Timing Chain Guides

[Shel_B]

I've seen a number of engine teardown videos and observed numerous damaged and broken guides.

If good (appropriate) oil is used and is changed at appropriate intervals, why might the guides become damaged?

Besides proper oil maintenance, what else can be done to minimize the chance of damage to the guides?

What material are guides made from?

 

[oldhp]

I found this; The most common material used for this is graphite and molly filled nylon 6.6 as it is a lot cheaper than nylon 4.6, however OEM automotive companies specify Stanyl when and if the 66 fails life cycle tests. They get typically 3 times the life and up to 9 times the life from the Stanyl parts over nylon 6.6 parts.
I would think keeping RPM's lower over the life of the engine would help. Using the proper "clean" oil has got to help.

 

[Chris142]

Most guides are a plastic like material. They just break. The better ones are plastic lined metal.

 

[Shel_B]

I found this; The most common material used for this is graphite and molly filled nylon 6.6 as it is a lot cheaper than nylon 4.6, however OEM automotive companies specify Stanyl when and if the 66 fails life cycle tests. They get typically 3 times the life and up to 9 times the life from the Stanyl parts over nylon 6.6 parts.
I would think keeping RPM's lower over the life of the engine would help. Using the proper "clean" oil has got to help.

Thank you. That's a good starting point for further investigation. I discovered that Stanyl has a melting point of 295-deg C, so engine heat should have little if any, effect on the material. I need to do more reading.

I'd like to find out what material the guides are in my car, not that there's much I can do about it at his point. It's just a matter of curiosity.

These "plastics" seem to be relatively new materials. I wonder what was used before they became available. Since these materials came into general use around mid-20th century, I wonder if any cars used timing chains AND needed guides prior to WWII, which, to my understanding, seems to be the time that the development of plastics and polymers started to accelerate. Carothers developed Nylon around 1939 and started working with synthetic rubber in the early 30s. I know that there were just a handful of engines using overhead cams prior to 1910. I'm guessing that they were gear driven.

Anyway, thanks ... some interesting reading lies ahead.

 

[Astro14]

Thank you. That's a good starting point for further investigation. I discovered that Stanyl has a melting point of 295-deg C, so engine heat should have little if any, effect on the material. I need to do more reading.

I'd like to find out what material the guides are in my car, not that there's much I can do about it at his point. It's just a matter of curiosity.

These "plastics" seem to be relatively new materials. I wonder what was used before they became available. Since these materials came into general use around mid-20th century, I wonder if any cars used timing chains AND needed guides prior to WWII, which, to my understanding, seems to be the time that the development of plastics and polymers started to accelerate. Carothers developed Nylon around 1939 and started working with synthetic rubber in the early 30s. I know that there were just a handful of engines using overhead cams prior to 1910. I'm guessing that they were gear driven.

Anyway, thanks ... some interesting reading lies ahead.

My Packard has a timing chain. No guides. Just a tension adjustment.

 

[Greasymechtech]

Good oil isn't good enough.
"Appropriate" is an unknown entity concerning intervals.

But don't worry, after a century of motor oil development, API/ILSAC SP/GF6 finally addresses timing chain wear.... which just might help the rest of the valvetrain too.

 

[D60]

Guides can become damaged from chain slap. If you're a Ford engineer you design plastic hydraulic tensioners with poor seals that blow out. Also be sure to make the chains REALLY long, that helps magnify slap.

It's also best to introduce the inferior tensioners after you've successfully been using all metal, ratcheting (non-hydraulic) tensioners. Good engineering always seeks a non-existent problem then finds an unnecessary solution.

 

[D60]

Start around 3:00. He specifically talks about chain slap causing guides to fail.

Starting at ~5:45 he shows the chain wore through the plastic AND the metal backer! The piston of the tensioner punched through the guide and the piston is now in contact with the chain.

 

[Shel_B]

Start around 3:00. He specifically talks about chain slap causing guides to fail.

Starting at ~5:45 he shows the chain wore through the plastic AND the metal backer! The piston of the tensioner punched through the guide and the piston is now in contact with the chain.
youtube]EPFv0veBO8k

This was a useful video. Glad you posted it. Thanks. needing to be changed at intervals, it

Got me thinking about the value of a chain vs a belt. While it seems that a belt would be more maintenance needing to be changed at intervals, a chain and its components might cause more damage when it does go bad. I'm sure that the overall design of the engine and components is a major consideration, but in general might, do you think there's some validity to the idea?

 

[Greasymechtech]

Notice the uptick in chain wear over the last 30 years. But, the engines are squeaky clean. Noticed the uptick in excessive oil consumption too. And, no one argues flat tappet cam wear even though the blame game was a joke. Ford also doesn't care for the newer diesel oil specs with their older engines. Fuel dilution was ignored for too long by too many. Thin oil sure helps MPG but what about wear?. Lower zddp levels sure help with o2/AF sensor and catalytic life... Should a sensor or catalytic converter outlast an engine? Or should those cheaper parts simply be replaced as needed?

The wear is happening. The automakers, and oil/additive companies, seem to be continuously behind what is happening out there, in the real world. The R&D is happening at the consumer level.

So, I use a grade thicker oil, and/or maybe bottle or 2 of thicker oil, and I use oil with more zddp than required, a pretty good oil filter, and a typically shorter than 'recommended' interval. All my timing chains/guides/tensioners/vvts are doing pretty good. I don't suffer from oil consumption issues(except for the 2-strokers and rotaries). Most of my engines are doing pretty good with compared to neighbors/relatives/colleagues/coworkers/contractors, and definitely better than the 100's of threads started in 100's of forums complaining about engine noises, sludge, oil consumption, and failures.

But, the thought of changing the oil out a little earlier, using a quality oil/filter, using the dipstick often, being selective with fuel/oil/filters/intervals, is beyond the capability of zombie sheeple drones only worried about their drivethru products and phone glued to face lifestyle. More trust their radio talk show or youtube/instagram/tictoc personality. If there is something you can do to prevent the make believe 'inevitable', would you do something about it?

Its just all antidotal anyway, just like automaker R&D. So, what are you going to do about it?

I don't surrender to "inevitable". And, my antidotal experiences are certainly against the grain of the fools that surrendered.

I also don't have a perfect commute or boring driving style. I could 'egg on gas pedal drive' pretty much any engine for a long low wear life but don't like causing traffic jams(see these clowns daily).

 

[D60]

This was a useful video. Glad you posted it. Thanks. needing to be changed at intervals, it

Got me thinking about the value of a chain vs a belt. While it seems that a belt would be more maintenance needing to be changed at intervals, a chain and its components might cause more damage when it does go bad. I'm sure that the overall design of the engine and components is a major consideration, but in general might, do you think there's some validity to the idea?

There's so many variables. The complication tends to come w OHC. Chain routing on old pushrod V8s is basically a single speed bike

But all things being equal I'd rather push my luck with a metal chain than a rubber belt

 

[supton]

Got me thinking about the value of a chain vs a belt. While it seems that a belt would be more maintenance needing to be changed at intervals, a chain and its components might cause more damage when it does go bad. I'm sure that the overall design of the engine and components is a major consideration, but in general might, do you think there's some validity to the idea?

Don’t know about more damage, both setups can be interference engines. Both can be hard and costly to replace, belt or chain, but on a belt setup it might be designed in to make it somewhat less painful.

 

[JHZR2]

This was a useful video. Glad you posted it. Thanks. needing to be changed at intervals, it

Got me thinking about the value of a chain vs a belt. While it seems that a belt would be more maintenance needing to be changed at intervals, a chain and its components might cause more damage when it does go bad. I'm sure that the overall design of the engine and components is a major consideration, but in general might, do you think there's some validity to the idea?

It’s a fallacy that chains are maintenance free or can just be ignored.

 

[JTK]

It’s a fallacy that chains are maintenance free or can just be ignored.

I believe that as well.

Although manufacturers are not building them such that can be maintained. They can, but at astronomical cost.

Here's an interesting write-up on a ~185k mile 2017 Nissan VQ35DD T-chain replacement..

High Milage 2017 Pathfinder Timing Chain...

www.pathfindertalk.com

 

[SC Maintenance]

My Nissan VQ40 had the secondary tensioner guides wear needed to be replaced. That was actually an issue with the chain links themselves - the stamper didn't inspect their dies and the links had burrs which would wear the guides. There was a class action.

When we got it open our primary guides were OK, but I have heard of a lot of Nissan's having these break Its not a lubrication problem, but a problem with materials or design. The primary guide was really long and curved and they would wear more at the spot the chain first landed on the guide. Eventually this part thinned out and the plastic guide before it would break off from the chain slap. I think they came up with a better design - not sure what was changed.

Not sure there is much in the way of lubrication that would change this. Other than the guides everything else looked fine - including the chains.

 

[PimTac]

I would guess that chain and guides wear more due to inconsistent oil change intervals plus revving up cold motors and jackrabbit starts. No oil is going to hold up to those conditions.

 

[Astro14]

There's so many variables. The complication tends to come w OHC. Chain routing on old pushrod V8s is basically a single speed bike

But all things being equal I'd rather push my luck with a metal chain than a rubber belt

Agreed on the variables.

However, I have had a timing set failure (worn gear, chain jumped a tooth, engine died) on a Ford 302.

Never had a belt fail.

So, in my 40 years of car ownership, timing belts have been more reliable than timing chains...

 

[dishdude]

There's so many variables. The complication tends to come w OHC. Chain routing on old pushrod V8s is basically a single speed bike

But all things being equal I'd rather push my luck with a metal chain than a rubber belt

I totally agree, I do not like timing belts. Chains will generally make a lot of noise and give plenty of warning before failing, a belt can just break without notice. Also, to do the timing belt job properly, all the components need to be replaced - WP, idler, tensioner.

I do think that poor maintenance can cause chain issues, especially engines run low on oil.

 

[brianl703]

I do think that poor maintenance can cause chain issues, especially engines run low on oil.

I've seen at least a couple of YT videos where a 2.2L Ecotec needs timing chain work...

...and what's under the valve cover looks like the bottom of a well-used charcoal grill.

 

[JHZR2]

I believe that as well.

Although manufacturers are not building them such that can be maintained. They can, but at astronomical cost.

Here's an interesting write-up on a ~185k mile 2017 Nissan VQ35DD T-chain replacement..

High Milage 2017 Pathfinder Timing Chain...

www.pathfindertalk.com

On my MB diesels, there is standard procedure to measure wear (“stretch”), woodruff keys to offset it, and then you can just roll another in. Some of these V engine monstrosities that I see chains in have me wondering…….