2.0 Vvti Timing Chain - Job Halted By Unexpected Hitch

[GavinML]

Hi there,

My family car is a 2002 Avensis Verso 2.0VVTi with 1AZ-FE engine at approx. 85,000 miles. The car has had regular oil & filter changes but does a lot of cold starts and short journeys. A recent worsening rattle from the LHS of the engine has prompted me to inspect/change the timing chain, tensioner, etc. as needed.

I'm just about at the point where I can remove the LHS of the engine. However, the Toyota tech docs state that the drive belt tensioner assembly must first be removed. The problem is that the pivot bolt for this assembly is too long! I have backed it out by about 20mm, to the point where the head of the bolt is now making contact with the bulkhead and cannot be unscrewed any further. The bolt in question is indicated by the upper arrow in this image from the docs:

And here it is backed out as far as it can go ...

Am I missing something here?! Having removed 13 of the 14 bolts around the edge of the engine cover, access to the last one is now obstructed by this assy and I'm not sure if I'll be able to remove it. I suppose I could cut the tensioner assy pivot bolt but that surely isn't necessary!

Even if I can get to that 14th bolt, it doesn't look as though there would be enough wiggle room to remove the engine cover with the tensioner assy attached.

Has anyone else encountered this problem and solved it? As a newbie here, any advice would be greatly appreciated. Whatever the solution turns out to be, I will make sure to post again to let readers know ... though hopefully somebody here will provide the solution ready made!

Thanks,

Gavin

[alan333]

Figure out which engine mount you need to remove to allow you to move the engine over a bit out of your way. Carefully use a lever to assist movement if necessary.

[t-spiritpete]

Hello,

can you not just take the chain tensioner out first and check if that's ok. It does look like the r/h engine mount will need to removed to get the belt tensioner off, if you can DO NOT turn the engine.

Click on the drawing to enlarge it.

Pete.

[t-spiritpete]

Hello again,

you may have this but if not this is the engine manual attached, it covers all engine types.

Pete.

ENGINE MECHANICAL.pdf

[GavinML]

Thanks for your replies and the images/docs, much appreciated! OK, I managed to remove the bolt and tensioner assembly.

I used a breaker bar for leverage (carefully!) between the bulkhead and the beefy part of the engine cover to which the LH engine mount attaches (i.e. the protrusion above the tensioner assy bolt in my earlier pic). Thankfully, I didn't need to remove the RH engine mount. There was just enough give in the RH insulator to allow a gap of 2-3mm to be created when some leverage was applied. That was enough to finish unscrewing the bolt and free the tensioner assy. Thanks again guys, I'm back on track now.

Regarding the suggestion to remove only the tensioner ... I'm now at the point where the LHS engine cover can come straight off. So what do you reckon? Bearing in mind the effort needed to get this far, I'm inclined to keep going now and just replace the chain as a precautionary measure, along with anything else in there that looks like it could do with freshening up (e.g. tensioner slipper, vibration damper). However, maybe some other significant hurdle awaits me there - if there are any you're aware of, please let me know and I may reconsider.

I see there's another smaller chain driving the oil pump. Am I correct in thinking that this is unlikely to need any attention? I haven't seen any problem reports relating to this item.

If you have any other tips or advice about completing this job, they would be much appreciated.

Thanks again,

Gavin.

[Druid Boy]

If it was my car, I wouldn't bother with the chain driving the oil pump. It isn't anywhere near as stressed as the timing chain.

[antony17]

Hi there,

My family car is a 2002 Avensis Verso 2.0VVTi with 1AZ-FE engine at approx. 85,000 miles. The car has had regular oil & filter changes but does a lot of cold starts and short journeys. A recent worsening rattle from the LHS of the engine has prompted me to inspect/change the timing chain, tensioner, etc. as needed.

I'm just about at the point where I can remove the LHS of the engine. However, the Toyota tech docs state that the drive belt tensioner assembly must first be removed. The problem is that the pivot bolt for this assembly is too long! I have backed it out by about 20mm, to the point where the head of the bolt is now making contact with the bulkhead and cannot be unscrewed any further. The bolt in question is indicated by the upper arrow in this image from the docs:

1AZ-FE_Tensioner_Assy_TechDoc.png

And here it is backed out as far as it can go ...

1AZ-FE_Tensioner_Assy_480x640.JPG

Am I missing something here?! Having removed 13 of the 14 bolts around the edge of the engine cover, access to the last one is now obstructed by this assy and I'm not sure if I'll be able to remove it. I suppose I could cut the tensioner assy pivot bolt but that surely isn't necessary!

Even if I can get to that 14th bolt, it doesn't look as though there would be enough wiggle room to remove the engine cover with the tensioner assy attached.

Has anyone else encountered this problem and solved it? As a newbie here, any advice would be greatly appreciated. Whatever the solution turns out to be, I will make sure to post again to let readers know ... though hopefully somebody here will provide the solution ready made!

Thanks,

Gavin

Hi Gavin

I have the same problem on my Avensis you dont fancy doing another one do you or know a good mechanic who can sort for me? Antony 07557 434240

[GavinML]

Hi Antony, I'm based in Dublin, so unfortunately I'm not in a position to help directly. I tried to call you but couldn't get through. I've PM'd you my mobile number, if you want to chat.

Replacing the timing chain is an awkward and labour intensive job, so be sure you know what you're getting into if you're going to do it yourself. There are a couple of particular challenges along the way.

Also, I have an embarrassing admission to make. After all the hassle of replacing the chain, I turned on the engine and the damned rattle was still there!! It turned out to be the water pump, which was a whole lot easier to change. Lesson learned: focus more on the diagnosis before starting work!

On the other thread which you started, fastbob72 recommends ruling out the ancillaries driven by the external belt. I would absolutely follow that advice before proceeding with work on the timing chain.

The external belt drives the alternator, water pump, power steering pump, air conditioning compressor and the idler wheel attached to the belt tensioner (at least that's the arrangement on my 1AZ-FE engine). Remove the external belt and then start the engine. If the rattle is absent, then you know it is related to one of those items. Obviously, don't leave the engine running for too long, since it has no cooling with the belt removed.

Like I said, you're welcome to give me a call anytime. I'm quite happy for someone else to learn from my mistakes!

Good luck with the job.

Gavin.