Cold Start Timing Rattle Problem
One common problem with Toyota models with the VVT-i system controlling your engine’s timing is that of a growing rattle that becomes increasingly noticeable whenever you cold start your car nearing 100,000 miles on its engine.
Where the Rattle Comes From
Basically, here is what that rattle is about:
With the oil pressure-controlled type of VVT-I timing system, the camshaft position on the intake and exhaust valves changes via a camshaft VVT-i camshaft gear that upon signals from the car’s computer (to an oil control valve) can either advance or retard the rotating camshaft as needed under oil pressure control to ensure optimal performance over a range of RPM values. This is often referred to as “cam phasing”.
Cam phasing is possible due to a two-part adjusting camshaft gear with inner vanes against which oil pressure acts on to either advance or retard camshaft timing. There is also an oil-pressure controlled locking pin within the cam gear that places the cam gear components into either a locked or unlocked state as needed.
Cold start rattle becomes a problem when the cam gear is wearing down internally and the inner components of the cam gear are getting sloppy. For example, the vanes hitting the cam gear body from the inside. A sticking locking pin can cause rattle as well. (For an in-depth dissection of the inner workings of a cam gear used in a VVT-i system, check out this video).
In the best-case scenario, the wear is relatively mild, and you can drive your Toyota without need of immediate repair. However, in a worst-case scenario, the cam gear wear is bad enough that it grenades on you resulting in major damage to the entire timing system including the timing chain guides, the chain tensioner, the timing chain, the camshaft and the valves.
The point here is that when you begin to notice that cold-start rattle don’t panic…but don’t put off its repair too long either.
Two Mechanics, Two Videos on Toyota Engine Cold Start Rattle Problem and Fix
What prompted this topic are two YouTube videos that demonstrate a fix of a Toyota Highlander and Rav4 engine cold start timing rattle problem. The first video is an experienced mechanic who normally does not work on Toyotas but offers a watch and learn demonstration while he is learning how to do the repair on a Toyota. The second video is by an experienced Toyota expert who is doing the same repair on a similar Toyota engine with a VVT-i system.
What makes the videos interesting as a comparison is deciding whether or not the Toyota VVT-i system is a DIY repair a novice shade tree mechanic should attempt.
The first video makes this look like a possible “Yes” given that you understand the repair manual/instructions, take your time and have at least some mechanical experience.
The second video makes this look more like a definite “No” proposition because there are all these little points that if not explained in the repair manual/instructions, can lead to miserable failure.
Related article: Timing Chain and Timing Belt Problems and Repair Demonstrated by Mechanics
The value of the first video is that the host demonstrated an important car repair practice many of us regret not doing: when things are not working, stop and take a break and reassess what is happening before continuing on. Plus, a good point about why the wording on some repair instructions are often unclear and can lead to confusion.
The value of the second video is that it goes into more detail and a slightly different approach to the same repair as the host points out “the devil is in the details” when it comes to attempting this type of repair on a Toyota engine. Plus, the host explains exactly when you should begin to worry about that cold start rattle problem.
That said, watch both videos in order provided (and in their entirety) and you will be sure to learn something new about your Toyota with a VVT-i system and a cold start rattle problem and how repairs should be done to fix the problem.
Timing Chain Rattle Fix for A 2.7L Toyota Highlander
When Should You Fix Your Engine Cold Start Rattle | Important Things That Are Often Missed
The point to all of this is the importance of understanding that with almost any DIY repair it pays to consult multiple manuals and videos to ensure that you have ALL of the information you need to be prepared to do a repair correctly.
For additional articles related to Toyota engines, here are a few for your consideration:
• Should You Buy a Toyota Corolla in 2023? Not This Particular Model Warns Toyota Expert Mechanic
• Toyota V6 Engine Warning for Owners
• The Biggest Problem with the 3.5L V6 Engine in Toyota and Lexus Models Owners Need to Know About
Timothy Boyer is a Torque News automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on Twitter at @TimBoyerWrites for daily new and used vehicle news.
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