Timing Chain Setting

Why ??

 

Sprocket marks line up one every other turn of crank, like in every 4-stroke piston engine. Chain to sprocket may take tens of rotations.

But why are you replacing lifters? They are solid.

 

All right, I'm feeling sheepish now because I'm absolutely sure I went through that exercise some time around 3 years ago, and just now I thought "easy! I'll just search out the thread where I posted it back then" and I can't find it at all. Looks like I didn't post it at the time, and where those notes are now, I'm out of ideas.

So ... if you don't mind redoing it ....

Count the teeth on one cam sprocket, call the number T.

Count the links in the chain, call the number L.

Find the greatest common divisor (gcd) of T and L, call it G. If rusty on finding gcd, see Euclid's algorithm.

Divide L by G, call the result Q. Q is the number of full turns of a camshaft from where the marked links line up until the next time they line up again. So, in the very worst case (the engine was just past that point when you took it apart), you would need Q-1 camshaft revolutions to get back there.

The crank spins twice for each camshaft rev, so in terms of crank revolutions, 2Q-1 in the very worst case. If placing an even-money bet, you should bet on succeeding within the first Q crankshaft revolutions.

I really wish I had posted the result, because IIRC neither the tooth count nor the link count were in the manual, and I had to hunt them both down by googling for aftermarket parts that listed the spec (or had good resolution images I could count from), which was a PITA. So when you've got the number, please post it!

You sound like you know what you're doing ... I trust you've carefully noted the steps in the manual that are devised to make sure you never pass any piston within ±40° of TDC until the timing is properly set, unless the cam bearings are loosened enough to unload the valve springs.

-Chap

 

Set the crank and cam marks to their datum marks. Install chain making sure it's taught between the non tensioner side. Adjust tensioner. Rotate two full crank rotations and ensure marks realign.
Chain marks in relationship to sprockets is immaterial


iPhone ?

 

Presumably the OP's engine has logged many miles (well into six figures) and he is adjusting camshaft clearance by replacing the lifters.

 

Brilliant.
Unless he is putting back in stock lifters and the wear is on the cam.

 

Valve clearance in the 1NZ-FXE is adjusted by choosing the correct height of stock lifter for each position. They don't use separate shims.

-Chap

 

I'm sorry to hear of this problem. Do you have a sound file of the noise? Any information on when it is louder or softer? Do you have compression or leakdown test figures for the engine?

Out of curiosity, can you describe your experience in doing the valve adjustment? How long did it take you, and were there particular difficulties you encountered? When I was considering doing a valve adjustment, I was afraid it could be very difficult to loosen the plug over the tensioner lock, and very difficult to guide tools into it to release the tensioner, just because of the tight clearance to the wheel well. Can you describe your methods?

When I was considering the job, it appeared to me that it might not be less trouble than replacing the engine. I'm impressed that you took it on.

-Chap

 

1. Start with basics: check cylinder compression using Mini VCI to run the Toyota Techstream commands to spin the engine for a compression test, and a cylinder compression gauge. Let's see the extent to which the engine is worn after 270K miles.
2. Excessive noise could be due to excess play in a bearing, but that by itself would not cause reduced engine inefficiency.
3. Check the iridium spark plugs and replace if the gap is more than 1.1 mm or if they look like they have problems such as excessive deposits

 

Probably need a leak-down test too to check for badly worn or warped valves.
Does it have conventional valve springs........that could be weak or broken.

 

They're conventional springs, if a shade lighter than normal, as it never revs high.

I would be interested in a sound file of the noise.

-Chap

 

That sounds VERY much like an exhaust leak to me........and NOTHING like lifter noise.......and probably not a loose bearing either.
Hard to tell without being there though.

I once completely rebuilt all 16 hydraulic lifters on a 283 Chevy engine......only to find out later that the tapping noise was coming from a broken spring in the fuel pump.

 

Maybe something related to the EGR system?

 

Prius doesn’t have (or need) EGR system.

 

That's surprising. The Gen 3 definitely does in North America.

 

I didn’t know gen 3 had one. But it’s not important here since we are talking about gen 2.