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Discussion Starter #1 (Edited)
How big an impact wrench to get the Trans Pan drain out?

Like the subject says, I have been trying to get the factory over tightened trans pan drain plug out.

So far I have snapped my favorite 3/8" extension by using a 6' cheater bar on it.

Then I went to air tools, but my cheapie impact wrench is not up to the job.

I was at Lowe's, and there is a Kobalt 500 ft lb on clearance for $67 that only uses 4 CFM.

There is also an IR 600 ft lb for $179, but it will overmatch my compressor at 23 CFM.

I don't want to buy anything that won't do the job, but the Kobalt wrench would do everything else I need.

Is 500 lb ft enough to get these drain plugs out?

Thanks!
 

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You aren’t looking for a torque wrench, you're looking for a breaker bar but shopping for an air powered impact wrench. If it’s the pan bolts that I know of, I would not use an impact on them.

IMO you need to try some other methods besides pure grunt, like heat via propane torch. Heat around the bolt if possible, otherwise heat the bolt and the surrounding area (moderate heat only) and then try loosening the bolt(s). There could be oxidation or goo locking the bolt in place, the expansion and contraction could break the bond enough to extract the bolts.
 

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Discussion Starter #3
Correct, I'm shopping for an impact wrench. I need to remove the trans drain plug, which is removed by inserting a 3/8" socket extension.

I have soaked it with PB Blaster. And I have used a breaker bar, at least until my 3/8" extension snapped.

I hesitate to use heat, because a) it already gets plenty warm from the transmission and b) I don't want to cook the tranny fluid in the pan.

There are plenty of posts about the plug being factory over tightened and difficult to remove, and other posters have had success with using an impact wrench.

I just want to find out how big an impact wrench was big enough.
 

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Discussion Starter #5
I haven't been to the dealer for any car in recent memory, except for recalls. I e-mailed a service advisor at the Honda dealer where I get parts from to see what they say. I have taken a few donuts from the service waiting room as I pass through to the parts window
 

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OH the drain plug!!! It looks like your post has been edited to be more clear now!

Try removing it after a long drive, when the tranny is hot. Use a long 1/2" breaker bar with an impact grade 1/2 to 3/8" reducer. Thats what I had to do.

The top fill plug on mine was even worse than the drain plug, and I found this out AFTER I drained 3qts of ATF. I was pissed, but I did get it loose.
 

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Discussion Starter #7
Thinking back to when I broke my 3/8" extension, I had too long an extension. The up and down (versus rotation) leverage is likely why it snapped.

Your way is much better, with a short adapter on a 1/2" breaker bar. I even thought about using the floor jack to push up on the breaker bar, but that would add an element of danger. And I don't think I will need to.

If the top fill plug is tight as well, can I fill it through the dipstick tube? That is what I do on the Volvo (no fill plug).
 

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rvaughn801 said:


If the top fill plug is tight as well, can I fill it through the dipstick tube? That is what I do on the Volvo (no fill plug).
Its what I do on my Accord, but on the ODY the dipstick hole is too small. It can be done, but I sure would not want to try it. Break loose the fill cap before you do the drain plug IMO!
 

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Don't laugh, but I have an impact-quality 3/4" to 3/8" reducer for just such nightmares...it has such wierd proportions, it almost looks silly. The impact-grade 1/2" to 3/8" drive reducers are definitely stronger than a regular reducer.

I've got the same tranny (4-spd HondaMatic) on my 1998 Accord. The dipstick hole is much wider...I think I used a long tranny funnel last time.

+1 on trying it after a drive, all warmed up. This has worked for me when I was hesitant to pull anymore with either size breaker bar (1/2" or 3/4" drive) when it was cold. IF you do choose extra heating, use only propane for a short while, and not anything hotter (like MAPP gas...some of us have sad stories from threading a bottle of gas onto a torch, thinking it was propane :( ).

OF
 

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Had a similar situation with our '06 Pilot on the transmission and rear diff.

Here's what worked well for me.

1. Go to Harbor Freight and get these.

2. Get a fairly sturdy 9/16" wrench. (or one you don't mind possibly breaking)

3. Get a 2 or 3 lb hammer (brass if you can afford it, will have more controllable impact, and will not damage the wrench) Brass or Standard

4. Put the Odyssey on Jack stands.

5. Put the adaptor in the drain plug and put the 9/16" wrench on it positioning the wrench so it's pointing straight down (if you can).

6. Tap the wrench with the hammer with increasing force until it pops loose.

They're not over tightened. They just get tight because the transmission housing is aluminum and the plug is steel. They expand and contract with heating and cooling at different rates and that makes them tighter over time.

Yes a warm, but not too hot, transmission will help. If it gets too hot, the steel will get as hot as the aluminum and you'll have the same problem.

Also, if you drive it a long distance, and let it sit for a while, the aluminum will cool faster than the steel, and will make it even tighter.

In short, start with a cold engine or drive it for 10 min or so, then do the job, don't try it after an hour drive.

GOOD LUCK!
 

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noanswer said:
...Yes a warm, but not too hot, transmission will help. If it gets too hot, the steel will get as hot as the aluminum and you'll have the same problem....
You're assuming they expand at the same rate. They don't. That's one reason why it has a crush washer (the term "crush" is a little bit of a misnomer...it deforms a little, but it's akin more to compression with a small amount of plastic deformation when you torque it to spec). Rincon is still right...I've tried his method on my used 2003 after a good long drive on a really hot day, and it was a big help.

Of course, I let it cool down before unthreading the plug all the way. I don't want to get burned by a splash of really hot ATF, just like anyone else.

Warm or hot or really hot, they'll both be at the same temperature. I don't have the pic, but when you see the orientation of the plug in the sump, you'll see why.

This thing mirrors the heat sink effect between a threaded gun barrel and its receiver. The only way to get a temperature differential between the case and plug is to get a torch (propane only!) and heat the case just a little inboard from the plug for a very short time, and then immediately crank on the plug in your attempt to break it free. Any delay will result in both being at the same temperature.

longo2 mentioned (in another post) his recipe for a super-duper penetrant. He uses a 50/50 mix of used ATF and Varisol. I know some aircraft mechs who use 50/50 cheap ATF & acetone with very good results.

OF
 

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Discussion Starter #12
I really like the Harbor Freight adapters. Taking a hammer and beating on my ratchets will only ruin the ratchet bearings. Hammering on a box end wrench probably won't hurt anything, and will work a lot better (less give than the ratchet, more torque goes into the drain plug). But at that point, we are really back to an impact wrench type solution.

The Volvo has the same steel drain plug/aluminum crush washer/aluminum trans case arrangement, and the drain plug unscrews easily every 15-20k. So I don't think it is heat cycles making it too tight. I believe it comes from the factory too tight, and once it is popped loose it will be easier from here out.

I don't know if Varisol is a hardware store item. Google did not turn up much. But if Varisol and acetone simply thin the ATF, acetone is on my shelf and will do the job.

The Volvo has lots of torx fasteners that all seem to be a bit light duty, especially after 200k of heat cycles. So it feels on the edge of stripping out instead of unscrewing. I spend a week or so dribbling PB Blaster on the hot fastener with an eye dropper, twice a day. Thankfully the car is not rusty, so the fasteners have always let go. But they always do so with a "Screeechhh-POP". After all the work with PB Blaster, I'm always hopeful for the steady tension then slow release of a properly torqued, un-stuck bolt.

The dealer service advisor e-mailed back that the trans service I requested (drain/re-fill) was $89.95. I already have Z1, and a new crush washer, so I really want to do it myself.

Thanks for all the advice. When it gets above freezing, and I can get all the snow crap swept out of the garage, I'm confident I can get this drain plug out. If you have anything further, please add it on. This is good stuff.
 

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Many have felt that it's torqued way too tight out of the factory. Mine was a used 2003 EX that never had an ATF change (over 50,000 miles), so a little bit of galvanic corrosion factored in too, probably.

Those impact-rated square drive socket caps look like the real deal.

OF
 

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0dyfamily said:
You're assuming they expand at the same rate. They don't. That's one reason why it has a crush washer (the term "crush" is a little bit of a misnomer...it deforms a little, but it's akin more to compression with a small amount of plastic deformation when you torque it to spec). Rincon is still right...I've tried his method on my used 2003 after a good long drive on a really hot day, and it was a big help.

Of course, I let it cool down before unthreading the plug all the way. I don't want to get burned by a splash of really hot ATF, just like anyone else.

Warm or hot or really hot, they'll both be at the same temperature. I don't have the pic, but when you see the orientation of the plug in the sump, you'll see why.

This thing mirrors the heat sink effect between a threaded gun barrel and its receiver. The only way to get a temperature differential between the case and plug is to get a torch (propane only!) and heat the case just a little inboard from the plug for a very short time, and then immediately crank on the plug in your attempt to break it free. Any delay will result in both being at the same temperature.

longo2 mentioned (in another post) his recipe for a super-duper penetrant. He uses a 50/50 mix of used ATF and Varisol. I know some aircraft mechs who use 50/50 cheap ATF & acetone with very good results.

OF
We're sort of saying the same thing.

They absolutely heat at different rates. So on a long drive, they would both have time to heat up to full operating temperature, thus negating the piont of warming the transmission.

On a short drive, the transmission housing would be warmer than the drain plug because of the thermal conductance differential (aluminum being the better conductor, thus heating faster), and the fact that full operating temperature hasn't been reached would ensure that the housing would be warmer than the plug.
 

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rvaughn801 said:
I really like the Harbor Freight adapters. Taking a hammer and beating on my ratchets will only ruin the ratchet bearings. Hammering on a box end wrench probably won't hurt anything, and will work a lot better (less give than the ratchet, more torque goes into the drain plug). But at that point, we are really back to an impact wrench type solution.

The Volvo has the same steel drain plug/aluminum crush washer/aluminum trans case arrangement, and the drain plug unscrews easily every 15-20k. So I don't think it is heat cycles making it too tight. I believe it comes from the factory too tight, and once it is popped loose it will be easier from here out.

I don't know if Varisol is a hardware store item. Google did not turn up much. But if Varisol and acetone simply thin the ATF, acetone is on my shelf and will do the job.

The Volvo has lots of torx fasteners that all seem to be a bit light duty, especially after 200k of heat cycles. So it feels on the edge of stripping out instead of unscrewing. I spend a week or so dribbling PB Blaster on the hot fastener with an eye dropper, twice a day. Thankfully the car is not rusty, so the fasteners have always let go. But they always do so with a "Screeechhh-POP". After all the work with PB Blaster, I'm always hopeful for the steady tension then slow release of a properly torqued, un-stuck bolt.

The dealer service advisor e-mailed back that the trans service I requested (drain/re-fill) was $89.95. I already have Z1, and a new crush washer, so I really want to do it myself.

Thanks for all the advice. When it gets above freezing, and I can get all the snow crap swept out of the garage, I'm confident I can get this drain plug out. If you have anything further, please add it on. This is good stuff.
You're right, I would NEVER beat on a ratchet, that's why I suggest a disposable or very sturdy box end wrench.

I have a fairly powerful pneumatic impact driver, and still couldn't loosen the plug.

With the hammer, you're probably generating a good 500 or so ft/lbs (average human foot fall is 300 lbs of force, and the hammer strike exceeds that, multiply the force by the length of the wrench in feet for fot/lbs).

Impact is the way to go when removing these, because a slow push (as with a jack)could also damage the housing or tools if not done correctly.

I've installed bearings, couplings, and all sorts of equipment using thermal methods to expand and contract metals over the years, and you would be surprised what repeated heating and cooling cycles will do to metals of different composition.

Also, these only go back to 35 ft/lbs or so they won't be hard to get off in the future.

The brass hammer, and the socket/hex adaptors with box end wrench are the way to go for the first change. After that, you'll be in good shape for future changes.
 

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noanswer said:
On a short drive, the transmission housing would be warmer than the drain plug because of the thermal conductance differential (aluminum being the better conductor, thus heating faster), and the fact that full operating temperature hasn't been reached would ensure that the housing would be warmer than the plug.
They'll be about the same temp, short or long drive. There's a nice pic on our forums with the case split open showing the orientation of this type of plug on Honda A/T's (and why this is so). I also fitted a K thermocouple into a homemade 18x1.5mm plug to measure ATF sump temps at the plug face. I found that the case actually ended up a shade cooler than the plug, whether moving or standing still..*edit*...actually, I couldn't detect a big enough difference worth posting....*edit*



Note how the plug magnet sticks out into the ATF (lower right hand quarter of the pic)...but not as much as you'd think. How it gets a uniform coating of metallic particles attracted to it (like in all the images on this forum where people post a pic of the plug during an ATF drain/refill) is a mystery to me...

While measuring sump temps, I felt I wasn't getting the best readings I could because the case was pulling a good bit of the heat from the ATF in the sump, and in essence helping with ATF cooling. As well, I couldn't find a good place to measure case temp on the outside because it varied so much. What I needed to do was remove the dipstick tube and drop in a rigid thermocouple probe and get readings for both the bead probe I installed in the A/T drain plug and a rigid probe immersed in the A/T sump's fluid. Never did it, because we were just trying to figure out ATF sump temp and where it fit between ATF exiting the A/T, and ATF returning to the A/T from the OEM cooling circuit.

I spent way too much time on this

These are things I never would have suspected had I not instrumented my Ody. watt-man was the first on the forums (that I know of) to fit probes, and it kind of inspired me to get some diagnostic gear and try my hand at it.

Found out other stuff I didn't expect, like underhood temps are very close to ambient temp on cool days, even when only moving at a few miles per hour.

OF
 

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Discussion Starter #17
Had a similar situation with our '06 Pilot on the transmission and rear diff.

Here's what worked well for me.

1. Go to Harbor Freight and get these.

2. Get a fairly sturdy 9/16" wrench. (or one you don't mind possibly breaking)

3. Get a 2 or 3 lb hammer (brass if you can afford it, will have more controllable impact, and will not damage the wrench) Brass or Standard

4. Put the Odyssey on Jack stands.

5. Put the adaptor in the drain plug and put the 9/16" wrench on it positioning the wrench so it's pointing straight down (if you can).

6. Tap the wrench with the hammer with increasing force until it pops loose.
Just like noanswer says, 3 taps with the hammer and it is out! The adapters are the best $3.99 I ever spent at Harbor Freight.

Thanks for the great advice.
 
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