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Transmission Fluid Always Low

I am new to this site so because I find it difficult to navigate I may miss someones response to my question. I hope someone can help.

I purchased a pre-owned 2004 Lexus es330 95K miles in Jan. I noticed it shifting hard so when I got gas I had them check the transmission fluid. It needed fluid. This went on for the next 4 fill ups. After that I only need to put transmission fluid in about every 4 fill ups. I now have 104K miles.

When this initially happened I had the mechanics put it up on a lift to look for leaks and they also took it for a test drive. There were no visible leaks.

I park in the same spot in my driveway. There are no leaks under my car.

Why is the transmission fluid disappearing? Where is it going? Is this a dangerous situation or a warning signal of what is to come in the future? Because of this situation I purchased an extended warranty in the event that I will need a transmission :frowning:

How does the engine coolant look? Does it have an oily slick on it, when you open the radiator cap (with the engine stone cold, so there’s no pressure)?
The transmission fluid cooler is very likely integral to your radiator. If you see an oily slick on your coolant, it could be that it has a leak and it spills into your coolant. Your mechanic should know to check for that.

When I had them check the fluid today I looked under the hood and the reservoir was… empty… or low. So I asked him to put some coolant into it to top it off.

I will ask them to check the coolant for an oily slick. IF there IS a slick is this a big repair? What will it entail to repair it?

Actually, if there is a leak and it is spilling into my coolant can I just leave it like that, or will it cause damage to the engine?

LindaLexus wrote:
Actually, if there is a leak and it is spilling into my coolant can I just leave it like that, or will it cause damage to the engine?

You don’t want the fluids mixing in either direction, if that turns out to be the case.

If there is a leak of the transmission cooling coils located inside the bottom tank of your radiator, you need to get this fixed immediately. The ATF (automatic transmission fluid) getting into the coolant isn’t going to do a lot of harm, at least not a little, but coolant getting inside the transmission and mixing with the ATF will do serious harm to the transmission very quickly.

Your coolant needs to be checked in the radiator, not the overflow. If there is ATF in the coolant, you will see it when you remove the radiator cap. This must be done when the engine is cold. You need to see the ATF for yourself, even if you need someone else to locate and pull out the dipstick. The ATF must be a clear bright red. If it is brown (or black) or milky, it must be changed ASAP. If milky it must be change immediately.

If milky, or if there is ATF in the coolant, your radiator needs to be replaced ASAP, then the transmission fluid changed.

Normally I am against any kind of transmission flush, but in your case, if the ATF is milky red or milky brown, or there is any other evidence that the ATF and coolant are mixing, then I will make a conditional exception. First, no flush, but sometimes flush is a term used for a fluid exchange machine. If the shop is using a fluid exchange machine and they drop the pan and clean the filter first (this filter gets cleaned instead of replaced), then I will agree that it should be done.

BTW, you probably need an ATF change anyway, especially if the ATF is currently a clear reddish brown, but in this case, just have them drop the pan, clean it out and clean out the filter, then reinstall the pan and refill. This only changes about half the AYF, but that is enough to renew the additives and extend the life of the transmission. If the ATF is a dark brown or almost black, again do the drain and refill described above, but then in a week, have the fluid drained and refilled again, but this time, they only need to pull the drain plug, they do not need to drop the pan.

I hope it is not too late to avoid damage, but you should not be driving any automatic if there is a leak causing mixing of coolant and Automatic transmission fluid.

Good Luck

Agreed. It may need a transmission fluid replacement and new radiator, if you’re lucky.
If so and no further damage was done, that’s not a huge deal.

Ok. I just went out and opened the radiator to look at the fluid. There was no FILM floating on the top of it. The COLOR of the fluid was clear and golden ish, but clear. Is this how it should be?

Since the fluid was clear in the radiator with no film, would it be the modulator VALVE sucking transmission fluid up into the INTAKE manifold? I do not even know if the Lexus es330 designed to work like this… any one?

If it IS burning the fluid through the engine is this going to cause damage? I have noticed, on very rare occasions, a small amount of exhaust while the car is warm and running. I thought perhaps I was burning oil but I am not low on oil.

(((helloooo))) anyone?

This vehicle does not have a modulator valve.
How much transmission fluid is being added each time? If this is a quart each visit I find it hard to believe the leak could go unnoticed. They may have been adding a small amout each time. Check the fluid level to see if it is now overfilled.

Your coolant is good, it should be a clear color. The color varies by brand, a clear yellow is typical of the newer universal, long life coolants which are perfectly fine for your vehicle. The Toyota brand coolant is a clear red, kind of like the transmission fluid.

You don’t have a modulator valve. BTW, the fluid is checked with the engine OFF. If someone is checking with the engine running, then the fluid level will appear low,

Now you still need to check the ATF for color. I’m kind of wondering if the person who keeps adding the fluid is actually doing anything, or just saying they are and charging you for it. The reason I wonder is that if you have the 5 speed automatic, there is no dipstick and you can’t add fluid without a special pump. This is not done at a corner gas station, you almost have to go to a dealer for this, but some independent mechanics are now getting this pump.

Next time you are told you need ATF, ask to see the dipstick for yourself. ALOS, Toyota’s need a special ATF, the regular off the shelf ATF’s commonly sold will harm your transmission.

All ES330’s have a transmission dipstick, ES350’s do not.

Check the fluid level with the engine running, transmission hot, after driving at least 5 miles, 10 miles in a cool climale.

Drive the vehicle so that the engine and transaxle are at normal
operating temperature.
Fluid temperature: 70 − 80 °C (158 − 176 °F)
(a) Park the vehicle on a level surface and set the parking
(b) With the engine idling and the brake pedal depressed,
shift the shift lever into all positions from P to L position,
and return to P position.
© take out the dipstick and wipe it clean.
(d) Put it back fully into the pipe.
(e) take it out and check that the fluid level is in the HOT position.

Nevada, Toyota’s are done with the engine OFF and the dipstick has markings for both hot and cold.

I copied the message above from the service manual.

What service manual?

Looks like a moot point, this car has the 5 speed. I haven’t dealt with one of these 5 speeds but I’ve been told that they have no dipstick and the transmission is not serviceable without that special pump.

According to my neighbor who has a shop up in town, there is a way to get around this special pump, but the car has to be up on a lift and you will spill a little ATF doing it.

I am using TIS, service manuals online through the Toyota comapny web site. The special pump (for WS fluid vehicles) is no different than a gear oil pump.

The local Toyota dealer here made it sound more complicated. I was there getting a pan gasket for my daughters Corolla and we got to talking about the new transmissions with a service advisor. He didn’t particularly like them.