Nissan 720 4x4 reliability

[DankDatsun]

I’m new to owning older Nissan/Datsun trucks and recently got a 1985 Nissan 720 4x4 to use for my beekeeping business and some camping. I’m usually in bee yards that are in the middle of nowhere on really rough and steep dirt roads where a tow truck would most likely not make it or would refuse togo, no crazy wheeling or anything like that things just slippery in the spring when everything is wet and green so I’m not beating the crud out of it but I do need the 4wd to be dependable. Often times I have no cell service so getting stuck or breaking down would leave me taking the shoelace express. So with that said I’d like to know what are the common problems with these trucks (1985 720 2.4L 4x4)and what I can do to prevent them from happening. I’d also like to know the overall reliability and durability and if there is any kind of preventive maintenance I can do to keep them from leaving me stranded like how often should I be changing things before they go out (water pumps, timing belt, fuel pump, alternator, ETC.) 

[IZRL]

I would start with the basics. Replace all fuel hoses & fuel Filter, replace all brake hoses, change gear oil (transfer, tranny, both diffs), Engine Oil Change, replace Air Filter. Check wheel cylinders and replace if necessary. Make sure all lights are in good working order. Check windshield wipers are also working. Check Coolant, fill or replace if necessary. Check Spark plugs & spark plug wires replace if necessary. Check distributor cap and rotor (one of the terminals on my distributor cap disintegrated into powder when I disconnected a spark plug wire).  I would replace all accessory belts. Go over all the vacuum lines and replace the cracked/brittle ones. Check tires to make sure they're not sun baked and cracked.

Edited February 5 by IZRL

[bottomwatcher]

You are dealing with a 40 year old truck. IZRL gave good advice. It may seem expensive to do all of these things but you could have bought a newer truck so it comes out in the wash. Know how to use a voltage ohm meter? Probably one of the most useful tools when something electrical gets jiggled loose in the sticks. Also give the front end a good look over. Wheel bearings. Balljoints, tie rod ends, idler arm, and centerlink. Have someone slowly turn the wheel back and forth while you watch the linkage.

[datzenmike]

The '83 and up are equipped with the Z24 engine and they are notorious for blowing the head gaskets every 100K. The preventative is to loosen each head bolt separately and torque to 60 ft. lbs. Any pattern you like but only one bolt loose at a time. Do this on a COLD engine once a year to keep the head gasket clamped tightly.

 

There is no change scheduled for water pumps, alternator, fuel pumps as they are quite reliable unless they have been replaced with after market parts which are almost always inferior. They are replased if/when they fail. The Z series engines have a timing chain. I have never seen a worn out one and never a broken one. The chain guides are nylon? coated and they can wear.

 

Plugs, wires, cap and rotor are the only replaceable parts on the ignition system. Plug wires are the highest replacement part and you should get 5 years at least out of them. Anything that looks bad IS. Replace with NGK parts only!!!!!!! Again stock parts are superior to after market so don't change the coils.

 

If you don't know the maintenance history I would replace the fluids.

 

Transmission steering box and transfer case...... GL4 80w90

Differential.................................................................GL5 80w90

P steering.................................................................. DEXRON ATF Top up

Brake fluid................................................................. DOT 3 Flush out the old

Antifreeze coolant.................................................... flush system and use 50/50 with distilled water. Top up with distilled.

 

Fuel filter every 3-5 years

 

Engine oil. Use a 'high' ZDDP oil such as Shell Rotella T4 which has the same ZDDP content to the oils back when the truck was new. T4 is 1,200 PPM todays oils have lowered since '93 to 500-600 PPM today. ZDDP is an anti scuff zinc additive essential to protecting our valuable valve trains.

 

Do NOT use Fram oil filters. Use WIX or NAPA gold. They are still quality parts.

 

 

While a volt meter is useful for knowing the voltage when chasing a charging problem, a cheap $5 test lamp is often all you need to know if there is power or not on any wire/fuse.

[DwayneOxford]

10 hours ago, datzenmike said:

The '83 and up are equipped with the Z24 engine and they are notorious for blowing the head gaskets every 100K. The preventative is to loosen each head bolt separately and torque to 60 ft. lbs. Any pattern you like but only one bolt loose at a time. Do this on a COLD engine once a year to keep the head gasket clamped tightly.

 

There is no change scheduled for water pumps, alternator, fuel pumps as they are quite reliable unless they have been replaced with after market parts which are almost always inferior. They are replased if/when they fail. The Z series engines have a timing chain. I have never seen a worn out one and never a broken one. The chain guides are nylon? coated and they can wear.

 

Plugs, wires, cap and rotor are the only replaceable parts on the ignition system. Plug wires are the highest replacement part and you should get 5 years at least out of them. Anything that looks bad IS. Replace with NGK parts only!!!!!!! Again stock parts are superior to after market so don't change the coils.

 

If you don't know the maintenance history I would replace the fluids.

 

Transmission steering box and transfer case...... GL4 80w90

Differential.................................................................GL5 80w90

P steering.................................................................. DEXRON ATF Top up

Brake fluid................................................................. DOT 3 Flush out the old

Antifreeze coolant.................................................... flush system and use 50/50 with distilled water. Top up with distilled.

 

Fuel filter every 3-5 years

 

Engine oil. Use a 'high' ZDDP oil such as Shell Rotella T4 which has the same ZDDP content to the oils back when the truck was new. T4 is 1,200 PPM todays oils have lowered since '93 to 500-600 PPM today. ZDDP is an anti scuff zinc additive essential to protecting our valuable valve trains.

 

Do NOT use Fram oil filters. Use WIX or NAPA gold. They are still quality parts.

 

 

While a volt meter is useful for knowing the voltage when chasing a charging problem, a cheap $5 test lamp is often all you need to know if there is power or not on any wire/fuse.

I keep a test light and VOM in my vehicles, use test lite the most by far.

[DankDatsun]

Has anyone ever been left stranded in their 720?

[datzenmike]

Surely they have, however there is an vast difference between the old Nissan 720 and a newer EFI vehicles. If you can't fix the Nissan on the side of the road at least with a few common sense checks you know what's wrong with it.

 

 

 

[DankDatsun]

And that’s mainly todo with the fact that it’s carbureted? So what your saying is that its only as reliable as my ability to diagnose and potentially fix problems on the side of the road which would be more difficult with EFI?

[datzenmike]

Pretty much. If an EFI vehicle stops about all you can tell is that about it is that it won't start. You might hear the electric fuel pump chugging away but basically that's it. Even a technician can't do much with it on the side of the road without testing equipment and a shop so..... call the tow truck.

 

 

 

 

 

[DankDatsun]

Is there any other types of common failures? Particularly with the 4wd system or is it pretty solid?

[IZRL]

Get yourself a small toolbox and fill it with a few basic tools. Screw drivers (flathead and philips), Dykes, pliers, a few wrenches 10mm 12mm 14mm, crescent wrench, battery terminal cleaning brush, test light, and some assorted fuses, and toss it behind the seat. Make sure you have a properly inflated spare tire, the tool to drop the spare tire, a lug nut wrench, and jack. Carry jumper cables. I also keep a small rag tucked away somwhere in the engine compartment for the occasional oil level checks. You can take it up a notch and carry a small container of Dot3 brake fluid, quart of engine oil, and quart of ATF to fill power steering. You can take it up even another notch and carry a basic door lock-out kit. I carry one in my daily driver. I try and stop to help people who are broke down on the side of the road when ever possible. I've helped about 6 people unlock their doors when they lock their keys inside with my kit. All this should get you out of most pickles on the road.

 

Other than that when in an older car, or any car for that matter. You need to keep your eyes, nose, and ears on high alert. Listening for new noises and smelling for things like coolant leaks. Get in the habit of checking your gauges regularly (coolant temp, fuel, and oil pressure). Check your rpm gauge every once in a while during idle and while driving for any changes from the norm. 

 

Most of your major components will give you small warning signs that they're about to go out. If you keep an eye out for these signs you can be proactive and replace parts before they leave you stranded. The Alternator thats about to die might start making sounds from the bearings going bad. There might be a drop in the charging volts its putting out. If you turn your key to start the truck and it starts 99% of time. But every once in a while you turn the key and nothing happens. Your starter might be on its way out. Some vehicles have water pumps with little holes on them specifically to warn you that it's about to go out. If you start seeing coolant start to trickle out the hole. It's a sign your water pump is about to go out (Not sure about the 720 water pumps?) Aside from that always keep an eye on your driveway where you park your truck. If you see any kind of fluids on the ground. Investigate and fix. Familiarize yourself with the look and smell of engine oil, gear oil, ATF fluid, and coolant.

Edited February 6 by IZRL

[bottomwatcher]

Every time I get in my datsun I kind of give it a pre flight check. Once started I watch the oil pressure rise and keep an eye on the temp going down the road.  The nose is always on high alert for coolant smell, smoke, oil burning smell or gas leaks. Old truck stuff.

[Seven Two Oh No]

I've got the same truck and have had zero issues with the 4WD system, but I'm also not rock crawling or mudding so it gets relatively light use. Just make sure you inspect/clean/replace the front wheel hub components, and check/change fluids in front diff and transfer case. As for the rest of the truck, I've experienced the following which have the potential to strand/greatly inconvenience you:

1. There's a fuel pump relay on the inside passenger side firewall that can fail (you can hear it click when its working). Mine died because the solder joints on the relay board had cracked (a common failure), so I just reflowed the solder with a soldering iron and it worked fine again.
2. There is a small harness coming off the positive battery terminal that uses fusible link wires that can fail/work loose. This harness feeds a number of components like your lights (most common symptom in my experience). Can replace with regular wire in a pinch until you get back home.
3. I had a bad distributor drive spindle (or the fitting at the distributor was bad) that would occasionally jump one tooth while driving and severely retard the timing. Was able to rotate the distributor far enough to limp back home, where I dropped the oil pump and reclocked the spindle. This happened twice so I think I grabbed another distributor/spindle out of the junkyard and haven't had issues since.

4. A failing thrust washer in the (manual) transmission led to all sorts of weirdness which I wrote up here - https://ratsun.net/topic/75933-fs5w71b-failure-analysis-1985-720-4x4/. Long story short, don't drive in 5th gear under load for long periods of time since it puts strain on the gear and can cause it to bind to the adjacent thrust washer, which locks up the transmission.

[IZRL]

Ooh I forgot to mention. I carry one of these battery jump starters/power banks in my daily driver. If you're going to be driving in the backcountry solo. I would highly recommend one of these. It might not help you if you're battery is completely dead. But if you're still getting a clicking sound when you turn the key this will start your car right up in my experience. It also has usb charging for your gadgets. I have the nexpow 2500A listed below. Which has been good to me so far. There are more expensive options, not sure which is best so do you're own research. 

 

https://www.amazon.com/Battery-NEXPOW-22000mAh-Portable-Q9B/dp/B082ZZ2W14/ref=asc_df_B082ZZ2W14/?tag=hyprod-20&linkCode=df0&hvadid=416926807659&hvpos=&hvnetw=g&hvrand=7414993350869440120&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1013523&hvtargid=pla-871189774749&psc=1&mcid=31000cb942273a4492e4fd72242a1b20&tag=&ref=&adgrpid=92859401246&hvpone=&hvptwo=&hvadid=416926807659&hvpos=&hvnetw=g&hvrand=7414993350869440120&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1013523&hvtargid=pla-871189774749&gclid=Cj0KCQiAzoeuBhDqARIsAMdH14HG8WByCeISMhS5xwgEYQTLY-11Oz7ytSoAqfVteLk4Dk0-0m6dHuMaAnqxEALw_wcB

Edited February 6 by IZRL

[datzenmike]

DankDatsun most of the problems are one offs and pretty rare. Things wear out naturally and sometimes it's just bad luck. Abuse is definitely a cause of failure (and also totally avoidable) and so is lack of maintenance and preventative maintenance. A good Idea is to fix any problems right away and only replace with quality parts. The only real common failure point is the blown head gasket I mentioned earlier and how to avoid it.

[banzai510(hainz)]

If everything works and nothing rusted or rotted II woudnt change shit.

always monitor the voltage and oilpressure. If any hint of soemthing bad check into it.

 

Most alternator and starters from autozone o rileys are all junk

 

water hoses? its up to you but one can alwasy make it worse when you pull off a hose and the alumim is rotted underneath and would have been fine untill you fuck with it..  alot of smaller hose might not be avail so changing out eveything might not be worth it.

 

I wouls have gotten a toyota truck form the late 80s early 90 with a 22RE motor.   I love my 2 trucks I got cheap.Never work on them

[IZRL]

2 hours ago, banzai510(hainz) said:

If everything works and nothing rusted or rotted II woudnt change shit.

What are the odds of that on a 40 year old truck?

[bottomwatcher]

19 hours ago, datzenmike said:

Pretty much. If an EFI vehicle stops about all you can tell is that about it is that it won't start. You might hear the electric fuel pump chugging away but basically that's it. Even a technician can't do much with it on the side of the road without testing equipment and a shop so..... call the tow truck.

 

 

 

 

 

My 82 720 is EFI. If it stops on the road I can check the codes on the computer to tell me what is wrong. If it's the computer I carry a spare. Not just guessing what happened like having a carburated vehicle. Doesn't matter to me I have both carburated and EFI vehicles and I don't think computer vehicles are any less reliable.

[banzai510(hainz)]

12 hours ago, IZRL said:

What are the odds of that on a 40 year old truck?

with the amount of chinese made stuff one usually might change it sooner.

 

I would go thru brake master and clutch master slave parts every 5 years. Most time the orginal Japan made stuff in the truck last longer if still good. Or find the japan made parts then change when bad