what type timing system do the 2012 toyota camry engines have , the 4 and the v6
gears? belts? or timing chains?
gears? belts? or timing chains?
2012 camry engines - belts geas or chanis
- Thread starter edwardh1
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Both are timing chains.
You can look this info up on the Gates website. I believe it also mentions if an interference engine.
I think chains are/should be better, but chains are not the simple kind like in my old GM 5.7L engine. They are more complex in their path and drive more stuff. While I have never had a chain or belt break, they do.
I think chains are/should be better, but chains are not the simple kind like in my old GM 5.7L engine. They are more complex in their path and drive more stuff. While I have never had a chain or belt break, they do.
The hybrid has no belts of any kind, timing chain and all else is elec motors, even the water pump.
I think (not sure) toyota/yamaha went with lashless roller follower system on the cams when they specd the 2AZ family for 0w20 ILSAC grade oil - this is important as the camry engine didnt have adjustable valve clearance without a multi hour engine teardown to replace bucket tappets to maintain proper valve clearance. I would prefer a dry timing/belt system as its easier on the oil and less troublesome - but I dont keep my car to 100K miles.
Minor rant - IDK why folks dont just web search this info instead of getting 3rd hand information here - unless they are secretly hoping for that wonderful BITOG editorialising
Minor rant - IDK why folks dont just web search this info instead of getting 3rd hand information here - unless they are secretly hoping for that wonderful BITOG editorialising
Bit ot. However why do some engines have belts and others chains. It is my understanding that chains are more durable but more expensive and make more noise. Is this correct?
Chains are far more expensive to design in.You need to seal off the chain in a timing cover and it needs a constant oil feed.Instead install seals on the cam and crank,sling a belt over sprockets,and apply a cheap $20 plastic cover and its done.This is the main reason why the Chrysler 2.2/2.5 used a belt.They mulled using a chain,but the added expense to extend the front of the engine,enclosing it in a cast/steel cover with oil flow and chain dampers were strictly out of budget.And I guess it was a good idea,the lousy 2.6 Mitsubishi engine they used had 2 chains,and neither would stay unstretched for long.
Also, chain systems often have tensioners, and some are oil fed.
A modern external belt is my choice .
A modern external belt is my choice .
Chains also offer a more compact engine design (shorter). I think that's a major reason we're starting to see timing chains become more common in TFWD layouts.
Originally Posted By: Hokiefyd
Chains also offer a more compact engine design (shorter). I think that's a major reason we're starting to see timing chains become more common in TFWD layouts.
Volvo used a T-chain instead of a belt, plus a few other tricks, and it enabled them to put a 3.0L transverse straight 6 into several models.
I don't believe I ever read of another company installing a 3.0L straight 6 installed transversely.
Chains also offer a more compact engine design (shorter). I think that's a major reason we're starting to see timing chains become more common in TFWD layouts.
Volvo used a T-chain instead of a belt, plus a few other tricks, and it enabled them to put a 3.0L transverse straight 6 into several models.
I don't believe I ever read of another company installing a 3.0L straight 6 installed transversely.
I read an engineering analysis of Toyota's 1.8L ZZ series engines for the Corolla. Verbatim, from the SAE paper:
Quote:
The four different chain drive systems shown in Fig. 19 were considered for determining the basic specifications. The timing belt in No.1 is the lightest, though system No.4, which uses a single chain to directly drive both the intake and exhaust camshaft from the crankshaft, has been found to be advantageous. It uses a small-pitch (8mm) chain to make the system affordable in terms of the overall length, the number of parts used and cost. In drive system No.4, it is necessary to provide a wider pitch between camshafts than in drive system No.1 even though the cam sprockets were made smaller by adopting the small-pitch chain. Nonetheless, it meets the dimensional requirements orig- inally planned for 1ZZ-FE and was thus adopted.
They apparently evaluated four different systems. (1) was a rubber timing belt hooked to the exhaust camshaft, with the intake camshaft driven from the exhaust camshaft via a scissors gear. (2) was the same thing as (1), except for a timing chain instead of a belt. (3) was a short timing chain to an idler sprocket, then another short timing chain that drives both camshafts. (4) was a typical single timing chain, turning both camshafts.
The solution chosen (number 4), is 110% of the mass of the timing belt design, but 8.8mm shorter overall. All of the timing chain solutions were 8.8mm shorter than the rubber belt design, but (2) was 126% of the mass and (3) was 121% of the mass. It appears that overall length was the primary factor, and they chose the lightest design that met that factor.
Quote:
The four different chain drive systems shown in Fig. 19 were considered for determining the basic specifications. The timing belt in No.1 is the lightest, though system No.4, which uses a single chain to directly drive both the intake and exhaust camshaft from the crankshaft, has been found to be advantageous. It uses a small-pitch (8mm) chain to make the system affordable in terms of the overall length, the number of parts used and cost. In drive system No.4, it is necessary to provide a wider pitch between camshafts than in drive system No.1 even though the cam sprockets were made smaller by adopting the small-pitch chain. Nonetheless, it meets the dimensional requirements orig- inally planned for 1ZZ-FE and was thus adopted.
They apparently evaluated four different systems. (1) was a rubber timing belt hooked to the exhaust camshaft, with the intake camshaft driven from the exhaust camshaft via a scissors gear. (2) was the same thing as (1), except for a timing chain instead of a belt. (3) was a short timing chain to an idler sprocket, then another short timing chain that drives both camshafts. (4) was a typical single timing chain, turning both camshafts.
The solution chosen (number 4), is 110% of the mass of the timing belt design, but 8.8mm shorter overall. All of the timing chain solutions were 8.8mm shorter than the rubber belt design, but (2) was 126% of the mass and (3) was 121% of the mass. It appears that overall length was the primary factor, and they chose the lightest design that met that factor.
I used to prefer chains over belts, now I prefer ease of service. If everything is easily accessible and there is room to work, I would rather a belt. When belts had to be replaced every 60K it was a nuisance, now with 90+ K intervals I don't really mind. Maybe I have to do it twice during the time I have the vehicle?
It seems that the manufacturers are moving back towards chains en masse, I am not sure if it is due to packaging, price, customer perception, etc. I suspect it is at least partly that they replace the engine as a unit and by the time the timing chain wears out by design, the engine is probably ready to be rebuilt (replaced). In reality, my experience has been that chain guides/tensioners wear out or break causing catastrophic failures before the chains do and before the engines are worn out (DOHC V engines) With a timing belt engine you would replace the idlers/tensioners at belt change.
It seems that the manufacturers are moving back towards chains en masse, I am not sure if it is due to packaging, price, customer perception, etc. I suspect it is at least partly that they replace the engine as a unit and by the time the timing chain wears out by design, the engine is probably ready to be rebuilt (replaced). In reality, my experience has been that chain guides/tensioners wear out or break causing catastrophic failures before the chains do and before the engines are worn out (DOHC V engines) With a timing belt engine you would replace the idlers/tensioners at belt change.
Interesting. I didn't realize Suzuki did I6's
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