my g/f coworker's 94 chevy truck 189k miles..timing chain broke. I'm assuming the engine was interference because he's getting a new chevy cobalt this weekend. this made me think of my 96 sunfire with 125k original timing chain. I always hear about timing belt changing for preventive maintenance. what about the timing chain? what are the recommended replacements for them in general? how long are you on your timing chain?
FYI: timing chain
- Thread starter Cutehumor
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A properly tensioned and lubricated timing chain will outlast the rest of the engine. Before real problems happen, a chain gives plenty of progressively worsening warning noise. You can be pretty sure it wasn't just the chain that broke for no apparent reason. I hope I'm safe with these generalizations.
I've never had a timing chain fail but I have always used synthetic oil. I recall a study that someone posted that showed that syn. oils were better for timing chains.
Here is what I have had fail with timing chains:
**** Nissan had a known problem with timing chain tensioner guides that would fail unexpectedly in some of their older 2.4L engines. I had to replace the tensioners at 100k miles when I started hearing noise and had chunks of tensioner in my oil pan. The chain was still goood but ended up replacing it anyway.
Here is what I have had fail with timing chains:
**** Nissan had a known problem with timing chain tensioner guides that would fail unexpectedly in some of their older 2.4L engines. I had to replace the tensioners at 100k miles when I started hearing noise and had chunks of tensioner in my oil pan. The chain was still goood but ended up replacing it anyway.
I agree with Tosh. A timing chain should last for the life of the engine. A timing chain will wear over its life and sloooly the valve timing will be less than perfect but, I'll take it over a timing belt anyday.
I don't think there is a single part on a car that doesn't fail once in a while. I don't deny timing chains do fail. I remember my one chemistry prof having the one of his Alfa break back in the 60's.
A timing chain is still a maintenance part, even if some think it should last forever. Usually they are good for 200k+ on an OHV engine, but they still will eventually wear out. Some engines have other problems that may take them early like the nylon sprockets used in the 80s.
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Just check if yours has excess slack in it. Easy to do ..unless this is a GT. The SE lists a rotor for both available engines. Pull cap ..rotate crank by hand ..note the amount of crank movement required to get the rotor to turn. Some insist on putting number one cylinder on TDC ..but I don't see why. Slack should be slack
I guess if you've got timing marks ..it will tell you the number of degrees of slack you have. You'll get the 2:1 gear reduction ..but there should be a pretty direct relationship between the two.
I'm not sure what the criteria is for it being shot, though
My daughters 3.0 Vulcan had enough slop in the chain @ 130k to have it replaced (water pump and a broken bolt in the timing cover brought on this discovery). This was a 13 year old vehicle at the time.
I'm not sure what the criteria is for it being shot, though
My daughters 3.0 Vulcan had enough slop in the chain @ 130k to have it replaced (water pump and a broken bolt in the timing cover brought on this discovery). This was a 13 year old vehicle at the time.
Kestas
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Timing chains WILL wear out on high-mileage engines. Rule of thumb is that they need to be replaced if there is 10° slack. This is checked by rotating the crank back and forth while watching both the dampner timing marks and distributor movement.
Some old Ford engines were the worst because the timing gears were coated with nylon to reduce noise. They are notorious for jumping a tooth at high mileage.
Some old Ford engines were the worst because the timing gears were coated with nylon to reduce noise. They are notorious for jumping a tooth at high mileage.
Many cars had nylon coated gears for the timing chain to attenuate noise.
The plastic would harden and chip off, and problems would ensue.
The plastic would harden and chip off, and problems would ensue.
A well designed timing chain system (running in oil) will last untill the engine needs rebuilding. My belt will fail at 1/2 that distance with desasterous (sp) results. I hear all kinds of excusess for using timing belts like less noise, uses less power etc. I think it is a cheaper way to do it and let the customer pay later. Lots of manufactures are going back to timing chains after years of touting the benefites of belts.
Usually, a timing chain will give enough warning before breaking, in MB OM616/617 engines, during valve adjust, you can check for stretch and beyond a certain point, its warning for one to change, I have seen regular life of over 200,000+ miles for the chains in these engine with proper maintenance.
Years back when I had one of them Toyoters w/ a 22R engine at 200k miles, I had a noise problem coming from under the hood. The shop suggested it may be coming from the chain, but after evaluation it turned out only to be the water pump. They suggested that the timing chain would wear out quicker if the only changes were too extended. At the time I probably had an oci of 3-5k on 10w40 anything and usually Fram.
They did away with the nylon-coated gears for the HO version of the 302. I can't imagine why.
it was usually the plastic/nylon guides on those 22r's that broke first and wore against the cover. they were known to break randomly after 80k plus miles and/but sometimes lasted much,much longer.. they were and are still a great engine and have that dear place in my heart for the first truck that started it all.. 84, 2x85's, 2x86's.. all outlasted the trucks. and have given the last one, a 86 4runner to my nephew that drives the snot out of it.. good times..
mudd..
mudd..
I've always been curious about how much a timing chain contributes to oil shearing.
Anybody have any ideas?
Anybody have any ideas?
IVM - Good question. Probably a significant amount - I can't see anything except an oil pump in an engine 'crunching ' the oil more.
I've heard on this board that twin-cam engines are known to crunch the oil.
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