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1970 521 L16 - Likely water pump kablooey


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A block from my house I look down and the temp needle is pegged. Immediately limp home, let her cool off, check radiator, it's empty. 


(*edit: swear.  a LOT.) Load up on coolant, start it, dribble dribble off the bottom of the block, hoses are all dry. Heater core appears fine. 


Now, because I'm a slob, the engine is filthy, and now I'm getting all the "i told ya so's" from my buddies about why you need to keep everything clean... so you can pinpoint leaks. Yeah ok, I didn't clean things up and I'm a dumbass... moving forward...


What am I looking at as far as parts and labor (my own) to do this? Haven't had the pleasure before, so I'm going in kinda blind. What do I need to watch out for? What else should I do while I'm in there? Stuff/parts/mistakes to avoid? 



*Note the "theft prevention" coating 😄





Edited by fredges
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1 hour ago, fredges said:

What am I looking at as far as parts and labor (my own) to do this?

To do what??????????


add water is free.

 To watch where it leaks as it idles and heats up to temp and gets hot ids FREE



Was this a daily driver or what?  drive down the road? every day or you let this sit?


the motor is oily but I cant tell from that if its a water leak. Let it heat up and see what happens.


Nice looking truck if that the avatar. Maybe ezer for you tell sell it to me for 500 and Ill take care of it. and make it last another 20yrs.


you even ck the oil to make sure it hast goon in there?

Maybe water comiing out the weep hole of the water pump.

look at the spark plugs maybe one cylinder is sucking up water and youll have a really nice clean spark plug!

Edited by banzai510(hainz)
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First you should have shut off and let cool down not drive it home. Once cooler top up with ditch water. Over heating is absolute murder on cast iron blocks and aluminum heads. Heads will warp and or the valve seats pop out. Then the block will really stop leaking oil.



Power wash that shit off!!! Shit always runs down hill. So look up higher. Then replace the valve cover gasket, the one with all the RTV gooped on it.



Water leak? Probably on the driver's side. Either water pump, thermostat housing or coolant by pass pipe or hose fittings. Follow this smaller metal pipe up to the intake at base of carburetor.




Yeah... check your oil level.





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  • 5 months later...


Well, that took forever... I really need to retire and move somewhere I can work on my car without having to worry about hypothermia. (At least I got the promotion!)


Checked the oil yesterday, looks clean and plenty of it. Loaded it up with water and started it just long enough for a buddy to nail the exact location of the coolant leak (gasket). No clouds of smoke, sounded fine. Whew. Pulled the water pump with no trouble at all, and it's just a little crusty. Putting in a new one anyway. Looking on Rock Auto, but no idea which one to get. I'll throw a dart. Found a place a few blocks away that does steam cleaning for a lot of the local guys with WAY nicer rides, so, she'll get a bath as soon as I can drive her there. Then I'll go to work on heater hoses and other crusty bits that are begging for the sweet release of death. 

Further news as events warrant.



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Damn that's filthy! Wire brush it clean. Drain and flush the entire system specially the radiator. Crap like that will block up the internal fins in the radiator and heater core. Maybe someone put some 'stop leak' in....terrible stuff.

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Aisin WPN 032 is the one to get made in japan


If you over headed the motor Im thinking its worse. Most water pumps dont go bad from a over heat. You lost water but maybe the bearing is wearing out. That why one alwasy ck the front your your vehecle when comming up to it to see if water leaks from the front.


if you really think its the pump then get this one. so you dont have to pull it all out again



going by the photo of your profile that looks like a nice truck you should have pressure washed the motor a long time ago and keep it nice than letting it go.

Edited by banzai510(hainz)
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As long as the pump spins it's pushing water. We did get one member that had the pressed on impeller come off... an extremely rare event. If bearing worn out it will make noise and the fan will wobble. If seal is gone it will leak out the weep hole on the bottom of pump. Over heating is unlikely to be the pump so don't waste $80 to fine out that didn't work. There are a myriad of reasons for over heating.

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  • 2 months later...

Closure: Replaced the pump and the thermostat, and cleaned all the gobs of permatex from the last guy's install (that was fun), and now there are no leaks and she doesn't run hot. Success? I'll take it. Got all that grime cleaned up much better. Note to self: don't spray off your greasy car into your wife's flower beds. 

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16 hours ago, banzai510(hainz) said:

March till now to replace a water pump and stat?

Yup. I'm a busy fella! (But mostly I hate working outside in the cold and rain. Damn, I need a garage.)

Got the brakes all adjusted nicely last night. Fixed the horn, too. Had to take one of them completely part, but it works now. Now they can hear me coming when the brakes fail. 

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