Whitey
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Hey all,
My auto has been running quite hot lately with the OEM cooler, so I recently upgraded to a 30 plate Davies Craig 679, which has made a big difference;
http://www.pradopoint.com/showthread...l-in-Prado-120
Previously with the OEM cooler, I saw the transmission temperature peak at 115C on the beach in soft conditions, and I’d have to back off. With the 679 up the front I haven’t gone past 93C (radiator temp) in the worst of hot conditions, 45C ambient, 60C sand temps. It’s typically running 70-75C around town.
My auto wasn’t always this way, and I’ve been across Australia with it, Simpson, plenty of Fraser etc., so the running temps have been slowly creeping up over time. I’ve done four auto fluid flushes since I bought the Prado at 80,000km, typically after long hard trips. I decided it was time to inspect the pickup screen after 155,000km.
I have heard the anecdote that some A750F transmissions run hotter than others, and maybe it runs hotter with the 1GR-FE in front of it. I have also heard of at least one FJ cooking his auto oil so badly that he clogged his pickup screen and starved the torque converter to the tune of 3K worth of replacement.
I ordered new OEM pickup screen (3533060050), o-ring (9030131014), and pan gasket (3516860010) through Amayama UAE.
While this job is a bit on the fiddly side, you can definitely do it at home on the ground, but before you begin this job, it’s best to make sure everything is spotlessly clean. Vacuum under your Prado, seal off around the auto so no dirt/sand/dust etc. can get near it. You definitely need to keep the innards of the auto clean!
First step is to drain then drop the pan. This might be a problem straight away as I discovered 5 of the bolts along the pan sides had seized in place from corrosion. This happens because the top threads are exposed and just washing under your Prado will get water on them. I’ve also done a fair few water crossings. Unfortunately those 5 bolts were seized beyond recovery, and I had to snap them off. No amount of soaking or ezy out was working. These pan bolts are very weak, and are only torqued up to 4.4Nm. The photo below shows the remains of the 5 corroded bolts;
If you have seized bolts, don’t stress too much. Once you’ve determined how many bolts are seized and you’ve snapped the heads off, put the pan back on and put all the cleaned up un-snapped bolts carefully back in. Make sure you use a template so you know which bolt came from which hole, like below;
Once you’ve got the pan back on and the auto innards are protected, you can then drill out the seized bolt threads. I used a 6mm drill. It’s a little bit tricky drilling from underneath, so take your time. There isn’t much room for bolt heads on the passenger side of the box, so your holes need to be well aligned. I didn’t bother re-threading the drilled out holes, I used 6mm socket head bolts with metal lock nuts instead.
So once you’ve dealt with any seized pan bolts, you can then go ahead and replace the pickup screen. The photo below shows the location of the screen towards the front;
The pickup screen is held in place with four M10 bolts, and is quite simple to remove and replace. There’s an o-ring on the valve body connecting pipe, so you need to wiggle it on and off. You’ll also drop more fluid out when you take the pickup screen down, so be ready to catch more fluid.
Once you’ve dropped down the old pickup screen, you can inspect the gauze filter, as shown below;
You can see small particulate on the screen. These are sticky organic colloids that have formed due to the ATF breaking down at high temperatures. My old pickup screen was also covered in a darkish film, old compared to new below;
I would say most of this is burnt oil, potentially some of it is very fine metallic grit, as the pan magnets were also covered in something similar as shown below;
While you have the pan off, you’ll need to completely degrease it and clean the four magnets which you can just pull off the pan and clean up.
Once you’ve cleaned up the pan and magnets, put the magnets back in place in the pan and the pan back on with the new gasket. I also used new bolts along the pan sides. The front and rear OEM bolts (4 at each end) must be re-used as the threaded holes for them run into the auto block housing, and they won’t take a longer length bolt. It might take a bit of fiddling getting the bolt/nut done up in the drilled out holes. I went bolt head bottom on the driver side, bolt head top on passenger side. Be careful not to over torque them. Have a feel of the OEM bolts by hand when you’ve torqued them to 4.4Nm, and apply that same feeling to the new bolt/nut drilled out holes.
Once you’re happy the pan is happily torqued back up, you can then add back in the same amount of new ATF that you drained out. Then do your standard flush and check the level through the overflow valve at 46C. When you’re undoing the filler plug up the top, note that a 15/16” socket is the best fit, as it’s easy to burr the head of this bolt.
After a few test drives, everything is nice and dry so my drilled out bolt/nut has worked well. I’ve also noticed the auto is changing more smoothly after flushing in around 5 litres of new oil, so just that 93C ATF temp on my last Fraser trip has been enough to damage the oil a little bit. I am using Penrite ATF LV, and they recommend optimal operating temperature range of 50-80C, and recommend to not let the ATF temp exceed 100C.
I’m planning on flushing the ATF after hard beach trips, and if I keep seeing high temps I might consider a valve body upgrade in the future.
Keep those autos cool!
Best
Mark
My auto has been running quite hot lately with the OEM cooler, so I recently upgraded to a 30 plate Davies Craig 679, which has made a big difference;
http://www.pradopoint.com/showthread...l-in-Prado-120
Previously with the OEM cooler, I saw the transmission temperature peak at 115C on the beach in soft conditions, and I’d have to back off. With the 679 up the front I haven’t gone past 93C (radiator temp) in the worst of hot conditions, 45C ambient, 60C sand temps. It’s typically running 70-75C around town.
My auto wasn’t always this way, and I’ve been across Australia with it, Simpson, plenty of Fraser etc., so the running temps have been slowly creeping up over time. I’ve done four auto fluid flushes since I bought the Prado at 80,000km, typically after long hard trips. I decided it was time to inspect the pickup screen after 155,000km.
I have heard the anecdote that some A750F transmissions run hotter than others, and maybe it runs hotter with the 1GR-FE in front of it. I have also heard of at least one FJ cooking his auto oil so badly that he clogged his pickup screen and starved the torque converter to the tune of 3K worth of replacement.
I ordered new OEM pickup screen (3533060050), o-ring (9030131014), and pan gasket (3516860010) through Amayama UAE.
While this job is a bit on the fiddly side, you can definitely do it at home on the ground, but before you begin this job, it’s best to make sure everything is spotlessly clean. Vacuum under your Prado, seal off around the auto so no dirt/sand/dust etc. can get near it. You definitely need to keep the innards of the auto clean!
First step is to drain then drop the pan. This might be a problem straight away as I discovered 5 of the bolts along the pan sides had seized in place from corrosion. This happens because the top threads are exposed and just washing under your Prado will get water on them. I’ve also done a fair few water crossings. Unfortunately those 5 bolts were seized beyond recovery, and I had to snap them off. No amount of soaking or ezy out was working. These pan bolts are very weak, and are only torqued up to 4.4Nm. The photo below shows the remains of the 5 corroded bolts;
If you have seized bolts, don’t stress too much. Once you’ve determined how many bolts are seized and you’ve snapped the heads off, put the pan back on and put all the cleaned up un-snapped bolts carefully back in. Make sure you use a template so you know which bolt came from which hole, like below;
Once you’ve got the pan back on and the auto innards are protected, you can then drill out the seized bolt threads. I used a 6mm drill. It’s a little bit tricky drilling from underneath, so take your time. There isn’t much room for bolt heads on the passenger side of the box, so your holes need to be well aligned. I didn’t bother re-threading the drilled out holes, I used 6mm socket head bolts with metal lock nuts instead.
So once you’ve dealt with any seized pan bolts, you can then go ahead and replace the pickup screen. The photo below shows the location of the screen towards the front;
The pickup screen is held in place with four M10 bolts, and is quite simple to remove and replace. There’s an o-ring on the valve body connecting pipe, so you need to wiggle it on and off. You’ll also drop more fluid out when you take the pickup screen down, so be ready to catch more fluid.
Once you’ve dropped down the old pickup screen, you can inspect the gauze filter, as shown below;
You can see small particulate on the screen. These are sticky organic colloids that have formed due to the ATF breaking down at high temperatures. My old pickup screen was also covered in a darkish film, old compared to new below;
I would say most of this is burnt oil, potentially some of it is very fine metallic grit, as the pan magnets were also covered in something similar as shown below;
While you have the pan off, you’ll need to completely degrease it and clean the four magnets which you can just pull off the pan and clean up.
Once you’ve cleaned up the pan and magnets, put the magnets back in place in the pan and the pan back on with the new gasket. I also used new bolts along the pan sides. The front and rear OEM bolts (4 at each end) must be re-used as the threaded holes for them run into the auto block housing, and they won’t take a longer length bolt. It might take a bit of fiddling getting the bolt/nut done up in the drilled out holes. I went bolt head bottom on the driver side, bolt head top on passenger side. Be careful not to over torque them. Have a feel of the OEM bolts by hand when you’ve torqued them to 4.4Nm, and apply that same feeling to the new bolt/nut drilled out holes.
Once you’re happy the pan is happily torqued back up, you can then add back in the same amount of new ATF that you drained out. Then do your standard flush and check the level through the overflow valve at 46C. When you’re undoing the filler plug up the top, note that a 15/16” socket is the best fit, as it’s easy to burr the head of this bolt.
After a few test drives, everything is nice and dry so my drilled out bolt/nut has worked well. I’ve also noticed the auto is changing more smoothly after flushing in around 5 litres of new oil, so just that 93C ATF temp on my last Fraser trip has been enough to damage the oil a little bit. I am using Penrite ATF LV, and they recommend optimal operating temperature range of 50-80C, and recommend to not let the ATF temp exceed 100C.
I’m planning on flushing the ATF after hard beach trips, and if I keep seeing high temps I might consider a valve body upgrade in the future.
Keep those autos cool!
Best
Mark
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