Diagnose failing water pump. 98 Chevy Truck

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Last weekend I had no heat in my truck and noticed my temp gauge fluctuating up and down but never in the "red" danger zone. When I got home I checked the fluid level in the radiator and had to add quite a bit of anti freeze. I went to camp this past weekend and on the way home noticed the same problem. I am losing anti freeze. When I got home and opened the hood the front of the engine block and hoses/lines were wet with anti freeze but I couldn't tell where it is coming from. I wish it were a simple hose or line somewhere but suspect the water pump since it is right in that area. Is there a way to diagnose the water pump? I plan to fill the radiator again and run it to try and figure out where the fluid is escaping from but wondered if there was another way to diagnose.
 
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Well you can fill the radiator, and use a pressure tester to put pressure on the system to see where the leak is, but you do need the tester for that. Otherwise just fill and run till pressure builds up, shut off, and look for the leak. Unless it is leaking so fast that it won't build pressure.
 
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Look on the top of the water pump and the botrim a mirror is helpful. See if the weep holes have antifreeze residue . If the leak is above that it could be intake gasket thermostat gasket or a hose. If you could take a couple pictures and post them that may be beneficial.
 
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This is one of those problems that is pretty much worthless over the internet. You need to get in there and do some inspection. Could even be a pinhole in the radiator blowing all over from your description of the issue.
 

Nick1994

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Originally Posted By: Oil Changer
You more likely have the infamous intake manifold gasket leak.
Beat me to it. These are known for bad intake manifold gaskets. Still could be the water pump but likely an intake manifold gasket
 

01rangerxl

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Originally Posted By: old1
Well you can fill the radiator, and use a pressure tester to put pressure on the system to see where the leak is, but you do need the tester for that. Otherwise just fill and run till pressure builds up, shut off, and look for the leak. Unless it is leaking so fast that it won't build pressure.
X2. Losing that much, you should be able to catch it in the act.
 
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There's a weep hole on the bottom of the water pump. When the bearing goes out, the bladder will rupture and leak coolant out that hole. Check the hole with an inspection mirror with the engine running. If you look at the picture on RockAuto of the Bosch pump, it shows you that weep hole location. Another check is for excessive play of the water pump pulley. If the pulley wiggles around a lot, the water pump shaft bearing is shot.
 

wolfehunter

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Thanks for all the diagnosing help. I will pull it in the garage tonight and do some investigating. Will report my findings.
 

wolfehunter

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I got my nose in there tonight after warming the truck. I have a pinhole at a connection I think goes to one of the heater core hoses into the dash. The leak sprays on top of the manifold behind the passenger side valve cover. I am going to try and post a picture. [img:center][/img]
 
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01rangerxl

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Yeah, those are a common leak point now that these trucks are getting old. It's about $44 for the hose from GM...I am assuming this is a C/K1500. I would go ahead and replace the connector too to play it safe, the connector is about $21. Hose p/n should be 15708626 and the connector should be 15265200, but I would get that verified by the VIN before ordering.
 

wolfehunter

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Oh no. I barely touched it and it snapped off. How am I going to get the broken off piece out of there? It was so corroded when I touched it with 3 fingers it broke off. There really isn't anything I can get on it with to try and turn out what is in there. Also worried about getting dirt and pieces of metal into the intake when I try and get it out. Any suggestions? Here is picture: [img:center][/img]
 

Nick1994

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Is it metal? If so see if you can fit a grinder in there to clean it up or a dremel and get a bolt just big enough to set in there and weld (or have welded) to it and then you'll have a hex head to twist it off. Otherwise you'll have to take off the intake manifold.
 

01rangerxl

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Originally Posted By: stevejones
there's a tool for that...Lisle 62200...
Yeah, you want a coupler remover. They probably have them in stock at parts stores up there. As weak as it was, it could have let go at any time if you hit a pot hole or something. At least it broke at home.
 

wolfehunter

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Thanks guys. I ordered a Lisle 62200 and a Dorman connector off of Amazon for $17 and some change. Hope it comes out ok. Will keep you posted and thanks again!
 
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Fair warning on the Dorman connector- their o-rings are low grade and will rot out early in life and leak coolant. I've seen it happen with their GM cooling elbows and their GM quick connects time and again. In fact I'm going to replace one for the second time (on my third total) in my wife's old car tomorrow or the next day.
 

wolfehunter

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I tried the easy out and felt like I had a good bite but ended up chewing and crumbling the existing metal up. It was too corroded. Of course the easy out has nothing left to bite to. So does that mean I will be pulling off the intake? I never used a tap and dye before but would like to tackle this myself if you have any suggestions. I will have to figure out what kind/size the threads are on the fitting. I was counting on that easy out....dang it!
 

01rangerxl

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Ouch. You may be able to get away with cleaning up with a strong Shop Vac and small nozzle attachment, but I'd probably take the intake off so you can clean up debris more thoroughly and make the critical work of tapping easier to do. At least you will have a fresh intake gasket set on it too. Also, if you find you need to replace the intake itself, half the work will already be done. Bummer.
 
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