Clunk from front suspension when letting go throttle

Clunk from front suspension when letting go throttle

Postby eehgil on Sun, 27 Nov 2022 3:36 +0000

Hi,

Just got a 2013 Hilux 2,5d manual, 93000km. Had it at Mercasol anti rust threatment, and after this it have got a very distinctive sound that seems to come from front left side suspension. Its a clear "clunk", and I also can feel some vibration through the floor and thour the steering wheel when the sound comes. It comes everythime i let go of the gas pedal, at all speeds, both goint straight and turning. Lounder and clearer when letting go from hard acceleration. It also sometimes comes when at stedy speed and going over a bump.
The sound also comes from stand still, if i let the clutch out and then in a bit hard.

The sound is present in all "modes" 2H, 2L 4H and 4L.

Any tips to what to check?

Thanks in advance for reply.
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Re: Clunk from front suspension when letting go throttle

Postby Rob_Wood on Sun, 27 Nov 2022 4:19 +0000

eehgil wrote:Hi,

Just got a 2013 Hilux 2,5d manual, 93000km. Had it at Mercasol anti rust threatment, and after this it have got a very distinctive sound that seems to come from front left side suspension.


If you're certain the noise has only been there AFTER the rust treatment, then I'd suggest checking components that might be affected by the treatment ... A bead of dried anti-rust on a shock absorber stem for example.
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Re: Clunk from front suspension when letting go throttle

Postby eehgil on Sun, 27 Nov 2022 4:30 +0000

Yes, I'm certain. The sound is very clear.

Should probably written in first post:
-Stock suspension.
-Stock wheel dimension (265/70-16).
-I have checked wheel bolts and tried to look and check for obsious things in suspension by hand, but so far not found anyhing.

something in the shock absorber stem sounds like a good tip, whill check that. Thanks!

It "feels" like there is somthing that is moving (that should not move) when going from accelerating to decelerating, and when going from steady speed to decelerating (not touching the brakes).
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Re: Clunk from front suspension when letting go throttle

Postby ptrl1600 on Sun, 27 Nov 2022 7:31 +0000

Also check the engine mountings, particularly on the left side as this is the one that usually splits. The engine has a tendency to try to spin around the crankshaft causing it to lift on the left side and when you back off the throttle it comes back down. Look for any excessive movement by the gear shifters. I've never had this happen with a Hilux, but have with other cars.
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Re: Clunk from front suspension when letting go throttle

Postby Chopps on Sun, 27 Nov 2022 9:02 +0000

Sounds very much like tail shaft thud. Phenomenon known as "Stiction" when incorrect grease used or possibly over greasing
It will feel like something is shoving the vehicle from the rear end when taking foot off the right pedal
The sound will go right thru the chassis and may sound like its coming from the front end.
Failing all other suggestions:
Purchase Moly disulphide NGLI2 lithium grease - no other grease will alleviate this clunk symptom
Pump about 20 pumps into rear slip yoke
Remove zerk fitting - purge air and grease
Jump up and down on rear of tub - a little more grease will pop out
Reinstall zerk
Enjoy clunk free acceleration / deceleration
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Re: Clunk from front suspension when letting go throttle

Postby eehgil on Wed, 07 Dec 2022 5:45 +0000

Update! Even if it sounded like the klunk was coming from the front, it is probably from the back leaf springs.

One strange thing is that the sound is very loud and clear when the weather is dry. But when it is raining it dissapers, it is not even possible to make it sound with "extreme provocation".

Before anti rust theatment they did some sand blasting. Are there any parts on the leaf springs that could be damaged by the sand blasting that could cause this clunk?

https://toyota-europe.epc-data.com/hilu ... is/4804/#1

48252 SILENCER, REAR SPRING - if this is damaged, can this cause souch a sound?
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Re: Clunk from front suspension when letting go throttle

Postby ptrl1600 on Thu, 08 Dec 2022 9:56 +0000

eehgil wrote:One strange thing is that the sound is very loud and clear when the weather is dry. But when it is raining it dissapers, it is not even possible to make it sound with "extreme provocation".

Before anti rust theatment they did some sand blasting. Are there any parts on the leaf springs that could be damaged by the sand blasting that could cause this clunk?
48252 SILENCER, REAR SPRING - if this is damaged, can this cause souch a sound?


Usually rubber bushes and mounts make less noise when they are moist or wet.
The rear spring silencers are basically just plastic insulators that are fitted between the leaves to stop the metal leaves from touching each other. If they touch each other they rub and usually squeak, but also the insulators prevent the leaves from rusting after they rub through the paint.
If you are sure that it's coming from the rear springs, it could be the shackle rubbers or front eye bushes, but if it does it without the car moving, I would be checking the engine and rear transfer case mounts.

Maybe try spraying some silicon lube on all the rubber bushes to see if the noise goes away?
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