Change water pump on 98 Silverado 5.7L

Discussion in 'Chevy C/K Truck Forum' started by chabunga, Nov 5, 2011.

  1. chabunga

    chabunga New Member

    Anybody got any tips on how to change a water pump on a 98 Silverado 5.7L. I changed one years ago on a 76 C10 with a 350. Things were a lot simpler then. From what I can gather, the clutch fan can be a problem and requires a special tool. If anyone could direct me to any videos or diagrams to explain this process that would be swell! Thanks!
  2. chevyracingss

    chevyracingss New Member

    Here is what I can tell ya, I believe the fan clutch nut is like 30mm or bigger. i do know that when i got a fan clutch tool kit from AutoZone, none of the tools fit. They were either too big or too small. Same story with Oreilly's and advanced. I wound up taking the water pump off with the fan clutch attached still, putting the whole assempbly in a vise, and using a bigazz f****** pipe wrench. Before you reinstall though, pay extremely close attention to thouroughly clean ALL of the previous gasket material from the block. This bit of advice comes from personal experience. even using blue RTV, it will still leak. I have found that applying the BLUE RTV to the gaskets and attaching them to the block first is MUCH MUCH easier. Allow the RTV to set(about 15 min or so) and then carefully attach the pump to the block. then the fan clutch and yada yada yada.
  3. outalne94z71

    outalne94z71 Member

    you should never mix rtv with a gasket, that is asking for a leak, its one or the other, using a gasket with some high tack works best

    if you dont have the correct clutch wrench to get the clutch off some people use a air hammer with a chisel tip right on the edge where the clutch wrench would turn the nut and give a quick tap and it usually breaks it loose right away
  4. chevyracingss

    chevyracingss New Member

    I have heard of the chisel trick, some people swear by it. I personally have never been able to make it work. As for the RTV, if you use it as "glue" and apply it in a thin cost to the gasket, I have never had it leak. The people that glob it on (like I was taught in the Army) are the ones usually seeing the leak return in short order. I was later corrected after my stint in the service and taught the proper way to use RTV in conjunction with gaskets to "maximize" the effects of both. I am just sharing my personal experiences that I use, however everyone does have their own way. As for the videos you previously requested, I would check youtube. I am actually thinking about posting more videos about actually repairing our C/K's. It seems the majority of the videos on youtube of our truck is just showing how cool they are when their lifted, mudding and loud. (not that I have any problems with any of those) But sometimes you can get lucky.
  5. chabunga

    chabunga New Member

    Thanks everybody for the responses. I decided to tackle the water pump replacement Sunday morning. It went pretty well, but it probably took me 4-5 hours. That included going and getting the water pump. The spring type hose clamps are a bear. I guess there is a tool, but I don't have it. By using a combination of water pump pliers and vise grips I was able to get them off. I had to trim the stop on one in order to make it open wide enough to fit over the lip of the new water pump. I started by removing the top half of the fan shroud, six bolts. I found it necessary to remove the bottom half as well in order to easily access the radiator drain plug. This I did from underneath first removing two bolts that allowed the splash guard to swing down and allowing access to the two bolts holding the lower half on fan shroud. Next I removed the clutch fan. First I used a chisel and hammer and struck it about 4 times. Being fearful of marring the nut I switched to a large punch and with two more hits it started to move and I was able to spin it off. There is a video of this on another site. It's a different year and motor but the the clutch fan removal is the same Then I removed the serpentine belt. Then the idler and tensioner (1 bolt each). I also remove two bolts and one nut so I could swing the alernator out of the way. These steps were recommended in other posts. This made it much easier to access the clamps on the bypass hoses and the water pump itself. Four bolts later and the disassembly was complete. There didn't appear to be any old gasket material on the engine block, but I did use a wire brush and paper towel to clean it up. I put RTV on the new water pump and then applied the gaskets to the water pump. I didn't think about letting is dry for a while as the gaskets did slide around a little and I had to readjust them. But it would have been a nightmare without the RTV. An extra pair of hands is helpful at this point. The water pump is heavy and trying to hold it with one hand and start the bolts with the other is challenging. I had to enlist the wife to start the bolts while I held the water pump. The rest of the reassembly went pretty well. I did replace the the lower radiator hose and the two bypass hoses as long as I had everything all apart. Note: there are two bypass hoses but the parts houses only carry one. You have to buy two of the same hose and trim one of them to fit. The bypass hoses were $10 each! Radiator hose was $16, the water pump $50 and the tube of RTV was $3.50. Hundred bucks, 4-5 hours and I no longer leave a coolant puddle where I park.

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