Jump to content

My Dragon Datsun 521


Recommended Posts

Yesterday, I did some work on the exhaust system of Dragon, prompted by the exhaust system on Ratsun, my other 521 project getting some attention.  The muffler on Ratsun has holes in it, and is getting louder lately.

But this is the Dragon thread.  The  muffler on Dragon is also rusted through, and there are holes in the exhaust pipe.  I had a 2 inch system  installed on Dragon many years ago.

I jacked Dragon up enough to work under it.  The back wheels, I put on a large piece of steel rectangle tube, raised it about 5 inches, and I put the front wheels up on a pair of ramps I have. 


I then unbolted the exhaust system from Dragon.  it unbolted really easily.  All three lower manifold nuts came off easily, well, two nuts, and one bolt.  The manifold had one stud missing, and the shop that did the exhaust many years ago, just put a bolt into the manifold, instead of a stud that required a nut.


The whole exhaust system was welded together.  I cut the muffler off, and that freed the tailpipe.  But I could not get the pipe from the muffler forward out yet.  I then cut about the middle of the forward pipe between the muffler, and collector.  That allowed me to get the rest of the exhaust system out of Dragon.


I then inspected the system, and decided I could still use the collector, and also one piece of the old exhaust, with a 45 degree bend in it.

Then I ordered some mandrel bends and straight tube from these guys.



Here is the most of the old exhaust system.



Close up of the muffler.



Then I took the old collector, and cleaned it up.  I then also got the good 45 degree bend from the old system, and cleaned it up.  It has surface rust, but was in pretty good shape. 

Then I bolted the collector on the exhaust manifold, and carefully eyeballed exactly where I need to attach the 45 to the collector, to fit between the torsion bar, and transmission.  Not a lot of room, especially with a 2" pipe. 

While holding the pipe on the collector, and moving it around exactly where I wanted it, I took a felt pen, and made a mark across both the collector, and pipe.  Then I made two very small tack welds in the pipe and collector, and tried the fit again, and that looked pretty good.  remove it, many more tack welds, retry the fit, and finally finish welding.


then I cleaned up, or in my case ground off a lot of the less than perfect welding.  Then I wirebrushed most of the rust off the pipe and collector.  Then scrubbed it with phosphoric acid, and steel wool, and then washed it with Dawn and water, and dried the pipe.  Then I cleaned  it with one of these,


and spray painted it silver with a high heat rattle can paint I had on a shelf from I do not know how long ago.




My plan it to put the exhaust system back together, under Dragon, by mostly bolting.  Then remove the exhaust system from Ratsun. and have parts already fitted into Dragon put in Ratsun.

This is the page, post 277 of my Ratsun thread where I covered some holes in the muffler by wrapping it with thin metal cut from old paint thinner one gallon cans.


Link to comment
  • Replies 344
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Made is a little too much credit for me.  The collector is the stock 521 one, and this truck already had a 2 inch pipe on it.  i have another 521 collector, with a short piece of stock pipe on it, and was planning o using that,


My initial though was to use the other collector I have, it was in better shape, and some new pipe when it arrives, but I figured I would try to use this collector, and an old but pretty good piece of pipe.  Get some practice that way, and I figured if I could weld the older more rusted parts together, it would be easier to weld the new stuff.

Link to comment

Just some unsolicited advice - solder is actually a pretty poor conductor compared with copper, so you're best off if you make a strong crimp connection first and then apply solder after if you want, but really only to add a little more conductivity to the air gaps and to help prevent corrosion inside the crimp.  Solder can also wick up the wire making it hard, leaving it prone to breaking due to vibration.

Link to comment

I do a crimp connection first.  the solder is there to seal the connection. 

If the wire is vibrating enough to fail when soldered, well, copper work hardens too.  You try to feed enough solder into the connection, but not so much that it wicks up into the wire past the terminal.


i have been doing soldered connections for years on cars, boats, dune buggys, boat trailers, and other stuff.  To my knowledge, no failures yet due to the solder making the connection brittle.  I have seen many connections fail that were crimped only, usually due to corrosion between the metal of the terminal, and the copper wire itself.  I have also seen a few crimped connections just pull apart.  And do not get me started on the "tap-a-splice" connectors that force a metal tab that cuts through the insulation, to tap a second wire into an existing one, usually used when adding a trailer light socket to a truck.

Link to comment

Been busy last two days, on Dragon.  Lets start with this.  This is the exhaust pipe to manifold gasket, and some stainless steel nuts, available at your local Nissan dealer.  The stainless nuts do not seize as easily to the exhaust manifold studs as plain steel nuts would.  You will like having put them on the next time you have to remove the exhaust pipe from the manifold.
This is how I reach the nuts. I use this extension, with a 14 MM socket.
It will go right up to all three nuts.
Thursday morning, I took the stock down pipe, the bottom one in the picture,
and cut the small exhaust pipe off it.  I also did some welding on the side of it, where it was coming apart after cutting the pipe off.  While doing that, FedEX stopped by, with this,
You will notice four flanges in the picture.   More on that later
With new pipe, and bends, time to start fabricating an exhaust system.
Remember this down pipe? 
I bolted it to the manifold.  This is the clearance between it and the torsion bar.
and it has this much room between the pipe and transmission.
If the transmission looks a little odd, it is because it is a five speed. 
With this piece of pipe, I can "adjust" the location of the down pipe a little. 
I am pointing to the ares UNDER the transmission crossmember where the exhaust pipe goes. 
Right after the pipe goes under there, it crosses over to the right side of the truck, and goes OVER the center support bearing crossmember, about where the "adjusting" tool is balanced.
First, I bolted the two inch down pipe I made on Wednesday, on the engine. 
Then, I took one of the flanges, welded it to the end of one of the 4 foot pieces of straight pipe, and slid that over the manifold down pipe, and made a mark where I needed to cut the straight pipe to put in the elbow. 
I was just cutting, and trying, and guessing where pieces of pipes would fit.  After a lot of that, I ended up with enough exhaust pipe to hang over the bearing cross member, and meet the down pipe.  I attached the exhaust pipe to the down pipe with a pair of flanges.
Here is where the pipe goes under the transmission cross member.
and this is the pipe going over the bearing crossmember, with a supporting clamp already installed.
 A close view of the pipe clamp.
And finally, this is where I ended up. with the pipe hanging under the bed, where the muffler will be located. 
I have not got the muffler yet, I ordered it this morning, and it should be at a local auto parts store for me to pick up on Saturday.
I ordered a Walker SoundFX universal muffler, part number 17877.  2 inch inlet, and outlet.  Muffler case 4 1/4 x 9 3/4, 19 incheds long.  Overall length, 23 1/2 inches.  Inlet and outlet opposite corners of oval.
Like I said before, I plan on making at least two exhaust systems for my 521 trucks.  That is why I am building my own exhaust.

Link to comment
  • 2 weeks later...

Before I needed to make an exhaust system for Ratsun, that I used Dragon as a model for, I was working on the floor of Dragon.  Dragon also has been involved in an accident, and has some front end damage, that was repaired previously.  Now, I am going back and doing more repairs.
This is the front of Dragon, without fenders, or apron, or lower grill,opening rail.  I have been working the left side, removing several layers of paint, and straightening metal.
The right side needs work too.  In this picture is a fixture I made to pull the headlight bucket.
While Dragon is up on blocks, when I was working on the exhaust system, I noticed a coolant leak on the rear of the engine.  I think I will have to pull the engine to find out where the leak is

  • Like 1
Link to comment
  • 9 months later...

The truck has been a "Hanger Queen" since September of 2013.   Maybe I will get it running in 2015.  My, how time flies.

Today, I drug her out of the carport, with my Aerostar, and took some pictures.


Left side.  the engine in the back is a L-18, that I am planning on putting in to a third 521, one I call Dragon 2.


This is the L-18 engine in Dragon.  It was last ran in the Summer of 2013.   I think it is still OK.  But It was leaking some coolant, when I was making an exhaust system for Ratsun.  


This is the floor, it had some rust damage, but was mostly intact.  There area few small pinholes in the floor, however.


  • Like 2
Link to comment

It may seem like I was totally ignoring Dragon, with gap of March, 2014 to Jan 2015 between posts.  In October, I had a problem with the alternator in Ratsun, and to keep Ratsun on the road, I took the alternator out of Dragon.  It was bad, too.  I also got the alternator from another project truck, Dragon Two.  That alternator was also bad, as soon as I hooked up the battery, there was a good size spark, from current drain. 

To confirm all three alternators conditions, I took them all to be tested.  The alternator that was on Ratsun had a bad internal regulator.  The alternator that was on Dragon had one bad diode, and only 2/3 of its rated output.  The alternator from Dragon Two had at least two bad diodes, and also the lower mounting holes were work oval from running with loose bolts.  That alternator was returned for the core charge, when I got a rebuilt alternator for Ratsun.


Thinking I may need an alternator in the future, last January, I got an alternator, at a junk yard, from a Nissan Pathfinder.  It turned out it would not fit on Ratsun, with a stock L-16 lower alternator bracket, so the Pathfinder alternator was just put in storage.


In October, when I was messing around with alternators. and voltage regulators, I noticed the lower alternator mount for L-18 engines, the cast one, holds the alternator lower than the stamped steel alternator bracket used on L=16 engines.


And now, the good part, the pictures. and a few more words.

This is the alternator on a L-18 engine in one of my project 521 trucks.   This alternator came out of a Nissan Pathfinder, Pathfinders are real common in junkyards in the USA.   I do not know what Nissan calls Pathfinders outside of the USA



This shows the bottom alternator mount.  The mount is the same width as the space between the mounting ears of the alternator, and more importantly holds the alternator in the correct forward and back position for the V-belt grooves to line up properly.



This is the top mount for the alternator.  The slot for the top mount actually matches the radius the top mount bolt moves in.



A better view of the top mount.



This shows the view looking down on the belt, in pretty good alignment.


  • Like 1
Link to comment

While I am working on putting a floor into the cab that will go on to Ratsun, I need to get Dragon running again, or at least capable of moving itself.  So. yesterday, I pulled the engine out of Dragon.  The engine runs, but was leaking coolant from somewhere in the back of the engine.



This is the engine, a L-18.  The tractor in the background, I used to pick the engine and stand up, to move it into the garage.   Engine stands do not roll well on gravel driveways, in the winter.





This is the engine back in Dragon.



Link to comment

Spent more time getting rid of rust.  I found rust under the seam sealer, in corners where cab sheet metal comes together, and ground, picked, and wirebrushed out what rust I could.  I am not going to get it all, without taking panels apart, and that would do way more damage than the rust that is left. 

So after getting a lot of the rust removed, that I could reach, I mixed up a small batch of PPG DP40LF primer.  Really small.

Two teaspoons of DP40LF epoxy primer, one teaspoon of DP402LF catalyst, and a little less than a teaspoon of DT860 low temp reducer.

I mixed it in a CLEAN yogurt cup, using a popsickle stick, and painted the primer into the seams, and cracks, with a 1 inch paint brush.

drivers side.


passenger side,


Passenger side, under glovebox,


DanielC what are your plans if any to prep the pitted areas of the floors?  The areas that are not rotted through.

Link to comment

In a post I made, I covered more cleaning of the floor, and then I sprayed PPG DPLF primer on the floor.  That is where the floor is currently.

The work I did removing rust did open up a few pinholes. Ideally, I should weld them, but I have not decided, yet.


There was a steel plate on the roof of Ratsun, that was just screwed down to the roof.  See this page of Ratsun's thread.



Rather than weld all the holes in the roof, I cleaned it good, sprayed a wash primer, then an epoxy primer.  After the epoxy primer cured two days, I put a patch of fiberglass, with Tap plastics Marine epoxy for resin on the area of the roof that had the holes for the steel plate.   I avoided the heat and warping of welding, and I just left the headliner in the truck.  After the fiberglass, and epoxy cured, I sanded it, filled low spots with plastic filler, more sanding, and so on.

When I did the roof repair, I figured it was just an experiment.  If it works, great.  If not, try another solution.  My biggest concern, steel and fiberglass/epoxy expand and contract at different rates, and that might work the fiberglass patch loose.  So far, it has not.  I really did not detail that repair, because it is a bit out of the normal body repairs, and I really did not want to tell people, "OH, yea, don't bother with welding and just slap some fiberglass on it"   I did not know if the patch would last three months, or longer.  So far, it has held up well.  but for all I know, it could pop off tomorrow.


Having said that, I am thinking of doing a similar fiberglass/epoxy repair on the floor of Dragon.

  • Like 1
Link to comment

Today, I spent some time looking for cooling system leaks.  I did this with the engine from Ratsun, and now with Dragon's engine.  With the engine on a stand, I hang the radiator I am going to use in the truck by string, from garage rafters.




Side view.



I have a cooling system pressure tester, and I plugged the heater connections with some hoses, and rubber plugs.  Then I pressurize the cooling system, and listen for air leaks.


If you hear an air leak, you can take a hose, hold one end up to your ear, and move the other end arounf where you think the air leak is coming from, and pinpoint the leak.


So what I found is the hose that connects to the pipe going to the intake manifold had a leak.



Hopefully, tomorrow, I can get, or at least order the hose.

I asked about the 521 heater hoses, they are no longer available, from Nissan.

  • Like 1
Link to comment

Back to getting the cooling system not leaking, on the engine and other parts for Dragon.  I normally try not to do this, robbing parts from one Datsun project, to make progress on another Datsun project, but sometimes I do.  I had put a new intake heat hoses on the engine that is going into Dragon 2.  This morning, I called my local Nissan dealer, and gave them part numbers for the intake manifold heat hoses, and they are still available, they said.  One would be at the dealer in Tuesday, and the other on Saturday, a week from now.  So I took the hose missing from Dragon's engine, off Dragon 2's engine.



I have not checked heater cores, yet, that is next.  But first, lets see if I can pressurize the cooling system on Dragon.  Without a heater, I need to plug the heater connections.  This is how I did that.

This is the long heater hose.  I put a rubber stopper in it.


The short heater hose for this engine had a crack in it.  I just used a piece of 5/8 vinyl hose, with another rubber stopper in that hose.


If you have the right piece of pipe, you could just join these two hoses together.   I try to pump up the pressure in the cooling system, and it is not holding any pressure.


I decide it is time to check some radiators.

This is how I check the radiators.   This is 1" schedule 40 (i think) PVC pipe.  The OD of the pipe is pretty close to the ID of Datsun 521 radiator hoses, close enough to seal.



Here is the PCV pipe, and the upper and lower radiator hose plugged into a radiator, and holding pressure.


This is the fourth radiator I tested.  The radiator that was in Dragon leaked.  So did the radiator out of Dragon 2. 

Those radiators are on the left in this picture.  The radiator on the right, I got at Pick-n-Pull last year, just as a spare.  It might have a small leak, it was bleeding off pressure slowly, but I could not hear any air leaking.   I might pressurize it again, with air, and hold it under water, in a small kiddie pool, to see if I can find a leak, or if the pressure tester cap, or one of the radiator hoses was leaking.

Interesting the two radiators I though were good, were not.




I took the radiator that held pressure, and hung it in front of the engine for Dragon.  I hooked up the hoses, and pumped it up.


That picture was taken after I removed the fan shrouds from the two leaky radiators.  they need to go to a radiator shop, to get repaired.


I still need to test several heater cores, to see if they leak.  But this engine can go back into Dragon, and I know it should hold water.  What I found, why Dragon was not holding water, was two bad hoses, and a bad radiator. 

Maybe I will clean up the engine a bit, before I put it back in Dragon.

  • Like 1
Link to comment

Tonight, I pulled the heater out of Dragon, and hooked it up the the engine on the stand in the garage.


Unfortunately, the whole system was leaking air a little too fast for my liking.  Tomorrow, i maybe will try some different heaters, or heater hoses.

  • Like 1
Link to comment

I think I have three heaters, but some are apart.  This is my only conventional motor heater.  All my others have the pancake motor.

I ended up adjusting a few hoses, and tightening some clamps, and got the system to hold air good to my liking.  Since I pulled the engine out, to look for water leaks, time for it to go back in.



I am not going to detail the entire engine removal, or replacement steps.  Just some tips.

A clutch disk alignment tool makes it much easier to get the clutch disk in the right spot.  if it is off, even a very little, it becomes very difficult to put the engine and transmission back together.



The tool will hold the disk on the flywheel, and you can then put the pressure plate on.  Before you tighten the pressure plate bolts, make sure the disk is as close to exactly centered as you can.  Taking an extra minute or two to check will save you A LOT of time and frustration later.



I lift the transmission with a jack, so it is lightly up against the bottom of the cab.  This holds the transmission in place, while you move the engine around.



I drop the steering idler arm, to get the steering tie rod out of the way of the oil pan as the engine goes in to the transmission.



Once the parts are close, I put the two bottom bolts holding the engine and transmission together.   The weight of the engine hanging on the hoist will close the gap between the engine and transmission, even without the two top bolts.  then you can lower the engine down to the motor mounts, and put the two top bolts between the engine and transmission in.


Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.