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Engine knock at take-off

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  • Engine knock at take-off

    Hi guys. My Fortuner has about 4000k on it now, Ever since I bought it it has what sounds like a heavy diesel knock when taking off from stopped. It is a manual and this pretty much only happens as I take up the load on the clutch as I take off. Sometimes it happens as I change into second at really low revs with engine under load. Took it to dealer and was told it was an engine sound and no problem. I have been driving diesels for years and never had this problem . Sometimes when the engine heats up it almost goes away, but never totally. When cold it is a loud, very loud knocking sound till the clutch is released. As engine warms up it starts to go away. Some times it does but most times it is still present at a quieter level. Sometimes a quiet knock is even present while driving. It's really a cross between a knock and a rattle. Probably a bit difficult for dealer to diagnose because by the time I get to the dealer the engine is hot and the knock is now quieter more normal. This is a knock knock sound not a tapping sound. Any one else having this happen as if others are having the same sound it is normal, although hilux users (same engine and clutch et) apparently don't. The car has a tow bar fitted but has as yet not towed anything at all, so is not a vehicle abuse or overloadng problem. It is an as delivered to me condition. Vehicle had 40 km on odometer and 23 km on the trip meter. I would doubt it was caused at the dealership there fore and would be an off the production line condition if one exists. Any help or advice or suggestions appreciated.
    Last edited by davidd; 18-12-2015, 10:26 AM.

  • #2
    Hey mate, that does not sound good at all, I guess if the dealers haven't found anything then I guess you will just have to closely monitor and if it gets any worse I would take it back and get it seen to again. I have heard something similar to what you are describing when an FJ cruiser puts the crawl control on, but that is auto and suppposedly normal as well and although it sounds pretty hectic it does no harm.

    Unless anyone else has ideas?
    Fortuner Forum Default Signature!


    • Wiza
      Wiza commented
      Editing a comment
      Davidd, I hear the same knock in the Crusade. I have noticed it though when pulling off. The same sound is made by the towbar's tow ball fitting that has a little play in the tongue (hope that made sense)...when ever u go over a speedhump it makes the same knocking sound. I think half of what you hear is from the towball moving in the tow bar. My Triton had a bolt you could tighten to take up the slack. The Toyota towbar doesn't have the bolt.

  • #3
    Hi mate. This not a bit of a quiet knock at the rear, and the tow ball is stowed not fitted in place. It is a loud noise (very loud) coming from under the vehicle and forward of the drivers door. With window wound down it is even louder and sounds like a mechanical knocking sound not a diesel knock. It only occurs while the clutch is being released pretty much. It can be heard plainly by anyone standing alongside the vehicle as it moves off. So far approaches to the dealer have met with no result sort of evading giving an answer or muttering something about coil spring rear end which i would say is total rubbish. I've had all coil suspension vehicles and other Toyota coil spring vehicles don't make this racket. The noise frequency seems in synch with the engine as if from one cylinder only. But thanks for your input.


    • #4
      Maybe take another manual for a test drive at the dealership. See if they make the noise too? To me it sounds like a bit of play in the driveline, when you release the clutch it has a small amount of slack before having a solid driveline. My old jeep used to clunk like that when the uni joints were a bit worn


      • #5
        Thabks mate. Any techies or mechanics on the forum please???


        • #6
          Hello, I got similar problem as you, my crusade auto is around 4000km, I did notice the sharp sound many times within 1000km new car check, then I wrote a describtion letterto dealer about this problem to dealer at 1000km check, but they told me everything is normal and engine is normal, the problem I got as follows:

          Several times engine sound suddenly louder than usual when press accelerator pedal.

          At same time, I can feel a little bit vibration when the noise happen, especially at accelerator pedal.

          When it happen, feel power is not enough, need to press accelerator more deeper, but more deeper more louder.

          Originally, I thought might be gear changing problem, but after driving some distances, personally, I think gear might be ok, or might be other reasons.
          ( normally, if gear is in low position, people will feel not enough power and more noise coming from engine),

          But it feels a little bit different from that, the gear changing seems ok, but nosie still come out.

          Turn off engine, restart again, seems OK, but after driving some distance, this problem happen again randomly and according to my memory, it seems happen always at like , waiting Mac Donald drive though or waiting for the traffic light, once the car start to move again, the engine sound change louder when accelerating, not always, but did happen several times.

          thank you


          • #7
            Hey guys, just reading thru all your descriptions on this issue coz my crusade auto started to hace this knocking kinda rattling sound which I think is coming from behind part of the car. I dont have a tow bar fitted but have noticed this on my trips. Any news on this issue so far?


            • #8
              Is this happening while driving or pulling away from stationary, accelerating or what mate. Under what circumstances is it happening please. And from where in the vehicle is it happening.


              • #9
                Ive driven to sydney and canberra from brisbane. It took me few hours to notice the knocking sounds. Like vibrating or cracking and quite disturbing yet very annoying sounds. You need to be on a motorway speed to hear it. It comes on and off but mostly on during acceleration on a constant high speed. No sounds ive heard when i pull over the car, the moment I go out on minor roads on just 60 kms speed then the sounds is gone. Any thoughts mate?
                Last edited by river; 20-01-2016, 11:36 AM.


                • #10
                  Hi River. I've had the main problem from new. dealer reckons it is diesel knock which I am a bit dubious about.. The whole car was a bit strange till today. I get a loud knocking sound from under the front of the car probably the rear of the engine bay around the clutch area. It occurs every time I take off from rest. It stops once the clutch is let completely out and if I stay at rest and hold the weight of the car on the clutch it keeps going until the clutch is completely released or clutch pedal is depressed again. Sometimes a vibration can be felt through the clutch pedal. Today I got sick of it and decided to do something about it. I revved the engine a bit , quite a bit and rode the clutch pedal. The noise and vibration was violent so I depressed the pedal again. Tried it again at lower revs with same result. Tried it a third time with still a few revs on. There was a loud clack noise from the back left and the clutch pedal kicked up under my foot, the clutch engaged nd i was off. The engine was running the quiet and smoothest it has in ages, except after a while on a highway run, like it should run and it seemed to rev more smoothly and was just a much better car. I have often heard the same clack noise from the front left and from the centre rear, like around the diff..and from the left rear . It then worked fine till I parked and applied the hand brake after braking to a stop. Then when I started again the knock returned and had to go through the same rev and ride clutch thing till it shut up and worked properly again. Occurred to me that I had often had a clack from two wheels and the right front had often dived and caused a sharp braking incident. Was becoming apparent that this is probably a brake problem.. The riding clutch out is probably stuck calipers being unstuck and the clack noises are probably calipers coming unstuck.. Have often got home. got out of car and locked it and as I have walked round the rear of it heard a clack from the left rear. I think I have either got a bunch of bad brake calipers or a faulty ABS unit. Stuck brakes would sure cause a lot of noise as the brakes fight all attempts by the engine and clutch and gearbox to move the car forward. Clack from centre rear could be a faulty diff locker unlocking.. .any way it's a theory that could be right, not much more in the corners except wheels and brakes so a noise seems to have to be brakes. racket at front probably the clutch and gearbox and drive line complaining . Any other suggestions more than welcome. .
                  Last edited by davidd; 20-01-2016, 05:36 PM.


                  • #11
                    hello david

                    your describsion is quite similar to mine's, especially :

                    1."Sometimes a vibration can be felt through the clutch pedal"
                    2."It occurs every time I take off from rest"
                    3." I have often heard the same clack noise from the front left"

                    currently, I just ignore this noise, can not do something about it, dealer told me evreything is fine, so.. you know.

                    to see what happen next...

                    tku for update the describsion.^_^


                    • #12
                      Originally posted by river View Post
                      Ive driven to sydney and canberra from brisbane. It took me few hours to notice the knocking sounds. Like vibrating or cracking and quite disturbing yet very annoying sounds. You need to be on a motorway speed to hear it. It comes on and off but mostly on during acceleration on a constant high speed. No sounds ive heard when i pull over the car, the moment I go out on minor roads on just 60 kms speed then the sounds is gone. Any thoughts mate?
                      I have no idea mate. Is it engine or body do you think?


                      • #13
                        I dont think the noise is coming from the engine. The engine runs very good. If im not mistaken noise is from behind of the car or underneath. When im on stop mode and I try reving engine, no noise can be heard. Its just prominent on motorway speed between 80 and above speed then a rattling, vibrating, grilling noise comes in. Very annoying indeed on a new car.


                        • #14
                          Really don't know mate. Have you tried climbing under with a good light and checking all the suspension components . Just a thought but unlikely is a really badly balanced rear wheel. They start to play up at about 80kph. Also the spare wheel is underneath at the rear. Try checking to see if the wheel is wound up tightly and the chain is not rattling about on bumps. Try tying the chain up where it can't rattle and see how that goes. Might be a help. Apart from that don't know mate.


                          • #15
                            Ok mate, ill try those advices, I have to take it to the dealer tomorrow to have it checked too. I found an article about understanding different car noises that I googled and its quite interesting too.
                            I let you know whats the diagnosis mate.