2001 100 series Auto Drops out of top gear

[Smeg]

Hey guys and Girls How you going?
This seems to be the place of Smart Landcruiser owners Could i have some advice please?
I have a wonderful NZ new 100 series 2001 Landcruiser 4 speed Auto (with the towing package).
Rego JQA129
Toyota Land Cruiser (HDJ-100R-NGPEZW)
Engine model: 1HD-FTE
History 450k mostly 1.5+ hours motorway use. Well maintained trans oil/filter changed every 100k. At about 370k The expensive long life ATF put in. 1st 180k Previous owner no towing. Last 270k a bit of towing 2.5ton wake boat.
I have seen the trans over temp light come on twice (stuck in traffic going up the mountain just above idle. Dropped it into 1st gear light went strait off) done another 60k and never seen it happen again. I Don't use it a lot now just occasionally towing the boat to the ramp or on clients farms

Problem is left home pulled onto motorway (start of normal 1.5 hour trip to Town) cruising at 100km 5 min later it dropped out of top gear revs came up so turned around went back home grabbed the girlfriends car
Done it 3 times in a row so i have a issue!

I have done some research and I have heard that the A442f can get a faulty valve (if overheated) or just the valves get blocked up which needs demagnetizing and cleaned them out.
Iv got a set of new solenoid valves coming.
30 years ago I was a mechanic and had to clean up/reckon some turbo400's and 350's (1 in my in my bro's fJ40 with 350chev) so I think I can Drop the valve body and replace them myself.

What do you guys think please? anything ells you think i should look at please.
Thanks for any advice

logan

 

[uHu]

Yes, there have been cases of failing valves after a few 100 k Kms. That's a bit beyond my expertise, but a much simpler cause could be the adjustment of the gear shift linkage. Sometimes the position of the shifter gets out of sync with the positions of the gearbox. This can be because of worn out engine and gearbox mounts, e.g.
Check the cheapest solutions first?

 

[Jon Wildsmith]

When you say dropped out of top gear, it's probably the torque converter unlocking, which feels like another gear? You should be able to change the solenoids without removing the valve body. Just the oil pan needs to come off.

You shouldn't be getting the trans temp warning light coming on, especially not crawling along in traffic. That sounds like a cooling problem. The trans cooling is massively affected by the engine fan and radiator efficiency, and engine coolant temps, especially at low speeds.

If changing the solenoids fixes your current problem, I'd still give the cooling system a check over to find out why the box is getting so hot.

 

[Smeg]

Thanks for your advise guys
I have the new valves ill get them swapped. Only got hot twice over a year ago a crawl up a steep long hill which was resolved at the time by holding it in 1st keeping the engine fan moving a bit quicker the light went out strait away. I did get it checked and trans fluid changed after that trip they said it was fine.
Hoping the valves will fix the dropping.
Thanks and have fun out there peeps

 

[Mick W]

Does the 100 share the same cooling system as 90 i.e. the auto box is in line with the engine. I just had a new radiator installed just to make sure but previously had the cooling system flushed and the radiator checked for blockages as it was 20+ years old.

 

[Smeg]

Hey mine has the original towing package installed with a big Auto (AT) radiator cooler. If it runs through the bottom of your normal radiator. Best thing is to install a large independent AT cooler. Real easy to do Just check out youtube im sure you'll find a video