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Discussion Starter #1
Every 500 miles or so the clear plastic tank is down to "cold minimum" and the upper radiator hose, when squeezed, feels empty. I poor in a couple of quarts of coolant, squeeze the upper radiator hose to displace the air, then finish filling the plastic tank with another quart. No puddle of coolant, no patterns of leaking from hoses- maybe what might be a slight film of coolant on the inside of the water pump pulley. I took off the fan belt, wiggled the fan blades to check the pump bearing wear- just a slight rock. Is any "rock" acceptable? The belt tensioner and the idler pulley are original and both have 200k miles. Change them out because I'm there? If not what rocker is acceptable? There are no coolant droplets in the engine oil. If the coolant isn't disappearing from the water pump seal, and no pattern of coolant from block freeze plugs, where would I be loosing coolant? I've been good about changing the coolant-could it be an eroded head gasket? Any thoughts? Thanks
 

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Very little if any rock is ok but very very little I would clean it all up start truck and check water pump as it runs. If water pump is original to truck it is probably time to replace.


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Several of us have noticed our trucks prefer to stay right below the cold full mark. My truck, personally, will stay at that level indefinitely. If I fill it to the upper fill mark, within a week it will be back down to a point right below the cold full mark where it will stay for years. I quit fighting that.

That said - no play in the water pump is acceptable. Go ahead and swap that out. You can get the Airtex pump from RockAuto at a great price. The tensioner and idler pulleys are rebuildable. A Timken 203 bearing (or a 6203 any other brand) will fit. I keep a few extras in my center console just in case I ever need a side of the road repair. Change your hoses and get a new degas bottle cap while you are at it. Get the "dual alternator" upper hose so it goes around the belt instead of through it.
 

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Discussion Starter #4
I bought the motorcraft water pump and a new belt. I just ordered a tension pulley, idler pulley, thermostat, upper and lower hoses. I watched this month my 1999 turn 200k- giving her a going over. Question: I'm doing a coolant change with the new water pump. I've been using Prestone Heavy Duty coolant. What's the best coolant for an early 1999 coolant system? Thanks
 

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For an early 99 with the stock injector cups, you need to stick with an SCA based diesel rated coolant. Peak Fleet Charge is a good one that you can get almost everywhere. You'll need 4 gallons of the concentrate if you want to do a proper flush and refill. Here is the procedure:

https://www.thedieselstop.com/forums/f47/coolant-changing-instructions-163800/

I personally don't take out the block plugs. Just do an extra distilled water flush and you'll get everything out without the cussing and bleeding knuckles you'll experience pulling the block plugs.
 

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Discussion Starter #6
I'm installing the Motorcraft $399 list($250) water pump. The less expensive Dura Pro only lasted 60k before it carved the impeller into the aluminum front of the block. The Motorcraft has a rubber gasket with little nipples on both sides of it. Anyone install the Motorcraft pump with this gasket? Should I put dish detergent on the rubber that will contact the" block" to allow it to slide a little when mating up the surfaces? Thanks
 

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For coolant gaskets I usually use Indian Head gasket sealant. That stuff has been around for 50 years I think, but it works well.
DENNY
 
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