It's a known fact that some modern Toyota vehicles, with Toyota's VVTi cam gears (or phasers, according to Ford motors), have been known to make such rattling noises, on start-up anytime the engine is cold.

This problem, has been diagnosed mistakenly in some climes, to mean, a bad engine, that needs urgent replacement.

Some have also diagnosed such noise on start-up, to mean, that the oil pump or connecting/crankshaft bearing caps and/or crank journals are failing.

With the cost of goods and services increasing daily, motorists would be happy, to get an alternative to engine replacement, if such situations presents itself.

Some symptoms of this problem?
1. Well, on start-up, when the engine is cold, a rattling noise comes from the top cylinder area of the engine.
If you're not careful, would mistaken this noise for engine knock.

2. No matter how you keep changing engine oil viscosities, thinking, a more viscous oil would make any change.

3. The noise gradually increases, and could lead to engine damage(siezure), and engine replacement.

So how do you fix this?
1. The ultimate fix to this is to order a BRAND NEW CAMSHAFT VVTi gears or phasers for the intake and exhaust.
Ensure the part number on the gears matches that recommended by Toyota.

CASE STUDY
Car: Corolla 2008
Transmission type: Autos
Engine capacity: 1.8L

Customer complaint:
At every cold engine startups, rattle noises occurs, and disappears, within seconds, until, another cold cycle start-up is required.

TRYGO:
It's a known fact that some modern Toyota vehicles, with Toyota's VVTi cam gears (or phasers, according to Ford motors), have been known to make such rattling noises, on start-up anytime the engine is cold.

This problem, has been diagnosed mistakenly in some climes, to mean, a bad engine, that needs urgent replacement.

Some have also diagnosed such noise on start-up, to mean, that the oil pump or connecting/crankshaft bearing caps and/or crank journals are failing.

With the cost of goods and services increasing daily, motorists would be happy, to get an alternative to engine replacement, if such situations presents itself.

Some symptoms of this problem?
1. Well, on start-up, when the engine is cold, a rattling noise comes from the top cylinder area of the engine.
If you're not careful, would mistaken this noise for engine knock.

2. No matter how you keep changing engine oil viscosities, thinking, a more viscous oil would make any change.

3. The noise gradually increases, and could lead to engine damage(siezure), and engine replacement.

So how do you fix this?
1. The ultimate fix to this is to order a BRAND NEW CAMSHAFT VVTi gears or phasers for the intake and exhaust.
Ensure the part number on the gears matches that recommended by Toyota.

2. To be continued

currently got this issue with a highlander under my care.
my question is, isn't possible to get a used one considering cost of the part?
also can this brand new part be sourced in Nigeria?

@automoto. You can get a used one, but you got to be careful with the part number, considering that, the used one you might get, could be same defective one too.

Diagnosis
Diagnosis/fix:
1.Replicated the problem, and sure enough, it occurred again.
2. In this case, there wasn't a check engine light on the dashboard. This tells you, this fault was a mechanical one, which necessarily wouldn't trigger the light.
3. Engine was turned inorder for #1 piston to be at TDC(top dead centre), making sure that valve cover (s), removed.

4. Be organized, and pay attention to the timing marks on the camshafts, and crankshaft pulley marks.
5. Loosening the camshaft bearing caps was started from middle to outside.
Always be careful when loosening the 10mm/12mm, so they don't get snapped.
6. Use some kind of robe, to secure the timing chain, after removing the auto tensioner, to prevent it from slipping into the engine.
7. After removing all the camshaft bearing caps, and placing them somewhere, in an organized way, slide, and remove the camshafts.
8. Used a 17mm socket wrench, to break loose the bolt fastening the camshaft gear to the solid shafts, before fixing the new one

PS: apply some silicone grease to the new camshaft gear, before affixing to the camshafts.

9. Install the camshafts, and cross check everything you've undone in the reverse way this time around
10. After parts replacement, engine started, and allowed to run for a few minutes.

That's the engine camshafts, etc, exposed.

Intake/exhaust camshafts, with the new camshaft gears installed

Figure shows the removed camshaft bearing caps, and how placed side by side in an organized manner.
Don't mix or interchange the positions when arranging.

Figure shows the replaced camshaft gears, and where I positioned the robe used in fastening the timing chain, and tightened it on one portion of the bonnet.
I don't need to spend much time, removing the timing chain cover. You can actually replace or do a job like this, without the timing chain pulled off.

Intake/exhaust camshaft gears shown replaced.

Old or bad camshaft gears removed, and placed side by side.

How new camshaft gears looks like

Cam gears

Old and new cams placed side by side, ready for installation

New and old camshaft gears

Total cost 150k. Mechanic don hammer like 60k inside. Camshaft at least 50 60k, gear oil.

TRYGO:
New and old camshaft gears

I have this same issue with my Highlander, my mechanics can't seem to understand it, some say it's oil pump, some say it's tarpet valve
I think this your explanation is the solution
Thanks for sharing

@mikkyjay. Great you found the write-up, encouraging.

Good job

What is the total cost of this repair

Cokahot:
Total cost 150k. Mechanic don hammer like 60k inside. Camshaft at least 50 60k, gear oil.

Which gear oil?

Oando dextron IV oil,same wit toyota IV

Dozieson:


Which gear oil?

Cokahot:
Oando dextron IV oil,same wit toyota IV

He didn't work on the gear? So why buy gear oil ?

He wanted to loose my engine,instead of taking rhe passengers carpert out,he went towards the gear middle plastic ,broke it and lied thatbwas hw it was. I jus taya for all of them. My gear tube connecting to the radiator was faulty,had it been I know I would have loosed it myself. The quack mechanic took out my gear and still scammed me. In the end,the gear is now too sharp. If I put it in drive,it will be too sharp. I just taya and I dey drive am like that,dey find buyer.

Dozieson:


He didn't work on the gear? So why buy gear oil ?

How much is this camshaft for Corolla 2004 pls?

Cokahot:
He wanted to loose my engine,instead of taking rhe passengers carpert out,he went towards the gear middle plastic ,broke it and lied thatbwas hw it was. I jus taya for all of them. My gear tube connecting to the radiator was faulty,had it been I know I would have loosed it myself. The quack mechanic took out my gear and still scammed me. In the end,the gear is now too sharp. If I put it in drive,it will be too sharp. I just taya and I dey drive am like that,dey find buyer.

E be like say rewires, mechanics and electricians wan send you go village. They simply substitute one problem with another for you.

Bro all mechanics are quacks. U can't be thr with them 24/7. The moment u leave their sight,na spoil

Blacklaurel:


E be like say rewires, mechanics and electricians wan send you go village. They simply substitute one problem with another for you.

This is a common problem with Corolla 2010. Bought mine with this same problem from onset as a tokunbo back in 2019. I got criticized that engine was going to get knocked in 6 months. Went on toyota forum and most people with similar problem said they have been using car like that for years without any issue. Those that attempted to fix theirs (even with Toyota dealership ooo) ended up having bigger issues.
My Corolla still runs like a dream till date. Rattling sound still comes up on every cold start.
I don't think that should be fixed if nothing is broken.

@walexyll. Clients are different. Your comments, kinda suggest a client with a mindset of, "if e no go stop me for road, make e de there like that".
It may be fine with you driving the car with the rattle like that, but this client, just detests that noise always coming up when engine is cranked.

Insightful

Case Study of fixing a cold start uprattle noise on a VENZA TOYOTA 1AR 4 cylinder engine.

I have had encounters with some of these engine types, found on some Rav4s, and even on the 2012 camry. 2ARs.
The noise on cold start is just so terrible and annoying.
The major cause of this noise is as a result of defect. In the INTAKE CAMSHAFT gears in these engines.

You can opt to replace on the intke camshaft gear, or better still, if i will advise, is to replace both the intake and exhaust camshaft gears, in pairs.

For this particular Venza, it was for a user on NL, who i encouraged to purchase a brand new camshaft gear, including the timing chain upper damper,on ebay, instead of risking using old or used part from the open market, as a replacement part.

Everything costs the client, about close to #250'000, just in parts, without labour, and an ~ 2_3 weeks delivery to Nigeria.

The 2012 Toyota Venza 1AR engine with hood opened