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Logic of AT Pans with No Drain Plug

As I’m soon to be covered in trans fluid I’m pondering the rationale behind not putting drain plugs on all pans as a standard.

Any thoughts?

I lay down a big piece of cardboard and put the drain pan underneath, then you loosen the bolts on the pan some and open on corner for the fluid to drain out of. Then pull the bolts from one side, and finally pull the whole pan down. Then you throw the cardboard away because its covered in fluid anyway but somewhat controlled. Or pay the shop $100 to just do it.

As a non-engineer, I suspect its two fold. The trans with drains seem to be the ones that have no pan and the assembly is cast rather than sheet metal. On the sheet metal ones, it would be an extra operation to weld the threads on. Then there would still be that hump in the middle so all the fluid still would not come out. Then you still have to get the pan off to change the filter. Really in a shop its no big deal. Its just laying underneath the car that makes it hard.

I got a 3x4 plastic bin at garage sale for 1$. Is about 6" deep. Works great. Get one at Walmart for $5

The logic is that the design is not geared toward DIY repairs. Professional mechanics have lifts and special transmission drain/support rigs that can be wheeled directly beneath them. They don’t need a drain plug and in fact, since they change the filter or clean the screen during every service, a drain plug is superfluous.

That being said, I never understood why any shadetree mechanic wouldn’t install a drain plug the very first time you drop the pan. I do. That way I can do much more frequent changes in very short amount of time with little mess or expense. About every third fluid change I drop the pan and change the filter.

The plugs are cheap. I find the best spot in the pan for the plug. Then I tape something inside the pan at that location that represents the height of the plug inside the pan. Then I put the pan up to the trans to see if it fits without hitting anything. I leave the gasket off while doing this to see if there is margin. If it doesn’t hit anything without the gasket in place, it will have that much more room when the gasket is used. Then mark and shoot the hole. Install plug and reassemble.

I agree with @TwinTurbo. It forces you to remove the pan and replace the filter rather than just doing a drain and fill.

I’ll add that it saves 50 cents per car and it eliminates one more failure point in the system.

As a counterpoint, I have a Saab with an Aisin automatic tranny with a drain plug. It has NO filter and only holds about 8 quarts of fluid. A drain only nets 4 quarts. Recommended drain intervals are 60,000 miles (waaaay too short with only 8 quarts!) It is very easy to do the drain and put in a fresh 4 every 30,000. Completely opposite other manufacturers philosophies; 15 quart capacity, filters and “lifetime” fluid.

Not installing a plug saves money for the manufacturer. A few pennies add up over millions of cars. And the car companies customers don’t really need a plug. BTW, you are not the customer of the car manufacturer, the dealer is. You are the dealer’s customer. Have you noticed the increase in transmissions without drain or fill ports? That makes more likely that owners will take their cars to dealers for transmission work, including a simple drain and fill. Just taking care of the customers.

Hey, lok at it this way: Jiffy Lube can’t mess up a trans fluid change anymore!

“Jiffy Lube can’t mess up trans fluid change anymore!”

The hell they can’t!

All they need to do is connect the tranny fluid exchange machine and put in the wrong tranny fluid.

Tester

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The dipstick delete is more of a scandal to me than a lack of a drain plug. Makes it near impossible for most owners just to check the trans fluid. It seems that the manufacturers want to sell more transmissions and transmission service by making it as hard as possible to do for the DIYer.

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“a drain plug is superfluous.”

I couldn’t disagree more strongly

When I am doing a fluid and filter service, I much prefer the pans with a drain plug

It’s a lot easier maneuvering a pan that is 85% empty, versus one that is full

Because of the exhaust configurations on some vehicles, it’s not always easy to loosen one corner and drain the oil.

One day I worked on two Tahoes, back to back. The first had a drain plug. The next did not. They were the same model year, same trans, transfer case, engine, etc.

The problem on these vehicles was that the y-pipe had to be lowered so that you could actually remove the pan. On the vehicle with the plug, I didn’t have to worry about the fluid sloshing around, when I got around to lowering the pan.

I am extremely opinionated, when it comes to trans pan drain plugs

I think the lack thereof is due simply to cost cutting, and nothing else

How else could you explain the two Tahoes I mentioned. The one without the plug was probably assembled on the day that the plant manager was encouraged to cut costs

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I have heard of numerous crap places draining the tranny and overfilling the oil.

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@‌db4690

"a drain plug is superfluous."
I couldn’t disagree more strongly
When I am doing a fluid and filter service, I much prefer the pans with a drain plug

Right, it’s a preference not a need.
The marketing guys call a feature like that a “delighter”. It’s not a CTQ that makes the list in terms of cost vs benefit ratio. Therefore, most vehicles do not have one.

“How else could you explain the two Tahoes I mentioned. The one without the plug was probably assembled on the day that the plant manager was encouraged to cut costs”

Have you ever worked in a production environment? It doesn’t appear as though you have based on that comment. It’s not up to the production supervisor or plant manager what parts are installed on a vehicle. I have what I believe are some likely scenarios for you to consider:

  1. The owner had that drain plug installed after purchase.

  2. A similar pan from another model was installed after purchase.

  3. The production pan was revised to include a drain plug for the reason you mentioned and cut into production at some point. The WIP and materials on order were exhausted prior to the cut in. Therefore, some have them, some don’t.

I think the lack thereof is due simply to cost cutting, and nothing else

There would be no other reason but that is one of the primary motivators above almost everything else being considered. Cost is one of the top 3 weighted factors in a manufacturing operation (often #2).

BTW- as mentioned, I am a fan of drain plugs. I also work in an environment where cost targets are difficult to achieve and manufacturing costs are closely scrutinized so I understand why they are rarely included.

My 2002 Sienna has over 205,000 miles on it. Very often I have drained 3 quarts of ATF and added back 3 quarts. Never have had the filter changed. Different sources even disagree on what is in there. Some say a filter; others say a screen. Fluid is perfectly clean, transmission performs flawlessly (so far, heh, heh.)

I would not want a car with no transmission drain.

@TwinTurbo‌

1 No. These are fleet vehicles. The fleet manager is not authorizing the mechanics or anybody else to install plugs after the fact

2 No. I guarantee you 100% the pan with the plug was not originally on another vehicle

  1. Maybe

As for drain plugs “rarely” being included, I firmly believe the domestics are cheap, in some regards, at least. I truly believe it’s as simple as that

Food for thought . . . Why did every single Benz I ever worked on have an auto trans drain pan plug

Why did every single Toyota auto trans pan have a drain plug, at least all the ones I’ve seen?

It might be argued that those “delighter” features are to be expected on a Benz

Now please use that logic to explain the drain plug on a cheap, common as dirt Toyota

The Japanese and most Euro cars have used transmission drain plugs for as long as I can remember and I might respectfully disagree with the premise about most vehicles not having a transmission drain plug.

The disagree would be that most cars have a drain plug other than most of the domestic branded Big Three vehicles.

Adding a drain plug during production would add only pennies to the cost but the bean counters are going to make each and every penny bleed and scream for mercy as it’s pared down.

It’s the same reason they may use a rivet instead of a screw in a certain spot, or plastic push clip instead of a rivet or screw, or a plastic bushing instead of bronze or brass, etc, etc.
A tenth of a penny here, 2 tenths there, and soon you’re talking big money… :slight_smile:

Lack of a drain plug also saves a little wear and tear on the machine tooling…

I am old enough to remember when we didn’t really have imported cars in this country, way less than 1 percent of sales our domestics were way more than the big 3 and I never ran across a car with an ATF drain plug in the 4 years I worked changing oil, greasing cars and doing tune ups in the 50s.

“I never ran across a car with an ATF drain plug in the 4 years I worked changing oil, greasing cars and doing tune ups in the 50s.”

They were out there at the time. Maybe you just didn’t notice them. In fact…a lot of domestic models even had torque converter drains on them. I really don’t remember all the exact models but I do know that most of the drain plugs were about the size of a half dollar on the transmission pans. The torque converter drains were much smaller. My first boss insisted that the pan be dropped without removing the drain plug because the filter needed to be changed along with the fluid anyway. My '58 Buick Special had one and I’ve included a picture of one for a '56-'59 Cadillac. I think it’s the same plug used for Buicks.

'56-'59 Cadillac.

Like @irlandes, I too have done a drain-and-fill on a 2002 Toyota Sienna, and was glad to have that drain plug.

I think the thinking from most manufacturers is that they want you to go to the dealership so they can hook up the machine they use to flush the transmission fluid (and your wallet), and leaving the drain plug off probably saves them a couple bucks.

I too don’t want a car that doesn’t have a transmission drain plug. For that matter, if I get a car with an automatic transmission, I expect it to have a dip stick or some other way to check the transmission fluid. It would be nice if manual transmissions came with dip sticks too. The lack of a dip stick is why I change my manual transmission oil so often. Once you’ve removed the fill plug to check the level, you’ve done half the job of changing the oil, and since my Civic’s manual transmission only holds 1.9 quarts of oil, I just drain and refill once every couple years.

As for drain plugs “rarely” being included, I firmly believe the domestics are cheap, in some regards, at least. I truly believe it’s as simple as that

Right, no one has disagreed with that point, especially me, I reaffirmed that in the last post. we can move beyond the motivation for omitting them- it is to save money.

Food for thought . . . Why did every single Benz I ever worked on have an auto trans drain pan plug

Have you compared the sales price of a Benz against the models that do not have drain plugs (at least for the historically “serviceable” transmissions)? By and large most Benz cars are considered high end vehicles, no? There’s a lot of wiggle room for niceties in high end vehicles…

Why did every single Toyota auto trans pan have a drain plug, at least all the ones I’ve seen?

I suppose Toyota thought it was worth the expense to include them.

It might be argued that those “delighter” features are to be expected on a Benz
Now please use that logic to explain the drain plug on a cheap, common as dirt Toyota

Now you are confusing common with cheap. Toyotas are common but they are not cheap compared to models more commonly found without drain plugs. For example, my Camry cost quite a bit more than the equivalent Chevy available at the time. Regardless, I do not believe that has any bearing on the matter:

Since you make the comparison, riddle me this- why does my Chevrolet of the same vintage as my Toyota include automatic headlights but no AT drain, whereas my Toyota has manual headlights but does include an AT drain??? The Camry costs more, why doesn’t it have a nice feature like automatic headlights when they seem to have found a way to do it in the competitive cheaper make/model? The presence of a “convenience feature” has little to do with common-ness or “cheapness” but likely more to do with the perception of what will be beneficial in selling that make/model while remaining at a competitive price point.

We seem to have strayed from the intent of my original post. Drain plugs are preferred but not necessary. That much is clear since not everyone includes them and their omission has not prevented anyone from servicing the trans. It is nice to have but not essential. Omitting them saves money for the manufacturer. People like to downplay the expense but it isn’t pennies you can bet on that unless you are talking about several hundred pennies. The cost to produce a hermetically sealed weld on the threaded bung into the pan and then thread in the plug is more than “pennies”. The materials alone amount to more than that even in 10k qtys…

Like I said, on my Acura I appreciate the drain plug and is a simple matter of draining the fluid and adding four 3.3 quarts back in. On my Pontiac though, a drain plug would be worthless because the car has to be up on a lift to fill it again through the plug by the axle (evidently but I’ve never found it). So it just has to go to the shop for drain and fill and filter replacement for $100. Which isn’t really a bad price considering the mess.