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Spoke with a gentleman with over 500,000 miles on his 1st GenXb.Says he changed his timing chain at certain mileage intervals (can't remember if he said this was a factory/dealer recommendation )Anyhow ,his motor is still running strong.If I chose to do the same,how difficult /easy is it to change and any special tool requirement that might offset the cost of having a shop do it?
 

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Since you seem he!!bent on unnecessarily replacing the timing chain, the FSM process is pretty involved, including removing the head, oil pump, water pump, and crank pulley and damper. Book time for a shop is probably in the neighborhood of 8-10 hours. From past experience with other repairs, you can expect a first-time DIY to take at least 2-3 times as long. The FSM lists special tools for the crank bolt and the crank pulley.

The official Scion Maintenance Guide makes no mention of the timing chain at all, so the recommendation probably came from a dealer looking to pad its service income.

With dealer labor rates at $100+ an hour, and dealer parts markup, you'll pay just as much for one timing chain replacement as you would to have a trusted independent shop install a junkyard engine with a warranty (ballpark of $1300-1700).

Replacing a timing chain on an engine with no history of problems with that component is overkill. If the 1NZ-FE had a history of timing chain or tensioner failures, I could see treating it like a belt and replacing at set intervals. But that is not the case.

In the end, it's your car. Do what you want.
 

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Discussion Starter #3
Thanks for the though and obvious (has done your homework) response.Its a no brainier ,no(maintenece) replacement of chain for me! Like you said only if it needs it ,but then again ,I would take your advice as well on getting another motor at one of the yards. Curious ,what are the signs of a necessary replacement , in your motor or if you were to buy another XB? I'm assuming ,misfiring ,and unable to time it?

---------- Post added 12-06-2015 at 02:39 PM ----------

Probably ,also , noise in that area?And also you probably have to take a number of things apart to confirm?
 

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I agree with Steve. I've got many years experience with the Toyota product line and have yet to find a routine replacement of the timing chain. I have seen an occasional timing chain tensioner needing replacement due to oil leaks but not from mechanical failure but this was on the 1ZZ-FE motor.

The 1NZ-FE motor is probably one of the most reliable Toyota engine I have seen. If an issue sprung up and the need for major engine repair is needed, I think a used engine would be your best bet vs. the labor time required to replace the timing chain.
 

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A break would hose your engine. Worn chain, tensioner, or guides would be more gradual. Initially, you might have rough idle or a misfire. You might hear the chain hitting the walls of the oil pump assembly, especially on startup (aka death rattle). Things will get progressively worse.

I don't have the space or the tools to do an engine removal and re-installation, so my threshold for seeking professional help is when all the diagnostics for relevant sensors, electrics, and small mechanical bits come up empty, or when I've completed the steps a moderately-skilled DIY mechanic can do and there are more left that require knowledge, tools, or skill I don't have.

---------- Post added 12-06-2015 at 10:14 AM ----------

I agree with Steve. I've got many years experience with the Toyota product line and have yet to find a routine replacement of the timing chain. I have seen an occasional timing chain tensioner needing replacement due to oil leaks but not from mechanical failure but this was on the 1ZZ-FE motor.

The 1NZ-FE motor is probably one of the most reliable Toyota engine I have seen. If an issue sprung up and the need for major engine repair is needed, I think a used engine would be your best bet vs. the labor time required to replace the timing chain.
These are not terribly sophisticated engines by today's standards, so you won't need some specialist guru to handle difficult repair jobs. Just about any competent, experienced mechanic will have plenty of skill to tackle nearly any job. The engine has been in production largely unchanged for 15+ years, with VVTi as the only complex system you don't see on basically every single other engine in America.

In the 4.5 years I've had mine, it's seen a shop for tire installation and my state's biennial inspection (and I had a mobile electronics guy fix a broken wire on my cruise control install). I've done everything else myself in my driveway or garage - fluids, filters, brake pads, spark plugs, water pump, hoses, thermostat, exhaust, shocks, struts, a battery, aftermarket seat heaters, a new stereo head unit, and nearly all of the cruise install. I don't have an extensive tool set, but I've bought a few as needed when it would save me money.
 

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The timing chain gets noisy once in a while until the tensioner goes to the next tooth.Then it will be quiet again for a while. When the noise will not stop that's the time to replace the chain, guides, tensioner .... before it jumps time and the pistons strike the valves. If that happens you will have to remove the head. But if you replace the chain before that happens you do not have to remove the head only the valve cover and timing chain cover. This can be done with just a few metric wrenches .The space between the engine and the frame is only about 3"...So it is a tight spot to work in. Good luck
 
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