My 1971 521

[DanielC]

521 stock clutch hoses are SAE threads, 3/8-24.  Every auto parts store in the USA should have one.

[d.p]

Yeah guess I will be going there to get one, Hoagie asked for money for the parts so will just get it locally.  

[d.p]

OK I think your clutch hose is fine enough unless you have OCD.

 

what one needs to do is put the slave hose on 99% threaded if before one puts it on the trans to do the final tightning.

 

also make sure that slave is adjusted correctly where you have abut 1/16 play at the fork arm. YOu see that jam nut and hal ball threaded on there? you need to adjust that soemtimes so you dont wear out your T/O bearing

 

Got it, clutch seems to be working fine and still not sure where the leak is coming from.  Right now anyones guess.  

[d.p]

Anyone know why I the fuse for the dash and turn signals(far right side 10a) would constantly blow? Seems like everytime

I drive it I have to replace that fuse.

[uberkevin]

Bad ground maybe..

Them damn grounds I was chasing for a while.

 

Had to add two or so to the rear tail light harness.

Just something to check.

Could be a bulb tho.

The switch is also a possibility.

[wayno]

Water/moisture in the turn signal buckets?

[d.p]

Fuck this is frustrating.  I guess I have to go through and check all the grounds?  No water in the turn signal buckets, dry as a bone.  Not raining today and went for a 5 minute drive and on the way back fuse blew again.   Its almost like a short or loose wire somewhere that when I hit a bump it goes out.  I haven't been able to catch it blowing yet though.  Just look down and see the gas/temp not working and then I know its blown.

 

So should I just be checking all the grounds to make sure they are free and clear of rust?  Clean a switch? if so which one?  

[banzai510(hainz)]

cna be a dirty connection and cause a high resisitive circut which will blow a fuse. Try cleaning the connections first as it work already.

and yes maybe clean ground or the wires where they screw in the fuse box(on 521s)

[d.p]

Yeah they all work just fine, just not very long once I start driving.  I soaked the fuse box but will clean the ground connections, should I bother cleaning the connections behind the dash.  

 

I did notice the passenger side taillight ground is stripped, the screw just spins and I can't back it out.  Maybe that could be the cause? 

[banzai510(hainz)]

if the ground is bad at the pass side light then remove the bulb and drive it and see if it pops .If not then its not the proplem there. But would clean it.

 

one can just reseat the instrument panel connector  a few times to clean any corrosion there

[DanielC]

A bad ground generally would not cause a fuse to blow.   A bad ground would generally cause an electrical item to not work and thus have no current going to it.

 

Look at the fuse that blew.  Is the glass clear, and does it look like the fuse element just melted?  That is a slight overload condition.   If the glass is cloudy, and it looks like the fuse element exploded, that is a direct short to ground, without a load on the fuse.

 

On page two of your thread, there is an electrical wiring diagram.  Tracing the wire on the fuse that constantly blows will give you an idea of what should be in that circuit.   It may take some hard work looking at the wiring diagram, the picture is busy, and it is easy to jump to the wrong circuits. That will give you an idea of where to look on the wiring harness for problems

 

There are three wiring harness in a Datsun 521.  The engine room harness, the cab harness, and the bed, or body harness.  The cab harness plugs into the engine room harness with a bunch of connectors by the glove box.  The bed harness plugs into the engine room harness with two plugs down by the starter. 

 

If you suspect a problem with the bed harness, you can unplug the bed harness, and see if the fuse still blows.  that will disable the lights on the rear of the truck, however.   You can also unplug plugs by the glove box, to further isolate the problem.   This will also cause other electrical items to not work.

 

Crawl under the truck, inspect the wiring harness and look for bare wires work through that may touch the frame, or bed of the truck.  Crawl under the dashboard, inspect the wiring harness there also.  This will be difficult, the cab harness is really tucked up in the narrow areas of the dashboard.  look for wires that may be close to the wiper linkage, that have insulation worn through.

 

Be careful unplugging the instrument cluster plug.  It is easy to break one or more of the pins off the printed circuit board.

[d.p]

Its blown without a doubt,  element split in half and black on the sides of the glass.  So a shore...bare wire touching metal somewhere?  That would explain why it would happen when driving around, hitting a bump or accelerating could cause it. 

 

Got a pic of the bed harness? I think now I just need to go through the process of elimination.  

[DanielC]

That is a bare wire touching ground somewhere.  Tell me the colors of the wires on the side away from the battery are on that fuse.  If you still have the fuse box cover, what is printed in the inside of the cover for the circuits on that fuse.

 

I need a few more details about your truck.  Does it still have a dual point distributor?  Stock Hitachi carb?  Does you truck have the stock four speed?

 

Nissan used a system of relays and a carb solenoid to control exhaust emissions on the 1970, and 1971 521 trucks.  I believe that system got its power from the fuse you are describing as the one that blows.   A previous owner may have disconnected part of that system, leaving wires not connected.  This system uses connections in all three wiring harnesses. (engine room, cab or dash, and bed or body)

[d.p]

Its flashers, reverse signals and combo meter (gas and temp gauges).  Wires coming off that fuse are green and blue/yellow and its the left most fuse in the pic below.   Truck is stock to the best of my knowledge, yes to Hitachi and yes to four speed.  

 

 

 

[DanielC]

Its OK to clean the leaves off the fuse box. 

I do not have time to look at electrical diagrams right now.  I believe one of the wires on that fuse power the combo meter, turn signals, and reverse lamps.  The other wire is for the emission control system.  Unplug the blue with yellow wire, see if the combo meter, turn signals, and reverse lamps still work.  If you lose those items, plug the blue with yellow back in, and unplug the other wire. If the combo meter, turn signals, and reverse lamps then  work, and the truck seems to run normally, take the truck for a drive and see if the fuse still blows.

[d.p]

Its OK to clean the leaves off the fuse box. 

I do not have time to look at electrical diagrams right now.  I believe one of the wires on that fuse power the combo meter, turn signals, and reverse lamps.  The other wire is for the emission control system.  Unplug the blue with yellow wire, see if the combo meter, turn signals, and reverse lamps still work.  If you lose those items, plug the blue with yellow back in, and unplug the other wire. If the combo meter, turn signals, and reverse lamps then  work, and the truck seems to run normally, take the truck for a drive and see if the fuse still blows.

 

 

haha its clean now!  That was an old pic before I soaked and cleaned the fuse box.    

 

It may be awhile for me to test it out, but for sure I will.  Thanks for your help Daniel.  

[d.p]

Also anyone know what size set screw for the heater knob?  I can't seem to find it. 

[DanielC]

I believe it is a #4-40 screw.

[abbylind]

Did you get a replacement drivers side mirror? If not I had a glass shop cut me one for another car

[d.p]

Did you get a replacement drivers side mirror? If not I had a glass shop cut me one for another car

Nah but I had thought about doing that but wondered if it needed to be convex? What did you get?

[d.p]

Green wire is emissions, blue/yellow is for the flashers, reverse and meters.  Disconnected the green one and ran some errands today and the fuse did not blow so thats good...will update if it blows again.  

[d.p]

Haven't blown a fuse as of late so that is good.  

 

Still have vibration at 50-55 on the highway, had the wheels rebalanced and switched front to back but its still there.  Shop said the wheels wouldn't balance out to 0 but they got it as close as they could.  Anything I should look at other than wheels and tires?  I wish had another set to try but don't right now.  Also the truck gets significantly louder above 60mph, any idea why that would be? 

[wayno]

Haven't blown a fuse as of late so that is good.  

 

Still have vibration at 50-55 on the highway, had the wheels rebalanced and switched front to back but its still there.  Shop said the wheels wouldn't balance out to 0 but they got it as close as they could.  Anything I should look at other than wheels and tires?  I wish had another set to try but don't right now.  Also the truck gets significantly louder above 60mph, any idea why that would be? 

 

You have lowered it, so the carrier might need shimmed or you might need wedges for the blocks you installed, as lowering these trucks can cause drive line angle issues.

[d.p]

You have lowered it, so the carrier might need shimmed or you might need wedges for the blocks you installed.

 

I haven't lowered it yet my dude....stock height still.  

 

[wayno]

I haven't lowered it yet my dude....stock height still.  

 

 

Sorry, I read post 57 and thought it was you, turned out it was another member.