Hello..

I'm rebuilding a 1972 521 and want to install the heater core and connect the core to the engine block (supply??) fitting and return line to the waterpump suction fitting(return?). The heater core has 1/2" diameter nipples on the core but the existing fittings coming out of the rear of the block as well as the fitting on the return to the pump are of a larger diameter. Nothing in the Haynes manual shows the correct flow or heater hose circut and I'm confused about the transition in diameters. If you have a 521 with original config I would appreciate the description of what the circut looks like.

thanks...AutocorpsePeter

so the core you got has smaller diameter than the fittings on the truck?

interesting... 2 questions for ya... has the engine ever been swapped in your truck? and are you 100% sure the supplier you got the core from gave you the correct part?

if everything is good on your end then i hope you can find some help here!

I faced a similar problem with my 1970, 521. I had to buy two 1/2" heater hose elbows (Napa found them for me- not from a datsun) to get out around the rear of the head then use two 1/2 brass fittings to connect to lengths of 1/2" heater hose. I installed new galvanized fittings (a nipple that screwed into the block, an elbow that screwed onto that and a longer, (approx. 2"), to accept the heater hose. I mounted the block fittings so the nipple faces forward to make the bend in the heater hose less severe. It has worked fine for several years. It is NOT stock of course. The stock hoses that attach to the heater core outlet were NA then (05) and I have not seen any since. Contact me at [email protected] if you want to know more or want pics. Hope this helps.

update on that issue.... I found an original set of hoses with the correct bends and flares in the tubing for the different sized fittings on either end. The little snakey s bent hose and the other were a bit expensive @ $40 but are perfect. Its all Good!

I've also rebuilt the window felts on the window glass tracks and they work flawlessley and don't rattle anymore.

Peter