Car Guys/Mechanics- Transmission Fluid

Speedbowl14

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Hi all,

I've got a 2009 Rav4 with 110,000 miles on it. I bought it used and it has had a history of tranny issues (burning fluid and original owner went too long without changing it). I got the car at 85,000 miles, and my mechanic just did a drain and fill on the transmission fluid at 110,000 miles for the first time I've had the car. Old fluid was very poor quality...discolored but no metallic bits or anything super alarming. I think it had been last changed at 70,000 miles, so a standard 40,000 mile interval. I've been driving it around for around a week since the mechanic did the drain n fill (50-60 miles total) and I'm leaking transmission fluid very slightly. Like a 3" diameter wet spot on my driveway each morning. Dipstick still reading high. I crawled under there today and it *seems* that it's just leaking from the drain plug. Would it make sense that the mechanic stripped the screw or ruined the gasket when they put the drain plug back on? Or is it possible that with the new fluid my transmission is slowly destroying itself in the many many many ways that a poor transmission could destroy itself after replacing old fluid with new fluid?

The car is shifting much better than it did with the old fluid. My key question is...I know trannies can go bad after adding new fluid...but it's my understanding that usually takes a few hundred or a thousand miles before you'll run into problems...is that possibly happening in this case or did the mech simply not tighten the drain plug and/or stripped it?

Regardless it's going to the mechanic again Monday or Tuesday for him to check out. This is a local shop I've been going to 10+ years, not an AAMCO or a chain. Mechanic told me not to do this fluid change...but...I insisted when I bought the car that the dealer put a warranty on the transmission for me to buy it, which they did. Not like I want to go through that process though if it is dying on me.

I have no idea who else to tag... @Nitro Dude @BobbyFord
 

Clutch

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Hi all,

I've got a 2009 Rav4 with 110,000 miles on it. I bought it used and it has had a history of tranny issues (burning fluid and original owner went too long without changing it). I got the car at 85,000 miles, and my mechanic just did a drain and fill on the transmission fluid at 110,000 miles for the first time I've had the car. Old fluid was very poor quality...discolored but no metallic bits or anything super alarming. I think it had been last changed at 70,000 miles, so a standard 40,000 mile interval. I've been driving it around for around a week since the mechanic did the drain n fill (50-60 miles total) and I'm leaking transmission fluid very slightly. Like a 3" diameter wet spot on my driveway each morning. Dipstick still reading high. I crawled under there today and it *seems* that it's just leaking from the drain plug. Would it make sense that the mechanic stripped the screw or ruined the gasket when they put the drain plug back on? Or is it possible that with the new fluid my transmission is slowly destroying itself in the many many many ways that a poor transmission could destroy itself after replacing old fluid with new fluid?

The car is shifting much better than it did with the old fluid. My key question is...I know trannies can go bad after adding new fluid...but it's my understanding that usually takes a few hundred or a thousand miles before you'll run into problems...is that possibly happening in this case or did the mech simply not tighten the drain plug and/or stripped it?

Regardless it's going to the mechanic again Monday or Tuesday for him to check out. This is a local shop I've been going to 10+ years, not an AAMCO or a chain. Mechanic told me not to do this fluid change...but...I insisted when I bought the car that the dealer put a warranty on the transmission for me to buy it, which they did. Not like I want to go through that process though if it is dying on me.

I have no idea who else to tag... @Nitro Dude @BobbyFord
Have you tightened the nut?
 

Musrat#2

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Nitro Dude

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More then likely it is a gasket or o ring depending on which one you have if the drain plug is tight now.
 
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Speedbowl14

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I never updated you guys...

Yes, it was just a gasket which the mech apologized for profusely, replaced for free, put me in the bay right when I got there, and had me going again in 20 minutes.

Then, a week later, on a road trip, I hit the gas at a red light and GRIND GRIND GRIND. So I thought "well there it goes". No reverse or drive, just grinding like it's trying to select a gear but can't. 2 hours later AAA comes and the truck driver pops it into gear and get it half way up the flat bed before it starts grinding again. I thought "well that's odd". Car gets delivered to my house. I didn't like the positioning of it so I started it up and moved it about 10 feet....no grind. Today I went out and went up/down the driveway, around the block, put it in all the gears....did this for about 20 minutes so the fluid was certainly warm if not hot. Car was fine.

So now I'm completely lost. Of course I don't want to drive it knowing the same thing could happen again and strand me, but I'm also certain the transmission mechanic won't drive my car around his shop for 30 minutes waiting for a "problem" to begin.

So now this is wayyyyyy beyond my level of comprehension. I guess I don't have severe gear damage or else I wouldn't have made it this far. I thought maybe the fluid just got too hot...but the A/T fluid temp light did not come on. Also the car was parked for nearly 2 hours waiting for the tow truck. The fluid probably wasn't cool by then but definitely not hot anymore, and it started to grind when it was loaded onto the bed. In the 20 minutes of HARD driving I put it through in my neighborhood it certainly would've gotten hot (as it did when I checked the dipstick).

I thought maybe it was a clogged filter that unclogged itself but there's no hesitation changing gears.


I'm totally lost.
 

BobbyFord

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Filters don’t unclog themselves. When I was a mechanic people would bring me their cars and sometimes I’d have difficulty diagnosing an intermittent condition. I’ve had customers leave their car with me and tell me to drive it like it was mine for a week to see if it would happen while I was driving it. I was an auto trans mechanic for Ford in the 80s, I’ve never heard an auto transmission “grind.” They usually slip in gear or skip a gear when something is wrong but very seldom make grinding noises. Drive it like you stole it until something really breaks then get it fixed.
 

Speedbowl14

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Filters don’t unclog themselves. When I was a mechanic people would bring me their cars and sometimes I’d have difficulty diagnosing an intermittent condition. I’ve had customers leave their car with me and tell me to drive it like it was mine for a week to see if it would happen while I was driving it. I was an auto trans mechanic for Ford in the 80s, I’ve never heard an auto transmission “grind.” They usually slip in gear or skip a gear when something is wrong but very seldom make grinding noises. Drive it like you stole it until something really breaks then get it fixed.

Ok that's all good stuff. Maybe grinding isn't the right word. It's a very loud hum and it wasn't selecting into gear.
 

KTMLew01

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Ok that's all good stuff. Maybe grinding isn't the right word. It's a very loud hum and it wasn't selecting into gear.
Does it have a transmission dipstick? Low fluid level will allow air into the system/pump which COULD? make a noise? On level ground check the fluid with engine off. Should appear to be over-filled. Start engine and check again. Does fluid level drop on stick when running? If level doesn't change from off to running something ugly is happening. It's possible some control valves are stuck.
 

Magnethead

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first thing, anytime you buy a used car, get all fluids changed so you know the exact service history at least during your ownership.

I'm with Lew, I was thinking shift solenoids. They control the oil flow to apply various clutches. Did a quick google search, doesn't seem there's any mechanical-electrical shift motors. Also looks like it's an AISIN transmission, same as some 2018+ FCA vehicles (and a good manufacturer).
 

BobbyFord

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first thing, anytime you buy a used car, get all fluids changed so you know the exact service history at least during your ownership.

I'm with Lew, I was thinking shift solenoids. They control the oil flow to apply various clutches. Did a quick google search, doesn't seem there's any mechanical-electrical shift motors. Also looks like it's an AISIN transmission, same as some 2018+ FCA vehicles (and a good manufacturer).
Faulty shift solenoid with throw a code. Check engine light would be on.
 

Speedbowl14

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Faulty shift solenoid with throw a code. Check engine light would be on.

That's what I thought.

I'm thinking it's just fluid got hot and couldn't provide friction anymore. Maybe not hot enough to throw the sensor, but hot enough to not be able to provide lubrication.

We had been driving an hour on hilly roads at night following the hottest day of the year....but only an hour of driving, me and one passenger, and air temp of 80 degrees is a hellova lot less than what it's been through.
 

KTMLew01

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This is exactly why I (current ASE Master Tech) don't answer automotive questions. BobbyFord is sure to throw a grenade in the conversation. Good luck with it.
 

Speedbowl14

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This is exactly why I (current ASE Master Tech) don't answer automotive questions. BobbyFord is sure to throw a grenade in the conversation. Good luck with it.

Anything is appreciated! Thank you I'll keep y'all posted.
 

BobbyFord

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Hard to say. Solenoid can be electrically okay but mechanically sticking, and wont always throw a code. Depends if there is a correlating sensor.
Not always but usually will cause the check engine light to come on. I’d pull codes just for giggles.
 

BobbyFord

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Also, what is the condition of the fluid? Color? Smell burnt?
At the very least get the trans serviced and the filter replaced. It likely has a fiber filter and not just a screen. Don’t let them just do a trans flush, have them pull the pan and replace the filter. This way they will also see any “surprises” that might be in the bottom of the trans pan. Have the converter drained at the same time if yours is equipped with a drain plug.
 

BobbyFord

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Sorry, I just reread the original post and see that the fluid was changed 25k ago. Check to see if the fluid condition is still semi-new.
 

Speedbowl14

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There is a torque converter TSB on that vehicle. Check to see if your vin falls in these parameters. Check and see if this is the same engine/trans combination.

Vin matches, and the scenario matches that it wouldn't throw a code and would happen under light acceleration between 30 and 40mph.

Would I lose my ability to shift to any of the PRNDL gears with a bad torque converter (well, it would shift but just hum loudly in anything but neutral).
 

BobbyFord

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Vin matches, and the scenario matches that it wouldn't throw a code and would happen under light acceleration between 30 and 40mph.

Would I lose my ability to shift to any of the PRNDL gears with a bad torque converter (well, it would shift but just hum loudly in anything but neutral).
Well it seems yours has been having this problem for a while so you don’t know what other damage there might be. Given the mileage on your vehicle I’d say an overhaul is probably in your near future.
 
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