4th gear sounds/feels weird

[jaymac90210]

Hey all,

Got a 2003 D22 3.0L and my navara feels weird in 4th gear. It's going to take a bit of explaining so apologies haha.

When taking off and shifting gears, I always shift at around 2-2250 rpm.

1st to 2nd drops down to around 1,200 rpm and pulls no worries.
2nd to 3rd drops to about the same, pulls fine no labouring sound.
3rd to 4th (now this is where it gets interesting) the revs drop to only about 1,500 rpm however this almighty struggling sound comes from the engine/gearbox and vibrations through the car (like it is struggling) up until around 1800rpm then it is fine.
4th to 5th drops to around the same 1500rpm yet barely (if at all) makes the same noise like 3rd to 4th...

I have no idea why it does this and it's really weird. I do hope someone could shed some light on why it could be doing this, or at least tell me that theirs does the same. Have done EGR and got a 3 inch exhaust and didn't change anything. Cheers all.

 

[jaymac90210]

Bump

 

[happy john]

Hey mate i wasn't going to reply as yours is a bit older but my 2010 does just that only in 3rd and in 4th under load it only happened after i did all the performance mods now it is putting out big h/power but it's simply driveline noise basicly those two gears vibrate under load once the revs come up away it goes nobody on here had a clue when i asked the same thing my excellant mechanic worked it out very quickly and it's not a problem just annoying mind you i have only done 36k anyway hope it is of some help to you regards John.

 

[jaymac90210]

Hey mate i wasn't going to reply as yours is a bit older but my 2010 does just that only in 3rd and in 4th under load it only happened after i did all the performance mods now it is putting out big h/power but it's simply driveline noise basicly those two gears vibrate under load once the revs come up away it goes nobody on here had a clue when i asked the same thing my excellant mechanic worked it out very quickly and it's not a problem just annoying mind you i have only done 36k anyway hope it is of some help to you regards John.

Hey mate sweet as thanks for replying anyway, any bit of info from you no matter what engine is better than none! Because we'd still share pretty much the exact same driveline I can only think of the two differences being the engine itself and the diff ratio so your mechanic said it is normal for them to do it?

 

[happy john]

As far as i know the box is the same the best i can describe is like a vibrating chattering noise at that rpm 1800-2000 then goes once the revs improve but like i said i had no dramas before chip exhaust and boost increase he tells me the 3.5 pajero is bad with the same noise the gears vibrate under load once you get them going better but it's a little known problem hence no replys to your query.

 

[jaymac90210]

As far as i know the box is the same the best i can describe is like a vibrating chattering noise at that rpm 1800-2000 then goes once the revs improve but like i said i had no dramas before chip exhaust and boost increase he tells me the 3.5 pajero is bad with the same noise the gears vibrate under load once you get them going better but it's a little known problem hence no replys to your query.

Mmm sort of that noise, I'm not too sure. Mine sounds more like it struggles heaps (like it's labouring really badly) around 1400-1800rpm and only in fourth gear... I probably need to take a Navara for a year drive to see haha

 

[jaymac90210]

Bump

 

[nakedape]

Could this be another NPS problem? Not really sure, just throwing it out there!

 

[jaymac90210]

Could this be another NPS problem? Not really sure, just throwing it out there!

Any idea is better than no idea, I must try that!! Cheers mate!

 

[fourocker]

I really believe you're shifting too early and your getting gear chatter through the gearbox/transfer, the truck needs to be actually rolling faster on the road before the motor torque is forced into the drive line.
Turbo boost starts coming on around 1800rpm so ideally when you drop into the next gear the revs shouldn't be under that, I try shifting at 2500 - 2700rpm on the flat, maybe 2200 down hill and around 3000 on decent up hills, these trucks are designed to rev between 2000 - 3000 rpm and will do it all day, they don't like under and don't make extra above, in fact I find I get similar to you describe if I labour it too much (under rev).

 

[jaymac90210]

I really believe you're shifting too early and your getting gear chatter through the gearbox/transfer, the truck needs to be actually rolling faster on the road before the motor torque is forced into the drive line.
Turbo boost starts coming on around 1800rpm so ideally when you drop into the next gear the revs shouldn't be under that, I try shifting at 2500 - 2700rpm on the flat, maybe 2200 down hill and around 3000 on decent up hills, these trucks are designed to rev between 2000 - 3000 rpm and will do it all day, they don't like under and don't make extra above, in fact I find I get similar to you describe if I labour it too much (under rev).

Thanks mate will do

 

[bods]

Tried it in mine this morning in both 4th and 5th and didn't notice any weird noises or vibrations. Mine is a 2010 with around 37000km on the clock. Still got stock tyres on though so I'm not sure if you're running larger tyres? Shifted both 3-4 and 4-5 at 2250rpm and go no shudder or vibration, just accelerated normally.

I agree though, if it sounds like a labouring sound rev it s bit higher between shifts. I normally shift 2500-3000 and still get decent economy. Egts climb very quick when revving above 3000rpm though I have noticed even with standard tyres and no chip. I can quite easily get mine up to 500c post turbo with a burst in 3rd and 4th up to about 3500rpm

 

[jaymac90210]

Tried it in mine this morning in both 4th and 5th and didn't notice any weird noises or vibrations. Mine is a 2010 with around 37000km on the clock. Still got stock tyres on though so I'm not sure if you're running larger tyres? Shifted both 3-4 and 4-5 at 2250rpm and go no shudder or vibration, just accelerated normally.

I agree though, if it sounds like a labouring sound rev it s bit higher between shifts. I normally shift 2500-3000 and still get decent economy. Egts climb very quick when revving above 3000rpm though I have noticed even with standard tyres and no chip. I can quite easily get mine up to 500c post turbo with a burst in 3rd and 4th up to about 3500rpm

Thanks for trying it for me mate I appreciate that. Yeah I know it's shifting too low but I just found it odd that only 4th gear made the noise not even 5th... I am running slightly bigger tyres than stock however it still made that noise whilst I was running stock tyres. That's pretty high EGT's! But yours is the common rail one so that wouldn't be too high as opposed to my 3.0L haha

 

[fourocker]

How long since the gearbox oil has been replaced ? I noticed an improvement in mine after replacing it recently, also 4th gear is the only one that is 1:1 with motor revs, maybe that just shows it up more than the others.

 

[jaymac90210]

How long since the gearbox oil has been replaced ? I noticed an improvement in mine after replacing it recently, also 4th gear is the only one that is 1:1 with motor revs, maybe that just shows it up more than the others.

Not too long I imagine mate I get the fluids changed regularly when needed haha. What do you mean when you say 1:1 exactly?

 

[fourocker]

Through the main shaft in the box, 1 revolution of the motor = 1 revolution of the drive line. 1st-3rd are all reduction ratios off the main shaft and 5th is over driven off the main shaft, don't worry I didn't mean to get too techy, see how it goes shifting at the higher revs, doesn't mean you have to flog it, just drive it nice but hold each gear a bit longer.

 

[happy john]

Spot on thats why dynotuners use 4th when testing if gives the most accurate reading

 

[jaymac90210]

Through the main shaft in the box, 1 revolution of the motor = 1 revolution of the drive line. 1st-3rd are all reduction ratios off the main shaft and 5th is over driven off the main shaft, don't worry I didn't mean to get too techy, see how it goes shifting at the higher revs, doesn't mean you have to flog it, just drive it nice but hold each gear a bit longer.

Oh nah mate don't worry about getting too technical haha so that's what you mean! That would most likely explain why my box does that then. Thank you for filling me in on what that meant. I'll just hold 3rd-4th for a bit longer then.

 

[happy john]

Probably a silly idea have you checked g/box mounts e/mounts and exhaust?

 

[jaymac90210]

Probably a silly idea have you checked g/box mounts e/mounts and exhaust?

Yeah they're all good had a service not long ago and my mechanic did all that. It's just one of those weird sounds/feels my navara has. Lots and lots of character hahaha