Hi all. Got a 2005 Prado (same as the 4Runner) with the 1GR-FE engine in it. 260,000km (160,000 miles) on the clock.

Has the infamous timing chain cover leak over PS pump so have removed valve covers and timing chain cover. Have done a valve inspection while I'm there and one valve is out of spec (one of the cylinder 3 intake valves is 0.30mm – spec says it should be between 0.15mm and 0.25mm). Looking at going the extra mile and swapping the lifter out but never taken chains off before.

Following my Haynes guide which is yet to let me down and have a few questions:

1. The cylinder head cast dots don't align perfectly with the camshaft sprocket dots when the crankshaft key is aligned with the timing line, see pictures below. Maybe 5mm (1/5th inch) off. Does this matter?

2. I've seen folks say to get the marks on the chains to align with the dots before removal. Haynes says nothing like that. Those marks are just to aid reinstallation, right? Not important to have them anywhere in particular before removing? Have gone through several rotations and they won't come to alignment easily.

3. The Haynes guide is VERY specific about not rotating the crankshaft after the chains are off for obvious reasons. However in the re-installation section, it says to rotate the crankshaft back about 45 degrees whilst reinstalling chains then rotate forward again before finishing the main chain. Is this safe? Any advice here? How precisely does it have to end up back in the same spot to avoid timing/explosion issues?

4. Is that valve out of spec enough to warrant the effort of changing the lifter?

5. I didn't take the oil pan off, as per advice found online from others that have done the job, and the Haynes guide suggesting it can be done without taking it off. Anyone had any issues with the seal at that joint when they put it back together?

Thanks all!

Passenger side looks spot on, but driver side should be centered between the two marks on the intake cam sprocket/VVT actuator and it looks a few degrees retarded. Did you rotate the crank backward a bit?

The chain marks are there for initial installation/reinstallation as you stated. There's some math to be done calculating the number of engine rotations needed to get the color-coded endlink plates back on the dots...no value in doing so during disassembly.

I used the factory service manual when I did mine, and didn't see any steps involving rotating the crank backward 45 degrees. I lined up the dots and assembled using all 3 reference points {block mark, chain endlink plate color, sprocket mark} at each component.
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Listed tolerance is the bible, if it's beyond tolerance then it's time to replace.

I didn't remove my oil pan (and front differential) and it worked out fine.

I posted my notes in July-Aug 2018 after finishing the project, including use of gasket adhesive to hold the oil pump pickup o-ring in place during assembly. Notes are here: https://www.toyota-4runner.org/3023099-post21.html

Entire thread may be of use: Timing chain stretch: '07 4Runner

I did mine in July 2018 at 178K miles, it's now at 230K miles and no leaks or other problems since then.

If your timing marks are not aligned after 240k kms, then it's probably due to natural wear and tear and chain stretch. I'm not saying it's stretched beyond specs, just not at factory settings anymore.

Look at the tensioner piston. It's likely to have evidence of some extension.

Thanks for the info! Feedback below

Not right before taking the photo, no. When taking the bloody tight crankshaft bolt off, the pin spanner slipped a couple of times and the crank turned back maybe 20 degrees but after each time I'd rotate the whole thing forwards again. That shouldn't have resulted in this right? When I take chain off and put back on again, should I wind that camshaft back to aligned by hand or just leave it where it is?

Awesome, thanks.

I have the service manual too, I'll go have a look. I find it sometimes lacks detail and I'm certainly not a qualified mechanic, just someone good at following instructions and who has now pulled a lot of stuff apart and put it back together again with no issues to date


Amazing, thanks so much. I'll go take a look!

Pic of tensioner below, not sure what normal extension is?

Pic isn't showing up

Whoops, here it is:

That looks good to me. I can see one band around the piston where it's extended a little to compensate. Timing might be off a bit, but would still be fine.

Thanks! Should I turn the cam that is slightly off back when I have the chains off? Or just leave it where it is?

If you follow the shop manual procedure verbatim, you'll be retracting the plunger completely during reinstallation anyway.

edit: you'll also be rotating the cams slightly while installing the side chains and sprockets. Be aware that valvespring pressure will work against you...there's a sweet spot at the zero mark, and a few degrees either direction will offload pressure and cause the cam to rotate quickly. Keep a hand on the wrench you're using to rotate/hold the cam.

As the other guy posted, the telltale black ring shows the plunger has extended by one ratchet tooth to compensate for chain elongation. This is fine. Your call whether you want to replace the chain while you're in there ($192 or so for a Toyota replacement). I wouldn't, given the minimal wear indicated by the tensioner.

Thanks. Yeah no plans to replace timing chain. Just wondering if, when the chain is off, I should get the camshaft sprocket marks perfectly aligned while Cylinder 1 is at TDC and crankshaft pin is aligned with timing mark? Or should I leave the camshafts and crank shaft precisely where they are and just install timing chain again as is?

See my edit above. Put all timing marks on zero including the exhaust cam sprockets before installing the chain.

Also soak the chain in clean motor oil prior to re-installing it.

Ah ok, so the camshaft, in some ways, will want to self-centre on zero anyway if it's slightly off?

The opposite...when you rotate past the tipping point of valvespring pressure balance, that sucker will rotate wildly away from zero.

Haha ok got it. Will make sure it comes back to zero before doing anything else with it then. Last thing I need is it getting a mind of its own and smashing a valve into my nice TDC piston. Maybe that’s why Haynes suggest winding the crankshaft back 30-40 degrees after taking the main chain off. I assume that, as long as the camshaft is at zero, removing the camshaft to change a lifter won’t result in any sudden twists either? I realise there is a certain order I have to loosen the bearing caps in...