Tony620

How did your ITM timing cover work out for you? Did you use a gasket or RTV?

I'm reading here that the ethanol risk isn't unique to Datsun motors. So no special care need be taken beyond any normal coping with ethanol measures already in practice. Here's an article covering ethanol in fuel discussion: https://www.popularmechanics.com/cars/hybrid-electric/a6244/e15-gasoline-damage-engine/

I did search for this one, I mean it... Oil Drain Plug seal: Nylon Ribbed or Crush Washers? I've been very happy with nylon ribbed on my Dodge 318, a Hyundai, a Kia, and a Suburu... Some folks swear by Copper Crush..

Maybe kinda related (older engines, newer fluids) is the topic of Ethanol Blended Gasoline... Any opinions there? Are L series particularly at risk from higher levels of Ethanol mandated in USA gasolines nowadays? I do have the option of buying Ethanol free gasoline, if worth the premium. Thanks,

You guys are awesome! So helpful. Much appreciated. Used my garden hose tonight to flush the Radiator, the Heater Core, and the Engine until the water ran clear. Removed the radiator, disconnected the heater hoses, the bypass hose, but didn't remove the thermostat or housing. I'm lazy (cheap?) and didn't want to have to redo the gasket if not needed. I have new radiator hoses already. Getting new Heater and Bypass hoses 'cause they're brittle. Also changing the oil while I'm at it but that's a whole nuther thread... Hope to make some progress this week. Will post photos to show my appreciation.

Oh yeah, I read here about how the cast fins in the water pump are the ones to get, not the aftermarket bent steel ones. So I saw Amazon had one with the cast fins and ordered it. Well, I'm in the process of returning it now because it arrived with the bent steel fins, despite the picture in the listing. Here's the image from the listing: Here's my picture from the received part: Beware.

Now that I've got my wiring at a minimal safe operating standard, I'm moving on to the cooling system. I'm planning to disconnect and flush 1) the Heater Core, 2) the Block, and 3) the Radiator. I'm happy using the clutch fan I have on there now but i have no shroud and eventually think I want an electric puller fan. Anybody have an opinion on finding a fan shroud? My radiator isn't stock, though. I think it's OE from a Z car and needs to be mounted proper; it's presently right against the battery. I'm inclined to get a new radiator that better fits the space but that will have to wait until after I've tackled other engine issues. Any good advice on what NOT to do when flushing these components? I've read here some good tips like distilled water and such. I'm a little nervous because round about 1998 I killed a Z24 720 by flushing the Radiator and putting on a brand new fancy radiator cap. Driving it 40 miles home two nights later it overheated on the highway, the wall of the radiator had split open, and by the time I got it parked the head was too warped to save it. To this day I'm convinced I caused a disturbance in the force trying to do "the right thing" by flushing my filthy orange soupy radiator fluid. Like I weakened the walls or created a hot spot (air bubble?) somewhere critical. Maybe dislodged something which later blocked something, etc. Anyway, would hate to kill this engine with kindness so early in our relationship. Thanks,

Thanks! I have the l20b too but the radiator is from (?), maybe a Z? It's the same stamped Datsun radiator style seen everywhere but much wider than the 620 mount points and has a straight lower port, rather than the 90 bend to the outside. Yesterday I didn't pay close enough attention to the lower rad hose when I tightened my alternator and the fins gouged it... It's super tight in there so and kinda wonky the way it fits, so I'm in the market for something else. Any opinions on aftermarket Rads? eBay has some which seem to have the stock look and fit. There are others, like Champion, which are more angular and look taller. Opinions? I supposed I'm after effective and reliable more than pretty but stock fit makes things much easier, if possible. 2 v 3 v 4 core? Does the 620 use the same mount pattern as the 521 and/or 510?

Headlamp Wiring, including the aftermarket relay, works like a charm! Soon will be time for a new thread... about that **** cooling system...

I'll do that then! Best to keep with convention in case I ever become the PO the NO (next owner) will be less likely to cuss me out.. Swapped Coil Power and Ground leads below to reflect Hainz's recommendation: 1) Fused Power from Headlamp Switch (R)=30 2) Relay Coil Ground via Dimmer (RY)=85 3) Relay Coil Power also from Headlamp Switch (R)=86 4) Low Beam Circuit (RB)=87a 5) High Beam Circuit (RW)=87

Thanks Crash. I think you really set me on the right path here. I think I finally got my mind right... and I can't fault the PO since my photos weren't really good enough to act as a reference here. Using my Service Manual circuit diagram, Crash's tip, and going back to the drawing board, NOW I think I see what the Tech Wiki was getting at. 1) Fused Power from Headlamp Switch (R)=30 2) Relay Coil Power also from Headlamp Switch (R)=85 3) Relay Coil Ground via Dimmer (RY)=86 4) Low Beam Circuit (RB)=87a 5) High Beam Circuit (RW)=87 This way, when the Headlamp Switch is OFF, no power is on R and nothing is powered. When the Headlamp Switch is ON but Dimmer Switch is OFF, R is powered but since the Relay Coil isn't grounded it remains Deactivated, routing R to 87a, the Low Beam Circuit (RB). When Headlamp Switch is ON and Dimmer Switch is ON too, R is powered AND the Relay Coil is now grounded through RY and Activated, Opening the 87a circuit and Closing the 87 circuit, routing R to 87, the High Beam Circuit (RW). I'm posting this here 1) for folks to shoot it down if I'm dead wrong, and 2) in case my phrasing (if I'm right) helps anybody to better grasp this concept.

That explains it! I was wondering where my alternator mount came from! Looks like I've already got the 720 mount. I bet the PO was a Ratsuner! Now I understand why this alternator is hitting the Water Inlet and why the old (bigger) one was bumping the Idler. I think I have plenty clearance over the idler with this smaller Alt; I might test fit a longer belt just to move it a but lower away from the water inlet.

Here's something: Looks like the PO followed this tech article to use an aftermarket Relay for the Head Lamp circuit. It recommends using R for both the Power (30) and Signal (85) source. 1200 Tech Wiki 620 Headlight Wiring Anybody else try this? It's breaking my brain. Using R as both the Power and the Relay Signal, I'm not understanding how the Low Beam (RB) Circuit ever gets powered. It looks like only the High Beam (RW) Circuit is ever powered, then modulated between high or lower power states via the Dimmer switch. If that's so: 1) how does RB ever get powered? and 2) how does RW perform in the low power state of the Dimmer switch?

I'd be interested to know about the 720 outboard idler. I'm not up to any fabrication for the time being. But I am replacing this 100A with a 60A for a Subaru Loyale. It's smaller than the 100A but still larger than the stock 35A and the current size belt has it pinned against the radiator hose at the water inlet. I'm thinking a longer belt could help. I'm also curious whether my engine mounts are too wore out; whether newer mounts would get me more clearance above the Idler Arm. I'm sure I can get it running for now but I'm worried about conducting heat from the water inlet, as well as having that hose split directly over the alternator...