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2003 Toyota Rav4. 4 cylinder, 145k miles. Recently started making a ticking noise. Noise only happens on startup and for about 15 minutes and ONLY when under load. So, start the car and fast idle sounds normal. Put it in gear and start pulling away and you hear ticking. Not rod knock. Clicking sound like playing cards in your bicycle spokes, but louder. Push in the clutch, get off the gas at a stop or going downhill, no ticking, no backfire, nothing; clean idle. Engine gets hot and you don't hear it after that. Obviously little worrisome and annoying.

Tried: Ran oil flush/refill, still ticking. Tried thickening oil with STP - still ticking. Reloaded with straight (non-ethanol) gas - still ticking.

Plugs were replaced and the air filter was also replaced. I've done all I can think of that's fairly easy. Any ideas? Only things I can thing of is to try cleaning the throttle plate, MAF, cold air throttle positioner.

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    Have you checked for an exhaust leak where the manifold meets the head? This can give a ticking sound much like you're describing. When the manifold is completely hot, it might be enough deformation to seal the leak and stop the tick. Look for black carbon traces around each exhaust outlet. Mar 17, 2018 at 12:36
  • Okay, couple of votes for exhaust leak. I'll try and get my flashlight and mirror out. I did have two failed O2 sensors so it is a real possibility. Not sure if they pulled the header or just unscrewed the sensors. I'll post if I see anything. Mar 18, 2018 at 10:00
  • Just to be sure, the ticking tracks engine speed?
    – George
    Nov 1, 2020 at 2:39
  • One possibility that would get worse under load and maybe disappear when warm is piston slap. However, you'd probably hear it during cold idle too.
    – juhist
    Oct 22, 2022 at 8:10

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Really sounds like a manifold leak. There are other things that can do the same and go away once the engine is warm too, Rocker Arm knock (5.3 are famous for them) and the infamous ford tick with is lifters. Both of these are irritating but can go on for years with no issues to speak of.

Toyotas are pretty solid and I don't really see a lot of engine issues with them at work.

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