Transmission drain plug

Stephen Newell · Jul 16, 2019

Anyone ever put a retro drain plug on a transmission pan on a car or truck? I've tried to pump the fluid out the dipstick hole and still end up getting transmission fluid in my face when removing the pan. There has to be an easier way to do maintenance. I found a drain plug where you drill a hole in the pan and insert the drain through and put a nut on the outside. I have to wonder if anyone has had problems with such a plug.

Jeff NWOH · Jul 16, 2019

I used to just take a steel 1/4" pipe coupler, cut it in half and weld it to my transmission pans. I welded them to the bottom so there was nothing sticking up in the pan and it would drain everything. I used to change the fluid pretty regular on the trucks I plowed with, but not the filter every time.

Matt from Oz · Jul 16, 2019

Hi Stephen

Years ago had to have a rebuild on a second hand tractor differential. The dealer mechanics could not get one of the plugs out so drilled and taped the thread. Easy when everything is apart. Working on my Farmall H years ago and the thermostat plug was stuck in the side of the block. Used a greased drill and an easy out, that was brass. Not much help to you but a couple of ideas.

Stephen Newell · Jul 16, 2019

I just have a stick welder. I'm not sure how that would work to weld on a sheetmetal pan. I had thought about doing just that.

Mule Meat · Jul 16, 2019

Places like JEGS, Summit and some auto parts stores have bungs that are made for what you want. Just drill the pan and istall.

The Moroso 68900 is a good weld in one for steel pans.

If the pan is aluminum. They also have threaded bungs with rubber washers that do not need welded that will also work on steel pans.

timcasbolt · Jul 16, 2019

I've added one of those drain plug kits to every vehicle I've owned for the last 25 years. It's a lot easier to drop the pan without making a mess if you dump the fluid out first.

Wheres Waldo · Jul 16, 2019

A Mapp gas torch and braze on a brass fitting.

Stephen Newell · Jul 16, 2019

I knew that some places sold replacement pans with drain plugs but didn't find out until this evening they made some you could add. Not long ago I changed the fluid on a dodge truck and pumped nearly a gallon of fluid out the dipstick hole and still got fluid in my face when I removed the pan. Today when I changed the fluid on a chev van I just used a mortar pan under the transmission and still got oil all over everything.

First chance I get I going to order the plugs for all but one vehicle. The jeep doesn't have an automatic transmission.

4wdtom · Jul 17, 2019

If you drill and tap for a 1/8" NPT thread you don't need much thickness for a plug. It will of course drain slow from such a small hole but works. Just keep trying the plug for fit and don't go any deeper with the thread than you need to. You do need to know you have a bit of space to drill and tap into behind where the hole will be.

Stephen Newell · Jul 17, 2019

The pan on the transmissions I have are just sheet metal, not more than 1/16" thick. There wouldn't be anything to drill and tap. This is what I was proposing installing. It would just get the majority of the fluid out to make the job less messy to remove the pan and change the filter. I had thought about welding a pipe fitting to the pan but I think my welder would burn up the pan.

Stephen Newell · Jul 17, 2019

I've never been able to do that. I even bought a mapp gas and oxygen torch and couldn't do anything with it.

Mule Meat · Jul 17, 2019

Steve. That is the type of bung I was talking about.

Three things.

1. Install it on the side of the pan and not the bottom.

2. Make sure that you drill high enough for the washer to completely seal.

3. When you change the fluid next. Use a wrench to hold the bung when you remove the plug. It will keep the bung from spinning and damaging the washer which could cause a leak.

rlp in Co. · Jul 17, 2019

Have you ever wanted to have a heart to heart talk with an engineer?

Stephen Newell · Jul 17, 2019

I don't think any engineer would want to talk to me. Everything I buy has some design flaw I have to correct. This flaw seems to be pretty universal down through the ages. I think there is only a few vehicles which are made with a drain on the transmission.

Stephen Newell · Jul 17, 2019

I'm not sure any of the vehicles I have would allow the bung to be put on the side. The pan slides against the components when putting the pan back on. Then the Chevrolet van I have will be difficult to put anywhere. There is so little clearance the filter is literally resting on the bottom of the pan.

timcasbolt · Jul 17, 2019

(quoted from post at 23:08:32 07/17/19) I'm not sure any of the vehicles I have would allow the bung to be put on the side. The pan slides against the components when putting the pan back on. Then the Chevrolet van I have will be difficult to put anywhere. There is so little clearance the filter is literally resting on the bottom of the pan.

I always put them on the bottom of the pan. You have to look around at the valve body to find the area with the most room. Putting the plug on the side would leave at least 1/2" -3/4" of fluid.

Stephen Newell · Jul 17, 2019

The worry is running over something and tearing a big hole in the pan. On my van there is a steel beam running across the transmission holding it up. I will probably put the bung up as close to it as I can.

timcasbolt · Jul 17, 2019

(quoted from post at 00:28:05 07/18/19) The worry is running over something and tearing a big hole in the pan. On my van there is a steel beam running across the transmission holding it up. I will probably put the bung up as close to it as I can.

Use a plug that is broached for an allen wrench.

dhermesc · Jul 18, 2019

What vehicle are you dealing with? Lots of After Market suppliers sell pans with the drain plug - many actually sell a "deeper" pan that hold more fluid (20 quarts of ATF instead of 12-14). I put a "deeper" pan on my Tahoe that holds 3 more quarts. When I bought it I dropped the pan and filter and put the deeper pan on with the drain plug. Drove it for a week then simply drained the fluid and refilled. If I recall correctly the refill was 8 quarts - a little more than half the current fluid in the transmission. Combined with the early change I have about 75% of the fluid changed. I change it again at 30K to keep everything fresh.

https://www.ebay.com/itm/04-07-RAINIER-TRANSMISSION-4L60E-4L65E-4L70E-76-6mm-DEEP-PAN-265-811/392304923692?fits=Year%3A2002%7CModel%3ATahoe&epid=2295631711&hash=item5b5732142c:g:JccAAOSwDk5T7jfL

https://www.ebay.com/itm/B-M-70260-Automatic-Transmission-Oil-Pan-Fits-GM-4L60-4L60E-700R4-Adds-3qt/333260121642?fits=Year%3A2002%7CModel%3ATahoe&epid=112874337&hash=item4d97d9e62a:g:bSAAAOSwP7ZdIjZD

timcasbolt · Jul 18, 2019

$50 for a aftermarket pan, $5 for a drain plug kit. Just sayin'.

Stephen Newell · Jul 18, 2019

I first started thinking about the replacement pans but they run 50-60 bucks each and I would need three of them. Lot to pay not to get splashed in the face with a little transmission fluid. Then I found the retro-fit drains. That seems doable.

Goose · Jul 20, 2019

For no more often than you drain a transmission, I've taken a SHARP punch and poked a hole in the pan.

Then after the pan is off, tap it flat with a hammer and braze it shut.

timcasbolt · Jul 20, 2019

(quoted from post at 15:41:26 07/20/19) For no more often than you drain a transmission, I've taken a SHARP punch and poked a hole in the pan.

Then after the pan is off, tap it flat with a hammer and braze it shut.

To each his own. I'd rather spend the five bucks once and be done with it.

Stephen Newell · Jul 20, 2019

I have old vehicles and tend to change the fluid more often than most. Did have an issue with a dodge truck I thought I would going to have to play trial and error changing out sensors but the jerking problem cleared itself up. I had been using aftermarket filters from a local parts store. Then someone told me that dodge trucks don't do well with them so I put a mopar filter on it. For the most part it cleared up the problem right away and left it jerking just a little between first and second gear. After a month of driving though that cleared up. I just have a problem with the pan leaking fluid a little. The mopar filter didn't come with a pan gasket.

Transmission drain plug

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