Finally fixed a defect the big three auto manufactures have neglected to do.

[737mechanic]

I have never understood why the big three auto makers have never put a drain plug in their transmission pans. Well I finally did this on my wifes GMC jimmy. Transmission is a 4L60E.

What I did was buy one of the drain plugs that you drill a hole and screw it together in the pan but the problem with that is there is going to be about a 1/4in of fluid that will not be able to drian because of the backup nut thickness so I sawed off the threaded part of the drain plug and welding it flush to the pan so now all the fluid that is in the pan will be able to drain.

Main reason I wanted to do this is because I do all my own maintenance and I would neglect the transmission service because it is a mess and a pain but now I will be able to keep fresh fluid in the trans more aften than I would.

[737mechanic]

Rest of pics

[TSOR]

Looks good!

I never really understood why transmissions have no drain plug.

[tnjind]

The reason I was given years ago is because with a plug then the fluid gets changed but not the filter. If you have to drop the pan just to drain it then you may as well change the filter also.

BTW my 2000 GMC 1500 was a tranny drain plug. I am not sure which automatic it is though.

[Jolly Roger]

My dad has been installing drain plugs in automatic transmissions for years. Braze a half collar on the pan and stick a pipe plug in it.

[Black Wolf]

Tim is correct. The manufacturers WANT the pan dropped so you change the filter.

Also, if you only change the fluid in the actual pan, you are only replacing a small percentage of all the fluid in the system. You are not taking into account the fluid in the Torque Convertor, the Cooler and all lines to and from, and also the fluid in the transmission itself.

A better way to keep your transmission in top condition is to replace your filter, then take it to a shop that you trust where they will hook up the appropriate equipment in-series to replace ALL the fluid in the system. It can be done simply by hooking into the transmission cooler lines, and or a pressure line. Depends on make and manufacturer.

Just changing the oil in the pan leaves many litres (or quarts) of used and potentially burnt fluid in the system.

[TSOR]

Originally Posted by tnjind

The reason I was given years ago is because with a plug then the fluid gets changed but not the filter. If you have to drop the pan just to drain it then you may as well change the filter also.

BTW my 2000 GMC 1500 was a tranny drain plug. I am not sure which automatic it is though.

Ahhh, I see!

I still like the drian plug though! Less mess to remove the pan when it's empty!

[123weld]

What everyone said about filter is true, but its alot nicer to drain pan before dropping it. I bought two of those plugs7 or 8 yrs. ago. Each time I make an excuse why I don't have time to install them.

[737mechanic]

Originally Posted by Black Wolf

Tim is correct. The manufacturers WANT the pan dropped so you change the filter.

Also, if you only change the fluid in the actual pan, you are only replacing a small percentage of all the fluid in the system. You are not taking into account the fluid in the Torque Convertor, the Cooler and all lines to and from, and also the fluid in the transmission itself.

A better way to keep your transmission in top condition is to replace your filter, then take it to a shop that you trust where they will hook up the appropriate equipment in-series to replace ALL the fluid in the system. It can be done simply by hooking into the transmission cooler lines, and or a pressure line. Depends on make and manufacturer.

Just changing the oil in the pan leaves many litres (or quarts) of used and potentially burnt fluid in the system.

Problem with your theory is that unless you have a bad transmission the filter is most always in perfect condition and does NOT need to be replaced as often as the fluid needs to be changed.

Next time you drop your pan take a good look at the filter and see how clean it still is.

BTW whether you drop the pan or not you will never get the fluid out of the converter.

If you just keep the fluid changed you will extend the life of the transmission by thausands of miles even if you don't change the filter.

I should go out in the trash and take a picture of the old filter and let you see how clean it still is. It didn't need to be chaged at all.

What kills a transmission is burnt fluid NOT clogged filters. And filters can't do anything to help burnt fluid.

BTW some of the jap imports have no way to change the filter without removing the transmission, all they have you do is change the fluid by draining it from a "you guessed it" a drain plug.

[littlefuzz]

I was impressed with saturn's spin on tranny filter.

[Carl26]

That's a nice modification there 737mechanic. Yeah littlefuzz my 98 Saturn SC2 has the spin on transmission filter. It looks just like an oil filter.

[737mechanic]

Originally Posted by littlefuzz

I was impressed with saturn's spin on tranny filter.

That is the best thing a auto maker ever did in my opinion. I used to love working on saturns when I was a auto mechanic because of many mechanic friendly things they did.

[tresi]

There was a time they had drain plugs. The torque convertor had a drain plug as well. Then they started making disposible cars in the 70's.

[Weldordie]

Darned nice photos, too!

[goodoleboy]

Good job OP..to all who say that the filter needs to be changed its true..But, many DIY dont wnt to undertake the dirty/messy task of a pan drop and ignore changing it until something goes wrong (WHICH IS TOO LATE).

So with the Op doing regular changes every 7-15K., He will have a better tranny than the people who says the filter needs to be changed and pan dropped., becuase most of them are not changning the filter or fluid becuase of mess or the costs..I beleive most are not going to pay a shop every 7-15k $100 for a drain of the tranny or do it themselves.Though they are one or two who would.

The option is there for the OP to change the fluid or filter, and the filter more likely to get changed with the fluid all drained out before unbolting.

Besides this is a good idea, becuase it makes changing the filter a whole lot less messier..Good work again OP!

[jcaro10894]

Yes, but then came the power flushers. (Power Flushers to the rescue)

[Broccoli1]

Originally Posted by tresi

There was a time they had drain plugs. The torque convertor had a drain plug as well. Then they started making disposible cars in the 70's.

They developed better Tranny fluid too
25-30,000 miles

100,000 miles with Dexron

@ 60,000- 100,000 miles a lot of people have a new car anyway


Oil Change is 5000 miles, remember 3,000 mile changes??

[jamlit]

Nice job. Done a few myself.

The only thing to remember is that some manufactures void the tranny warrenty if you do this. I know of a couple guys that had this trouble when I work as a mechanic a few years back. Wasn't a good seen.

[Black Wolf]

Originally Posted by 737mechanic

Problem with your theory is that unless you have a bad transmission the filter is most always in perfect condition and does NOT need to be replaced as often as the fluid needs to be changed.

Next time you drop your pan take a good look at the filter and see how clean it still is.

BTW whether you drop the pan or not you will never get the fluid out of the converter.

I will respectfully disagree with your comments based on the following:

My post had nothing to do with a "Theory"..... I am a Journeyman Automotive Mechanic, and I am factory trained by Ford Motor Company as I worked at a dealership in the early 90's.

Agreed - the filter does stay clean as long as your friction disks do not wear.

Agreed - the filter really does nothing to help with burnt fluid.

Disagree - Dropping the pan or not has NOTHING to do with getting ALL of the fluid out of the transmission. You can only replace ALL the fluid (with tranny still in vehicle) using two methods:

1) Drop Pan and Drain Torque Convertor - still leaves a small percentage of "old" fluid in the valve body and passages, cooler and lines.

- For the ones that did not come factory with a drain - It was common practice to drill a hole in the torque convertor to drain it, then thread in a pipe tap, and install a pipe plug. We did LOTS and it was a FORD approved modification.

2) Hook up in series with a Tranny flushing machine. Looks kinda like a two chambered Varsol tank with a bunch of hoses etc. One reservoir you filled with new fluid, the other reservoir was filled with the old fluid as the vehicle was ran. FORD approved - heck, it was a FORD service tool made by "Rotunda"

- Because you are hooked "In Series"... ALL of the transmission fluid can be exchanged with new product (never mathmatically 100%) and is the best method of servicing the transmission.

When to change the filter is up to the manufacturer, and varies by make and model.

When flushing the tranny, it is also a good idea to have an experienced technician checkover the tranny - Take a reading on line pressures etc, and to tighten bands where possible.

Mechanic getting up and leaving, Welder sitting back down....

Back to the point of the original post. Nicely installed plug. Good thoughts to make it flush and weld it on. Welds look nice. It should do a good job for years to come.....And it will make it much cleaner and easier to drain the fluid from the transmission oil pan for WHATEVER reason you may have.

[Oldtimer]

I'm a stickler for maintenance and have always done my own servicing. It's much cheaper than having someone do it and I know it's done and not just charged for. Yeah, I have seen this done more than once but once is all it has ever happened to me.

I have read more than once that you should braze transmission pans because they are brittle and will crack when welded. I guess they can. I've welded up several that had holes knocked in them from running over some of our caliche rocks and welded several drain plugs in too. I have had exactly one crack. Really bothered me wasting that new ATF when I pulled it off to fix it but I wasn't about to try to save it.

[weekender]

A little off topic; but thought you guys would love this...Where I work the started is under part of the manifold! Awesome.

[kolot]

I have and after market pan on my 7.3 Diesel, torque converter has the drain plug and I usually open the line above the tranny cooler and blow out with compressed air.Don't know if this is OK but has worked for me. About that business of drilling the torque converter to place a plug, is there anywhere that more info could be found. That seems like a must have on the converters if you are going to do your own services. Thanks .

[737mechanic]

Originally Posted by Black Wolf

I will respectfully disagree with your comments based on the following:

My post had nothing to do with a "Theory"..... I am a Journeyman Automotive Mechanic, and I am factory trained by Ford Motor Company as I worked at a dealership in the early 90's.

Agreed - the filter does stay clean as long as your friction disks do not wear.

Agreed - the filter really does nothing to help with burnt fluid.

Disagree - Dropping the pan or not has NOTHING to do with getting ALL of the fluid out of the transmission. You can only replace ALL the fluid (with tranny still in vehicle) using two methods:

1) Drop Pan and Drain Torque Convertor - still leaves a small percentage of "old" fluid in the valve body and passages, cooler and lines.

- For the ones that did not come factory with a drain - It was common practice to drill a hole in the torque convertor to drain it, then thread in a pipe tap, and install a pipe plug. We did LOTS and it was a FORD approved modification.

2) Hook up in series with a Tranny flushing machine. Looks kinda like a two chambered Varsol tank with a bunch of hoses etc. One reservoir you filled with new fluid, the other reservoir was filled with the old fluid as the vehicle was ran. FORD approved - heck, it was a FORD service tool made by "Rotunda"

- Because you are hooked "In Series"... ALL of the transmission fluid can be exchanged with new product (never mathmatically 100%) and is the best method of servicing the transmission.

When to change the filter is up to the manufacturer, and varies by make and model.

When flushing the tranny, it is also a good idea to have an experienced technician checkover the tranny - Take a reading on line pressures etc, and to tighten bands where possible.

Mechanic getting up and leaving, Welder sitting back down....

Back to the point of the original post. Nicely installed plug. Good thoughts to make it flush and weld it on. Welds look nice. It should do a good job for years to come.....And it will make it much cleaner and easier to drain the fluid from the transmission oil pan for WHATEVER reason you may have.

All good points. I forgot to mention that before I became a aircraft mechanic I was a ASE certified master auto mechanic or technician whatever you prefer. To be a certified Master auto mechanic you have to pass all 8 ASE test which includes both automatic and manual transmissions. I also have my advanced engine performance ASE license. All are expired now but I could retest and get them back if I wanted too.

I know what the manufactures say and they also sell parts so of course they will want you to change filters whether they need it or not. I have probably done over 1000 transmission services and can tell you the #1 killer of transmissions is burnt fluid. If you install a tranny cooler and keep fresh fluid in your transmission you will NOT have any transmission problems. What causes the clutches to wear is burnt fluid because burnt fluid does not have the lubrication properties needed anymore.

BTW before I left the automotive mantenance industry the shop I worked at stopped changing the filter unless the customer requested it and then we charged extra. What we started doing was a transmission flush which did NOT include changing the filter. If changing the filter was that important then the shops would always change it after doing a flush. But they don't.

The vehicle I installed that drain plug on is my wifes 1997 GMC Jimmy and it has 165,000 miles on it and has only had the filter changed twice and the second time was about 6 days ago when I installed that plug. It was still clean and I would not have had any problems reusing it. I can also tell you that more than likely it is the last time it will ever be changed untill we get rid of it. It has although had many fluid changes and I even reuse the old pan gasket without ever having a leak.

I drive a 1992 chevy truck with 355,000 miles but it is a standard transmission so I have not had to worry as much about keeping the fluid changed in it.


P.S. Thanks for the comments on the welds.

[Black Wolf]

Well there you go.... sounds like we are coming from more or less the same background.

As you said - "All good points"

[denrep]

737mechanic, I was thinking about your dilemma...

When I saw this hydraulic pump reservoir, that needs to be drained... but there's no drain plug.



I replaced the torn boot over the pump handle, (it probably let rain water in) and Teflon taped the leaking pipe plug.

Since there's no drain, what we'll do is put a wand made of 1/4" tube in the fill hole, and pump the fluid out. We pull fluids out of lots of stuff that way.

About drilling torque converters - I always wondered if the metal chips trapped in the precisin built converter from drill break-through, could cause more damage than dirty fluid ever could.

Good Luck