Hi RogerHsr,
You need to remove the four screws on the back cover then remove the cover and look at the brush cartridges to see if they were knocked out of their socket. A number of time I've seen them knocked out and setting in side ways with a little bit of the brush riding on the commutator and making just enough contact to allows the tool to run.If this is the case just slide it back in the socket.Hope that helps.Good luck.
Tinker

Hi aquabill,
This seems to have been an issue with the detent pin in a lot of these drills. Some times you can run the drill in reverse while rotating the selector ring in to drill mode. Some times if you switch from 1 to 2 to 3 gear and run the tool it will free up the pin.Also by loosing the front screws about 1 turn of the way out and lightly turning the ring it will free the pin.But be very careful not to loosen the four front screws too much as the rear transmission plate will pop out and not allow you to tighten the screws without taking the transmission completely out.Just keep trying and in a good many of the cases it will just start working again.Hope this helps.Good luck.
Tinker

Hi Ducky,You will have to cut off the chuck outer case and cut off the ring nut.This will allow the pawls to be pushed out and you will then be able to reach the screw.Hope that helps.
Tinker

Thanks Tinker, I was hoping to avoid that, but I kind of figured that was my last recourse. Thanks again for the info, Ducky.

Sounds like bad brushes. They may be worn, cracked or just not contacting well.

Mine does this too. I have found that if you turn the clutch to the lowest setting and then hold it so that it slips, then you can turn it back to drill or hammer.

Chris and or Karl, I had the same problem and thanks to Karl it worked. Still need to look into why this is so. Seems like something is to blame for this. Guess i'll check with the guys at ereplacement

Hi Guys,
The DC988 had a number of issues with the transmission.The problems were clutch slippage,sticking rotator rings and jumping out of gear.there was never any service bulletin about the problem.Look at the bottom of the drill where the battery goes in and look for a date code.It will start with a 20xx xx-xx. The first 4 digits is the year the tool was made the second will be the week and i think the last where it was made.The transmissions have a three year warranty so if your tool fall within the three years you can get a replacement transmission under warranty. Hope this helps.Good luck.
Tinker

Remove the tail cap with the 4 screws. unplug the wires from the brushes. pull the brush assembly straight out to the side replace with new ones. plug the wires back in on the same side they were on and put the tail cap back on.

My drill chuck will work some then lock up until it s jarred lose may work a minute or two before locking back up.

Greg, before you do anything else, look further on this forum to Alberto's letter. Sounds very much like his as well as my same symptoms. Try the suggestion I gave to him and I feel confident you will have satisfying results.
Good luck with your drill!

Handy Dan

It's definitely unusual to have the spindle assembly come off when you're changing a chuck. That spindle is buried pretty deep inside the tool. As far as the chuck removal goes, you can read the post below by MikeF, or visit our chuck removal page here:

http://www.ereplacementparts.com/article/890/How_to_Remove_a_Drill_Chuck.html#threaded

You shouldn't need any special tools to remove the chuck.

Hi Alberto, Intermittent electrical problems with a tool can be very difficult to diagnose. The first thing I would do is remove the motor brushes and inspect them. Sometimes dirt or other debris will get into the brush holder causing the brush to jamb and loose contact with the armature. Make sure that the brush can move freely inside of the brush holder. If all looks good with the brushes then it is most likely the switch that has gone bad and will need replacing. The switch is part #152274-22 and is available from http://www.ereplacementparts.com Hope this helps you to repair your cordless drill! -Mark

Alberto, Be sure to remove the battery first. You should start by checking the brushes and commutator. To do this, you must use a Torx driver bit to remove the 4 screws at the back end of the drill motor cover and take off the cover. This will expose the brush assembly. Locate the wires that go to each brush assembly,attached by a spade connector. Carefully pull out the connector from each brush holder. Next, you must gently, but firmly pry straight out on the brush holder assembly ( 90 degrees to the motor shaft!) to slide it out. Not just the brush, but the assembly holding the brush. If the brush will extend at least 1/4 of an inch out of the holder, it will last a pretty long time. If not, you need to purchase new brush assemblies. Next step, and probably the most important, is to clean the commutator. (The part of the motor that the brush slides on.) Some VERY FINE sand paper or nail emory board will work. You will need to cut a strip only about as wide as the brush and try to gently buff the commutator until it is a nice bright brass color all the way around. Really, this is the most important step. Probably the main cause of your problem.
Put it all back together and try it out. I just did this on mine and completely solved the exact same symptoms you described.
Good luck. You should have no problems!
Handy Dan

The chuck replacement process is relatively simple. We have a full walkthrough on our site (including a video) that applies to most keyless chucks. You'll want to check the "Threaded-on" section of our article here:

http://www.ereplacementparts.com/removing-drill-chuck-c-8873_15176.html#Threaded

You'll need to start by removing the chuck screw, which is left-handed (meaning you'll have to turn it clockwise to loosen it), then put the biggest allen wrench you can fit into chuck. Tighten the chuck around the allen wrench, and secure the drill (preferably in a vise) before hitting that allen wrench (counter-clockwise) with a hammer a few times to get it loose. After that, you should be able to get the chuck off by hand.

Putting a new chuck back on is basically the same process in reverse. The whole thing should (hopefully) take no more than a few minutes.

Our article may have some details I may have missed, and the video has been pretty helpful to a lot of people, so I'd still recommend referring to it before starting this project.

Yep, just took a little more muscle, yes it was reverse threads, and no, there wasn't much of a surprise behind the 3 bolts in the drill face.

Hi diggla,

We have an article and video of a transmission repair on a DW987 Drill. Most of the information will also apply to your DC988. You can find the article and video at the following link...

Removing And Replacing DeWALT Drill Transmissions.

I hope this helps with your repair!

-UtahAV
-Mark

[QUOTE=diggla;5913]Does anyone know how to replace the clutch and motor on the 18v hammer drill? Is there a good write up that i could use?

Thanks" If you take the rear cap off removing the four screws, you can then lay the drill down on the table with screw side up.remove remander of screws take clamshell off.you will now be looking at inside of drill grab motor lift up pull to the left its now removed,take and lift gearcase and chuck up a little pull to the right its now removed . assembly is the reverse.when installing transmission there will be a pin sticking out the front wich you must align going back into gearcase look at notchs on the side of the transmission those will line up with ones inside of gearcase as you install it you may have to turn chuck to get it to seat all the way in motor is self explaintory its really pretty easy hopefully i have helped you out good luck

I'd say take the drill apart and clean it up inside and put new brushes in it would probably fix it. Don't forget to clean up the part of the armature that the brushes contact. I usually use some kind of real fine emory cloth for this or something like #600 sandpaper and then really clean that part of the armature up afterward so as not to leave any sand in it off of the sandpaper.

Fist off you should compare the two brushes to make sure thay're the same size (thkns and width) and if they are,then the holder probably has a build up of residue from the old brushes.so you shud try cleaing it out first using a small flat scewdriver (terminal type) and if that don't work lightly sanding wit a piece of sand paper shud do the trick.
Good luck

Quincy

Hi sbohne,

It sounds to me like the transmission is on its way out. It is an easy repair to make. We have an article that will walk you through the repair. You can find the article at the following link...

Removing And Replacing DeWALT Drill Transmissions

The new transmission is part #397892-05

Let us know how it turns out!

-UtahAV
-Mark

Hey arizzotto,
If you have the front housing removed..[4 screws] and then the housing half separated..the transmission will remove easily..but you do have to have the front part of the drill removed..
parts avail at ereplacementparts.com
hope this helps..:)
Craig

Hey rockydog,
Most likely it is the transmission..they do wear out over time..
part # 397892-05...avail at ereplacementparts.com..
hope this helps..:)
Craig

could you please tell how to replace the tranmission...see read about taking off four srews than what?

Hi jeep,

We have an article and video on our site that I think will help you with replacing the transmission on your drill. You can find it at the following link...

Replacing DeWalt Cordless Drill Transmissions.

Let us know how the repair goes!

-UtahAV
-Mark

Hey Gabi,

Welcome to the forum. So, you saying that there is a bit stuck in the chuck and you can't get it out?


If that is the case, here are two posts that will help:



Drill chuck is stripped


Bit stuck in chuck

thank you Dave for answering me.. I'll try doing what u tell me and I will thak you again after I will take out that bit! thank you anyway!

Hello! The brushes in your Dewalt DC988 are removable, but you have to remove the entire brush holder along with the brush. The brushes are housed in little clips that are attached to the motor. Here's a pic:

603754-01 Brush and Holder

You will need to unclip the brush and holder from the motor to replace it. Fortunately the brushes are sold along with the holder so all you'll have to do is clip the replacement assemblies in place and you're all set.

Hey Dan6531,
If you have an ohm meter you can test the different components..without.. it's kind of a guessing game..most likely it is your switch now....part #152274-22 avail at ereplacementparts.com..:)
Hope this helps..
Craig

One simple way to bypass your on/off switch to test your cordless drill’s motor is to hot-wire the motor. This test should help you determine whether your motor is the cause of your drill's problems, or if your switch might be the one to blame. All you will need besides basic tools to take your drill apart are two wires that will be used to connect the battery to the motor. Make sure you have a good and fully-charged battery. Follow these steps to conduct this test:

1.Once you have taken your drill apart and removed the battery, take the switch from the handle and disconnect the two wires from the switch.



2. Take a wire and connect it from one of the battery contacts to one of the motor wires.



3. Hold the motor firmly in one hand, then connect another wire from the second battery contact to the other motor wire.

Note: Do not worry about which wire you connect to which battery contact because it will not matter on a DC motor; it only determines which direction the motor will turn.



4. The motor should turn on to full power when you make the second connection. If it does not, your motor is not working properly. If it does work, then your switch is probably what needs to be replaced.

Keep in mind that to hot-wire your motor it has to be disconnected from the switch.

Let me know how it goes.

Odie

Thanks guys! I wish I would have found this site earlier!

Hey Kevand,
You may have the brush's wearing down causing excessive sparking and they may just need to be replaced,however the smoking is not a good sign..ugh.. worst case is your armature is shorted and it may be time for a repair or a replace [when you check your brush's be sure and look at the commutator of the armature [where the brush's make contact] and look for any signs of damage..
hope this helps...
Craig

It definitely sounds like the motor to me. Your magnetic field could be cracked or you may have a short in your armature. Either way, you need to replace the whole motor before it takes out your variable speed switch. The motor comes as a sealed unit and includes a new set of brushes. Here's a link to the motor for your drill:

eReplacementparts.com : MOTOR AND PINION [396505-22] - $39.50

[quote=chrisjo;359]i have a dewalt dc988 drill that throws sparks and occasionally smoke out of the vents on the back. Good burning smell too.
Brushes looked ok, but i replaced them anyway (only $4/brush).
It still does the same thing.
Wondering whether i should try replacing the motor or what?
Motor costs about $40 on ereplacement.
Any suggestions greatly appreciated.
Cheers,
chris"
safety first, remove the power source battery or unplug the tool--- had same problem with a dewalt cordless drill-try this if you are comfortable with taking unit apart. Get to motor, remove brush box (housing)-- i'm guessing you did this to replace the brushes--with very fine sand paper clean the commutator- the part of the rotor that the brushes make contact with until you see clean copper evenly where the brush will make contact. Blow out any junk from sanding,now you will notice small grooves or lines on the commutator-using a razor blade or very small flat head screw driver(jewelers size) carefully clean out each one until you can see a separation between each, again clean out with compressed air - reassemble.tool may spark some as brushes re seat them selfs should only 5 to 10 seconds on high speed.be sure to test in safe place no flammables etc.if still a major problem go with a new motor .
Hope this helps

Tried the cleaning and no help.
Ordered a new motor and put it in today.
Works like a champ.
Thanks for the help.
As the motor came with its own set of brushes, I have a spare set of those too :)
Cheers,
Chris

[QUOTE=Mike;363]It definitely sounds like the motor to me. Your magnetic field could be cracked or you may have a short in your armature. Either way, you need to replace the whole motor before it takes out your variable speed switch. The motor comes as a sealed unit and includes a new set of brushes. Here's a link to the motor for your drill:

eReplacementparts.com : MOTOR AND PINION [396505-22] - $39.50"

I recently replaced my motor with new set of brushes included but I still have sparks after testing it. Will the sparks go away after awhile?

MIne did the same. I havea new motor on order. since that is the easy way out lol. I have no clue how to get the brushes out anyways:rolleyes:

[QUOTE=Ben;3425]I recently replaced my motor with new set of brushes included but I still have sparks after testing it. Will the sparks go away after awhile?"

Yes, there will always be some sparks, that is normal. When a new set of brushes are put in, the end of the carbon that touches the commutator on the armature is flat. That surface will quickly wear to the curvature of the commutator. The excessive sparking you initially see is from the brush wearing to that curved shape.

-UtahAV
-Mark

Great website and it is VERY easy to find parts!

I just finished replacing the brushes and have the same issue as the previous posters. So I will now buy a new motor.

Will the motor slide out once I remove the leads to the brushes?
Do I need to be concerned about anything else when I pull out the motor?

Thanks in advance for the help.