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Discussion Starter #1
Hi! Long time without posting here...

Last week I started having a screeching noise from the front of the engine. Also the belt started to break and shred. I suspected new bracket problems, as in the past. First it was the left side, holding the compressor, years later it was the right side one, holding the alternator.

I removed the belt and found this in the pump pulley: https://youtu.be/ENOSRuxBcTA

I've had minor water leak for years, and I haven't noticed it being more severe lately... Should I replace the whole pump? Should I just change the bearing?

Is there a thread describing the removal? Will I need gaskets? I am in South America, so I need to plan ahead all parts purchases... They may take weeks to arrive. Meanwhile I can only watch the water level daily, and I hear the belt being slowly breaking, about to collapse. I carry a new belt with me all the time and I will be just driving around town, of course...
 

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Discussion Starter #2
Just in case it is relevant, just 6 months~2000 miles ago I had the crankshaft pulley and the HB replaced and everything was fine. Also the pulley is not the original, it was hand made in a lathe shop some 4 years ago. The original one had died a horrid and unexplained death. And I could not find without purchasing a whole pump. IDK how the pulley+propeller is attached to the pump shaft, perhaps it is only loose??
 

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Wow that doesn't look good! The fan clutch and pulley are held onto the water pump flange by the 4 studs and nuts you can see in your video. It doesn't look like they are loose though, it looks like the whole water pump shaft is wobbling.

Since you have to drain the coolant to replace the water pump its a good time to pull the radiator out and clean it, which is pretty easy and will give you more room to work on the water pump. Not all new water pumps come with a new bypass nipple, which threads into the water pump. If it doesn't come with one, you have to remove the one from your old pump and reuse it or buy a new one. Mine was quite difficult to remove but it came out with a big socket and an impact gun. Water pumps up to '98 don't come with a pulley, so if something is wrong with your custom made pulley you might have to find a new one. '99+ switched to a pressed-on pulley and a thread-on fan clutch.
 

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Hi! Long time without posting here...

Last week I started having a screeching noise from the front of the engine. Also the belt started to break and shred. I suspected new bracket problems, as in the past. First it was the left side, holding the compressor, years later it was the right side one, holding the alternator.

I removed the belt and found this in the pump pulley: https://youtu.be/ENOSRuxBcTA

I've had minor water leak for years, and I haven't noticed it being more severe lately... Should I replace the whole pump? Should I just change the bearing?

Is there a thread describing the removal? Will I need gaskets? I am in South America, so I need to plan ahead all parts purchases... They may take weeks to arrive. Meanwhile I can only watch the water level daily, and I hear the belt being slowly breaking, about to collapse. I carry a new belt with me all the time and I will be just driving around town, of course...
You will need to change out the whole pump..:HiHi:
 

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Discussion Starter #6
Thank you alpacalips, and OkDually for your info!
 

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Discussion Starter #7
Water pump listed in the part Section is shown as:
4 Bolt 130 Gal/Min AC Delco: #252717

Here is the 1998 C/K truck manual, Section 6, Engine cooling and electrical in pdf. format for you to save on your computer.
http://www.dieselplace.com/forum/attachments/63-gm-diesel-engines/21-6-5l-diesel-engine/332906d1428874704-gm-6-5-faq-obd-codes-diy-parts-list-manuals-info-sticky-look-here-first-1998-sec-6-engine-cooling-electrical.pdf
Also, I have been studying the need for the special 47mm wrench to remove the fan-clutch assembly. Is there another quick and dirty way to do it? 47mm is a very rare size, here I only can find up to 36 mm...
 

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You don't need any special tools to remove the fan clutch. It's just four nuts, 13 mm I think. It's only on the later years (99+?) that the water pump shaft is threaded and the clutch spins onto it.
 

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Also, I have been studying the need for the special 47mm wrench to remove the fan-clutch assembly. Is there another quick and dirty way to do it? 47mm is a very rare size, here I only can find up to 36 mm...
alpacalips is correct. It should be just four 13mm nuts.


In the video that you posted, you have the one that bolts on.
 

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A gasket is not needed, if you have that "make a gasket" stuff/goop. In the old days, I use to get gasket material and make my own for projects.... but it would be wise to get a gasket. There are actually two gaskets. One is the backing plate to pump and the other is the backing plate to block. I don't recall if the pump can come off w/out the backing plate or if you take it off as an assembly and then move the plate.....

Your pump is beyond toast.... mine hand a wobble, but NOT that bad. Mine, when removed, already had the impeller rubbing on the inside of the housing. Also, the clearance between the pump and back cover is not much, so it might be rubbing there also. Also, the longer you run it, the longer you risk the shaft breaking. And if that breaks, your fan will fly into your radiator....
 

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A gasket is not needed, if you have that "make a gasket" stuff/goop. In the old days, I use to get gasket material and make my own for projects.... but it would be wise to get a gasket. There are actually two gaskets. One is the backing plate to pump and the other is the backing plate to block. I don't recall if the pump can come off w/out the backing plate or if you take it off as an assembly and then move the plate.....

Your pump is beyond toast.... mine hand a wobble, but NOT that bad. Mine, when removed, already had the impeller rubbing on the inside of the housing. Also, the clearance between the pump and back cover is not much, so it might be rubbing there also. Also, the longer you run it, the longer you risk the shaft breaking. And if that breaks, your fan will fly into your radiator....
The backing plate has to come off with the pump because several bolts are on the back side of the plate. On that subject... make sure you put thread locker on those bolts when you assemble the new water pump and plate. If one falls out it can go into your timing gears.

I'm with VanBoy, I wouldn't be running that engine at all until it was fixed...
 

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I was about to do a quick post here thanking everybody for your advice, but I thought better to do a longer write up in case it is useful for somebody. This has to be done TODAY before I start forgetting details :)

(Sorry for my english in case it is not clear)

Finally I didn’t replace the pump. For those of you in North America, I wouldn’t hesitate to drop 30 dollars in a new pump, but here it could take several weeks and over twice the cost to arrive, so I thought better to try to fix/rebuild it. I did the R&R job, and handed the pump to my father, who is retired and has some access to better shop tools and has time to help with this stuff.

Also I didn’t use a gasket, which could take the same time to ship, so it was a typical fix “using whatever was available locally”

I read the procedure to remove it from the shop manual for which OkDually posted the link, but I found some steps were not really needed, ad some others could be more clear from a hands-on experience. Also it is useful to have the right tools to do it handy, you lose a lot of time fumbling for sockets.

So here is the REMOVAL work I did, step by step, (which applies only to my vehicle)

DISCLAIMERS:
a. YMMV, this is an accound of how I achieved it, there may be details or better practices that a more experienced owner or mechanic would do…
b. I may not be using the exact name for all the parts but will try to avoid using the words “thingy” or “watchamacallit”.

1. Put aside the positive battery cable that crosses across the upper fan shroud. Straps are clipped to it. Tool: Pliers.
2. Remove the upper fan shroud and put away. Three screws at the top, two on each side that holds it to the lower shroud. Tool: 10mm socket with extension
3. Remove the fan+clutch. Four nuts: Tool: 10mm wrench. Do it before you remove the belt, so the pulley won’t turn. Rotate the fan as needed to make room for your hands.
4. Go below the front end of the truck. Remove the plastic cover which is behind the bumper, at 45 degrees. It is bolted to the frame and front axle/crossmember, with 4 15 mm bolts. If you remove the lower 2 first, the cover will drop down like a door. If you are working from below as real mechanic in a real shop, it might be enough, but if you are lying on your garage floor on your side or on your back, you will also need to remove the front ones and put the cover away. Tool: 15 mm socket.
5. Remove the 2 lower fan shroud screws. From below. It is not that hard because they are clearly in sight, and they are only two. But the one in the driver’s side is really tricky because the power steering piping gets in the way. Tool: 10 mm wrench and lots of patience.
6. Remove the lower fan shroud from above, and put away. Now you can really see your workplace for the next hours.
7. Put a large pan below the radiator to catch your coolant. Now you can easily reach to the bottom of the drivers side of the radiator, for a small “tap” to purge the fluid. You should turn it CCW about ¼ of a turn, and then pull it back. Water should flow out of it but don’t expect a river, the hole is small. I would not recommed using pliers even if it feels stuck because it is PLASTIC and looks flimsy.
8. Use a proper lever in the square hole for the belt tensioner, or just get a long wrench to use as a lever. If your case is the second as mine, use a tire removal tong or a crowbar, wedge it between the tensioner and the tensioner spring casing and release tension on the belt.Maybe you can manage to rest the lever on the oil filling tube. Make sure it is stable, then you can use both hands to remove the belt. This will be more important when replacing the belt, especially if it is a new one, less flexible, you can sweat for a while trying to put it between each pulley.
9. Once you remove the belt, release tension on the tensioner and put the crow bar away.
10. Remove the pulley from the pump. It should be free after removing the fan and the belt.
11. Remove the weird stub-thing plastic tube coming from the air filter. It just gets in the way of removing the alternator. You need to remove the BIG torx screw that holds the AC pipes bracket. Tool: big torx bit.
12. Remove both bolts from the alternator. Put the alternator away, you do not need to remove the wiring, just place it over the passenger side battery, using a piece of rubber something else to insulate it. Actually you should do all this with your batteries disconnected. (I didn’t because I hate having to re-program radio presets!) Tool: 15 mm socket.
13. Now you can see clearly the 4 mounting points of the alternator+vacuum pump bracket. You have to remove one 15 mm bolt in the back (below the space where the alternato was), another sunk deep in the bracket (this one is broken inside the cyl head in mine) and two nuts behind the vacuum pump pulley. One is easier then the other, but the vac pump pulley has properly placed holes to insert a socket. Tool: 15mm socket, extensions.
14. Once this is done, gently pull the bracket to the front of the vehicle, carrying the vacuum pump with it, and remove it. BE CAREFUL not to break the vacuum line, it is rigid plastic and in an old engine it can crack easily. Unplug it carefully as soon as you can put your hand. There is no need to remove the vacuum pump from the bracket. Just put the whole thing away.
15. Remove the two nuts that hold the oil filling tube, and just pull the tube to the front of the vehicle. It is inserted in a rubber sealed hole, like a plug. Put it away. Tool: DEEP 13mm socket.
16. The short rubber hose going from the thermostat housing to the pump is called the BYPASS hose. Given that mine was quite old and softened, I just opened the spring loaded clamps with pliers and move them to the middle of the hose, and then managed to remove the hose by twisting, bending (and cursing) BEFORE removing the pump. It may be tricky but I think this saves you from disassembling the DRIVER side bracket, with the power steering and AC compressor… Really I didnt need to touch them. Tool: big pliers and appropiate curse words for your language.
17. Lower radiator hose: You should remove it by opening the clamps from either the radiator end or the pump end. My hose looked VERY old and bloated, but not cracked or broken yet. I did not have access to a new one, so I chose to release it from the radiator end, and keep it atatched to the pump all the time, because fiddling with it might end breaking it. Also mine had a smaller hose clamped in the middle, as a tap. I guess it is water returning from the back heater. (it is a suburban). Your vehicle might be different.
18. Now you can FINALLY get to remove the pump+backing plate. You can clearly see now that the top part is only backing plate and the bottom is pump+backing plate. Once you remove both together, you will understand that the backing plate acts as the cover for the timing gears. SO ONCE IT IS REMOVED BE SURE NOTHING EVER FALLS INSIDE OF THAT HOLE. :eek:
19. The pump+backing plate set is held by 13 different bolts and studs. I drew it in a cardboard box and made holes in it to place each bolt in its place, so nothing gets lost, nothing gets confused. Please see below which tool size to use
1. The top 2 ones are 13 mm studs (where the oil fill tube was held) Use deep 13mm sockets
2. the other 4 (2 in each side) below them, hold only the backing plate. 13 mm bolts. Use regular 13 mm sockets. If you have access to a torque wrench please see torque specs elsewhere. The only tricky bolt should be the one behind the bypass hose, if you couldnt remove the hose before. But it is reachable with your left hand with a wrench and some patience.
3. On the driver’s side, 2 15mm large bolts, and 1 stud (which in my vehicle made no sense because nothing was attached to it. Perhaps a remainder from an earlier disassembling. Use 15mm sockets.
4. On the passenger side, 2 15mm studs, where the alternator bracket was hanging. Use a deep 15mm socket if available, or a wrench.
5. Finally below the pump (you have to go by touch here because you can’t see them, 2 13 mm mid lenght bolts. This completes the 13 bolts removal. As I recommended before, please be sure to store these 13 with their position and not confuse them with other bolts. Why? Because later on when you replace the pump with the backing plate, if you will be using “make a gasket” goop as I did, time will be critical to correctly mount the pump and adjust all the mounting surface bolts BEFORE the goop gets hard. You won’t have much time and if you go back and forth you will mess the goop and have serious leaks. So it is important that you are ready to mount and adjust everything without interruptions, without fumbling for bolts of tools, etc.​
20. PLEASE BE SURE TO HAVE REMOVED ALL 13 BOLTS BEFORE TRYING TO PRY AWAY THE PUMP, OR ELSE YOU MAY DO SERIOUS DAMAGE, TO THE PUMP AND/OR THE PLATE.
21. Now use carefully a flat screwdriver between the plate and the engine block (NOT BETWEEN THE BACKING PLATE AND THE PUMP, THEY ARE STILL BOLTED TOGETHER FROM THE BACK!!!!”, hammer on it a little and once you can get the previous sealant and gasket to separate a few mm, it is easy to remove the pump!
22. Once the pump is removed, you can put it in a working table or hold it in a vise, and remove the SIX 13mm bolts from the back. Then pry away the backing plate from the pump.

End of disassembly so far. If you are replacing the pump, this will be easy. My father managed to rebuild it. To disassemble it you need access to a hydraulic press.

We followed more or less the instructions in this video. The guy is disassembling a big tractor engine pump, quite similar.

We managed to easilly find locally a new bearing, a new seal for very little money (These are more or less generic mechanical parts worldwide, you don’t even have to care to go to a GM parts store)

We assembled it back by using the hydraulic press. (as in the video)

VERY IMPORTANT: WHEN DISSASSEMBLING IT, make sure to record the exact position on which the front plate has to be pressed. The first time around it was left too far to the front and the pulley did not match the plane of the other pulleys, so the belt would be torn to pieces and break away! We learnt it the hard way, after assembling it back!!! THIS CAN’T BE FIXED WITH THE PUMP IN THE ENGINE, YOU CAN’T FORCE, OR HAMMER THE PLATE BACK, YOU NEED THE PRESS…. So I had to go ALL THE WAY dissasembling again from step 10 in my list, remove the sealant, clean everything and take the pump to the hydraulic press for adjustment!!! An interesting detail is that the front “plate” where the fan+clutch bolts, has 4 studs and 4 other threaded bolts. If you make the opposite mistake of pressing the plate too far back, you could just thread 4 8mm bolts on them, and tighten them pressing against the pump body, so as to use the plate as its own “extractor” and pull it closer to the tip of the axis. Then you remove the bolts. Interesting trick. :idea:

The reassembly is basically all 22 steps reversed, but here are some tips for it:

(a) AFTER connecting radiator hoses and tightening the clamps, but BEFORE replacing the shrouds and fan, fill with coolant. If you find that any hose is leaking, just by gravity, without temperature or the engine running, or needs tightening, it is easier now. The lower hose is practically inaccessible without steps 1 to 6. ALSO LEARNT THE HARD WAY.:bawl:
(b) Working with the plastic cover behind the bumper (it should have a name) removed has the benefit that most of the sockets and tools that will fall, go to the floor, else they get caught in the greasy depths of the front axle.
(c) Be careful with the radiator purge tap. It seems flimsy. I fear that if it breaks, you will need a new radiator.
(d) Radiator removal is recommended by some, but I didn’t do it. I feared having to disconnect the oil cooling lines, etc. and once you remove the fan and shrouds, there is more or less ample space for work. Anyway, be careful with tools that may fall and wedge in FRONT of the radiator, between it and the AC condensers.
(e) About the “make a gasket” goop/thing/sealant: DO NOT use regular silicone based sealant. It has to withstand temperature and oil. When reassembling, follow these steps
(a) clean and scratch gasket and sealant remains from the FOUR surfaces: engine block, back of the backing plate, front of the backing plate, pump
(b) Be thorough and precise when applying the sealant.
(c) Bolt the 6 plate-to-pump bolts at the appropiate torque and IMMEDIATELY APPLY SEALANT to the engine block and replace the pump and bolt everything. The six bolts DO NOT fully press the plate to the pump, everything needs to be sandwiched together and tightened, BEFORE THE SEALANT HARDENS. Have bolts and tools handy and ready.​
(f) About the six bolts that hold the plate to the pump, it is tempting to add grover washers to them. In any case, one of them falling inside the timing gears could kill the engine forever… BUT BETTER REFRAIN… The clearance between those bolts’heads and the gears seems TOO TIGHT…

I guess that’s all for now. Hope it is useful for somebody, some day… Thanks for reading.

HERE ARE PICS: https://www.dropbox.com/sh/2pr6vj4kziahvxb/AAAyI2zoP-dI5-wjZuHR7xsSa?dl=0
 

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Nice write-up and thanks for sharing your experience :thumb:
 

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Water pump.

Just my .02 on getting the pump backing plate to block to seal: Make sure you clean the plate sealing surface and the block sealing surface very good. Like you would a cyl. head and block. I've had that plate leak on me before and could have sworn I did a good job on it.

Posted this before I read page 2 of this thread. You don't need any advice from me Luis. :)
 
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