My 521 build, restore, maintenance story...

[jcard]

Hi all.

 

I'll give in to posting my ongoing challenges keeping my old family 521 going. When my pop passed 14 years ago nobody wanted his old1972 521 so I bagged it. I was there when my mom and dad bought it from the then Datsun dealer in San Rafael. ( I remembered drooling over the 240zs at the time and had no way of knowing that a little over a year later I'd buy a new '73 240z - blue)

 

So far I have done the following to the old girl:

 

changed the clutch master and slave cylinders

gone over the brakes- originals

replaced the radiator

installed an ersatz center console with a Pioneer eCenter

replaced points

had the seat reupholstered

had new black carpet installed

changed headlights to Cibies

Adjusted valve lash

Adjusted timing

changed points, plugs, air cleaner (I've only driven the old girl about 2k miles since pop passed)

 

I've had engine idle issues, especially when cold, I suspect the carb needs attention. I purchased a

Weber carb that was recommended here and just waiting for the chance to try adapting that. I wouldn't

mind trying to rebuild the old oem carb but never having done that I was concerned.

 

Now it seems I have a more pressing issue. I found that I have a coolant leak that has basically soaked the passenger side carpet ( :mad: ). I can't seen any dripping but looking from the firewall side I see wetness along a small ledge' flange

of the firewall right below where the coolant lines go into the passenger compartment. Anyone have this sort of failure?

 

It's my luck that the leak goes into the passenger side instead of the engine side making a mess of my new carpet.

I'm not happy. I know I have to remove the heater assembly and I'm sort of hoping it isn't as much work as it appears...

 

I see there's a fairly recent thread on heaters/ cores so I'll check it out. My heater control valve has worked smoothly and I don't see any signs of leaking from that area. I suspect the feed tubes?

 

Thoughts?

 

Ahhhh old cars- joyous things they are aren't they....?

 

 

Jerry

[datzenmike]

Drain the rad and put plastic over the carpet. Hoses are hoses, just replace them.

[jcard]

Thanks for the advice. It's probably a tad late for the plastic seeing how soaked it got already and the there's no dripping that I can see....

I will post more info when I find out exactly what went south.

 

Jerry

[DanielC]

Working down through your post...

You will probably have to remove the center console to remove and repair the heater, if you need to remove the heater.

If the carpet is removable, rinsing it with lots of water can remove the antifreeze, but may not remove rust stains.

You have to add relays to run headlights that use more current than stock.  The stock 521 fusebox is adequate for a stock 521, barely, when it was new.   If you add relays, you can take headlight current out of the stock fusebox, and the stock fusebox will be much happier.   You may need an alternator upgrade, also.  The stock alternator is 35 amps.  No need to go crazy, a 50 amp alternator will be plenty for a 521.

It is really easy to put a additional Bosch cube relay by the original headlight relay.  You can use the red with yellow wire to the coil of the Bosch relay, pin 85, and ground pin 86.  Run a 12 ga wire from battery positive to pin 30 of the Bosch relay.  Run a short jumper from pin 87 of the Bosch relay, to the open spot on the original headlight relay that the red with a yellow stripe wire was.

Modern cars have spoiled us.  The engine control computer can exactly adjust the fuel air ratio as the engine warms up.  Carburetors do not do that.  Each engine and carb combo has it's own personality, and you have to learn the exact way to start and run it when cold, and that will change depending on how cold it is, and how long it has sat since the last time it was ran.  You are on the right track by adjusting the valves, and setting the timing before adjusting the carb.  New spark plugs would not hurt, either.  NGK BP6ES.  Cap, rotor, and plug wires in good shape?  Work on getting a matchbox distributor, and coil. 

Stock Datsun carbs are really sophisticated, or complicated.  Take very careful notes, and pictures if needed to disassemble the carb, so you can get it back together.

Datsun L-16 engine are cold blooded.  Make sure the tube from the exhaust manifold supplies warm air to the air cleaner.  Make sure the water lines that supply engine coolant to the bottom of the intake manifold are clear.   Your 521 will be much happier if you let is warm up before trying to drive it.  If the truck runs good when it is warm, cold starting, and running is controlled by how the cover on the choke heater is adjusted.  You loosen the screws holding the cover, and can adjust it to hold the choke more open, or closed.  The choke closing operates a fast idle cam.  This cam had linkage going to the throttle shaft, and you adjust the relationship between the choke position, and throttle by bending the linkage.  And if you get the choke and fast idle adjusted perfectly for one temperature, it will be off if is is a different temperature.

Stock 1972 521 trucks use the externally regulated alternator to trigger the electric choke relay.  A common swap is to put an Internally regulated alternator on the engine, but this disables the electric choke relay.  A stock Nissan regulator is very reliable.  I have had good luck running a 50 amp stock "Datsun" externally regulated alternator with the original voltage regulator, that can in a 521.

The heater core tubes extend into the engine compartment.  The heater hoses extend in to the passenger compartment.  If the hose clamps for the heater hoses are not tight, the coolant will actually leak in to the cab.  You can get small heater hose clamps, that have about a 5/16 wide band.  You can then get two of these hose clamps on the heater hose connection, and maybe then can get the hose to seal better.  

Datsun 521/L-16 hoses
Upper radiator hose    21501-B2001
Lower Radiator hose    B1503-B2000
Short heater hose    B7020-B2000

Long heater hose    27020-B2000 or 27021-B2000

Intake manifold hose    14055-23000

Manifold pipe hose    A4056-23001

Most are NLA from Nissan dealers, but is does not hurt to ask.

 

This is a wrench I put a bend in to get to two of the carb bolts.

This is a 1970 521 wiring diagram, you will have differences to accommodate the electric choke.

[jcard]

I'm curious about the hoses. Can 'regular' automotive cooling system-compatible hose be made to work should I find mine are failing?

I assumed that the OEM hoses were NLA from Nissan dealers and assumed I had to make up my own. That

short heater hose    B7020-B2000 with that sharp bend could be trouble. I think my dad had already changed those heater hose clamps to

the worm drive types years ago; they seemed tight when I examined them.

 

Perhaps I'm looking for trouble but so far I've not had problems with the head lights. I do have a number of those cube relays I could use though

as you suggested.

 

I don't mind tinkering with the carb; I just want to know what I'm doing beforehand. The engine will stall out when cold, suffers lag when warm at lower

engine speeds; I think someone here already diagnosed it as running lean; the sprk plug colr supports that theory. The flexi tube for warm air

from the manifold shroud is a recent replacement I installed.

 

Thanks for your wiring diagram I've printed it before in a large format and has been a great help; better than the tiny one in my book.

 

Jerry

[DanielC]

There are a few posts about making heater hoses from preformed hoses for other more modern vehicles.  I also have worked on a few possibilities.   The big issue with heater hoses is the two engine heater hose connections are 14MM (Datsun L engines are metric standard) and the heater hose connections are 1/2 inch.   I realise 13 MM is close to 1/2 inch, and 14 MM is close to 9/16.

I have found a metal adapter that is 1/2 on one end, and 9/16 on the other end.   I will get that part number for you later today.  

 

A stock L-16 engine is not really happy at lower engine speeds.  They are not your fathers Oldsmobile.  Below about 2500 RPM the engine should not have any significant load.   In 25 MPH speed zones, use third gear on most cases.  Below about 35, if you want to accelerate, third gear is best.  35 MPH in second gear is fine.  The L-16 has a yellow RPM zone 6500 to 7000, 7000 is a safe red line.   Running at a low speed below 2000, you have to feather the throttle in, as the speed picks up.

 

A carburetor only "knows" how fast air is going through itself.  It does not know temperature, barometric pressure, engine temperature, air density, engine RPM, engine load, or any other parameters a computerised fuel injection engine knows.  You have to think for the carb,   Open the throttle too much, too soon, and the air velocity through the carb falls too low to accurately measure the fuel flow.

However, a constant stumble off idle is a symptom of the accelerator pump on the carb not working.   With the engine off, take the air cleaner lid off the engine, and reach under the back of the air cleaner base, and operate the throttle, and look for a squirt of gas out of a small curved tube pointed into the primary venturi. 

 

There are also some ports in the carb by the primary throttle plate, that are just above the plate at an idle, and are exposed to engine vacuum off idle.  One of these adds vacuum advance, the other is a transition port to help off idle response.  Ignition timing slightly retarded will also hurt off idle response.  A too fast idle can actually hurt off idle response, if the idle transition port is partially uncovered in the carb, at idle. 

[DanielC]

This is the 1/2 to 9/16 adapter I found.

 

These are 1/2 hose barb fittings that might come in handy, I got these at an Ace hardware store.

 

These are the two hoses used for the water heated intake manifold.  I was able to get these at a local Nissan dealer fairly recently.

 

This is the long heater hose used on a 521/L16 truck.  The bottom hose is an old stock one, the top hose I used a new Goodyear hose, and one of the 1/2 to 9/16 adapters above to splice into a usable piece of another old 521 heater hose.

 

This is the part number for the new section of hose in the above picture.

[gene knight]

Thank you for deciding to save the 521 from the scrap yard that may have been in it's future, I have 3 of them +2-620 kingcabs. If there is anything you need just ask, post some pictures of it also

[jcard]

Had some time earlier this afternoon to remove the heater core. The inlet/outlet hoses seemed to be in good condition and pliable.

 

the bottom of the heater box was wet which leads me to believe it was the core itself that had leaked but I'm just not certain

I will carefully remove the hoses and see if I could get something newer to work. Even though I see removal wasn't very difficult

I don't want to redo this anytime soon. My shutoff valve has not been a problem and works smoothly but I'm assuming I'd

have to remove it before I bring the core to a radiator shop? If I read the threads correctly it takes a wood dowel and gentle

taping to remove it? What holds it in place??

 

I'll look for a local shop who might be willing to take on rebuilding this.

 

Jerry

 

 

 

[datzenmike]

The valve is part of the lower tank and they are just removed and a new core soldered in.

 

 

First I would immerse the core, hold thumb over one pipe and blow hard in the other. Bubbles? Where? If the core probably cut to the chase and renew it. If on one of the tanks you could probably clean, tin and then solder it closed. If the valve... likewise it can be removed and with help here probably fixed?

[jcard]

I have an air compressor I'll substitute for me blowing...

 

So how is the valve held in place? Also the foam rubber pieces that sort of held the core in place are a bit sad after

all these years, will any high density foam work or is there some that will hold up to the heat better?

 

Jerry

[datzenmike]

Temp can only go near 200F so anything will do. You can get self sticking sheets of foam for insulating a house.

 

The valve I'm going to have to defer to a 521 owner on this. I had one 30+ years ago but never had it apart. Have a look through post 159 here.. http://community.ratsun.net/topic/8175-mklotz70-project-mend/page-8

[jcard]

I think I've got it. There's a small retaining screw. The one on mine was completely covered with black paint; so much so at first

look it just appears as a blob of black paint...

 

Jerry

 

 

 

[jcard]

Well my heater core as well as my original radiator( although I doubt it was a real Datsun original radiator)  are at the only local radiator fixit shop in my area.

Fortunately they seem to have a good reputation and have been in the same location for more than 20 years. They have a can do attitude to that's a

positive but the proof will be in the pudding as they say.

 

It seemed once that radiator shops were all over, I guess working with lead as they must make for a tough business.

 

I'll post the results here.

 

Jerry

[jcard]

I received the heater core back and reinstalled it and besides no detectable leaks in the cabin the heater seems to better able to keep up

with our California winter cold...( and don't say it I know we're wimps out here- but 30 degrees is still 30 degrees)

 

Now next cooling system problem! And I'm sorry this one has me stumped at the moment. I saw this before I started working on the heater core.

Something in the engine compartment is spraying coolant! I found it on the air cleaner cover, spattered on the distributor cap, wires, hood. Weird

thing is the truck runs with the stock temp gauge just past midway and my newer gauge registering barely 180. I had filled the radiator up to the

top after my first test and coolant had a chance to circulate. I must have run the engine for 30 minutes before going for a second test drive and while

it sat in my driveway I saw no signs of leaking anywhere so I'm thinking it only must show up under the dynamics of driving somehow. I don't see any signs

of leakage from the radiator cap- that area is clean, I don't see any obvious signs of leakage from the thermostat housing. I see no obvious leaks from the inlet/

outlet hoses to the radiator. The hoses to the heater core- are the small 'S' shaped is the original as it seems ok for now and the longer run hose is a length of new

hose. I should mention that I installed an new aluminum radiator from Champion Radiators; I see no leaks from it ether. I don't see any signs that it is the water pump.

Then there's the fact that it doesn't seem to be severely overheating. the overflow hose from the radiator is running into the overflow tank but I'll double check that hose;

there is a small amount of coolant in the tank(not getting sucked back into radiator upon cooling) so I don't believe that's leaking...

 

What the heck is causing coolant to be sprayed has got me. I've obviously got a leak somewhere but where is it! 

I'll try running the engine for a longer time today in my driveway after filling it back up. to see what happens...

 

[Charlie69]

I installed a 1980 720 Heater and AC in my 66 520.

 

 

[banzai510(hainz)]

there is a rubber hose right under the carb that feeds the intake manifold for the hot water.

also by the thermos stat the heater line might have a u shaped bypass(not all L16 have this ck there) But not destroy it untill you have a replacement.

 

I would get leaks under the intake manifold and exhaust . the the gasket gets bad or loose it might leak.

 

also re cheack the core/freezeplugs for leaks.

 

My 521 is a leaky Mofo.  thinkits a headgasket /heatercore and coreplus all combined.

 

 

maybe onnce pressurezied the rad pops a small hole.  or the radioator cap pops the valve slightly and sprays on to the motor. (that if you dont have a hose on the rad that use to tgo to a bottle. theyre are 2 types of radiator caps 1 for the return bottle and one that dumps out.  HOpe you have a hose that routes down

[jcard]

Interesting experience. The thermostat cover gasket I made failed. I was specific when I asked for gasket material to ask for coolant system

compatible material. I ran up the engine early in the morning when it was still cool( 35 degrees) so I could see anything going on. After amount 15

minutes I noticed a very slight cloud of steam around the front of the housing cover which grew to more spectacular proportions after 20 minutes

when it actually started gushing. I let everything cool off for a bit, drained enough coolant to clear the thermostat.

 

Long story short, clean parts, implement newer coolant compatible gasket for thermo cover, restart car. No more leak ( thus far ).

 

Very tricky!

 

Jerry

[jcard]

Ah guys... I'm updating this thread as I am essentially at wit's end.

 

I think I've mentioned how my last major change to my '72 521 was to swap out the old Hitachi car for a Weber. It has not run 'right' with it and

exhibited much of the same behavior it did with the old(and leaky I found) Hitachi. Backfiring through the carb when cold and often at lugging engine speeds.

I've lived with it by gingerly working the throttle up to higher engine speeds where it has seemed happier.

 

This all ended a few weeks back.

 

On the way back home from a routine run over to Orchard Supply to drop off a pair of spent 8 foot florescent tubes for recycling the truck just suddenly started running terribly, back firing through the pipe, wouldn't idle. I nearly didn't make it home. I'm sure I appeared like one of those comedic movies

with the guy in his old herky-jerky jalopy sputtering and backfiring down the road. It was awful, I was able to coax the thing into my driveway where it has stood ever since. Attempts to start her have been met with extremely difficult starts and serial carb backfires and no idle at all.

 

It is so frustrating as I only have weekends to work on this thing.

 

The last thing I did this weekend was I pulled the distributor to clean it up, replaced both condensers, and replaced some very old wiring that looked quite bad. I could swear I can see how one set of points was doing anything considering the wire to it was nearly  or possibly was broken, couldn't see that fact until I moved it. So I replaced two wires and the condensers.

 

The other thing I tried was to test gas flow from the fuel pump. I put on a length of fuel line to the outlet to the carb, after pulling off the carb line and used a plastic beaker to catch the fuel. I cranked the engine for about 10-15 seconds and got what I'd have to consider is a decent amount of clean, with no visible water, fuel.

 

Next weekend I'm going to dismount the carb and go through every, bolt, screw and hose connection to ensure I didn't bugger something. After that I'm not sure what I'll do.

 

To date I've changed these things:

 

carb( duh)

sparkplugs

spark wires

dist condensers

coil

fuel filter

 

In the interest of full disclosure I've also done these things:

 

changed to an aluminum radiator

replaced smaller hose on fuel tank

changed all coolant hoses

had heater core rebuilt which I reinstalled

installed pioneer 'entertainment system/GPS" ) - made steel brackets to install blow dash

installed oil pressure, water temp and tach gauges -  plan to install voltage gauge next

upholstery - seat redone -black carpet installed

 

 

So it's not like I'm shy of either doing work or having work done. I really like this old girl but in the last months it has become a drudgery.

 

 

If only I knew what I was doing Id fix whatever is wrong and be done with it. This little truck had always run well, never any problems It

just tootled along very much a pleasure to drive; no sputtering, backfiring never finicky. No she's the truck from Hell.... :-(

 

And all the more frustrating cause I'm sure it's my fault and wouldn't be so if I knew what I was doing!

 

Sorry for the rant.... :blush:

 

Jerry

[banzai510(hainz)]

If you put a new weber on its pretty much good. maybe a adjustment on the mixture

 

the distributor esp a point dist is the worst. If back fire ect then ck the timming . Mine will soetimes go out of time. maybe the bushing or weights blewup. also if you put a different coil on there the point mayb wear out fast or the condensor cant handle the extra juice.

This is a simple truck.

 

 

water gets in the tank cause the fuel hose is leaky in the wheelwell. whci will cause the tank to rust then get the idle jet to plugg up.

 

 

read Datsun tech on olddatsuns.com 

is the oil spindal timmed correctly? Distributor?

[bilzbobaggins]

Which weber adapter you get? The two piece are prone to vibrating loose. Gets a huge vacuum leak. Lock tite helps this. Is it a real weber or a knockoff weber? I would suggest getting a ei distributor as well. Good luck in everything.

 

And out of curiosity, what idle jet and main and secondary jets did yours come with? I think my weber is over jetted for my l16

[jcard]

Well it's been some while since I posted a followup to my last post.

 

You know my tale of woe of the angelic 521 that turned into the truck from 'heck...

 

Backfiring from the tail pipe and carb yet I swore there was nothing wrong...

 

Not quite true.

 

Long story short. New Weber carb was loose, two bolts on intake manifold either loose or missing( that last one will take some explanation)

 

Manifold bolts, top rear loose_ish, second bottom front missing- but in my defense very tough to see.

 

These were an easy fix- replaced both with high strength 8 x 1.25mm bolts. 

 

Carb was completely dismounted and the adapter/  mounting completely re-seated the way I should have done it in the first place. I reused the OEM

throttle arm which fit on the Weber perfectly..

 

Result? Except for having to fiddle with the throttle cable position - perfect. NO, N-O backfiring or hesitation at any point in the throttle range, hot or cold.

I KNEW it could run right...gawd it was aggravating before now...every so often when the old girl is hot I'll get some run-on after shutting her down but I'll get to that.

 

It my further defense- California roads suck. I hate to sink to cheap epithets but it's true. Because we want to be everything to everyone who can spell or point to the word

WELFARE our infrastructure, in particular our roads is slowly( and in some cases not so slowly), disintegrating. They are so rough and therefore hard on older cars like this

that monthly inspections for loose bolts has been mandatory. This is not the first time the roads here have led to damage, one of the bolts on my 521's steering box snapped

and before that the bolts joining the header to the exhaust pipe on a 1990 Miata I had snapped. Now every month I run this little truck here, and I don't drive it a lot and just locally

I'll have to check for 'missing things' - which stinks but there it is....These roads basically shake my truck apart...

 

I'm so glad my little truck is running ok, at least for the moment.

 

Jerry