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521 heater core


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Since I got 2 toyotas for cheap I been using them the last year and half and put the Datsun in the garage. The toyotas are great rigs and I love them , Nice more modern vehicles that stop start quiet when driving but no attention



So I pulled  my 510 and 521 out,I been using my 521 last month or so People love them wave as How much for sale ect.. I get home yesterday and notice massive amount of water in the cab. The Heater core has been leaky the last 10yrs or so but not enough to warrant anything major. But last night it I looked into it and the inlet/outlets must have cracked casue when I tried to get the hose off it was turning. then just snapped.

so I took it apart and said no wonder the heater was weak all the pin needle in there. I had 2 spare heater core from Ted in Olympia,Wa and I said fuck which one is good?  So i pour hot water in there till full and let them sit and picked the one that wasnt leaky.


Does anybody make new ones that can get basic measurement to make chinese clones or something?


I will install tonite and hope this dont leak. The heater valve in this one is broke and stuck but lucky is on the Open Mode where water will flow into the core.

521 heatercore.JPG

Edited by banzai510(hainz)
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I think the biggest problem with the 521 heat is the connection to the fresh air .... the heater box has no recirculation ability so your constantly trying to heat the colder outside air, if you have one of those boots still.. 

Last year I bought one of the heater boots and I have debated removing it ever since.... I had better heat without it ...

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20 hours ago, thisismatt said:

Why not fix the valve while you had it apart?

I wanted it to run now as I havent driven the truck for a year or so. I wanted to get my time driving it before the winter rains come.  I dont want to attemp to change and actually makle it worse. the other heater core was actaully leaking from  multiple areas and also the valve.


anyway I leave all my heater boxes on the ON open valve position to keep waer and tear on them to a minimun my 510s and my 521. The 521 vent and the shut off vent actaully keeps the heat out of the cab.


make a clone w/o the valve if this ever goes bad again but drove it all day to day and seems it will last a while

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