3.0 CRD Auto gearbox 'slipping' on steep hills

Hey guys

Recently got back from a trip in the high country out the back of Dargo and had a few issues with the auto gear box on some steep hils.

It would be climbing up nicely in low range, revs sitting around 2300 - 2400rpm doing about 30km/h, then all of a sudden it would loose power drop down under 2000rmp and slow down to 10-20km/h, it would not hanger down gears automatically and appeared to be 'slipping'. In one case I even had to stop the patrol on the hill, physically changed it down into 1st gear and off we went again.

Admittedly, some of these hills were very steep and long, and it was a hot as day - but I thought this was pretty average?

More concerning was driving along in 2H on main dirt access tracks doing about 60km/h, going up steep long hills again it would slow down to 20-30km/h and struggle to kick down a gear.

Has anyone experienced this type of issue before or have any suggestions?

The patrol was not loaded heavy nor was it towing a trailer.

Cheers

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Might be a silly thought but... Do those automatics have some sort of a overload / overheat protection, where they down-step them selves, in certain scenarios ??
Just a scenario my uncle had with his bmw where it was low on autobox oil, and because of it it wouldnt let him go above certain speed / gears once it reached a certain temperature ?
As I said, might be a silly notion, but just throwing it out there.

On a other note love those photos mate great pics of the HC! I'm jealous.

you weren't losing boost were you.
I had a similar thing happen , I tried to drive my Patrol when I first brought it like my 350 chev troopy
Select low 2 hit 1200 rpm and away we go, Not to be it would build boost then lose it build boost then lose it
I thought what a shite box these Patrols are. Noticed you had your revs up though, other than that I'd think maybe a sensor was telling you something
Do you have a SCAN Gauge fitted so you can pull up any errors

Hi Bacho86,
Doesn't sound like the automatic is slipping as you were also loosing revs, I'd expect the revs to stay high or increase and speed to decrease for it to be slipping.
Not sure if you have VDC (traction control) on your model but that was my problem. First time I took it up a gnarly track the system tried to take over and I lost power, not at all impressed.
Now I turn in off when I go into 4WD and never had the issue again and I've done some very steep climbs both with and without a camper on the back.

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Originally Posted by Hodge

Might be a silly thought but... Do those automatics have some sort of a overload / overheat protection, where they down-step them selves, in certain scenarios ??
Just a scenario my uncle had with his bmw where it was low on autobox oil, and because of it it wouldnt let him go above certain speed / gears once it reached a certain temperature ?
As I said, might be a silly notion, but just throwing it out there.

On a other note love those photos mate great pics of the HC! I'm jealous.

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Hey Hodge, I honestly don't know - all the oil levels were checked before the trip and were in good condition, however possible that due to the heat and work load the oil was over heating? I'm not sure, but wouldn't have thought so - not like I was doing beach work with lots of changing and stress on the auto?

Cheers mate - Yeh ive got a bunch more photos I'll put up later when I get around to it, it's a great area to visit!

might need a trans cooler, I know I'll be fitting one when funds allow

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Originally Posted by threedogs

you weren't losing boost were you.
I had a similar thing happen , I tried to drive my Patrol when I first brought it like my 350 chev troopy
Select low 2 hit 1200 rpm and away we go, Not to be it would build boost then lose it build boost then lose it
I thought what a shite box these Patrols are. Noticed you had your revs up though, other than that I'd think maybe a sensor was telling you something
Do you have a SCAN Gauge fitted so you can pull up any errors

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Hey 3D - you may have a point there, may actually be more boost related.... Not sure

Originally I was driving it similar to you, as I had driven my dads LC105 with the 4.2 turbo diesel, and that thing just pulls from real low with no issues but the patrol I definitely had to have it further up in the rev range - I recall reading somewhere the peak torque is developed around 2000 rpm so that was always my goal to try and have it sit there.... But when it started suffering I tried to keep the revs up further to compensate but without much luck

No scanguage or boost gauge at this stage - so couldn't tell excatly what was happening, just trying to piece it together...

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Originally Posted by Apollofish

Hi Bacho86,
Doesn't sound like the automatic is slipping as you were also loosing revs, I'd expect the revs to stay high or increase and speed to decrease for it to be slipping.
Not sure if you have VDC (traction control) on your model but that was my problem. First time I took it up a gnarly track the system tried to take over and I lost power, not at all impressed.
Now I turn in off when I go into 4WD and never had the issue again and I've done some very steep climbs both with and without a camper on the back.

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Hey Apollo - yeh perhaps more a boost issue. Only an ST model so no traction control I believe - how to you go with the camera trailer and the auto - have you fitted reduction gears or done any modifications to the auto box?

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Originally Posted by threedogs

might need a trans cooler, I know I'll be fitting one when funds allow

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I was of the understanding they already had a trans cooler fitted?

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Originally Posted by Bacho86

Hey Apollo - yeh perhaps more a boost issue. Only an ST model so no traction control I believe - how to you go with the camera trailer and the auto - have you fitted reduction gears or done any modifications to the auto box?

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No modifications to the auto at all, stock standard mechanically but may put in a torque converter locker when the warranty runs out. So far I've done about 16,000km towing over various conditions including the Cape and some sand, never missed a beat. Camper is a Jayco Eagle and fully loaded would come in close to 1400kg, must weigh it some time. Handled the Bloomfield Track and a pretty good climb up to Atherton with ease.

Mine did that once coming up a steep hill out the back of Newnes NSW in 2H on the tar. The hill is probably 500-600m long and steep with lots of sharp corners. All 20-30km/hr stuff. I just left it in "D" with O/D on and let it do its thing, but nearing the top it felt like it went into limp mode briefly. I'm thinking WTF! The car was basically empty. Next time I went up there I turned the O/D off and manually pulled it back to 2nd and had no issues. I've driven this hill a few times now with the latter technique with no issues, of late I've given it a fair booting up the hill to see if it was a heat related thing, no issues.

I've also drive some wicked hills in the Vic HC including 16 Mile Jeep Track (One of the longest steepest climbs I've been on) quite heavily loaded (no trailer) with no issues. O/D off and pull it back to 1st low range.

Coincidence or not, I don't know, but it works for me.

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Originally Posted by Bacho86

I was of the understanding they already had a trans cooler fitted?

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They have got a cooler fitted, and unlike some crap cars its independent to the radiator.

I fitted inline after my stock cooler a pwr trans cooler suitable for 8cylinder cars and I think it only cost 80-120$ and is an easy diy

I think Rocket Rod has hit the nail on the head....

Were you driving it like an Automatic, or were you preselecting gears before you started an ascent/descent?

Mic

On serious off road autos are not as "auto" as you think. They tend to change down too late and you lose the revs and therefore also the turbo. You have to select either low second or even low first on a very steep hill. OD should certainly be off.

If you are not sure join a club and do a free course.

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Originally Posted by happygu

I think Rocket Rod has hit the nail on the head....

Were you driving it like an Automatic, or were you preselecting gears before you started an ascent/descent?

Mic

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Thanks rocket and happygu

I had it locked down in 2nd gear low range for the big hill - and at certain points it really struggled I would have thought this be more than sufficient...maybe not?

My dad in his LC105 was doing it in 3rd gear low range and my brother in his hilux 2nd gear as a comparison.

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Originally Posted by BillsGU

On serious off road autos are not as "auto" as you think. They tend to change down too late and you lose the revs and therefore also the turbo. You have to select either low second or even low first on a very steep hill. OD should certainly be off.

If you are not sure join a club and do a free course.

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Thanks Bill.

I was preselecting gears before tackaling the hills I.e. 2nd gear and low range... For the steepness of the hill and based on experience from other 4wd's I would have thought 1st gear too be too low

Has anyone done any upgrades to their auto boxes to improve gear changes? Like a nomad body upgrade or similar? Are they worth the money?

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Originally Posted by Bacho86

Thanks rocket and happygu

I had it locked down in 2nd gear low range for the big hill - and at certain points it really struggled I would have thought this be more than sufficient...maybe not?

My dad in his LC105 was doing it in 3rd gear low range and my brother in his hilux 2nd gear as a comparison.

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Toyotas are geared a little lower than the Nissan's low range gear ratios, so you can't just compare them side by side .....

I have a manual so I can't tell you HOW to drive the 3 Litre Auto box, but I used to have a TD4.2 Turbo that I could basically nearly let itself idle up a hill in low first, and get out and walk beside it, so getting into the 3 Litre was a bit of a shock to me at first as I kept stalling it trying to drive the same way.

Now I know how the engine works, I never stall it on a hill climb, am always still in full control, and actually think I now drive a little better, but I had to change my driving style to adapt and can't be as lazy as I was ( The old 4.2 would pull out - just - from 1000 rpm so I never had to worry too much ). Now I basically drive to keep the engine in the 2000 - 2500 rev band, back off for the erosion mounds, and stab the throttle at the top of the mound to prepare for the next pitch up as the truck drops into the ditch over the mound, and it is a matter of stabbing the throttle just the right amount to get the engine on boost for the section. Obviously too much means you go too fast and can compromise line picking, and too little means that you may struggle to make it to the next mound.......

Mic

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Originally Posted by happygu

Toyotas are geared a little lower than the Nissan's low range gear ratios, so you can't just compare them side by side .....

I have a manual so I can't tell you HOW to drive the 3 Litre Auto box, but I used to have a TD4.2 Turbo that I could basically nearly let itself idle up a hill in low first, and get out and walk beside it, so getting into the 3 Litre was a bit of a shock to me at first as I kept stalling it trying to drive the same way.

Now I know how the engine works, I never stall it on a hill climb, am always still in full control, and actually think I now drive a little better, but I had to change my driving style to adapt and can't be as lazy as I was ( The old 4.2 would pull out - just - from 1000 rpm so I never had to worry too much ). Now I basically drive to keep the engine in the 2000 - 2500 rev band, back off for the erosion mounds, and stab the throttle at the top of the mound to prepare for the next pitch up as the truck drops into the ditch over the mound, and it is a matter of stabbing the throttle just the right amount to get the engine on boost for the section. Obviously too much means you go too fast and can compromise line picking, and too little means that you may struggle to make it to the next mound.......

Mic

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Thanks Mic - appreciate the response, sounds like I will also just need to be adjusting my driving as well!

I'd whip the inter cooler off and have a look underneath for oil.
Even being an 08 model it may be leaking, remove clean inside and pump some air with a bike pump with
one end blocked and see if it leaks, If it is leaking it could cause other issues like high EGTs

@ Happy that's exactly what I did with my other 4x4 low low
get out and walk beside tth car waving my arms as if giving instructions
My mates would think who the hell is driving Johns 4x4 after a while we all lol
My auto guy suggested I leave the auto alone as its my daily driver.
a few here swear by it though