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My 1971 521


d.p

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Maybe your dip stick tube is cracked or loose at the bottom, I am not inclined to tell you to pull on it to see if it will come out as I am afraid you could break it, but that is what I would do, but I have the tools to extract the broken part if it did break on me, not sure about your tool collection.

Have you tried cleaning it with a spray cleaner of some type like Lectra-Motive and then using some kind of heat resistant glue/epoxy/gasket maker around the base to stop the leak? 

 

If your vent hose goes to a stock air filter housing, then maybe there is a valve in there that is stuck, but this is assuming that your leak issue is a plugged vent rather than a bad oil stick tube issue like I mentioned above.

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Maybe your dip stick tube is cracked or loose at the bottom, I am not inclined to tell you to pull on it to see if it will come out as I am afraid you could break it, but that is what I would do, but I have the tools to extract the broken part if it did break on me, not sure about your tool collection.

Have you tried cleaning it with a spray cleaner of some type like Lectra-Motive and then using some kind of heat resistant glue/epoxy/gasket maker around the base to stop the leak? 

 

Nah, only thing I did was spray some carb cleaner on the block and wipe it down to see if I could pinpoint it.  Still not %100 sure and don't have the tools to extract it if it breaks so I won't mess with it until someone who knows more than me looks at it.

 

Vent hose goes to the stock air filter housing, so how would I check for a stuck valve?  

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Nah, only thing I did was spray some carb cleaner on the block and wipe it down to see if I could pinpoint it.  Still not %100 sure and don't have the tools to extract it if it breaks so I won't mess with it until someone who knows more than me looks at it.

 

Vent hose goes to the stock air filter housing, so how would I check for a stuck valve?  

 

I don't know anything about the stock air filter housings and all the crap they have on them, it may not have a valve, it may just be open to the inside of the air filter housing.

The way I got into this topic was that someone was saying the oil dipstick tube was blowing oil out of it, the only way that normally can happen is if the valve cover vent is deleted or plugged, then the oil dipstick tube is the vent, if that leak was somehow stopped, then the engine would start blowing seals/gaskets, as the blow-by has to go somewhere.

Now it sounds like the base of the tube might be leaking, you need to keep in mind that I don't believe I have a Datsun that don't leak oil at all, I may be able to build an engine that don't leak at first, but eventually they all leak, it's a Datsun. :lol:

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Plan on having the engine given a once over by a local Datsun mechanic.  For the most part the truck runs fine just a little hiccup here and there.    Dropped off the door card to be fixed, going to put some water resistant backing in it and replace all the clips.  

 

Oo another note is the choke supposed to be hard to pull?  Mine works just need to use force to pull it out.  

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You have to make sure the choke cable has as large of a bend as possible.  No kinks, in the outer and inner cable.  If the carb end of the inner cable is in good shape, you can pull the inner cable completely out of the outer cable, clean it and grease it.

The choke linkage on the carb also actuates a fast idle.  If you push the throttle to the floor, then pull the choke out, the cable moves easier.

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Thanks Mike.

 

Ran into another issue today.  Turn signals work fine when the lights are off, if I turn on the parking lights they work sometimes, but if I turn on the headlights they don't work 9/10 times.  

 

-Flashers work with the truck off and on and they work with the lights off and on.  

-Turn signals are only seem to be work consistently with the headlights off or with the parking lights on.    If the headlights are on they don't work and are generally slow to come on.  

 

Any idea why that would be?

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Never mess with a 521 wiring harness that is working, as the moment you touch it it bites you in the ass, that is one dog that don't like to be touched.

I have only one 521 with a stock harness, and when the turn signals don't work I stick my hand under the dash and start moving wires around till they start working again.

Another thing you may have to do is soak the fuse block in vinegar over night as they get all dirty and quit making connections, turn the signals on while the lights are on and wiggle the wires on the fuse block around, but be aware that the headlights could quit working when you do this, then you will have to wiggle the wires some more.

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Never mess with a 521 wiring harness that is working, as the moment you touch it it bites you in the ass, that is one dog that don't like to be touched.

I have only one 521 with a stock harness, and when the turn signals don't work I stick my hand under the dash and start moving wires around till they start working again.

Another thing you may have to do is soak the fuse block in vinegar over night as they get all dirty and quit making connections, turn the signals on while the lights are on and wiggle the wires on the fuse block around, but be aware that the headlights could quit working when you do this, then you will have to wiggle the wires some more.

 

 

Fuck me, lol.  I just did that and the fucking turn signals started working with the lights on.  I spent over a fucking hour changing fuses, testing wires, and swapping flashers to no avail.  

 

Owen-Wilson-WTF.gif

 

Soak it?  Like disconnect it and put it a bowl of vinegar?  If so I thought I wasn't supposed to mess with it? 

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Now you are in the fuse block adjustment loop, it took me a few years before I finally found a fuse block to replace that piece of shit, sometimes when I hit the brights the regular beam would not work anymore till stopped and lifted the hood and adjusted the wires, it got real old.

 

I am in the shit now.   good idea to soak the fuse box?  I am afraid that dog will bite me in the ass if I take it all apart to soak it.   I also notice when turn my headlights on the dash lights dim, like they are losing power.  That typical of 521s as well?

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I am in the shit now.   good idea to soak the fuse box?  I am afraid that dog will bite me in the ass if I take it all apart to soak it.   I also notice when turn my headlights on the dash lights dim, like they are losing power.  That typical of 521s as well?

 

NO, the dash lights should stay the same, you be a screwed puppy. :lol:

 

DanielC has done several fuse blocks in vinegar, you should ask him or read about it in one of his threads. 

 

There are lots of things that 521 wiring harnesses do, right now my ign. light comes on a little when I turn the headlights on or use the turn signals, it just blinks away even though it's not the turn signal indicator light.

And if your ign. light comes on and you change out both the alt and regulator and it still comes on, just give up and use a internally regulated alt and wire it independent of the 521 wiring harness, otherwise you will be fighting that light till the day you die, you will lose sleep over it, it just isn't worth it.

 

By the way, I can pull every fuse in my fuse block and my engine just keeps right on running till I turn the key off, you just cannot mess with a 521 harness, it will make you regret it.

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wayno don't fucking jinx me!  Besides I got a modern car I can drive when this fucker decides to act up.  

 

Soaking the fuse box right now in vinegar and little lemon juice.  Is the IGN light bad or something?  Pretty cool you can remove all the fuses until you do that and the truck refuses to turn on again. You like to live dangerously? 

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I got your attention. :lol:

Too many people did to many things to my work truck electrically before I got it, now it acts weird sometimes, that is one of it's quirks, and I have had it do some outrageous shit before, like every time I let off the pedal the engine dies ignition wise, but the moment I put my foot back on the pedal it comes to life again, figure that one out, and I did figure it out.

I have had several 520/521s over the years, they all were converted over to Datsun/Nissan 720 wiring harnesses except the work truck, it has always ran for the most part, so I left the wiring harness alone, the only thing left that I originally bought is the cab/bench seat/wiring harness, absolutely everything else is from some other truck including the chassis.

The alt. light is not supposed to come on while the engine is running, I have no idea why mine does as I have bypassed all the original wiring harness except for the wire that goes to the dash light, maybe that one has melted into a wire next to it in the loom, and believe me when I say I have by-passed every wire except for that one, I made my own charge harness trying to get that light to go out, I mostly succeeded except for when I have the headlights on or the blinker is on.

I looked at that light half on for years and the guys at the auto parts store saying it was fully charging when they tested it, but when it quit charging I didn't know it, my only clue was when the radio would start cutting out, I then knew I only had 10/15 minutes left before it would quit running.

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Actually, I have never soaked a 521 fuse box in vinegar, other people have, with good results.

It is normal for a 521 to run without any fuses.  There are no fuses in the cranking, or ignition circuits.

I have replaced a stock 521 fuse block with a Blue Sea systems marine fuse box.

If the headlights were causing the dash lights to dim, I would think the headlights would be dim also.

 

All the electrical connections on your truck are 46 years old.  Any electrical connection exposed to water can get some corrosion in that time.  Just assume the electrical connections in a 521 were exposed to water.  i will promise you that sometime in it's life, there has been condensation inside the cab of the truck.

 

Dash light power goes through either the head light fuse, three always hot fuse box, or through a "all other lights except the headlights" fuse.  Never trust a glass tube fuse, you have to check for voltage on the load end of the fuse.  The fuse connects to a clip, and the wire carrying power into the wiring harness from the fuse box makes another connection.  There is a bunch of electrical connections between the engine room wiring harness, and the cab or dash board wiring harness, by the right side of the glove box.  These could have corrosion in them.  There is a plug in the wiring harness, that connects the light switch, another possible bad connection.  The instrument panel is connected electrically to the wiring harness by a plug that looks like an old vacuum tube socket, that connection could be bad.  The dash lights are in lamp holders, that just make a connection to the printed circuit on the back of the instrument panel.  The copper printed circuit can get corrosion on it, where the lamp holder makes contact. 

 

Check your grounds.  The negative battery cable connects to the cylinder head, by the fuel pump.  There should be a pigtail from the engine end of the negative battery cable to the alternator frame.  There should be a second black wire at the alternator that goes to the voltage regulator mounting screw.  This wire is very important, it grounds the cab to the engine.  If this wire loses connection, the cab will try to ground through the throttle cable, overheating it.  I would run a short jumper wire from the engine side of the rubber motor mount to the frame side of the motor mount.  If you have some odd problems with the tail lights, ground them directly to the frame.

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Actually, I have never soaked a 521 fuse box in vinegar, other people have, with good results.

It is normal for a 521 to run without any fuses.  There are no fuses in the cranking, or ignition circuits.

I have replaced a stock 521 fuse block with a Blue Sea systems marine fuse box.

If the headlights were causing the dash lights to dim, I would think the headlights would be dim also.

 

All the electrical connections on your truck are 46 years old.  Any electrical connection exposed to water can get some corrosion in that time.  Just assume the electrical connections in a 521 were exposed to water.  i will promise you that sometime in it's life, there has been condensation inside the cab of the truck.

 

Dash light power goes through either the head light fuse, three always hot fuse box, or through a "all other lights except the headlights" fuse.  Never trust a glass tube fuse, you have to check for voltage on the load end of the fuse.  The fuse connects to a clip, and the wire carrying power into the wiring harness from the fuse box makes another connection.  There is a bunch of electrical connections between the engine room wiring harness, and the cab or dash board wiring harness, by the right side of the glove box.  These could have corrosion in them.  There is a plug in the wiring harness, that connects the light switch, another possible bad connection.  The instrument panel is connected electrically to the wiring harness by a plug that looks like an old vacuum tube socket, that connection could be bad.  The dash lights are in lamp holders, that just make a connection to the printed circuit on the back of the instrument panel.  The copper printed circuit can get corrosion on it, where the lamp holder makes contact. 

 

Check your grounds.  The negative battery cable connects to the cylinder head, by the fuel pump.  There should be a pigtail from the engine end of the negative battery cable to the alternator frame.  There should be a second black wire at the alternator that goes to the voltage regulator mounting screw.  This wire is very important, it grounds the cab to the engine.  If this wire loses connection, the cab will try to ground through the throttle cable, overheating it.  I would run a short jumper wire from the engine side of the rubber motor mount to the frame side of the motor mount.  If you have some odd problems with the tail lights, ground them directly to the frame.

 

You sure? On my truck the negative goes to the head above the alternator and the positive connects to the starter and the fuse box and nothing else. Wiring coming off the starter to various places.

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Yeah, I am pretty sure.  I had my first Datsun truck when I was in high school, and I graduated from there in 1973.  I had my first 521 in 1974, and then most 521 trucks were new enough to not have had the wiring molested.  By the way, I was taking electronics in high school, so I know a bit about electrical stuff.   Not so much about modern digital stuff, but trust me, everything on a 521 is very analogue and simple. 

 

There are four wires on the starter on a stock 521.  The positive battery cable, and two white wires that connect to the big connection on the starter solenoid, and the black with a yellow stripe wire that connects to the 1/4 spade connector that energizes the solenoid.  One of the white wires goes to alternator positive main output.  The other white wire goes into the wiring harness, and then to the voltage regulator.  The power to the fuse box comes directly from the positive battery terminal.

 

The third paragraph in my previous post basically described the path dash light current takes to get to the dash lights.  If you have a problem with an electrical circuit, you have to trace the path the current takes from the positive battery post, through the entire circuit, back to ground, and finally to the negative battery post.

 

But if you are having wacky electrical problems, experience has taught me to always check the grounds first.

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Cool.

 

Another issue today, on the freeway up a slight grade on a bridge and the truck backfired and went down on power.  Momentary then it came back fine and it happened again on the downside of the bridge.   Fine the rest of the way home (25 miles or so) then parked it for 15-20 minutes then it wouldn't start, had try like 10 times to get it to turn over.   Didn't matter if I had the choke or gave it gas, it wouldn't turn over.  It eventually started and was fine all the way home.  Started it again and it was fine.  

 

Seemed to be fuel related to me, like it was starved so maybe the fuel filter?   Funny too cause I was googling "521 loss of power backfire' and found this post from previous owner, post #2 in this thread:  http://community.ratsun.net/topic/19223-truck-backfiring-at-full-throttle/

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I could be ambitious, and read all your posts from the beginning, but I am just going to ask.  Was the gas tank cleaned out when you got the first got the truck running?   Quick test for that problem with the fuel pick up in the tank is when the problem shows up, blow air back from the fuel filter to the tank.  If that cures the problem, time to clean the tank.  This will tend to be more of a problem with the gas tank close to empty, than full.

 

Listen to the engine crank.  Does it have an even sound as each cylinder comes up on compression?  If you suspect compression, test it at home.

 

If you have just cranked the engine, and no start, go and smell the exhaust pipe.  Smell Gas?  Then I would look for an ignition problem.  If you do not smell gas, probably a fuel related problem.

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I didn't clean the tank and neither did the PO (who owned it since 2010), whether patd (previous previous owner) did or not I don't know.    Had a little less than half a tank in when the problem occurred.  Will listen for compression and smell for gas next time it happens.   But PO had a compression test done not too long ago and it came back as 125 in @1 and 145 in the other 3.

 

Is there anything I can check without waiting for the problem to arise again?  

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The end of the fuel pick up has no filter, or anything on it.  Just the end of the pipe, close to the bottom of the tank.  There is a drain plug on the gas tank of a 521.  Get the tank real close to empty, have something that can catch the gas, pull the plug, and see what comes out.   If you get a lot of crud out of the tank, let the gas you pulled out settle, and put the plug back in, put that gas back in the tank, and repeat the process.

 

Compression should be higher on a L-16.  Should be at least 159. at 350 RPM, and less than 10% difference. 

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