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Keeping a Datsun Truck vs Buying a New Truck

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First, only Datsun truck drivers know the insane attention and conversations these trucks produce due to their "way cool" look.  It impresses me that even grannies walk up to me and compliment my truck (I doubt they're not hitting on me but what would I know, LOL) - but the truck has Universal Appeal from children to octogenarians.


So while an old truck, it has something very special you simply cannot find elsewhere.


...and I like that.


My 620 is in need of some repairs - a complete exhaust for one.  So why not throw in the towel and buy a new Maverick for $20k?


I was seriously considering this.  The monthly payment would be about $340.  As I well know I cannot afford this on fixed income and would have to wait until I sold one of my collector cars.


But then I thought $340 a month.....  I've had my 620 for 8 years and aside from fixing it up when I got it, the only thing I really have done since then was put tires and brakes on it.  Imagine what my truck would be like if I spent $340 a month for a year.


And unlike a new truck that is worth less every time you make that payment, the Datsun would be worth more.


I know one guy that has a 1-man shop I would trust him to do "$500 worth of repairs" without being specific (!)  ...maybe $1000 worth just to get his attention.

But I am pretty much decided it's worth putting some money into my 620.

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  • 5 months later...

The big problem is there aren't any mechanics out there that know all the arts:  welding, carburetors, custom exhausts come to mind.  Most mechanics just swap parts - same with most body shops.  If you need mechanical rebuilding or custom metal working, you're boned.


There were 2 guys that retired (and died) that would have been perfect for managing any issue a 620 might have.


I spent years unfucking what jerks did to this truck and had trouble getting the seat upholstered and the SS 304 exhaust they did is a total butcher job.  So now my truck is "tagged" by some asshole's exhaust system.  That's about $650 for an exhaust that probably should be removed and scrapped except for the flange.


If I wanted to sink money into my truck, there isn't anyone around that can do the work beyond a brake job, tie rod end, alternator or starter.


If I had a 2nd car to drive, I'd remove the SS exhaust and fire up my KEMPPI TIG welder and redo the butcher y-pipe they did - they ran the tubes together, crushed them until round for simple weld to round pipe - so each tube has significant area reduction (nozzle) at the "collector."


But the one issue with my 620, is there is a significant rotating imbalance with the engine.  I know that they put balance shafts in 4-cyl engines to balance out the vibration.  In cold weather, the motor mount rubber is so hard, I can actually feel the engine vibration through the seat.  The steering wheel and shifter are upsetting to touch because of the vibration.  And this vibration causes all kinds of stuff to come loose.  I have a 5-spd for it and it will only go in if I have to replace the clutch - it's possible there is a balance problem with the clutch disc or pressure plate.


I haven't physically recovered from totaling my 87 Chevy Turbo Sprint and the Datsun now, unfortunately, is now a problem and not a solution.

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Nissan doesn't use a balance shaft on their 4 cylinders. Nissan balances all the rotating parts separately, so swapping them causes no problems. The shaking you mention is more severe than a second order harmonic. Engine vibration would be present in all gears. Vibration at higher vehicle speeds would be farther back.


1/ I guess the easiest thing to change would be the engine and transmission mount isolators but this isn't really ridding you of the cause which I think is mechanical.


2/ Next would be the 3 U joints. It's balanced as an assembly so if taken apart and joined 180 different, it might vibrate. Some work but you could 180 what you have now and see if there is an improvement.


Drive shaft out of balance, dented or bent. Balance weight may have fallen off. Carrier isolator may be damaged.


3/ Engine to transmission bolts loose.

Flywheel bolts loose... probably not, as they would have sheared off by now. Had this happen on my 521.

Damaged clutch disc or pressure plate.

Pilot bushing badly worn throwing the clutch disc off center.

Rear transmission output bushing worn.


4/ Anything after the drive shaft is a much lower frequency vibration at certain speeds and not in town and more recognized as a tire imbalance. Weight fell off, cord/tread separation, brake drum broken, lug nuts loose, mud stuck on inside of rim. Leaf spring mounting bolts loose.


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Engine vibrates when in neutral and you rev it.


My guess was pressure plate or clutch disc but engagement is smooth w/o chatter.


But Mike, you mentioned worn pilot bushing, while a possibility, wouldn't that be highly unlikely?


Problem is that previous owner(s) of this truck did some real butchery on it - I had to undo a bunch of FUBAR shit that was done to it.  So "other FUBAR shit?"


At 130k, could it still have the original clutch?  


I know at least one other 620 owner commented on how his vibrated and loosened bolts everywhere. 


I have no other experience with 620's however I had a 510, I think it was a 72 which means it should have had the L16. That engine was as smooth as silk


When Datsun changed to the L18 for one year, did the L18's vibrate while the L16's didn't?  I would not expect this and expect all L-series to have the same vibrations characteristics.


I also have no idea how to diagnose where the vibration is coming from - it feels like an out-of-balance rotating component.   But the cold weather makes it significantly worse - I'm pretty sure it's the motor mount rubber getting harder.


Could it be the motor mount rubber has "petrified" and become hard?  In hot weather, frankly I've forgotten about the vibration but when the weather is cold, it's back with a vengance.  I bot RockAuto motor mount closeouts for about $5 each (hopefully not so old stock they are already hardened) with the thoughts of installing which I never did of course.


But even if the motor mounts were soft, if you put your hand on the valve cover, there would still be the vibration - it's just that with soft mounts, you couldn't feel it transmitting to the frame and body when driving.

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They do wear out. The pilot centers the transmission input shaft and the clutch disc. If worn out the disc would be off center.


A duff cylinder will shake as anywhere up to 25% power will be missing. Pull each plug off one at a time when shaking at idle. If one cylinder has less of a reaction than the other three, something may be up. Spark may be weak, valve lash tight or burned valve on that cylinder. Maybe compression is down on that one and not pulling it's weight. 

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There is nothing wrong with the engine. 

Under load it is smooth sounding. 

No chugging of burnt exhaust valve (that is an obvious detection. 

Anything related to the 4 stroke is a once per 2 rev event,  I've seen engines with out of balance cranks and clutches and that is what this one feels like. 

The plugs look good. 

The gas mileage is good. 

It doesn't use oil

The power is good - can go up hills at low rpm in 4th w/o issue.


I don't know if there are diagnostic ways to deter where along the engine axis is the vibration located.  If accelerometers were placed on the front and rear of the engine, their phasing could determine that location.  There may be a method that master mechanics have for doing this on hyper expensive cars.


Going to try search"how to tell if clutch is out of balance?"  

Edited by Cardinal Grammeter
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How does Nissan factory balance the L18?


Is it possible the crank is balanced with the flywheel attached AND that the flywheel is NOT zero balanced?


IF YES (flywheel not zero blanaced), if they put a new clutch in, did they resurface the flywheel and NOT reinstall it in the same position? (are the crank bolts evenly spaced?)


IF YES & YES, then that could explain it.




While parked:  1) rev engine with clutch in and 2) rev engine with clutch out and trans in neutral

RESULT:  Should show the amount of imbalance in the disc and pilot bushing.

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9 hours ago, datzenmike said:

 Nissan balances all the rotating parts separately, so swapping them causes no problems.




Front pulley balanced. Crank balanced. Flywheel balanced. Flywheel bolts evenly spaced so can go on any way you like.


I've seen old GMs with paint on the crank to mark the 'heavy side' and the flywheels marked with the 'light side' so that one will help cancel the other.


Put a timing light on and see if the timing is jumping all over the place?

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I'm thinking of a vibration measurement:  I'm guessing if I placed a quarter on top of the valve cover and slowly increased engine rpm, the vibration would make the quarter slide off.


Maybe I could find some common thing that would just barely vibrate off and then see if other peoples' engines also vibrate it off OR if it stays put.


Or some method of comparing the magnitude of vibration on different L18's. 




Appears I can use my cell phone to perform rudimentary vibration analysis.  So I can put phone on top of valve cover and see what it measures.  

Edited by Cardinal Grammeter
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  • 1 month later...

I too have thought about buying myself a maverick. My girlfriend ordered herself one (we are still waiting on it to be built and if it takes much longer might just forget it and keep her 2017 rav 4) 


I had a nice newer f150 with the 5.0 but gas mileage was killing me and I am soon to move and I will have a 40mile each way commute. I wanted to trade in and finance a maverick and get the best of both worlds... I did not want the hybrid  like my gf ordered I wanted the awd 2.0 with a little bit of towing capacity.. but I realized I am lying to myself about what I need a truck for... I only tow something a couple times a year, same goes for using the bed. So I was better suited getting a comfortable commuter car with decent mpg I got a Newer used chrysler 300, and just use the 521 if I need a bed to haul. Major towing I can rent a truck for now....


A lot of guys I see get like a 30k-50k truck, then they justify getting a cheap commuter for a few grand to keep the truck nice. But they never use the truck as a truck but a few times a year.  Makes sense to me to get a nice used commuter car or crossover for 10k-20k and get a old junky truck to do truck things with for 3-5k and keep it forever using it sparingly.. plus old used trucks from the 70's and 80's don't have all the extra crap to go wrong and be complicated to fix.


I don't know your personal financial situation but a brand new maverick bang for the buck in this current economy isn't too bad of a deal. Its hard to get anything clean and newer under 50k miles on the used market for less than 16-18k, and you can get a brand new hybrid maverick for 20k and for the first time in history a new car seems like a reasonable idea. BUT picking up a car payment when you don't already have one and funds are a little tight really sucks and in my mind a maverick is right there at that financial limit for me personally. could I afford a $500 payment on something more expensive than a maverick? yeah I guess, but at that point am I buying more vehicle or more features? same goes for the maverick with the $350 a month payment, I can get just as much vehicle for $250 a month, less overall cost, and better in terms of its depreciation curve I'm just lacking a bed.. Ill use a beater truck for truck things... and in a few years maybe I can get a maverick used when they are more affordable used. 

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There are a few problems with new trucks:  they are cartoon high:  can't touch the engine with hood open, can't reach into bed from the sides, and can't see what's in front of you because truck is so high.  I guess these trucks are Big for Big Men - at least that's what they tell themselves.  My 69 C20 427 was like a Lambo compared to these monstrosities.




The Maverick sounds like it might be a decent value however Ford even in the 60's had no standardization or common sense.  Consider all the 351's or the 427, 428, 429 engines - too many engines.  And then there are the u-joints - probably 8 different types.  I think GM had 1 maybe 2 at most.  Studebaker had 1.  Ford had u-joints with a long and short cross, big and small caps, all combinations, all sizes.  And then in the early 10's that actuated clutch contraption instead of a torque converter - how many people bot those cars and thought they knew what they were getting?  I can only imagine what crazy designs could be lurking in that hybrid.


The "sensible" Maverick would be the standard engine for the +$1000 and front wheel drive.  Hopefully it would be a simple, truck that would go good in the snow.




Datsuns are know to "run forever."  The fact that you can replace the heater core in 5 minutes is enough to make me love these trucks.  The Hitachi carb is a real problem on the L16 and L18 - while the complexity will really bite you if screw start loosening or gasket start to leak, but kits for the early engines seem to be non-existent.  Might be worth learning how to use one of those "cutting" printers to "CNC" gaskets.  Accel pumps and bellows is another matter but the L20B kits are still out there.  I wonder what you could buy in Japan?  I wonder what carbs they use in Thailand and Malaysia?



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