ATF level confusing - what do you make of this ?

[youdontwannaknow]

Both Honda cars with Honda ATF.

When car is cold (overnight cold) level measures fine i.e. just below MAX. Then I started the car and put it into Reverse, then Drive, then Reverse again and then Park. I did not drive the car. Just stepped thru the gear positions. Shut off the car, measure the fluid again and now its below the MIN.

Then I drive the car for ~5 miles. Test ATF level again and now it is at the same as when it was cold i.e. just below MAX.

So which level do I trust ?
Is this fluid expansion ? although can't believe the difference would be so much.
Manual just says "car/engine should be at operating temperature".

 

[oldmaninsc]

Originally Posted By: youdontwannaknow
Both Honda cars with Honda ATF.

When car is cold (overnight cold) level measures fine i.e. just below MAX. Then I started the car and put it into Reverse, then Drive, then Reverse again and then Park. I did not drive the car. Just stepped thru the gear positions. Shut off the car, measure the fluid again and now its below the MIN.

Then I drive the car for ~5 miles. Test ATF level again and now it is at the same as when it was cold i.e. just below MAX.

So which level do I trust ?
Is this fluid expansion ? although can't believe the difference would be so much.
Manual just says "car/engine should be at operating temperature".



Unless Honda is different, I've never heard of checking the ATF fluid with the engine OFF. Every vehicle I've ever had you check it with the engine running - preferably at normal operating temperature.

 

[oilboy123]

Not many automatics are checked with engine off. I can't remember which ones were ever done that way. Newer Honda correct?

Should be with the engine running I believe. Check owners manual or dip stick to be sure.

 

[mechtech2]

Some auto trannys are checked with the engine off.
Follow the manual's instructions to the letter.
Also call the service dept at the sealer and ask how they do it.

 

[youdontwannaknow]

manual asks specifically to 'shut off the engine'.

 

[The Critic]

Honda's procedure is to idle the car until the cooling fan cycles twice (IIRC), go through every gear in the gear selector, then shut it off and check within 30 seconds of shutdown.

 

[Saturn_Fan]

Originally Posted By: The Critic
Honda's procedure is to idle the car until the cooling fan cycles twice (IIRC), go through every gear in the gear selector, then shut it off and check within 30 seconds of shutdown.


+1, IIRC, my Honda powered/trannied Saturn Vue called for the same procedure.

 

[youdontwannaknow]

where did you guys read about that procedure ? I have the factory manual for the MDX and it doesn't have any of that stuff.
It says the same thing as the owners manaul. Engine warm and off thats it.

Could Honda's procedure call for shutting off the engine only due to safety reasons or could it be something else ?

 

[AcuraTech]

Honda's - engine off, fluid at operating temp. Give it a few minutes after shutdown for the fluid to drain back into the pan.

 

[Saturn_Fan]

Originally Posted By: youdontwannaknow
where did you guys read about that procedure ? I have the factory manual for the MDX and it doesn't have any of that stuff.
It says the same thing as the owners manaul. Engine warm and off thats it.

Could Honda's procedure call for shutting off the engine only due to safety reasons or could it be something else ?


My bad, I should have said that the procedure I read is close to what TC said. I was just agreeing with the Honda engine off, check within 30 seconds deal. I haven't heard of the fan deal.

 

[JTK]

Originally Posted By: youdontwannaknow
Could Honda's procedure call for shutting off the engine only due to safety reasons or could it be something else ?


The main reason for the engine off ATF level check is because of the 'pan-less' vertically split cases and the way Honda transmission pump oil. You'd read low on an idling engine. Good thought on the safety aspect though. Honda engine compartments are easy enough to poke your skinners into harms way!

Joel

 

[gonesurfing]

This seems contrary to every other manufacturer's way of checking ATF level. It's impossible to know how much fluid has drained from the torque converter once the pump is off.

 

[benjamming]

gonesurfing,

It is contrary to every other mfg way of checking the ATF level (that I'm aware of anyway). But, as usual, The Critic & AcuraTech are spot on as that is the correct procedure. Honda electro-mechanical transmissions are unique.

 

[Gary Allan]

Can we shoot them? Honda and The Critic that is. We'll give AcuraTech a pass.




j/k

 

[doitmyself]

Just shoot Critic. Honda is still well liked here!

At Critic's age, most of us were only worried about girls and acne..... not giving out good car care advice. Keep up the good work, Critic. I especially like how you irritate Gary Allan (with an "a").

 

[Gary Allan]

 

[Ramjet Roger]

For what it's worth, try the reading both ways and see if there's any meaningful difference. On my Honda Pilot, the difference was minimal between a running at idle reading and an off for less than 30 seconds reading. However, with the running at idle measurement, the readings were much more reliable. I surmise that Honda really is worried about injuries/lawsuits since the ATF dipstick is low and the clearance between the hot motor and the radiator fans is tight.

 

[JHZR2]

Ive always had issues getting good, consistent readings on any AT-equipped vehicle. Usually there is a big variation from one side of the dipstick to the other too...

 

[youdontwannaknow]

although my curiosity was not whether engine should be ON or OFF but whether it should be warmed up or not, because there is a distinct difference in reading between cold and hot engine. Why would there be such a difference is what I am trying to find out.

I topped up the ATF keeping the cold reading as a reference, and the "clunk" I used to hear when throwing it into Reverse (from Park) has disappeared since then.

 

[mechtech2]

There is a big difference when checking any auto trans fluid level when hot or cold.
The metals and the fluid expand a lot more than we'd think.
Add any time to drain differences, level [same] surface, eyeball inaccuracies, etc, and it could seem far more.