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1978 Datsun 620 - "Sendy"


bxadook

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Hi everyone.


I am a relatively new lurker who has always dreamed of owning a Datsun since high school. I just hit 30 and have saved up a bit of cash to finally fulfill this dream. I am currently in Tucson, AZ and traveled to Albuquerque to pick her up. This is my first car that I will be working on. She was daily driven before me. I will not be daily'ing her now until I feel she is safe to drive. 

I drove her the entire 400 miles from Albuquerque to Tucson with a cruising speed of 60-65mph with no issues. She went full send.   We made it alive. I have named her Sendy because of it. (Yes I took out an insurance policy for this drive).

 

I do have the FSM from NICOclub. I just bought the car yesterday so a lot of these questions I need to look up on my own, but if you guys have insight that would be helpful as well!

 

https://photos.app.goo.gl/GnmMLxS5EfYcbgcT6

https://photos.app.goo.gl/DpGLvA4jzKcjqLWr5

 

She is a 1978 Datsun 620 with 116k original miles. Stock L20b with 4 speed manual transmission.

Reportedly rebuilt carburetor. New battery and alternator. Reportedly original clutch. Prefer a firm clutch so might end up switching this out at some point. 

She starts right up. She has a repaint to this red with some rocker panel rust but I did not see any paint bubbling to indicate overpainted rust. I think there are a few panels that were repaired. 

 

https://photos.app.goo.gl/Hx59LebMcSvs5Buk8


She has a reupholstered leather interior with a cracked dashboard. 

 

https://photos.app.goo.gl/PXBvFqzZh4LR6Y8A7

https://photos.app.goo.gl/v4gdKPVKpftMvsYXA

Oil leak supposedly from oil pan reported by previous owner but appears to be covering the transmission. Rear main seal?

https://photos.app.goo.gl/og7jPZd3MPUVgJPF8

https://photos.app.goo.gl/rkLLrAFjS6SqNwsp7

https://photos.app.goo.gl/t8Phdd7q8cdvhuF97


She has some floor pan rust that is pretty bad on the driver's side with evidence of previous repair. Will need new floor pans. 

https://photos.app.goo.gl/hhD15UjZsLRi1KSi6

https://photos.app.goo.gl/R8BpypaqStncTphcA


On the column, the driver's side turn signal works, but when pressed upward to get the passenger side to work there is some resistance, and when in position it remains lit. Is this a switch problem and does it need to be replaced? I've read the grounding issues cause things to work poorly, but because the switch on the column feels like garbage I feel like it is broken. 
Rear brake light remains on and the turn signal does not work. It was replaced and rewired, yet does not work. Previous owner told me to replace the cluster and wires. 

https://photos.app.goo.gl/zLM1mRQeZS2uBo546 - Wiring on the passenger side tail light. 

Bushings look bad in the front suspension. Squishy rubbery noise when rocking the truck side to side. Oil on shock absorber(coming from shock absorber?) 

https://photos.app.goo.gl/he8BKCrUEPSLgSU3A Passenger side - there is a gap between the upper control arm and the wheel knuckle. Is this normal? 

https://photos.app.goo.gl/ADqGB7kEGD9hbcUf9 Drivers side - lots of build of gunk. Where is this oil coming from? The upper and lower control arms look newer compared to passenger side. 

https://photos.app.goo.gl/Y6Z3PEw4cHZxHf9u6 Rear Passenger side - new shock absorber. 

https://photos.app.goo.gl/cUKhLxaT2Dd87Ppu8 Rear drivers side 


A fair amount of rust in the frame, but looks okay as far as deep rust? (Can someone weigh in on this?)

https://photos.app.goo.gl/ZYiyXUkgQXMBRcdo7 - gas tank rust 

https://photos.app.goo.gl/KJaMQ56J1iz8JjX38 - exhaust rust 

https://photos.app.goo.gl/i6Sn69R1xKpiEWmu8 - nice cake on the differential 


Emergency brake does not work and have to put the truck in 1st gear to act as parking brake. 

 

Lots of stuff to fix. If you guys see anything that looks emergency and needs fixing now let me know.I am not good at diagnosing or pointing out problems as you can tell.  This is my first project car. I have owned cars that required little maintenance so this is a deviation from that.  

 

My main goals this year are to make this truck safer by improving the brakes, getting the E-brake to work, suspension, steering, fixing the lights issue, and getting the floor pans taken care of. 

 

Ultimate goals are to eventually swap the L20b to a KA24DET using Redeye's mounts when the L20b dies. I will not do this until I feel the truck could handle the stress of speed. But until then, I plan on maintaining it stock. 
 

Thank you for this great community!

 

Ben

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I would definitely start off by replacing ALL Transmission and differential fluids immediately!!! Can't stress this enough. There's no telling when they were checked last or when they were replaced. It should be every 30K miles. 

 

Next change the oil and filter... always change the filter. NEVER use fram filters for anything.

 

If the front shocks are wet replace them.

 

The bushing you mention look to me like the rubber boots covering the ball joints. They tend to rot away. If money not a problem replace them all and the ones in the steering system.

 

If you replace the turn signal switch there were 3 different ones used during the run of the 620, it has to be from a '78 or '79. To get at you have to remove the steering wheel and separate the plastic clam shell covering around the steering column. Something has come undone and it may be that all that's needed is a little soldering.

 

Power wash the oil pan, transmission and differential and let dry. It may take 2 or 3 tries to get it properly clean. Then watch to see where the oil starts seeping. But first examine all around the valve cover for the leak. Oil will flow down hill. It could even be the valve cover gasket. Is there oil on the side of the block? below the spark plugs? Is there oil on the bottom front of the timing cover behind the crankcase pulley? It could be a bad front case seal.

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No... just the king.

 

Rust on exhaust doesn't mean much. If damaged or full of holes then yes try to replace it. I doubt you will find pre-bent pipes for a 40 year old truck but a good shop can bend up custom pipes. Ask around it's a mixture of skill and art and not all places are good at it.

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I think this looks like the one that was on CL a week or so ago. I would love to have grabbed this one up but if I were to bring another Datto home, my wife may very well cut my nuts off.

Welcome to the circus.

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I see no problem with replacing all fluids. Just keep a written record of all you do to the pickup (date and mileage), every time you do anything. This will make it easier on the memory.

 

Don

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4 minutes ago, bxadook said:

Is it okay to replace all these fluids at once? 

 

Plan to replace coolant, trans, diff and motor oil. Possibly all today. 

 

Ben

 

Sure, might as well do them all at the same time if you're under there. Use GL4 int he trans and GL5 in the diff. Delo 400 in the motor, 50/50 mix in the radiator.

 

Buy a quality filter, not fram.

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Will do Mike.

 

I was able to take care of the coolant today. It was green, not clear, with some black flakes at the top which I believe are paint from the frame. Will take pics in the sunlight tomorrow. 

 

Had difficulty finding GL-4 only fluid so I ordered some GL-4 specific Sta-Lube off amazon.

 

Have the GL-5 fluid but could not get the diff fill plug out so I am taking it to a friend's place to show her off. He's also got a breaker bar.  

 

Previous owner has the oil topped off to the H on the dipstick, its pretty light and it appears to have been serviced regularly. I messaged him today, and he said it was due for an oil change after the 400 mile drive I put on it so I should be taking care of that tomorrow as well. I will take care of the leak asap.

 

Thanks for the help and advice everyone!

 

Ben

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It may be that clear because the leak is so bad it keeps getting topped up!!! A rolling oil change. 😄

 

Engine oil. For this you really should do some research on the ZDDP controversy. ZDDP is a zinc anti scuff additive added to the oil but in the last decades oil makers have been dropping the levels from 1,200 PPM to as low as 600PPM for two reasons. Most engines today use roller cams and don't need the protection and it's harmful for today's catalytic converters so they are slowly fazing it out. Our Datsuns are 40 plus years in the past and were designed to use oils high in ZDDP. Primarily to protect from cam to tappet or cam to rocker scuffing. Oil companies have said that today's oils are reverse compatible and that the levels in the past were too high to begin with so lowering them does no harm.

 

Me? I say it's too late when my L20B cam chews up the rockers, so.... no thank-you. It's easier to just use oils that are still high in ZDDP. Such as? Well diesel engines are mostly push rod and use tappets and are exempt from using the lower level ZDDP. I'm using Shell Rotella T4 15w40 although you can get it lighter in 10W30 as well. Chevron Delo 400 is also good as are any over the counter racing oils, usually marked with an R. Just ask for a 'flat tappet' oil and the counterman will know what you mean. You can also buy ZDDP additive but really? why not just buy a diesel oil. Synthetic? Over kill protection you'll never ever need. It may also begin leaking from old seals that easily contain conventional oil but can't handle the thinner slippery synthetic.

 

So do some research and make your decision based on knowledge. I did, and get a good night's sleep.

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On 12/12/2019 at 8:34 PM, banzai510(hainz) said:

Replace the radiator fluid with 50/50 mix

 

Done!

 

I just realized that I had two datsun gods reply in my thread. Thank you hainz!

 

Ben

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23 minutes ago, datzenmike said:

It may be that clear because the leak is so bad it keeps getting topped up!!! A rolling oil change. 😄

 

Engine oil. For this you really should do some research on the ZDDP controversy. ZDDP is a zinc anti scuff additive added to the oil but in the last decades oil makers have been dropping the levels from 1,200 PPM to as low as 600PPM for two reasons. Most engines today use roller cams and don't need the protection and it's harmful for today's catalytic converters so they are slowly fazing it out. Out Datsuns are 40 plus years in the past and were designed to use oils high in ZDDP. Primarily to protect from cam to tappet or cam to rocker scuffing. Oil companies have said that today's oils are reverse compatible and that the levels in the past were too high to begin with so lowering them does no harm.

 

Me? I say it's too late when my L20B cam chews up the rockers, so.... no thank-you. It's easier to just use oils that are still high in ZDDP. Such as? Well diesel engines are mostly push rod and use tappets and are exempt from using the lower level ZDDP. I'm using Shell Rotella T4 15w40 although you can get it lighter in 10W30 as well. Chevron Delo 400 is also good as are any over the counter racing oils, usually marked with an R. Just ask for a 'flat tappet' oil and the counterman will know what you mean. You can also buy ZDDP additive but really? why not just buy a diesel oil. Synthetic? Over kill protection you'll never ever need. It may also begin leaking from old seals that easily contain conventional oil but can't handle the thinner slippery synthetic.

 

So do some research and make your decision based on knowledge. I did, and get a good night's sleep.

 

 

I chose the Delo 400 after Draker's recommendation and using the search function in the forums, and thank you for confirming this decision! Thank you for the information. 
 

Still hoping this leak is something minor to fix and not a rear main or head gasket. After googling L20b stuff, I discovered the magic that is hainz. 

 

Ben

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As promised here is my coolant:

 

https://photos.app.goo.gl/auPdKuMK6udoZXG56

 

Note black flakes and murky appearance. I have tried googling what used coolant is supposed to look like and seems to be okay if it isn't brown from an oil leak. I think these black flakes are just paint as it was draining. 

 

Ben

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Looks fine. I love finding an engine with bright green coolant in it. If you don't know when it was changed last.... change it now. Get a good name brand anti freeze and use distilled water that is free of dissolved minerals. If hoses need replacing (usually they rot from the inside out and it's not obvious) and have swollen or gone soft do that first. There's nothing quite like loosing all your coolant from a blown hose and changing it in the snow.

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Took care of the transmission fluid and oil today. 

 

Unfortunately did not get a sample to take a picture of as the oil pan I used was already contaminated with oil.

 

I can tell you the transmission oil was very dark and very much unlike the fluid I put in. 

 

The transmission feels better, and I feel as if there is less engine braking since the fluid changes which is a huge plus!

 

I could not break the differential fill bolt on my own, and will likely be taking it to a shop tomorrow or during the week. Given the level of debris on the axle, I am strongly suspecting 41 year old differential fluid. It is not stripped yet, and I would like to have someone who knows what they are doing try and break it open. 

 

Thank you for the help Mike!

 

Ben

 

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I have run into a separate issue. 

 

Maybe one of three times when attempting to start there is an audible click from the starter, yet the engine does not crank. After multiple tries, the engine will finally start. The motor has no problems idling or starting when it finally decides to crank. 

 

I have been told by the previous owner that you have to "keep trying" and "push the clutch in all the way." To me, it is seemingly random. I want to fix this. I will go through the FSM algorithm but before this any input would be appreciated. 

 

I was told that she has a new alternator, and when this problem first came up yesterday I actually tested the battery and it has "100%" life left. 

 

Ben 

 

 

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In no particular order...

 

Clean the battery posts and cable clamps. If the cable ends are those 'bolt on' replacements get rid of them and find some good one piece cables in a wrecking yard if you can't find any to buy.

 

Clean and tighten the negative cable where it bolts to the head behind the fuel pump. Clean and tighten the positive cable where it connects to the starter solenoid.

 

Make sure the small Black/Yellow stripe wire that sends the start signal to the solenoid from the ignition switch is snug on the connector.

 

Are the starter mounting bolts snug? The starter is grounded through it's case.

 

Still random starts? Pull the Black yellow wire off and measure the voltage while someone turns the key to start. It should be close to 12v. I had 7v on my 710 and this weak start signal was not enough to activate the solenoid. It's a combination of age, thin wire and about 20 feet of it causing a voltage drop. See what you get and we'll fix this.

 

 

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Okay Mike, 

 

I have cleaned everything, battery terminals, starter solenoid attachment, fuel pump attachment, and while trouble shooting my turn signal issue I even opened up the shroud around the steering column. Cleaned it all with CRC electronic cleaner. 

 

So far she is 1 for 1 on starts so I am hoping this works! 

 

Now on to my passenger tail light! Like I said, when I took a look under the shroud around the steering column, there was a lot of gunk on the inferior side of the turn signal. I hit it with some electrical cleaner. I feel as if the switch is moving a little bit better, and that it actually is engaging. Therefore, I believe the issue is at the taillight. Opening it up I have discovered rewiring and a burned Stop/Turn/Tail.

 

Prior to pulling the combo light from the truck the passenger side brake light stayed on no matter what happened. Driver's side works fine. 

 

I've located the FSM wiring portion of the RH light here: 

https://photos.app.goo.gl/PBzmh9asvUoc2i1E7

 

Here is the RH taillight: 

https://photos.app.goo.gl/LxHMtVqoigRK5njc9

 

Here is my interpretation of what is happening: 

https://photos.app.goo.gl/ouQNdNGzXaQpi8HN9

 

I believe that the taillight was rewired incorrectly. I also believe that it has led to overload of the Stop/Turn/Tail as you can see below with the rubber being blasted away:

 https://photos.app.goo.gl/2nUkwKaqcHNWhykn6

 

I do not have a multimeter, to test the stop/turn/tail to see if it is still working. But before that I have a few questions that if answered might correct my flawed thinking:

1. My interpretation of the diagram is that these connections need to be made before the 4-channel connector pin, is this true? 

2. If it is true, then several bulbs appear to be missing wires. Where are they?

 

Please let me know where I am getting this wrong. 

 

I will get a multimeter as soon as possible to see test these connections. 

 

Thank you so much, 

 

Ben

 

 

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Update on taillight issue:

 

So I took apart the turn signal switch and cleaned out all the corrosion on the switch contact points, checked all the wires and soldering points and there were no issues there. Unfortunately I did not take pictures of the corroded portion: 

Here is my switch: 

https://photos.app.goo.gl/KH2yaEirnpLV2ysi9

Undid the two screws on the left side of the switch to get the contact points and the bronze pieces that make contact with the springs. Put dielectric grease on them as well. 
 

After this, the turn signal still would not work. I ended up replacing a bulb, and VOILA it worked. 

The system was working well. The turn signals worked well after that but my brake light was still not working. 

Here is the wiring set-up made by PO:

https://photos.app.goo.gl/KH2yaEirnpLV2ysi9

 

I maneuvered the wires around in attempt to get the brake light on the right to work and ended up blowing a fuse.

After this, both brake lights stopped working. 

I ended up replacing two fuses, a 10A and a 15A in the top and bottom right respectively. 

I expected this to fix the brake light problems but it did not. 

I wracked my brain around why it would not work for a week. Eventually I checked the connections at the brake light switch to find one of the connections completely broken. I must have broken it somehow, because the brake light worked before. 

 

https://photos.app.goo.gl/nSE2Wqd3h4GvGRf69

 

I replaced the wire and the brake light works! 

 

The right brake light does not work still as messing with the wiring caused me to blow through two fuses. 

 

I have ordered a replacement OEM 4-pin tail light from a Pull-a-part in Oregon because the color coordination did not match and I do not trust my ability to rewire the light in accordance to the wiring diagram that I posted earlier. 

 

Hopefully this replacement tail light completes the fix. If anything, I will be able to compare the wiring to the previous owner's wiring and resell one of these lights!

 

In summary: 

1. Cleaned turn signal switch.

2. Replaced right front turn signal bulb.

3. Replaced wire to brake light switch 

4. Reordered a 4-pin taillight to replace PO's questionable wiring. 

 

Ben

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