VVT/timing chains failure prevention

[friendly_jacek]

I spend some time on corolla forums and recently people report VVT failures due to component wear in 1ZZ-FE engines with 100,000+ miles. Granted, not very common, but happens (picture below).
Also, I'm hearing that timing chains, which are fashionable again, can snap from wear at various intervals (not common in corolla though).

What would be the key element in oil preventing this wear: high level of AW additive (ZDDP), EP additive (if any oils have any), viscosity (high vs low), HTHS, friction modyfiers (moly), anything else?
Thanks!

From http://yotarepair.com/whatshot.html

 

[JHZR2]

My MB diesel mechanic said that the falures he saw in OM617 engines were timing chains breaking during the high torque exerted on the components at startup.

Clean oil makes a big difference, and it has been claimed that the chain 'stretch' in diesels can be halved by using a good syn oil.

Granted this is all from MB diesel cars, where 100k isnt even broken in, and >350k on the original engine is the norm.

JMH

 

[Ray H]

I'm trying to mentally picture why a diesel exerts more torque opening its intake and exhaust valves at startup than does an equivalent displacement gasoline engine... It's not like the valves are being opened against the cylinder pressures at the peak of the compression-ignition cycle. As far as the wear on that 1ZZ motor's CVVT component is concerned, it looks like dirty oil contaminants clogging a prescreen eventually left that component high and dry for lube and the inevitable followed.

[ July 16, 2006, 04:27 AM: Message edited by: Ray H ]

 

[the_oil_dealer]

ah the good ol' 1ZZ! The Yamaha engine. The engine Toyota Motor Co actually contracted the engineering out to a 3rd party... a nice engine, akin to the FORD Taurus SHO engine, well for the issue that you bring attn to, I would say that a more viscous oil would be a smart preventative measure. Don't rely on additives to save your chain.

 

[billstock]

I tought that the 2ZZ was the "Yamaha" engine.

 

[JHZR2]

quote:

---

Originally posted by Ray H:
I'm trying to mentally picture why a diesel exerts more torque opening its intake and exhaust valves at startup than does an equivalent displacement gasoline engine... It's not like the valves are being opened against the cylinder pressures at the peak of the compression-ignition cycle. As far as the wear on that 1ZZ motor's CVVT component is concerned, it looks like dirty oil contaminants clogging a prescreen eventually left that component high and dry for lube and the inevitable followed.

---

Im not entirely sure it does... we were talking about diesels, and he told his experience, FWIW.

imparting movement onto a stationary body, and the very high compression of a diesel engine needing to be turned at startup are the two considerations I can think of, not that theyre necesarily the reason.

I agree with you RE: dirty oil and the failure mechanisms.

JMH

 

[1sttruck]

Doesn't the stock 3.0 V6 in the Taurus use a timing chain ? Don't hear of timing chain problems, and the one in the older Taurus with over 200k seems fine.

 

[carock]

Due to extensive experience with Lotus, Mercedes, and Porsche timing chains I consider myself an expert on their survival.Purely self proclaimed, nobody has ever challenged me Timing chains do not stretch, the rollers wear out. The rollers wear because oil contaminates, mainly carbon particulates from blow-by, gradually lap the chain rollers and sprockets. This adds slack into the chain. If this slack cannot be taken out by the chain tensioner, the chain will eventually rub on something its not supposed to, or experience a sharp slacken/tension cycle that snaps a link, this is known a "load reversal". Load reversals usually happen during a downshift or sudden deceleration from shifting. Sometimes the chain tensioner fails before the chain wears, usually a hydraulic chain tensioner leak, or a simple plastic rubbing tensioner that breaks up. Some hot rod builders experience chain trouble from violent cam harmonics that come from their high lift, stiff spring valvetrains. In this case it is usually a valve train component that breaks, which jams the valve train and snaps the timing chain. I never knew it until recently, but chain wear can be almost compleatly prevented by using a bypass filter. The bypass filters remove the abrasive contaminates and the chain can last almost forever. a "normal" engine simply will not experience noticable chain wear with a constant supply of clean oil.

 

[JHZR2]

quote:

---

Originally posted by 1sttruck:
Doesn't the stock 3.0 V6 in the Taurus use a timing chain ? Don't hear of timing chain problems, and the one in the older Taurus with over 200k seems fine.

---

lets talk when you get to 350-400k, like the MB diesels I mention were seeing 'issues'.

at 220k on mine I had less than 1 degree of stretch... you dont even start putting offset woodruff keys in until ~4-6.

JMH

 

[GarrettSocling]

quote:

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Originally posted by carock:
Timing chains do not stretch, the rollers wear out. The rollers wear because oil contaminates, mainly carbon particulates from blow-by, gradually lap the chain rollers and sprockets.

---

I remember reading the post that jacek read as well, that pic is from yotarepair.com if I remember correctly. I think the conclusion that was reached is there is a small screen which protects the supply to the VVT components, essential for the screen to remain clean, else a pin wears? The thing that clogs the screen? Infrequent oil changes I believe I read.

 

[Hirev]

quote:

---

I spend some time on corolla forums and recently people report VVT failures due to component wear in 1ZZ-FE engines with 100,000+ miles. Granted, not very common, but happens (picture below).
Also, I'm hearing that timing chains, which are fashionable again, can snap from wear at various intervals (not common in corolla though).

What would be the key element in oil preventing this wear:

---

Change the oil often.

 

[friendly_jacek]

quote:

---

Originally posted by GarrettSocling:

quote:

---

Originally posted by carock:
Timing chains do not stretch, the rollers wear out. The rollers wear because oil contaminates, mainly carbon particulates from blow-by, gradually lap the chain rollers and sprockets.

---

I remember reading the post that jacek read as well, that pic is from yotarepair.com if I remember correctly. I think the conclusion that was reached is there is a small screen which protects the supply to the VVT components, essential for the screen to remain clean, else a pin wears? The thing that clogs the screen? Infrequent oil changes I believe I read.

---

Yes, the picture is from yotarepair.com as I referenced in my post. The yotarepair comment was they initially suspected the screen clogged, but it was not the case and instead the parts were worned out. But I guess the intervals could be the culprit. Manual for my 2003 corolla still states the 5000/7500 miles intervals (toyota changed them since). The severe service is poorly defined in the manual and there are probably people doing 7500 changes on dino oil. Based on my UOA, 10W30 dino oil thickened a bit at 5000 miles, so 5000 is the maximum I allow.

As for my timing chain question, I found a thread that beat the issue to death:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=010622;p=1

 

[1sttruck]

"...lets talk when you get to 350-400k, like the MB diesels I mention were seeing 'issues'."

The most miles that I've seen on a Taurus is 235k, and the most that I've heard about is a lady that was using HDEO in a Taurus wagon, at over 300k, so +300k Taurii are rare birds indeed. 500k in a Cummins isn't unusual, some have hit 1 million, and timing chains aren't mentioned much at all.

 

[427Z06]

quote:

---

Originally posted by carock:
...Timing chains do not stretch, the rollers wear out. The rollers wear because oil contaminates, mainly carbon particulates from blow-by, gradually lap the chain rollers and sprockets...I never knew it until recently, but chain wear can be almost compleatly prevented by using a bypass filter. The bypass filters remove the abrasive contaminates and the chain can last almost forever. a "normal" engine simply will not experience noticable chain wear with a constant supply of clean oil.

---

Thank you. I never did believe the "Thick HDEO" crowd when they proclaimed it would save timing chains.

 

[JHZR2]

quote:

---

Originally posted by 1sttruck:
"...lets talk when you get to 350-400k, like the MB diesels I mention were seeing 'issues'."

The most miles that I've seen on a Taurus is 235k, and the most that I've heard about is a lady that was using HDEO in a Taurus wagon, at over 300k, so +300k Taurii are rare birds indeed. 500k in a Cummins isn't unusual, some have hit 1 million, and timing chains aren't mentioned much at all.

---

The cummins might very well have a much bigger, heavier, heavier duty chain than the MB diesel. Even high mileage MBs have original chains... but often when they get 4-8 degrees of stretch (yes, wear really, but the common name is 'stretch'), they get a link ground out and a woodruff key put in. Unless the MB chain metalurgy is different from others to the point that it is only done with their engines, Id have to guess that other makes have had them put in too - possibly some cummins.

The MB is all mechanical, not a computer on the thing - which might also determine why one wants to ensure that timing is kept right... computers can probably compensate somewhat... a mechanical system just runs without a clue of what is going on.

JMH

 

[clockworks]

FYI... it is the 2ZZ engine that was designed by yamaha. I work for toyota and and have only seen 2 of these actuators in the 1ZZs fail. Far more common on these engines is excessive oil consumption due to poor maintenence intervals. The rings, especially the oil control ring sticks in their land. Since the tensioner is hydraulic, the low oil level can cause the chain to rattle like crazy. It is the same sound produced by these engines when the oil is changed and the filter is dry when the engine is started. For about 2 seconds, the chain rattles until pressure is built. Perhaps this will shed some light on chain and or VVT actuator failure.

Greg

 

[Hirev]

quote:

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Originally posted by clockworks:
Far more common on these engines is excessive oil consumption due to poor maintenence intervals. The rings, especially the oil control ring sticks in their land.

Greg

---

When I work in a engine remanufacturing shop in the early 80s ring(s) sticking due to poor maintenance was by far the most common major problem we seen in the short blocks no matter what brand. It seemed like once the ring(s) started sticking things spiraled out of control rapidly after that. Oil consumption went up. Owners would end up running them low on oil sooner or later.

 

[i]

Which MB diesels are all mechanical? Even current ones? If that's true I'm going to buy one.

 

[1sttruck]

"I never knew it until recently, but chain wear can be almost compleatly prevented by using a bypass filter. The bypass filters remove the abrasive contaminates and the chain can last almost forever. a "normal" engine simply will not experience noticable chain wear with a constant supply of clean oil."

But, diesels tend to dump lots of soot into oil, and again timing chain wear isn't one of the big concerns that one hears about, in spit of the sometimes long oi lchange intervals as well as long engine life.

 

[Leo]

In the Nissan SR20DET, the VVT actuator also fails. Its due to excessive wear, and can happen in low mileage cars too. I try to recommend HDEOs as the extra AW additives should prolong the life of these units.