Emiko, my new 520 work truck

[hucklefish]

In the morning, Ratsun!

 

I've edited this first post a couple times to update the name of the thread, and I figured I'd also add a couple pictures of Emiko at work here.

 

In front of a firewood shed I built, but on this day I just came back to do some sheetrock repairs inside the house.

 

Earlier the same day, parked in front of an American classic at the lumber yard (64 Chevy 1/2-ton, if I remember right) The perspective makes it look like the 520 is the same size, but it was clearly smaller in person:

 

This picture corrects that impression (I didn't notice the Chevy owner coming out of the store until just as I snapped the photo):

 

The following is the rest of my original post:

 

Do diagrams of the vacuum hoses or engine compartment layout exist for these trucks?

 

Any other advice about the following would be highly appreciated.

 

I just acquired a 1968 520, which I've named Emiko. After getting her home, I pulled the tranny and took it to a transmission guy who replaced the brittle leaky input shaft seal and gave it a clean bill of health otherwise. I put it back in and took a test drive around the block, got some advice on carburetors and a little tuning from a slightly high neighbor who at least seemed to know more than me, parked for the night and loaded tools for the following day. Neighbor recommended I get the vacuum hoses straightened out, replace the plugs and wires, and replace the electric fuel pump with the lowest pressure pump I can find. In the morning, it was impossible to start, so I tinkered with the the throttle and idle screws until it would stay idling, and then drove it 66 miles round trip. I readjusted the carb several times throughout the day to either get it running again or keep it running, or lower the idle speed to a more moderate scream. I either burned or leaked 2.5 quarts of engine oil, felt the clutch slipping (I think) a couple times, and pushed the brake pedal to the floor with no effect while pushing it into the garage at the end of the day (pushing because it was cold again and wouldn't stay running). And the accessory belt screams intermittently because the alternator top bracket is missing. So I've been working on it again instead of driving it for work.

 

Oil loss:

I found a couple pinholes in a plastic line to an aftermarket oil pressure gauge and just replaced the whole gauge cluster. I've got a roll of Fel-Pro 3/32" cork-rubber gasket sheet coming in the mail tomorrow, and I'll make a new valve cover gasket and see how much that slows down the oil leak. I'm pretty sure I'm burning oil as well, so while the valve cover is off I'll look at the valve stem seals and do a compression test.

 

Vacuum hoses and carb:

There was a sort of cobbled together length of different sizes of vacuum hose going from the port on the base of the carb to a loose perch on the vacuum advance. I bought an assortment of vacuum hose and replaced that one. I pulled some kind of accessory off the left rear top of the engine block. It has three vacuum ports and some disconnected wires. It was held down by an head bolt, which came out entirely. I carefully put the bolt back and torqued it to 45 ft-lbs per the manual, and am hoping I didn't wreck the head gasket.

 

Belt and alternator bracket:

It looks like I'm going to have to fabricate a new alternator top bracket, and if I can remove the broken bolt in the thermostat housing, the bracket will attach there where I think the original did, and if not, I was thinking I'd make a bracket that holds the alternator at all 3 points and attaches only at the 2 bolts lower down on the block.

 

Brakes and clutch:

I don't see anything wrong with the brake lines under the hood, and I haven't looked at the wheels yet. I'm planning to rebuild the lines with Poly-Armour, and  haven't look for wheel cylinders or master cylinder yet. Figured I'd cross that bridge after I address the oil loss. The clutch disc appeared to be oil-soaked, so I'm going to just drive it some more like that and if it continues to feel like it's occasionally slipping, start looking into replacement clutch set. I *think* the clutch disc from my 81 Rabbit may fit. It's the same outer diameter and spline shaft, but I don't know about thickness yet.

 

I'm having a really hard time finding engine parts or information. I've got the Nissan service manual.

Any advice?

 

The guy I bought the truck from said an L20B and 5-speed is a viable swap, so I found what I think was a good deal (running, out of a 1978 720 that's getting a KA24 swap) and bought it the next week. That seller said the tranny needs new synchros, so I took it with me when I went down to pick up my 4-speed from the transmission guy, and I expect he'll call in another week or so to tell me it's ready. I'm seeing a lot more parts and info for the L-series engines than the J13. If I think I can maintain the J13 I'd like to drive it for a year or so before doing the swap, and probably rebuild the L20B during that time. But if keeping the J13 proves too problematic, I might start thinking about doing the swap sooner. I just read yesterday that the 521 has 5" more space between the radiator and firewall. Will the L20B fit in the 520? Will I have to fabricate new motor and transmission mounts and/or move a frame cross member?

 

Thank you for your courage,

David

Edited August 14, 2023 by hucklefish
expanding thread title

[datzenmike]

I think there is only a ported vacuum line from the carburetor base to the distributor vacuum advance. It may be a copper tube with fittings on the ends so no hoses at all.

 

An L20B will be a tight fit where the J13 was, also the engine mounts on the frame do not match up. I would rebuild the J13 and call it good.

 

Have a care with the brakes as it's a single master cylinder, so a leak or failure ANYWHERE in the system means NO BRAKES at all. Later models had the front and the rear brakes separate with their own master cylinder.

 

The oil seals can be replaced easily enough without removing the head.

 

Oil on the disc won't be fixed by replacing it. The rear engine seal may be bad, and another source of oil loss.

 

Nissan and MG share some engine parts. Maybe someone can suggest something for rebuild parts. The J13/15 was also used in fork lifts.

 

 

You might want to take some pictures and post them. The vacuum lines on the head bolt don't sound right. A previous owner may have changed some things.

[Stoffregen Motorsports]

The J13 is about as simple an engine as one can find. It will only have one vacuum line on the engine (manifold to distributor).

 

To answer your L20B swap question, you need to ask yourself what you will be doing with the truck. If it's for enjoyment rather than transport, keep the J13. Parts are readily available from British car parts suppliers (Moss, Mini Mania, etc). Even if you want to daily drive it, the J motor is more than capable of getting you there. Reliability is as good as the mechanic working on it. Many of the engine and related parts are similar if not identical to parts found in MGA or MGB cars, so start your search there. Somewhere on this forum there's a thread about BMC to Datsun parts interchangeability.

 

The L motor is very tight in that engine bay. Pulling off a tight engine swap takes patience and fortitude. If you want it to look nice. Anyone can hack something into place, but taking the time to place the engine properly, then connecting all the dots to make it look like someone meant to do it, that's where the magic is.

[datzenmike]

If an L20B swap, the 4 speed from the 521/510/710 and A10 are physically the same as the F4W63 J13 four speed so no alterations to transmission mount or driveshaft needed. You will need to keep the bolt in spline from the J13 four speed.

[Stoffregen Motorsports]

A 4 spd with L bellhousing and fixed output flange. I don't know if that transmission exists.  Does it?

[datzenmike]

Yeah my bad. The 520 J13 F4W63 doesn't have the bolt on spline, only the L16 521s did. But if you get a 521 4 speed with the bolt in spline just unbolt it and the J13 driveshaft will slide right in.

[hucklefish]

Thanks both of you.

 

The L20B came with the 5-speed transmission that was in the truck it came out of. I plan to use this as my primary work truck for my handyman and remodeling service. It will typically be loaded with 500-1000 lbs of tools and materials. Once I get it running reliably I plan to build a canopy and lumber rack, and I'll probably store a couple long extension ladders on top. I have a full-size pickup I'll occasionally use for physically larger loads and pulling a dump trailer. I'd like to be able to go up a long 6% grade in top gear with all my tools.

Considering your advice about the swap, if if not doing it means I have to slow down to 40 in 3rd gear for that hill, I can live with that. If I end up in 2nd  with hazards on and sweating the semis overtaking me, I'll have to find something else. Maybe I'll start looking for a 521 to go with the L20B and 5-speed, or else just resell them.

 

David

[hucklefish]

and here are some pics I took this morning...

 

The unknown vacuum accessory I was talking about is that thing just above where I've got the wrench.

 

Same accessory looking straight down at it from above. The shiny surface around the top of the bolt is just part of the bracket, where the head bolt nut was tightened on it. In this picture it's just sitting on top of the head bolt, which just sticks through the hole in the bracket slightly. I'm also curious about the two vacuum ports on top on top of the brake line splitter in the upper left corner.

 

Here's an overall pic of the engine compartment:

 

 

 

 

 

Broken bolt in the left side of the thermostat housing, where I think the alternator top bracket arm should be.

 

Edited June 25, 2023 by hucklefish
inserting imgur links

[datzenmike]

 

The round thing upper left is actually the brake light switch. Should be two wires nearby for it. Any pressure in the system the switch closes and the rear lights come on.

 

 

 

 The black thing is a coolant recovery system. It has a special rad cap that allows expelled coolant out into the container but when the system cools down it opens and coolant will siphon back in. I used to top off my 720 L20B weekly in the summer and by winter the antifreeze was weak. With a coolant recovery system I check it once a year.

 

 

 

Vacuum switch. Some 520s had this usually on the intake. Emissions equipment were quite rudimentary back then. I don't know what it's for. Look for a wire that reaches to it. It appears that an electrical signal allows vacuum to pass through or shuts it off for some reason.

 

Where does the hose with the bolt in the end beside the dip stick go????

 

 

 

 

I would remove the thermostat cover and drill this broken bolt out. Use a nut and bolt to secure the adjustment strap. I would do this first as vibration can and eventually snap the alternator mount to the block and that's worse.

 

 

There should be an inline fuel filter where the fuel hose exits the front fender. The 520s used a glass one but a suitable plastic one in fine.

[Stoffregen Motorsports]

I love that you want to use it for work, but the kind of work you're describing might be a bit much for an almost 60 year old Japanese truck, even with an L20B. Drum brakes, kingpin suspension, short wheelbase and tiny cab. Plus, no A/C. You'd need to rebuild all the suspension and brakes at the minimum. The kingpins are likely shot by now.

 

A 60 year old domestic truck would be far more capable.

[datzenmike]

The 520 is rated at 1,000 Kg payload, or 2,200 lbs. It can handle the weight and it's got 4.875 gears, but 4 wheel drum on a single master cylinder makes my balls shiver. I had about 1,900 lbs on my 521 and it drove on a side road but the tires were squashed. The brakes wre ... OK but scary how much further it took to come to a stop.

[hucklefish]

No A/C isn't a big deal where I live. Is disc brake conversion possible?

On 6/23/2023 at 8:32 PM, datzenmike said:

The oil seals can be replaced easily enough without removing the head.

Do you mean these?

 

Are they on top of the valve springs? What are they sealing in that position? I've never had a valvetrain apart before, except on a Continental A65, which is probably completely different. But I thought the seals were under the springs, keeping oil from flowing between the valve stem and the hole it goes through in the head.

 

Does everything look normal here?

 

Also, thanks for the heads-up on the brake light signal. Mine has an obviously DIY switch on the pedal.

What's this one for (vacuum hose connects to port on intake manifold)?

Edited June 26, 2023 by hucklefish
correcting auto-correct

[Stoffregen Motorsports]

Yes, the stem seals are under the valve retainers. Are you familiar with the rope method of changing stem seals?

 

Everything under that valve cover looks normal. A bit dirty, but normal.

 

Did you remove a head nut to remove that vacuum valve? If so, I'd go ahead and retorque all the head studs/nuts.

[hucklefish]

I wasn't familiar with the rope method, but I am now - thanks!

Yeah, that vacuum valve was under a head nut, and the entire stud came up with it. I retorqued that one nut/stud to 45 ft-lbs, which I found in the manual. I'll retorque the rest too.

[datzenmike]

 

Looks very stock. Only the later '79 620, maybe the '78 had this. Under very high intake vacuum such as letting off the gas at high speeds or down shifting this vacuum switch turns the idle cut solenoid off. Otherwise idle fuel, which is not needed slowing down, would be simply blown out the exhaust. There would be a clutch switch and a neutral sensing switch in the transmission so the engine wouldn't stall during shifts. At least that's how the later one works. I never dreamed the 520 would have something like this.

[hucklefish]

Ok, another dumb question - where should I look for valve seals? Can I just replace with same size O-rings?

I found a gasket set on new-datsun-parts.com for $108, and it looks like it includes valve seals that are more than just O-rings:

http://www.new-datsun-parts.com/images/52178.jpeg

NAPAonline seems useless for this truck, but I'll try my local Carquest store again.

[datzenmike]

J 13s were also used in fork lifts and they get rebuilt over and over. Oh... Nissan made Datsun badged fork lifts. You want the 'umbrella' style seals.

[Stoffregen Motorsports]

25 minutes ago, hucklefish said:

Ok, another dumb question - where should I look for valve seals? Can I just replace with same size O-rings?

I found a gasket set on new-datsun-parts.com for $108, and it looks like it includes valve seals that are more than just O-rings:

http://www.new-datsun-parts.com/images/52178.jpeg

NAPAonline seems useless for this truck, but I'll try my local Carquest store again.

If you don't want to buy a whole gasket kit, pop by your local engine machine shop. They'll have something that will work.

 

Remember, MGA and MGB engine were almost identical.

[hucklefish]

more dumb questions...

I see two ways to remove the seals:

I think I have to remove the rocker arms and rocker arm shaft, and because the rocker arm shaft journals are fixed to the head by 2 bolts, and one of those is a head bolt as well, that means removing the head, right? Or can I remove those 4 head bolts and put them back in and retorque them without disturbing the head gasket?

 

The other way I see to do it is back out the screws that set rocker arm lash all the way so I can slide the rocker arms sideways to get them off the pushrods and then swing them 90 degrees to get them out of the way of the valve stem covers and springs coming off. I'll probably have to remove the cotter pins and washers on the ends of rocker arm shaft to get enough play on those rocker arms.

Here's this guy, Kentucky Yankee on YouTube, putting his J13 head back on (from about 8:58 to 11:58):

... and because didn't put the pushrods in first and he's already torqued the head bolts, he has to do something like I'm saying. I think I could do that with everything in the engine. I'll have to take the manifolds off though, and at this point I'm wondering why I shouldn't just replace the head gasket. Or all the gaskets for that matter.

I'm guessing later Nissan engines don't have those rocker arms shaft journals held down by head bolts, and that's why it's easy to replace the seals without removing the head. Am I missing something else?

[datzenmike]

 

Drain the coolant.

Loosen each of the 4 bolt nuts and 4 bolts a turn at a time going round and round. Don't loosen each one all the way at once because some rockers will be loaded against the valve by the cam and push rod. Once carefully loosened the rocker shaft and all the rocker arms can be lifted out of the way. When done tighten in the same manner and you shouldn't have to reset the lash.

[Stoffregen Motorsports]

One at a time is good advice.

 

You understand that retorque means loosening the nuts and then torquing them, right? They need to be loose to give an accurate torque reading.

[hucklefish]

On 6/25/2023 at 6:12 AM, datzenmike said:

Where does the hose with the bolt in the end beside the dip stick go????

It tees into the dipstick tube. Maybe a return line once connected to the PCV tube?

[hucklefish]

As might be obvious from my latest post above, I started stripping accessories off. I disconnected the battery ground cable and belatedly realized it was another head bolt. With removing the rocker shaft, that makes 6 out of 10 head bolts I've loosened, and I still have to mess with the on-engine type valve spring compressor and the rope trick, etc... I'm halfway to the head gasket and if I go just a bit further I'll have a new head gasket and I can examine the valves and everything else.

(red arrow bolts are already loose):

 

So I have all the head bolts loose and most accessories off, and now I realize I don't know how to loosen and separate the head from the block.

[Crashtd420]

Do your self a favor and keep those push rods In the correct order front to back..... they need to stay in the same hole....

 

[hucklefish]

Head is good and stuck. I've squirted lots of penetrant down alongside the headstuds, tapped with a hammer on bosses and protrusions on the sides of the head , tried a pry bar wherever there's a bit of head casting overlapping something below, tried driving a cold chisel in at the joint in a couple spots... I'm headed to the hardware store to get some new poly rope to stuff in the cylinder and see if pushing up on it with a piston will move the head.

Anybody have any other advice?

 

31 minutes ago, Crashtd420 said:

keep those push rods In the correct order front to back

Will do, thanks. I've been laying bolts and nuts in order as I take them off, but I think it's time to get a piece of cardboard and start labeling it.