LB7 water pump replacement?

[Mark Rinker]

A buddy called me - his water pump is leaking at 170K miles. He is a small engine mechanic, completely wrench capable, but wondering what to expect.

Anyone done this that could chime in here with your .02 worth? He's trying to decide if its a garage project, or a trip to the stealership...

Thanks in advance.

[OC_DMAX]

There is a pretty good DIY write-up at this link:

http://www.dieselplace.com/forum/showthread.php?t=214076


Since your going to pay the cost of the water pump hardware (no matter whether you DIY or the dealer does it), the question becomes is the pain worth it to save about $600. Each person will have a different answer to the question.

[Mark Rinker]

Thanks! I think he'll likely do it himself.

[mattb5150]

Nice write ups on Diesel Place but since I only have one vehicle looks like I'll be having the local shop do mine.

Does anyone have the part numbers for the pump, all of the water hoses, and o-rings?

If I get the parts from an online dealer I can get the job done cheaper.

Matt

[GMC Tech]

Need the tools to hold the flywheel and a 12 point socket to ket the harmonic balancer off. Torqueing the bolt is a real mofo. Aftermarket has the tools for it. I think there name is Lisle. Check with your autoparts store.

[Jakemax04]

i am changing water pump on lly right now which i believe is the same as lb7 except belt position. here is a good video that tells you exactly how to do it. it is a great video. http://www.youtube.com/watch?v=Q_Z5F--WU2c
i got a 40 in breaker bar to get that harmonic balancer off and it came off with a little muscle. dont let it scare ya.

[Jakemax04]

oh and got my water pump from dmaxstore.com..... comes with gaskets.

[DmaxMaverick]

The most difficult part of the whole job is negotiating the balancer. Getting it off and torquing it back on is easy, without special tools, if you "ignore" the common procedure.

You will need:

3/4" or 1" breaker bar and 36mm 12 pt. socket (conveniently, the same size socket needed for the front hub nuts, so you might as well own one). DO NOT use a 1/2" breaker bar. It will live up to its name, and break. If you try it, use a Craftsman bar. I replaced a 30 year old rusty bar doing a pump job.

A helper. You will need to be in two places at once. I've always found this easier with help.

A cover for the radiator. Thick cardboard or thin plywood will do. If you don't, you risk puncturing or otherwise damaging the radiator. Cover the entire inside (rear) of the radiator surface.

A deep socket, or other similarly shaped metal item (short piece of bar stock). Needed size described later.

One 4-6' 2X4.

One 2X4 or 4X4, 2-3' long. This will be used to protect the fender during the bolt torque procedure. If the socket loses grip on the bolt, the bar may dent the fender as you pull down. A board placed between the bar and fender will prevent damage.


Fender covers. Anything to protect the fender paint while working over the fenders.


What to do:

Remove the fan shroud, then cover the radiator surface.

Remove the belt, hoses, fan/clutch, and accessories needed or in the way. The A/C compressor can be set out of the way, still connected. The only thing left to deal with should be the pump and balancer. Pay attention to the connection of the lower pipe to pump connection, and account for the gasket when removed.

Remove the thermostat housing. You don't have to, but there's a risk of damage (leak) to the pipe and seal if you don't. It also makes pump R/R a little easier, with the pipe out of the way. There's a hidden pump bolt that's easier to get to with it removed.

Place the socket on the balancer nut and rotate the crank by hand until the breaker bar handle rests on the ground toward the DRIVER side. Use the 2X4 to hold the socket SQUARELY on the nut, and lever the board against the upper radiator support. This is very important. Use enough pressure to force/hold the socket onto the bolt, but not enough to damage the support. Once you are certain it is in place and secure, hold it there while your helper "bumps" the starter. It only takes the slightest bump of the key to break the bolt loose. Trust me. This works every time and causes NO damage to anything. Or you could spend a lot of time removing the starter and installing an expensive tool, then wrestle the bolt off.

Once the bolt is removed, pull (by hand) the balancer. You won't need a puller. It should pull off easily, or with a little pull/wiggle while tapping with a soft mallet. Don't use a hammer or anything on the outer ring/pulley. Locate the alignment pin on the crank (no woodruff key, only a dowel pin). If it's facing up, leave it in place. If down, remove it, or it may remove itself to somewhere you probably won't find. If it isn't there, the hole is probably facing down, and it fell out. Find it before it gets kicked or rolls out of sight.

Replace the pump.


Installing the balancer:

Rotate the crank until the pin hole is up. You can bump the starter as needed. Wipe the crank clean and install the alignment pin. Wipe clean the inner balancer. A little wipe of oil on the crank can help with install. Apply some oil to the balancer outer hub surface and the seal. If it's dry, it may roll the seal, which will cause it to leak.

Install the balancer and washer/bolt. If you are reusing the original bolt, coat it with blue Loc-Tite and tighten by hand. The bolt should pull the balancer all the way in easily, before the crank begins to rotate. Once tightened to the point the crank starts to rotate, stop.


Torquing the balancer bolt:

This is kinda' tricky, but works well and only takes a few minutes. It's easier than it sounds (and it helps if you got a little redneck blood in you). The balancer/pulley assembly has NO threaded holes or other traditional method of securing anything to it, so options are limited. I have considered designing/fabricating a tool for this, and may still. If you went through the hassle of installing the flywheel tool, you won't have to do this part. Just torque the bolt according to the procedure. The manual recommends (requires) using a new bolt, but I've done and know of several reused bolts with NO issues at all. More time may prove this wrong.

Locate a deep socket or other item (bar stock) about 3/8" - 7/16" outside diameter. I don't remember the size, exactly, but it should fit in the hole in the inner balancer hub. It should go deep enough in the hole so it doesn't work out with significant pressure on it, but large enough so it doesn't wobble too much.

Place the socket/breaker on the bolt with the bar/extension (cheater) over the driver side fender, long enough a person can pull down on it. Place a square handled breaker bar, or similar solid tool (don't use pipe, it will collapse/bend) between the bolt socket and small socket/bar, then rotate the crank until the end of the small bar rests on a frame member, while holding it all squarely in place. Use caution to NOT allow it to catch on anything "soft". Load the large socket/bar, and use the long 2X4 to secure the socket squarely on the bolt. Have your helper pull down on the bar, and reset as needed to achieve enough torque on the bolt. Watch everything carefully, to prevent anything from slipping off. Go slow. Do a little math to determine how much force needs to be applied to the bar to achieve about 300+ ft./lbs. torque. If the bar is 4' from the socket to the hand-hold area, you will need to apply at least 75 pounds to the bar. Err on the side of caution, and overdo it a bit to compensate for arc-loss and friction. You can use a torque wrench, but I don't have one large enough, and don't know anyone who does. It's easier to do it the "old fashioned" way. If you aren't a good guesser, stand on a bathroom scale while pulling down on the bar. Watch for the correct amount of weight to come off the scale. Yeah, I know. Redneck.

Once torqued, allow the Loc-Tite to cure a few hours before starting the engine. This should be enough time to assemble everything else. It's also a good time for a cooling system flush.

[Jakemax04]

dmax.... the special tool your talking about is 33 bucks and it comes with the socket and locking block. not too expensive and easy to use.

[DmaxMaverick]

dmax.... the special tool your talking about is 33 bucks and it comes with the socket and locking block. not too expensive and easy to use.
I know of a couple attempts with the "cheap" tool, and the results were less than optimal. One result was significant damage to some underhood components, fender, knuckles, and possibly flywheel damage. The part that engages the ring gear let go.

The GM recommended tool was well north of $100 when I last looked.

[GMC Tech]

The Lisle tool #22100 is what I used many times at the shop. If you follow the instructions it works great. Never had an issue with it.

[jjcsnlynn]

Great write up.

[More Power]

Here's a pic of the Lisle 22100 tool set.

http://www.thedieselpageforums.com/photopost/data/500/flywheellocking.jpg

The text on the right side says: "Locks flywheel in place when removing harmonic balancer on 6.6L Duramax engines with Allison automatic transmissions. Also includes forged 36mm 12-point short socket for use on the balancer bolt. See back for applications."

The toothed key is inserted into and through the inspection plate located at about 4-5 o'clock position on the bellhousing. This locks the flexplate. I haven't used it yet, but the tool set looks well made. The two different toothed pieces allow the tool to be used on either a pickup Allison or one in a 4500/5500. While I haven't verified any difference, it seems the inspection cover is different between the two transmissions.

Jim

[DickWells]

Thanks, DMAX. I fired up the printer, and made a copy of this, just in case my LB7 ever needs it. Will put the copy into my wife's "Dick's Stuff" manilla envelope for posterity.:D

Want to ask this question, if I may. While the thing is down for the water pump, what's your feeling about replacing the harmonic balancer with one of the after-market units? Worth it? And, if so, which one? The viscous one, or the "other" brand?

Another great thread!:) Thanks.

[DmaxMaverick]

That Lisle kit Jim posted looks very promising. Unless it's cost-prohibitive, it is far better than the GM/Kent. Locking the ring gear from the TC cover access is a much better, easier, quicker, and less painful process. While removing a Duramax starter is not the most difficult to do, it is what it is. I'm in the process of designing/fabricating a balancer lock tool, which may be better. I'll give it a try when I need one and post the results. The method I posted above works well, but may not be for the inexperienced or faint-of-heart.


Thanks, DMAX. I fired up the printer, and made a copy of this, just in case my LB7 ever needs it. Will put the copy into my wife's "Dick's Stuff" manilla envelope for posterity.:D

Want to ask this question, if I may. While the thing is down for the water pump, what's your feeling about replacing the harmonic balancer with one of the after-market units? Worth it? And, if so, which one? The viscous one, or the "other" brand?

Another great thread!:) Thanks.

I wouldn't recommend replacing the balancer without a need. Fluid Dampr makes some tall claims on theirs, and they are very proud of them. If the claims are valid (or possible), it would be worth it for someone who may drive enough to recoup the expense. A $300 difference for one component is a hard pill to swallow on an uncertainty. I'm not aware of any recurring or common issues with the Duramax balancer, which makes it even more of a reach. As far as "other brands", no. Stick with OEM if the need arises. This is a hard-learned lesson for some.

[Burl]

All the other stuff mentioned is great. The one thing I had a problem with were the o-rings on the connector pipe. The dealer sold me the wrong size and i put it together probably 15 times cutting the o-ring each time. I finally found the o-ring spec and went to the local hardware store. Once I used the correct size o-ring i had practiced so many times that it went together in a snap. Easy job but may require some patience.

Burl