Had to argue with mechanic about fluid temp for trans fluid check

I work in both systems so much I just do it depending on constants and coefficients. This one is in metric. We are working to a percent and last I checked the murican percent is the same as the metric percent haha.

 

Not aimed at you; just a rhetorical question.
Toyota instructs Techstream users to use temp check mode. Why not just instruct the user to monitor the temp sensor if there is no difference? Temp check mode puts the engine at a certain idle during temp check mode; what else is it[engine & transmission] doing that is neglected when simply monitoring the temp sensor?

 

I believe the high idle is to reduce to time it takes for the engine/ trans to warm up, ive done to check with a scan gauge to monitor temps, than in the temp check mode as a test and got the same level.

 

Not aimed at you; just a rhetorical question. What do you think the hamsters in the the trans/ engine are secretly doing when its in temp check mode?

 

https://youtu.be/XwZqCb_Im2g

Found this guy working on his daughter's LEXUS tranny. Interesting technique he employs!

 

This is another good example of why we can’t have nice things.

 

So my preliminary assessment after stress testing the truck on the drive home is that something is very much better. Monday and Tuesday I drove like a grandma and was barely getting 17mpg, the idle was noticeably less smooth and the truck felt like it was struggling to make power. On the drive home today I sent it hard, did 80-85, hard acceleration, followed by stop and go, the truck was responsive and smooth. I got 20.7 mpg. I believe that stressing that this needed to be checked to the proper procedure cause the mechanic to realize the trans was in fact low on fluid. His not charging me for the shop time or material used further has me believing this to be the case. Maybe I’m wrong but again I’m of the mind that if the specification calls for that specific temperature at the time of checking the fluid there it was engineered this way for a reason. I further believe (while I can’t prove it and honestly I’m just happy the guy finally came around) he realized he sent me off with a job done wrong the first time and this was a bit of covering his ass.

 

I wouldn’t put a lot of stock on mpg as a metric for testing. I drove up to Denver yesterday at 65 on cruise control and got 19.34. I drove back to the springs at 65 with cruise control and got 16.3..

Was hoping to hear something objective but glad your happy.

 

I’ve read that a low fluid condition makes the engine work harder. But here’s the facts:
Went in for drain and fill based on 6yr/60k suggested interval. Truck has 47k on it. After getting it back it idled rougher like it had a misfire, it struggled to make power, the tach was doing all sorts of crazy shit while cruising under babying driving conditions, and finally the trans had a huge slip on a take off. Previous to the service the truck ran smooth. It didn’t struggle to get out of its own way, it didn’t shake while I was stopped at lights idling, I regularly got over 20mpg when driving conservatively. At the end of the day brother the fact remains that this truck may have started with an already low fluid condition from the factory as many of these trucks have and it could have been exacerbated by not following the procedures that Toyota lays out. Time will tell if the issue persists and there’s something more sinister lurking but the fact remains I’m driving a very different machine after pressing for the by the book shit to be done

 

I appreciate your replies, knowing that you don't have to explain yourself to anyone, especially a rando on the internet.

Where I'm struggling to understand things is that none of those things are really characteristics of the transmission. Idling rough, erratic rpms while driving and a "slip" on takeoff are more characteristic of a fuel issue, could be fuel/air mix, water from condensation, etc.

Definitely keep your eye on it.

Did you have your plugs changed? If I recall the 60k service calls for new spark plugs.

Anyways, glad its back up and you are good to go.

 

Can we agree that decreased lubrication in the transmission would cause friction thereby making the engine work harder and decrease mpg? And when I say slip, I used to drive a manual transmission mustang, I learned on it and smoked a clutch along the way I know what a slipping trans feels like.

 

And honestly I appreciate the input but when the only thing I have to go on is the truck ran beautiful before service and started fucking up after it, it’s seems like it would have to a hell of a coincidence that all of a sudden I had fuel issues.

 

Your transmission FLUID is not a lubricant. It is a fluid. The transmission is more closely related to a hydraulic pump. In fact the transmission needs the fluid to create friction. If it doesn't, that is what causes the transmission to slip.

 

I don’t think the temperature range is because the fluid expands or contracts as this would be very minimal, someone above showed some math.

My guess would be that the fluid flows more consistently at 95 degrees and above and that there are valves/thermostats that open and allow the correct passages be utilized that would effect fluid level in the pan. Temp mode controlling the idle rpm probably influences fluid level in the pan as well.

Glad it worked out for you. Also, this can be done in the driveway, the right way, with a funnel and a length of hose to add fluid. 20 mins and minimal time under the truck.

 

You’re 100% correct. And realistically I should’ve just done it myself because then I could’ve followed the service manual. Time, schedules and not having a flat driveway to work on we’re the contributing factors to going to a mechanic. And honestly after many years of doing my own shit I just wanted a set it and forget it experience which I was happy to pay for. If the dude made it right then I’m happy.

 

No. It would cause all sorts of problems but friction is not one of them. Has nothing to do with efficiency unless it won't shift or is locked up.

 

Often times, especially as vehicles get "smarter" a problem in one system of the car can present itself as another. My uncle refused to listen to me and had his trans rebuilt twice in his F250 due to harsh shifts. Finally let me take a look at it and I discovered his plugs and fuel filter hadnt been changed in 145k miles. New plugs, new filter, and leaving the neg battery terminal off for 20 minutes? Drove like a brand new truck.

 

Is mineral oil a lubricant?

 

How do we do it on a 20+ without the jumper? I’m not at the mileage to service the trans yet, but I like to know for when the time comes. Every video and write-up I’ve seen just shows how to do the jumper method.