wrong valve timing from the factory?

[friendly_jacek]

OK, I took valvecover off to get ready for valve clearance check and to replace slightly leaking gasket. I was surprised how clean everything was. The car is 03 Corolla with 86,000 miles.

But here is my problem. The marks on the camshaft gears don't allign with the marks on the timeing chain. I'm the original owner and as far as I'm aware, no engine work was done. The engine runs fine, except for a bit disappointing MPG.

See the picture. Any ideas? Should I redo the chain timing if it's only one tooth off?

this is how it should be:

 

[spasm3]

Ignoring the chain,do the marks on the pulley line up when the crank is aligned. If the gear/pulley marks line up when the crank is alignment, then the chain itself will not make a difference. The factory may have aligned all the pulley marks and just did not pay attention to the chain marks. If the pulley and crank dots don't line up then you have a problem!

 

[Drew99GT]

What the...

I'd search around intensively before doing anything. I may do some searching myself just to see if this is a known issue. That is weird!

What about the other marks that should line up right next to each other in the middle of the gears? I can't see them; are they off?

I'd imagine if the cam timing was actually that far off, it would affect driveability, but maybe the intake cam phaser is making up for it.

 

[kr_bitog]

Actually for Toyta the mark on chain is used to id the position too. I believe since you have poor MPG, you should fix it. If it slips more than 1 teeth, more likely you will already notice bigger problem either the engine difficult to start, stumble or your internal hit each other.

 

[Drew99GT]

I think I can see the other 2 marks and it does in fact look like both cams are off by one tooth. The intake cam looks like it needs to go forward a tooth, and the exhaust back a tooth! Are you positive the number one cylinder is at TDC compression?

 

[GSCJR]

Ignore the chain marks, crank and cam marks are what counts. The marks appear to be way off from the pic. Are you sure your crank is bang on?

I once had a 1.8L VW that had this hesitation under acceleration from a dead stop or just in neutral when you would snap the throttle. It was at the dealer many times to try to correct it and other ghosts, while still under warranty. After many new parts and 3 frustrating years of my life I will never get back, a VW specialist repair facility with my assistance helped me trace and repair the problem. The camshaft timing was off from the factory. I also replaced the CTS to remedy an intermittent lack of power.

 

[rshaw125]

Not on a Toyota but on an Intrepid in the 90's. A friend and I had almost identical cars with the 3.5. His never ran as good as mine. Less power etc. The timing belt had the cams off one 'tooth'. The dealer actually figured it out and fixed it under warranty.

 

[Drew99GT]

Oops, I forgot the intake and exhaust side of these engines are different than the AFE Corolla engines. The intake and exhaust cams look like they are both forward 1 tooth.

 

[LeakySeals]

2 sets of aligmnet marks, don't confuse them! Its the one with the etch on the controller. Also I see perhaps you could use a new hydraulic chain tensioner.

 

[friendly_jacek]

Originally Posted By: LeakySeals
Also I see perhaps you could use a new hydraulic chain tensioner.


Why is that?

I was cleaning everything and din't align the crank yet. I was hoping I can move it without taking wheel off but can't see how.

 

[LeakySeals]

Originally Posted By: friendly_jacek
Originally Posted By: LeakySeals
Also I see perhaps you could use a new hydraulic chain tensioner.


Why is that?

I was cleaning everything and din't align the crank yet. I was hoping I can move it without taking wheel off but can't see how.

Compare your chain to the chain in your diagram and this pic. Or maybe you are off a tooth, why the chain appears to be loose. But I find that hard to believe. You have a vvt-i, should cause noticeable problems.

 

[friendly_jacek]

Thanks a million!

Good news. I was able to crank it by rotating alternator pulley (the belt slipped only some). After aligning the crank, the marks on gears are in correct positions. Looks like the person installing the chain at the factory didn't pay attention to the color marks on the chain. The chain is also stiff with no slack at this time.

Now to measure clearance.

 

[LeakySeals]

Me guesses the exhaust sides a lil' tight but overall its probably good.

 

[[email protected]]

Glad your timing wasnt off and just wanted to comment and say that engine looks pristine! You can barely even see any visible wear on the cam lobes and definitely little/no varnish

 

[friendly_jacek]

I got the clearance numbers. They are all at the upper limits, except for one intake valve slightly more than the limit (only by 0.03mm). I'm not adjusting yet. Will reevaluate in the next 90,000 miles or so and they will be probable all too loose. I'm happy the valves are not wearing tight on this one.

By the way, more pictures:

 

[Drew99GT]

Apparently it's a PTIA to adjust the valves on those because they don't have shims. It's a good thing they aren't getting tighter, especially the exhaust. That's the only thing that will cause a major engine problem is if the exhaust valves start getting tight.

I'm glad the timing isn't off; I assumed you had it at TDC!

 

[mechtech2]

I see two teeth off from the marks.
But that does not mean the cam timing is off, just that the marks [helpers] are off.
Sure, investigate more. Who knows what is really going on.

 

[SubyRoo]

Any time you set the timing on any engine once it has been rotated the timing will be right but the marks wont line back up again until several rotations later. Think about how far the chain has to rotate versus how little the cam gears do in comparison.

 

[friendly_jacek]

Good point. I noticed that myself when I rotated the engine several times. The initial picture was where the engine stopped and that confused me. This is the first time I opened valvecover in engine with chain.

One thing I learned from this was how camshaft lobes were always covered by a layer of oil after turning the engine several times and without oil pressure. Oil collected in buckets above the solid lifters. Great engineering.

Thanks you all for the great comments!

 

[RamFan]

Originally Posted By: friendly_jacek
I got the clearance numbers. They are all at the upper limits, except for one intake valve slightly more than the limit (only by 0.03mm). I'm not adjusting yet. Will reevaluate in the next 90,000 miles or so and they will be probable all too loose. I'm happy the valves are not wearing tight on this one.

By the way, more pictures:

And you're not going to tell us what oil and oci you've been using???