they're not indicative of normal use. Running an engine continuously for a long period of time is much easier on all the parts than the typical start/drive a few miles/stop cycles that the majority of cars will see. –  Brian Knoblauch Dec 1 '11 at 17:21
    
As with everything in a car: everything can fail :) and usually not close to the manual replacement time. Just follow symptoms. if something is giving you a clue that the timing chain is extended or broken, go after it (after checking other easier things that may also cause the same symptom, of course) –  gcb Jun 11 '13 at 23:00
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long chains will get loose sooner, hard shifting will knock it around and shorten its life, infrequent oil changes will interfere with lubrication as the carbon biulds up on the chain. most engines either have a auto tensioner, or a good guide to help it from slaping ,belts are good but some are very hard to change, to bad the manufactuers dont try to make the belt easy to change as it isneeds to be replaced at some significant exspence

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