Prado 90 Automatic transmission - delayed enagagement

[Boian]

Hello guys,

i have a small problem. My Prado is now 260k km, automatic box was flushed and the fluid fully replaced with Duglas ATF plus aw oil about 10k km ago. Lately after a few traffic jams a delayed engagement of the auto box appeared. When the car is hot its getting slower and slower on take offs - 2-3s. Guys from repair shop checked and the fluid is ok - crystal clear and without any smell..

Have you seen/heard about any similar issues? Do you have any suggestions what to check or repair?

Thanks a lot!

 

[chadr]

I know the fluid has been checked but have you checked the ATF level?

From memory, you need to check it when warm and in Park (P) after running up and down the gears positions a couple of times - i.e. shifting from P through to L and vice versa.

 

[Boian]

Fluid level checked. Found the probe behind the air filter.

Fluid was at the minimum when car was hot. We added ~200ml more into the system and things didn't change much. The guys said its just 200ml in a system of 12l+ and these few ml are quite insignificant. Further inspection showed no leaks around the gear box.

 

[Tonka Tuff]

Hello guys,

i have a small problem. My Prado is now 260k km, automatic box was flushed and the fluid fully replaced with Duglas ATF plus aw oil about 10k km ago. Lately after a few traffic jams a delayed engagement of the auto box appeared. When the car is hot its getting slower and slower on take offs - 2-3s. Guys from repair shop checked and the fluid is ok - crystal clear and without any smell..

Have you seen/heard about any similar issues? Do you have any suggestions what to check or repair?

Thanks a lot!

View attachment 146562 View attachment 146563 View attachment 146564

The issue sounds like the torque converter by passing as the oil heats up, Could also be the wet clutch pack within the automatic it's self. Has it had a filter change in the pan on the automatic at the same time the fluid was changed ? Not sure if there is a band adjustment on the Prado but would suggest all the above are checked and discounted before jumping into a full rebuild.
Also the very 1st thing I did when I got mine was to fit an external oil cooler and do away with the heat transfer unit that is in the radiator.
Hope some of these point of view help.
Cheers Tonka Tuff

 

[Boian]

Hi Tonka, thanks for your reply. Filter was changed during fluid change. Shouldn't Prados have at oil cooler by default? I'll take into consideration things mentioned above.

 

[Tonka Tuff]

Hi Tonka, thanks for your reply. Filter was changed during fluid change. Shouldn't Prados have at oil cooler by default? I'll take into consideration things mentioned above.

Yes Prado do have an oil cooler standard, However it from what I understand it is a heat exchange unit where the oil travels through the bottom of the radiator with in a heat exchange, Thus (not your problem) but the exchange can rupture and water can get into the automatic (Full expensive rebuild) so rather then wait for it to happen I got my old cooler by passed and had a slim line oil cooler fitted so at worst I can only ever get a oil leak and water can not enter the automatic.
The external oil coolers work so much better then the heat exchange units as well.

 

[Boian]

Well, external oil cooler sounds..cool

Was it a diy project, are there any ready cooling kits for this job? Last, but not least - where did you put yours? Just saw a few mods and coolers were positioned in front of the main cooler lower right.

 

[Tonka Tuff]

Well, external oil cooler sounds..cool

Was it a diy project, are there any ready cooling kits for this job? Last, but not least - where did you put yours? Just saw a few mods and coolers were positioned in front of the main cooler lower right.

 

[Tonka Tuff]

Yep, that's correct, The one I have is about 30cm long x 15cm high and 4cm thick (But) I have only just purchased this rig as a part done build. (No brand on it)
I intend to try and identify it's make and check it's quality of the cooler it's self (Lots of cheap knock off's of good brands out there)
If it's a good brand it will stay, If not it's gone and a quality one will be fitted.
From what I have found so far you could expect to pay around $150 to $250Au.
Here is a link to a known brand.
https://daviescraig.com.au/transmission-oil-coolers

 

[uHu]

Would be typical symptom of too little ATF, so I can just contribute with the mistake I made the first time I touched an auto box: ATF level has to be checked with the engine running. It makes a big difference on the level.

 

[Tonka Tuff]

Would be typical symptom of too little ATF, so I can just contribute with the mistake I made the first time I touched an auto box: ATF level has to be checked with the engine running. It makes a big difference on the level.

Your correct with old school auto's They must be checked with the engine running so the converter is full and also best checked when warm as oil expands in volume and the converter needs to be full.
I would like to add that later models the oil levels are checked cold with a converter at gravity level.
Things that were are no longer so best to check with the manufacture for specs.
Some later model stuff don't even have a dip stick for fluid levels and others will be destroyed if you use the old school ATF, Mitsubishi were a well known one of have to use a factory auto fluid and NOT ATF
PS: ATF is a high pressure purpose oil lubricant with only one viscosity so to light or to heavy is not a possibility.

 

[uHu]

90 series LC is definitely old school then.

 

[wobbly]

I thing the ATF used may be causing the problem - this is a fully synthetic atf designed for latest electronic gearboxs.

This is a 1990's truck with an older designed box - I would use a semi-synthetic oil personally.

 

[Beau]

I've been using Fully Synthetic in my box for the last 50k miles or so without a problem, so kinda doubt it's that.
\

Regarding your problem, check your earth wires from the box. One important one is earthed near the oil filter location. I had a similar problem years back with delayed take off and it was because this earth wire was barely tightened down.

 

[Boian]

Thanks, Beau, I'll check that. One think that appears a bit strange to me is that car doesn't rev up, before launch - we are both sitting and waiting until power kicks in and rpms get higher and it has quite enough power after that. Could it be something totally different from autobox? A couple of times I ran on almost completely empty tank.. I'll check cables though

 

[Beau]

What you described happened exactly to me and it was that earth cable from the box that was at fault. It would hesitate on take off until it got that initial kick

 

[Boian]

Small update..

Beau, thanks again!
The mechanic said it has probably nothing to do with automatic box. Same behaviour after putting a foot on the gas pedal - goes to 1100-1120 rpm, thinks for a while and then the car launches. Same behaviour after hitting the gas pedal from zero, regardless of the speed and gear. And the other issue is that time varies. Another thing that happened today is while driving to the mechanic - I stepped on the gas pedal and it was the laziest acceleration ever so far /and I am absolutely positive - there was some shaking of the toyo/...releasing the pedal and hitting it again - voilas...booost.

Guys from the shop told me engine was quite adequate in testing with no load - pressure, response, etc. I've a -2 correction on 3rd cyl and thats it..

We just put an aggressive additive in the tank, but they say it might be the controllers of the fuel pump gone.

Have you experienced anything similar?

Thats the: TLC J90 - 2001 - D-4D

 

[Bob]

I have, as have a few others, changed suction control valves on the pump, solving the hesitation problem. Not a guarantee that it's your problem, but it is something that the D4D engine can need.

 

[leeloo]

Small update..

Beau, thanks again!
The mechanic said it has probably nothing to do with automatic box. Same behaviour after putting a foot on the gas pedal - goes to 1100-1120 rpm, thinks for a while and then the car launches. Same behaviour after hitting the gas pedal from zero, regardless of the speed and gear. And the other issue is that time varies.

Thats the: TLC J90 - 2001 - D-4D

I actually did a drive test with prado 120 auto I was looking at to buy doing the same thing. I went with the owner to a garage and they concluded it was the sensor from the gas pedal. To make go I had to tap pedal 2-3 times , and after that the car will accelerate normally. From a full stop, I had to depress the pedal, the engine would not rev, just cruise, release it, tap one more time and it would go...
I ended not buying that one due to other issues..
It should be cheap to replace.

 

[Alastair II]

I have, as have a few others, changed suction control valves on the pump, solving the hesitation problem. Not a guarantee that it's your problem, but it is something that the D4D engine can need.

Hi, Just joined hope this isn't breaking protocol asking about a similar problem here -

I've had a very similar problem. Still unresolved. (2001 3.0D 240,000 miles). Starting from stationary it will go to 1100 rpm and sit at those revs accelerating with the available power. Seems I need to get to about 6-8mph and then the boost comes in. (Is 1100 the boost threshold?) When it's a light load just me driving it will be 1-3 seconds. Heavier load takes longer to accelerate to 6-8mph.

Knowing the problem was there I took it to an auto-gearbox specialist and had the oil changed before going away with my touring caravan.

I was towing last week (1600kg caravan). The behaviour was still the same. Full throttle and /or kicking down didn't make any difference. On one hill start it took a long time at 1100 rpm to get to 6-8 mph where boost kicked in.

I'm not a mechanic, but have an engineering background some 30 years ago (toolmakers apprenticeship/engineering degree). I've seen 4 possibilities mentioned here: suction control valve on a pump (which one?), throttle sensor, earth cable from the box (gearbox?) , and ATF level.

How easy are these to check and if need be replace parts?

thanks for your help.