• Advertisement

Loud grinding under light throttle or letting off throttle

Getting the best performance from your Isuzu, the in's and out's

Loud grinding under light throttle or letting off throttle

Postby Kerpre » Sun May 19, 2019 7:43 pm

Hi guys, have been scouring the forums for months trying to find atleast something similar to my problem but everything points back to wheel bearings, which have all been replaced, repackage and correctly tensioned (spring gauge 1.5kg).

Mu 1996
Manual hubs
Auto box

So what happens is, when driving anywhere above about 70kph, if I just lightly touch the throttle I can get the noise to stay constant, other wise it is when I press the accelerator or back off the accelerator. It only happens at the one position of the accelerator pedal. I was convinced it was directly related to my accelerator cable some how as I just can’t find anything else.

The noise sounds like a gear hasn’t been selected properly and is grinding on the synchro.
It appears to be coming from the front of the vehicle, from the gearbox forward I would say, very hard to pin point as it only happens when driving and it’s bloody loud, so hard to say.
I can only hear the noise, and feel it through the pedal, if this helps.
Things I’ve replaced so far, ( not because of the problem but since the problem started)

Front diff
Rear diff
Replaced front wheel bearings
Replaced rear wheel bearings
About to manual convert so this should eliminate the gearbox all together


I am a little concerned with the condition of my manual freewheel hub bearings as they are a little sloppy
Could this cause such a noise? Like the cv slipping around
Ball joints?


Any ideas of how to narrow it down would be greatly appreciated
Kerpre
Isuzu Baby
 
Posts: 17
Joined: Fri Aug 17, 2018 3:40 pm
Age: 27
Country: New Zealand
City: Tauranga
Vehicle: Isuzu Mu

Re: Loud grinding under light throttle or letting off thrott

Postby turnturn » Sun May 19, 2019 9:43 pm

Here's a couple of things to ponder. In no particular order.

1) When you replaced the front diff do you mean the whole diff or just the diff head? I ask because the noise may be coming from the actuator on the left hand side (passenger side) of the the front axle housing? It is a vacuum operated system that locks/engages the left hand axle.

2) Have you looked at all of the universals (4).

3) Maybe a stone jammed in somewhere in the drive train?

4) If you temporarily remove your manual hubs does the noise go away? It would have been drive flanges and not free wheeling or auto hubs from standard?

5) Does it go away if you engage your free wheeling hubs? Don't engage 4wd, just the hubs.
User avatar
turnturn
Global Moderator
 
Posts: 950
Joined: Wed May 13, 2009 4:26 pm
Age: 57
Country: New Zealand
City: Dunedin
Vehicle: 1992 Isuzu Mu 2.8 Manual (UCS55)
Snorkle, Intercooled
1993 Isuzu Mu 2.8 Manual (UCS55)
Spare Parts/Donor
1994 Isuzu Mu 3.1 Manual (UCS69)
Snorkle, Intercooled
1996 Isuzu Mu 3.1 Manual (UCS69)
Completely Standard


Return to Engines and Exhaust

Who is online

Users browsing this forum: Google [Bot] and 8 guests