Timing Chain Guides

[Shel_B]

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.

My thought was that a chain setup is more complicated and provides more points for failure, but maybe I'm mistaken. Do belt systems have tensioners and guides that can deteriorate or break? Interference engine notwithstanding, it seems to me that there are more metal and hard parts that can break with a chain system than with a belt, and those pieces can get into the engine and cause even more, sometimes catastrophic, damage. Am I mistaken about that?

 

[brages]

My thought was that a chain setup is more complicated and provides more points for failure, but maybe I'm mistaken. Do belt systems have tensioners and guides that can deteriorate or break? Interference engine notwithstanding, it seems to me that there are more metal and hard parts that can break with a chain system than with a belt, and those pieces can get into the engine and cause even more, sometimes catastrophic, damage. Am I mistaken about that?

Belts -- in my experience --usually have one tensioner and one idler pulley. The "right" way to do the job is to replace tensioner, idler, water pump and belt. Why not replace the serpentine while you are at it and any leaky seals?

3 of the 4 cars I currently own have belts, although I slightly prefer a chain. IMO a well-engineered chain will good oil change habits will last the life of the engine with no additional maintenance.

 

[supton]

Belt systems do have at least one tensioner, and usually (?) one roller, maybe more. Thing is, all of that CAN be replaced during the belt change, so in some ways, it's all starting from fresh again. Assuming quality parts are used, and it's installed properly (two really big ifs).

 

[Shel_B]

Thanks, guys. So belts are not as simple as I thought, but they still seem simpler than a chain system. Do they use less energy than a chain?

 

[zzyzzx]

Also be sure to make the chains REALLY long, that helps magnify slap.

I think that this might be the biggest problem with timing chains. Just replace timing chain components every 150,000 miles and you should be good. By 150K the timing chain cover is going to be leaking anyway.

Obligatory comment about timing chains in the Car Wizard's video here:


And I'm inclined to believe what he says about timing chains here. When timing chains were short and simple, they were more reliable than timing belts. Now that timing chains are really long and have plastic, or plastic lined tensioners, they require maintenance. Yet still another reason not to get the V6.

 

[SwampSurvivor]

I pulled the 131K mile engine from my Grand Marquis apart. This car lived in NYC for it's first 18 years. The tensioner arms (plastic around aluninum) were worn completely through. The timing chains were actually riding on the tensioner pistons!

 

[zzyzzx]

My thought was that a chain setup is more complicated and provides more points for failure, but maybe I'm mistaken.

You are not mistaken there. More parts = more potential failure points.

 

[4WD]

Belts -- in my experience --usually have one tensioner and one idler pulley. The "right" way to do the job is to replace tensioner, idler, water pump and belt. Why not replace the serpentine while you are at it and any leaky seals?

3 of the 4 cars I currently own have belts, although I slightly prefer a chain. IMO a well-engineered chain will good oil change habits will last the life of the engine with no additional maintenance.

Did that on our 3.5L C300 … not that much more money to get them all and nothing had broken at 108k …

 

[supton]

I think that this might be the biggest problem with timing chains. Just replace timing chain components every 150,000 miles and you should be good. By 150K the timing chain cover is going to be leaking anyway.

What's a minor weep? Free rustproofing if you ask me.

I keep a piece of cardboard under my car (while in the garage), but I think that is crank seal, I remember thinking, why replace it? it's not leaking right now... next TB I know for sure it's getting replaced.

 

[KGMtech]

I did the waterpump in our 2009 Flex over 3 years & 60k kilometres ago, the decision was to do all the chains and guides while in there, but I admit the old guides looked virtually as good as new with 206K Kilometres on them. Yes this Flex had a regular diet of PP 5W20, but I have no idea if this was the explanation.

 

[D60]

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.

Actually in thinking further about his question, I can see the logic that a metal chain is going to essentially grind if the plastic breaks apart. Plenty of Tritons with tons of metal circulating through the engine. Not great

I pulled the 131K mile engine from my Grand Marquis apart. This car lived in NYC for it's first 18 years. The tensioner arms (plastic around aluninum) were worn completely through. The timing chains were actually riding on the tensioner pistons!

Ford was seemingly perpetually updating their timing chain guides (also true of the 3.5NA in the Edge platforms).

It's almost as if they drew it up, ran a computer simulation and said, "Eh, oughtta work....probably." Then as real-world failures came in they discovered that theory and reality can differ. Who knew? OTOH, kudos for at least updating parts and making an effort.

 

[Astro14]

Chains wear. Guides wear. If the guides wear and break, the chunks of plastic can break off and cause the chain to jump a tooth.

The Mercedes M117 V-8 needs new guides every 100,000 miles. It’s an interference engine.

To have room to pull the guide pins and remove and replace the guides in the R107 chassis (450SL) the engine has to come out.

This engine, with 110,000 miles, was about 10 degrees out of time on one of the heads.

Timing chain stretch.

New guides, chain and gears put it back to right on.

 

[Shel_B]

Chains wear. Guides wear. If the guides wear and break, the chunks of plastic can break off and cause the chain to jump a tooth.

The Mercedes M117 V-8 needs new guides every 100,000 miles. It’s an interference engine.

I believe that was the engine in my 108 and my Mercedes tech strongly suggested I have the work done as the car approached 100,000 miles. When the job was done, Steve showed me what had been replaced and how the parts had worn. I was grateful that he had pushed me to stay ahead of the potentially disastrous problem that was waiting to happen had the work not been done.

This discussion has got me thinking about when to do the work on the Camry should I decide to keep it for the long haul.

 

[brages]

Your Camry is not a Mercedes... IMO, do the research and see if your Toyota engine is prone to timing chain problems before being concerned about your engine.

 

[SwampSurvivor]

It's almost as if they drew it up, ran a computer simulation and said, "Eh, oughtta work....probably." Then as real-world failures came in they discovered that theory and reality can differ. Who knew? OTOH, kudos for at least updating parts and making an effort.

The replacement engine actually has the updated timing components. It doesn't have the timing chain rattle either. I bought the car after 120K NYC miles so I'm sure that's actually significantly more actual miles.

 

[supton]

I used to own your Camry. While I did not inspect the chains, it was running just fine when it went away after 236k.

I have to wonder: with vvt, just how much chain slop can be accommodated? some degree I would think, but once wear starts, I bet it just simply accelerates.

 

[14Accent]

Putting aside gear-driven timing designs... I'm of the opinion that there's a case to be made for both belt-driven and chain-driven timing drives.

One can list countless engines that employ timing chains that suffer practically zero wear during their life, and vice-versa. Winners:

The original Ford modular engine, both the SOHC and DOHC. Very rarely do you hear about one of those failing.
Northstar engines. Head gaskets, sure. But timing chain issues? Never.
Chrysler 3.7/4.7. Again, plenty of other issues but timing chain isn't one of them.
Nissan VQ. Never an issue.

Then, you have the problem children... The aforementioned Ford engines, VW 2.5 I5 and VR6 engines, MB engines, etc.

Same goes for timing belts, though. A Honda J35 belt can look beautiful after 150k, whereas a Subaru EJ25 belt will look terrible by 80k. Not to mention, the J35 belt is puny compared to the EJ25. One need look no further than the amount of tension on the belt combined with both the routing and radius of bends a given belt endures to establish a reasonable conclusion: length+tension+flex=failure.

Using the J35 vs. EJ25 example: the J35 belt makes 6 bends in total. Crank pulley, idler, front cam, water pump, rear cam, tensioner.

The EJ25 belt, in comparison, makes 8 bends. 90% of which are MUCH tighter than anything the J35 sees, leading to advanced wear.

 

[Astro14]

To be fair, the MB engine I showed with the new timing set on it was from a 1975 car. It had run for 45 years when it was replaced.

Most new MB engines have very stout timing chains. There are plenty of V-8 Mercedes with well over 200,000 miles on the original chain and guides.

But, in 1969, when the engine was first built, DOHC V-8s and nylon guides were new technology. Turned out the guides didn’t last long. The retrofit double roller chains do last a long time.

 

[Astro14]

Here’s a view of a 1992 MB 300E engine and timing chain. About 120,000 miles on it, just finished a head gasket - which was a common failure point on the M103 six cylinder engine. Simple, single row chain, whose durability was helped by short runs and simple guides. They’re known to run forever on the original chain and guides.

 

[Shel_B]

I used to own your Camry. While I did not inspect the chains, it was running just fine when it went away after 236k.

I have to wonder: with vvt, just how much chain slop can be accommodated? some degree I would think, but once wear starts, I bet it just simply accelerates.

Thanks for the info. I'm neither concerned nor worried about tensioner and chain wear as suggested by another poster, just curious about the systems and, of course, how they may affect the Camry engine. The more you know, the better your luck.

I believe that once wear gets to a certain point, it does accelerate, but that's just a belief. I've not looked into it very deeply.