'79 620 in North Carolina - Rehabilitating a Mississippi Farm Truck

[slvrbk]

Hello (Datsun) World. My name is Alex, and I live in the middle of North Carolina - just west of Charlotte. I recently purchased a 1979 620, covered in mud, from a Mississippi farm. It's becoming more of a project than I initially thought it would be, but we're here and we're getting it back on the road.

 

 

Here's my current garage setup, sans the daily Buick wagon.

 

 

First up was a deep clean and a brake job. The thickness of the mud was impressive; I am still working to clean it up. The driver-side rotor was scored badly and needed replacement, but both hubs were welded onto the rotors. After separating the components, installing new rotors, rebuilding both calipers, and regreasing the hub and bearings, we were back in business. My wife even helped bleed the brakes with me!

 

 

 

 

Second are the valve clearances. Honestly, the truck runs like crap. It shakes, it ticks, and it bogs down under acceleration. It might be the original carb or the old gas. It might also be poor valvetrain maintenance. I started with the valves and quickly found an issue. Cylinder two's intake valve rocker lost its lash pad. I found it further down the camshaft out of harms way, but the rocker, or exiting lash pad, had slammed into the spring retainer enough to do some damage. The lash pad won't drop back in, so I think the retainer has to be replaced.

 

 

 

I have more planned, but this is where I can leave off for now. I am waiting on some parts and trying to research the best way of replacing the valve spring retainer without pulling the head, or dropping a valve. I am also crossing my fingers that I can leave the camshaft in place, but I don't know what my reach will be once I start the job. I'd like to keep it as simple as possible for now, as I get the truck operational. I'm happy to tackle bigger projects once I know the mechanical guts are good.

[datzenmike]

To get at the inner wheel bearing you would have had to pop the grease seal out. Hopefully you replaced both.

 

The valve train look great, someone changed the oil regularly. Always change the filter with a WIX or NAPA Gold.  NEVER USE FRAM FILTERS. As for oil you can't go wrong with Rotella T4 10w30. It's the same ZDDP level as when your truck was new. I don't know where you would buy a retainer but there are lots out there on L series engines. Try a want add and someone will mail you one... https://ratsun.net/classifieds/category/9-datsun-parts/ 

 

Replace spring retainer ...

 

Turn engine till #2 intake and exhaust valves are closed and you can feel the valve lash when you wiggle the rocker. 27mm socket on crankshaft pulley nut. Both cam lobes will NOT be contacting the rocker arms.  Turn engine backwards (counter clockwise) about 1/4 turn. Remove spark plug and insert about 3 feet of 3/8" nylon rope into the hole. Tie a BIG knot on your end. Turn engine by hand forwards, or clockwise and compress the rope up tight against the closed valves. You can now do anything you like the valve cannot drop into the cylinder. Using a very large screwdriver under the cam but not on a lobe, to pry down on the valve spring to compress it and pop the rocker off the pivot ball. You can figure out the rest. No special tools needed, you could do this on the side of the road.

 

 

 

Later change all the fluids...

 

2+ liters GL-4 80w90 transmission and steering box

1+ liter GL-5 differential

 

Grease the steering and ball joints

 

[Ooph!]

" It might be the original carb or the old gas."

 

Get rid of that fuel if its older.

There should be a drain plug on the bottom of the tank, draining it will aid in getting the loose rust out instead of pulling it through the filter.

[ggzilla]

Looking good!

[slvrbk]

Thanks, Mike. The write-up on replacing the retainer is helpful. Both the FSM and Haynes read a little more complicated and involved. The valvetrain is surprisingly clean. The odometer says 45K miles, and certain parts of the truck look like that could be true, but I have no faith that ticker is still working. I did replace oil seals on both hubs, and I went through the procedure on pre-loading the bearings. The calipers were completely cleaned and resealed as well. New hardware and fresh fluid finished off that project. I still have to do the rears.

 

@Ooph!, I'll definitely look at draining the gas. We have a few non-ethanol stations around, so that's what I'll trend toward using long-term. I have a siphon tube for my old SAAB because it sits long periods right now too.

 

Thanks for the help. It's great to get some eyes on this project and I hope to move it along. I miss the forum format. I was on the old SAAB and SOHC4 motorcycle forums before they gave way to Facebook groups.

[slvrbk]

Just now, ggzilla said:

Looking good!

Thanks! Just trying to make it incrementally better every time I work on it 😵‍💫.

[slvrbk]

Making slow, steady progress. Finished the valve train work, installed a Weber, got distracted with my wedding, and now jumping back in as winter sets in. The drive shaft is out for a carrier bearing replacement. I have the old bearing off and refitting a new National Brand kit. I have questions about it...

 

The new nut is different. It spins on three full rotations and then gets tight. I think there are some boogered threads, so I am chasing that. Is a 20x1.5 die correct? At the moment I am using the nuts to gently chase.

 

The kit came with what appears to be a grease seal or rubber isolator. Nothing like it came off during deconstruction, so I'm looking for advice on where (or if) it goes on. If I need to post a picture, I can do that when I get on my laptop.

 

Once this is done, I'll drain and fill the transmission, and do the same for the differential. After that it'll need an exhaust (badly!). Thanks for tuning in.

[datzenmike]

 

 

The bearing never goes bad. The reason one didn't come off is because it's always the rubber surround that rots away and the unsupported driveshaft bangs around and vibrates. 

 

Now would be a good time to check and replace any bad U joints. 

[slvrbk]

Still having fun wrenching on the weekends, especially now that the weather is getting nice here in North Carolina. I've rebuilt brakes at all four corners and have the truck running pretty good.

 

The parking brakes, however, are beating the crap out of me. I've installed new rear cables from RockAuto (Raybestos brand, I believe). I'm going through the adjustment, and I am far away from touching the threaded equalizer. Not a chance I can close that gap without having the parking brakes engaged.

 

Couple things to note if you can help me out:

1) All new drums, shoes, and hardware on both rears.

2) Shoe adjustment was done per the FSM

3) Pretty confident that I put the correct cable on the correct side, but I'm open to being wrong if there isn't a way to confirm other than disassembly and measurement.

 

I forgot what host I was using for images, so once I figure that out, I'll post the photos I took.

[slvrbk]

23 hours ago, slvrbk said:

I forgot what host I was using for images, so once I figure that out, I'll post the photos I took.

 

[NC85ST]

You’re sure that they are the correct cables for the truck? You matched them up with what you took off?

[datzenmike]

 Front hand brake pull must be fully down or OFF.                                                                                                                                                         

[banzai510(hainz)]

17 minutes ago, datzenmike said:

 Front hand brake pull must be fully down or OFF

See if there is a length adj for the center pull cable to ge to get a few more inches.

also make sure you pulled the cable on both sides as hard as you can as there is usually spring at the end. I recently did my 521 and had to pull each side and was still like 1 2 inch off the thailand rear parking brake cables. I made a plate and used a bolt. which worked. Your 620 uses a cage set up so your going to have to be creative on this. Find something in the turnbucklesection at a GOOD hardware store.

 

You get it running? Yes a lash pad can come off if valves not adjusted right. You loose a cylinder and usually EZ fix.  usually the lash pad is counter sunk on back side and should fit in the retainer with the side flush and then adjust the rocker arm.  I set mine tighter .006 in .008 exhaust.

 

I got this to spray under my 521.  if your going to redone it first before spraying but I dont care and sprayed my brake lines(rust) and certain stuff so dont dry rot 

https://www.amazon.com/Cosmoline-RP-342-Rust-Preventative-Military-Grade/dp/B01MRRYDMZ/ref=asc_df_B01MRRYDMZ?tag=bingshoppinga-20&linkCode=df0&hvadid=79989681302452&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=67529&hvtargid=pla-4583589157228683&psc=1&msclkid=451686cf6de91f8fe6ccef05b44f60ed

[slvrbk]

5 hours ago, NC85ST said:

You’re sure that they are the correct cables for the truck? You matched them up with what you took off?

 

I am positive that I ordered the correct lines, for the correct side, for the correct year, for the correct bed from Rockauto. I do not recall matching them up before installing. Rookie move. I do still have the old frozen cables hanging around.

 

5 hours ago, datzenmike said:

 Front hand brake pull must be fully down or OFF.                                                                                                                                                         

 

I double-checked the lever this evening when I got home from work. The handle was down (fully off). I also reached under the dash to check if the cable end was loose. Seemed fine, but I couldn't crawl under it, so I'll retrace those steps tomorrow.

 

4 hours ago, banzai510(hainz) said:

See if there is a length adj for the center pull cable to ge to get a few more inches.

also make sure you pulled the cable on both sides as hard as you can as there is usually spring at the end. I recently did my 521 and had to pull each side and was still like 1 2 inch off the thailand rear parking brake cables. I made a plate and used a bolt. which worked. Your 620 uses a cage set up so your going to have to be creative on this. Find something in the turnbucklesection at a GOOD hardware store.

 

I am going to try to tug on it to get more length. 😅

I might be able to fab up something at work, but I'll first start with taking it all back apart to measure cables and atone for earlier mistakes (if it comes to that).

[slvrbk]

4 hours ago, banzai510(hainz) said:

You get it running? Yes a lash pad can come off if valves not adjusted right. You loose a cylinder and usually EZ fix.  usually the lash pad is counter sunk on back side and should fit in the retainer with the side flush and then adjust the rocker arm.  I set mine tighter .006 in .008 exhaust.

 

I got this to spray under my 521.  if your going to redone it first before spraying but I dont care and sprayed my brake lines(rust) and certain stuff so dont dry rot 

https://www.amazon.com/Cosmoline-RP-342-Rust-Preventative-Military-Grade/dp/B01MRRYDMZ/ref=asc_df_B01MRRYDMZ?tag=bingshoppinga-20&linkCode=df0&hvadid=79989681302452&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=67529&hvtargid=pla-4583589157228683&psc=1&msclkid=451686cf6de91f8fe6ccef05b44f60ed

 

I did get it running. Quite well, in fact. It's registered and semi-drivable. I keep tinkering. The lash pad is back where it belongs, and the valves adjusted. I'll monitor it over time. Good to know on the rust preventative. While the truck is solid and rot-free, it's way rustier and dirtier than I was hoping for. I am chipping away at it as time permits.

[slvrbk]

I took everything back apart at the drums (pics 1 and 2) and removed the cables. The driver's (left) side matched up to an old cable (pic 3). The passenger side appears to be off by the extra length on the swaged fitting (pic 4). I thought I would be able to trim the extra length and gain 1/4". Apparently, I don't know how these fittings work; I thought I could sneak up on the stranded wire by cutting through the ferrule. It was solid throughout (pic 5). I purchased the "long-bed" cable for the right side last night. Other than the length difference in the right side cable, I couldn't find anything wrong with my setup. Nothing was binding or routed funny. Hopefully, the new cable gives me enough new length.

 

 

 

 

 

[datzenmike]

 

Might be the cable from the hand brake. You can see the rubber bellows is still compressed. It should only compress when handle is pulled.

[slvrbk]

8 minutes ago, datzenmike said:

Might be the cable from the hand brake. You can see the rubber bellows is still compressed. It should only compress when handle is pulled.

 

I have the stop nut threaded all the way down, so the rubber boot is bunched up because of that. I can take a closer look tonight.

[datzenmike]

Compare the lengths of the hand brake cables. 

[banzai510(hainz)]

I smear a little anti seize compound on the flat surface where the drum mates so later so drums come off ezer.

also if drum dont have jacking  holes to push drum out. some have some dont. I usually thread it for a intake size bolt

[slvrbk]

3 hours ago, datzenmike said:

Compare the lengths of the hand brake cables. 

 

I did compare the lines back to each wheel, as mentioned in the previous post. The main front cable is my original. It was in good working condition (and I couldn't find a replacement for the 1979 model year style). The driver-side cable matched one of the old cables, and the passenger-side cable was short by a bit. I couldn't see anywhere else on the truck that I would lose cable length, so I have to believe it was routed correctly and not binding. I'll see what the "long bed" version looks like when it arrives. 

[datzenmike]

The long wheelbase (king cab and long bed) rear cables will be about 9" longer but this won't help. The mounting point at the wheel and the one under the cab won't change. 

 

Can you show where the right cable is mounted to the cross member to the right of your thumb???

 

 

[slvrbk]

@datzenmike, I wondered about the cable length, but I panic-bought the parts, figuring the $25 wouldn't crush me. After the fact, I looked up the lengths and realized they were 9+ inches different. That took me by surprise. I'll either return it to Rockauto or put it up for sale here and on the FB page.

 

I don't have the image of the right side. I thought my photo captured it, but it obviously didn't. I can confirm that it was mirrored from the left side, as you see in the photo with my fat thumb. The bracket was mounted in the same orientation, with the cable clamp/holder/guide being closer to the outside of the truck. Here's a picture that was shared to my troubleshooting post on FB. This is essentially my setup...without the successful connection to the threaded adjuster.