Transmission low fluid?

My 2006 TRD has 135,000 miles. I just completed a 6,000 mile trip. The engine was idling rough so I made an appointment for new plugs and all of that. While waiting for the appointment day the transmission began to act up. If I came to a quick stop the truck would rev up and then lurch forward, as if in neutral. It also would occasionally not upshift from third gear. If I made a very easy stop it would behave normally. No engine codes, no check engine light.

So, a little more of the story, 40,000 miles ago I had a local shop, the one that normally does the things I cannot or do not want to do, do a flush and fill on the transmission. All was well until a few days ago. The shop then finds the transmission, using the Toyota procedure to check the fluid level, to be 1.5 quarts low.

Now, it drives fine again, smooth as can be and shifts and starts and stops normal as ever. Could 1.5 quarts low cause this lurching from a stop? And how would it get low? It has no leaks anywhere, absolutely none. About 15,000 miles ago Toyota, under warranty, replaced the forward CV joint and the center bearing and some other stuff, free of charge. Could they have spilled transmission fluid having done so?

We do tow a boat that is 3,500 pounds all up including trailer. Never had an issue towing. Just wondering where the missing fluid went to?

 

Yes it could cause the issues you described with the fluid being 1.5 quarts low. No doubt about it.

The overall system takes 11 quarts, but the pan takes 3 and if you are missing half of that fluid in there, well then those shift solenoids are not going to be happy.

 

The trans has to be at a certain temp when the level is checked via the runoff plug. There’s a little bit more to a fluid change than normal with these trans and if it wasn’t done properly the level could be low.. Check for leaks in the lines going up to the radiator https://www.tacomaworld.com/threads/diy-full-flush-for-automatic-transmission.68462/

 

Check and make sure your transfer case isn't overfilled while not a common occurrence the seal between the transfer case and transmission can sometimes allow transmission fluid to leak into the transfer case, that would be the only other explanation to where the fluid went if there's no external leaks and it was properly filled to begin with.

 

Yes, I am aware of the procedure and I am thinking the transmission has been low since the fill and flush. There are no leaks but I will check those lines again.

Thank you.

 

Yes, good idea. If fluid keeps going into the transfer case via the shared seal, would it not begin to leak or vent fluid?

 

Only if it got overfilled to the point it comes out the vent, just something that's easy and free to check

 

Yes, okay, I will check that this weekend. I would imagine that transmission fluid mixed in the transfer case oil should be readily evident. It has been so long since I did the T case I do not remember the oil type or amount, arrggghhh. I sure hope there is not a seal leak .

 

1.1 Qt API GL-4 or GL-5 SAE

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90

 

Okay, just some follow up. The transfer case fluid was at the correct level. Inspection of the fluid showed it to be in fine shape and has no transmission fluid in it. I refilled with 1.1 quarts, until spill over, with Mobil 1 gear oil. So, I do not have an internal leak to the t-case. The hoses connections are dry as is everything else. There are no external leaks of any sort and no leakage into the transfer case.

I believe now that the shop did not correctly fill the transmission some 40,000 miles ago. Once a few years ago, at the bottom of a very steep and boulder strewn trail I stopped at the bottom and when I stepped on the gas the truck did the same lurch.