Sharing Experiences: Airtrek Turbo 4G63T Timing Belt Replacement


3,000 RPM
Senior Member
May 27, 2009
This was something I shared in MLOC last time as we do not have a thread in ZTH. So now, I am reposting this here, just in case some of you have not read this before.

Since Evo engines are 4G63T which is similar to my Airtrek Turbo's engine (essentially detuned 7.5 GTA motor), I thought of sharing my experiences with timing belt change.

I changed my timing belt back in June 2009 at a reputable tuner/workshop in Klang Valley. I still remembered after the change, there was substantial power reduction. Boost dropped from standard 0.7bar to 0.5bar. I was then advised to add a manual boost controller to increase the boost to 1.0 bar. Was happily driving the car for almost a year.

Yesterday, I went to another workshop which is well known of repairing Airtreks/Evos near Balakong. I was there to get the qoutation of engine mounting change as I could no longer bear with the engine vibration, worsen when the boost kicks in.

When my car was tested by the mech, I was being told that the timing belt I changed previously was installed wrongly. One of the gear at the lower part of the engine (which is supposed to be a balancer) was not callebrated corrected to the timing belt during installation, hence the bad engine vibration during idling and acceleration. When boost kicks in, the engine felt very very rough.

After opening up the timing belt cover, we got another shocked. Apparently the previous timing belt replacement, a wrong bearing was used, causing the bearing edge to eat-thru my timing belt! Haiyo... anyway, cut story short, I have to get a set of new timing belt (despite I've done less than 10K only for the past 1 year) and new bearing for my car. Pictures will tell everything.

Correct gear syncronization not only solves the vibration problem, but the engine felt so smooth and quiet now, even during hard acceleration. It is more powerful too at lower end and car felt very willing to go. So to all, if you felt your 4G63T vibrates badly during aceleration, high possibility the timing belt is not installed properly.



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First time (when it was installed wrongly)
- Timing belt set, main belt, belt tensioner (mine broke) and labor = RM1175

Second time (the above correction)
- Timine belt only, timing belt bearing (as said above) and labor = RM405
Just like mine... After sent to Ah Wa, it's back to ori!
It happen to me also...think about 2 mths ago... engine became very sluggish and a lot of vibration....brought the car to Ahwah, changed the bearing...voila....problem settled....
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