1971 Datsun 521 Heartbreaker

[Matt H]

 

I realized i've been on Ratsun for a few years now and never posted any pictures of the truck. I'm calling her Heartbreaker as she's always doing the dirty on me.



Thats me cleaning 50 years of crud off the bottom of the engine.

Haven't needed to do too much to the truck as the previous owner did most of the heavy lifting. The camper shell is now gone. I'm not much of a speed freak so I'll be keeping the truck pretty stock. I'll follow up with some pics of the interior soon! 


 

 

 

[datzenmike]

Had a red '71 that was 5 years old. Did basically zero maintenance choosing to just fix as it breaks.

[Matt H]

Nice. Yeah i'm realizing that stuff breaking is just part of owning an older car. You cant really see it in the photos but the windscreen is actually cracked. That's next on my list..

[thisismatt]

Nice truck

[demo243]

I dig it! Sweet little truck.

 

In case you are after a decal- “heartbreaker” - https://importbible.com/shop/decals/heartbreaker-decal

[banzai510(hainz)]

LOVE  IT!!!!!!!!!!!!!!!!!!!!

[Matt H]

@demo243 Thanks for sharing! Liking the 240z project - very cool!

[pidge]

521 looks really good. Nice stuff. 

[mrbigtanker]

I love it, my favorite color as well. What's the plans for it.

[Matt H]

@mrbigtanker Hey sorry its been a minute since i've been on Ratsun. I'll try and post some more pics soon! Nothing too crazy... This is my first classic so need to learn the basics first 😅. Thankfully the previous owner did a lot of the heavy lifting. The truck was originally from Ukiah so its pretty solid in terms of not having too must rust. It originally had a camper on the back as the previous owner would use it for fishing trips and sleep on the back utility shelf he made.





 

[Matt H]

Hey Ratsun,

So my truck has been having a hard time starting for some time. (Regardless to how I set the choke I have to continuously pump the gas pedal to get it to start) It typically would take around 10 attempts and even when it gets going I would need to continue pumping the gas for a 15 seconds or so or it would fizzle out. Note: After it's been running it will then start right up first time with no problems.

Spark Plugs
I just just changed the plugs. Is it normal to see some oil residue on the threads? I have a feeling the valve cover may be leaking again based on the residue on the side of the engine block and around the plugs (It was replaced a couple of years ago.)

 

 

 

Carb Leaking
Also i've now noticed the the carb is leaking fuel. Question: If i'm continuously pumping the gas pedal as i'm trying to start it - Would it be expected that the carb would overflow and leak? Or does this mean that the float is stuck or a gasket needs replacing? The carb is leaking quite a lot of fuel from the bottom of the sight glass which I guess is also the lowest point on the carb

 

[datzenmike]

Take the top off the air filter and confirm that the choke plate is actually closing when the choke is pulled out.

 

If it is, the fast idle should also set. This holds the throttle slightly open to give it more air for the richer mixture and it should rev up by itself.

 

Behind that front glass of the float chamber is a rubber O ring, although it is not round but square and fits into a square groove in the casing. The glass is held against the rubber seal by the three retaining screws. Take the glass out and make sure that groove is clean and clear and the rubber seal is clean and in  OK condition. You can clean with carburetor cleaner and put back in. Make sure the rubber is not twisted when in it's groove. This is what does the sealing.

 

On the outside of the glass is a metal bezel with three screws and a cardboard gasket so the bezel isn't against the glass. Check that the screws have not been over tightened and bent the bezel. If deformed it probably isn't pushing against the glass properly. Sort of like what happens if you over tighten the oil pan bolts to stop a leak instead of replacing the gasket. 

[NC85ST]

Could it be that the float bowl is empty the first time you try to start it and it takes a while for the fuel pump to refill the bowl? If fuel is leaking at the bottom, the bowl will be empty the next morning when you try to start it. Let it sit overnight and confirm whether or not there’s fuel to begin with. With a mechanical fuel pump, you have to crank on it a while to get fuel to the carburetor.

[banzai510(hainz)]

mY 521 if not daily driven it takes awhile to get gas up front. Its a 50yr carb. Not going to live forever. The accell pump could be bad also as all above responses.when pumpn gas see if leaks. Sparkplugs look fine. All valve covers leak in time. I use the black felpro brand.bolt even pressure. Make sure carb intake tite. Ck point gap also. Mite start faster. Put antiseize in plugs

[Matt H]

Hey guys thanks for the fast response. @datzenmike I'd say your intuition is pretty on point. The choke cable is really slack! There is no tension in the line. If I pull the choke knob it gets even more slack. I can manually pull on the wire with my hand I can see the choke plate moving but this will not work normally as there is so much slack in the cable. I'm looking at the adjuster and it already appears to be set at its maximum. Am I right in thinking the choke cable is stretched and needs replacing?

 

 

@NC85ST The fuel filter is bone dry as is inside the sight glass. (The car has not been run now for a couple of months) It looks like the front metal bezel is a little bent in the bottom right hand corner. It looks like someone had previously prised it off with a screwdriver. It's also worth pointing out that the screws that were holding the sight glass in place were only hand tight. I literally could remove the bottom screw with my hands

 

(The glass is also ever so slightly chipped on the outer edge) 

 

 

@datzenmike I'm having a hard time trying to remove the glass as it seems to be lodged in there pretty tight! As far as I can see the rubber seal is not twisted although it does look as the the top half of the glass is seated ever so slightly closer in than the bottom half. Whats the best way to remove the glass - with a screwdriver? 

 

Edited December 31, 2024 by Matt H

[NC85ST]

Hopefully you’ve found the problem. Great looking truck!

[datzenmike]

 

 

The cable pictured is the throttle cable. Screw the adjuster away to the left in the picture and that should improve the pedal feel.

 

Post a picture more to the right and up. The manual choke should be there.

[banzai510(hainz)]

2 hours ago, datzenmike said:

The cable pictured is the throttle cable.

thats what I was thinking nothing to do with choke cable.

 

fuel filter empty? fuel pump or cracked fuel line not sucking. Even if sight glass was leaky once filled it should run fine. replace it fix sightglass gasket. see then what happens

[Matt H]

OK so I fixed the leaking carb issue. I managed to bend the bezel back into shape - It took a few attempts to get a good seal. For whatever reason the top two screws go in a lot easier the the bottom meaning if you over tighten them it will skew the angle of the glass which fails to seal. I now have fuel in the the sight glass and fuel filter. I do still notice a tiny bit of fuel residue around the bottom screw and also on those two bolts with the orange o-rings but i'd say its 99.9% sealed.





 

 

@datzenmike I tightened up the throttle cable and also located the choke cable and can confirm the choke is engaging. The choke plate only opens about 25-30% when fully opened. I presume this is normal?

 

I've changed the spark plugs and charged the battery - Now the car will crank but is failing to start. I also noticed some of the bolts on the valve cover has come loose and too my surprise the oil level seems to be considerably lower than it was last time i checked (Please note this is while the engine was cold)

For what its worth i'm also attempting to start the car on quite a steep hill (sideways leaning) and I noticed the dipstick was failing to read the oil which is a little concerning. Is this this normal for a cold engine to read so low? 

[banzai510(hainz)]

wHat ever is done is done. add oil. Ck for spark. See if gas squirting in carb

 

 

 

 

 

 

[thisismatt]

Choke should open fully when disengaged.

[datzenmike]

5 hours ago, Matt H said:

OK so I fixed the leaking carb issue. I managed to bend the bezel back into shape - It took a few attempts to get a good seal. For whatever reason the top two screws go in a lot easier the the bottom meaning if you over tighten them it will skew the angle of the glass which fails to seal. I now have fuel in the the sight glass and fuel filter. I do still notice a tiny bit of fuel residue around the bottom screw and also on those two bolts with the orange o-rings but i'd say its 99.9% sealed.





 

 

@datzenmike I tightened up the throttle cable and also located the choke cable and can confirm the choke is engaging. The choke plate only opens about 25-30% when fully opened. I presume this is normal?

 

I've changed the spark plugs and charged the battery - Now the car will crank but is failing to start. I also noticed some of the bolts on the valve cover has come loose and too my surprise the oil level seems to be considerably lower than it was last time i checked (Please note this is while the engine was cold)

For what its worth i'm also attempting to start the car on quite a steep hill (sideways leaning) and I noticed the dipstick was failing to read the oil which is a little concerning. Is this this normal for a cold engine to read so low? 

 

Check oil when truck is level. Keep the oil level up near the H line. Oil levels will always read highest when engine is cold or has been sitting. All the oil on moving parts has slowly drained into the oil pan.

 

Using oil can be leaks. Get a cardboard box and open it up under the engine and check in the morning.

[Matt H]

@datzenmike I ended up doing a complete oil change as the oil that was in there was filthy. I changed the filter and added some TB Zinc Plus. I'm pleased to say she's back up and running!! I had to readjust the throttle cable as it was idling a bit high but it honestly drives like a new car now. I think that might of solved another issue I had where it would hesitate every now and again pulling away in 1st (now there is no slack in the pedal). I think it also concludes that the leaky gasket was the reason i had to continuously pump the gas pedal to start it as the bowl was puking fuel. Now thats fix it basically starts by itself 😄

Thanks everyone 🙌

Last on my list is to fix the leaky radiator hose. Now its back up and running I can get a clearer idea whats its coming from.

 

 

 

I'm going to try switching out these hose clamps for the T-Bolt style ones. I want to make sure its not because the clamp is pinching the hose or done up too tight. If that fails then I guess its going to need re-soldering.

 

[datzenmike]

Hose looks squashed by the clamp. If it's gone soft replace it.

 

If replacing the hose I slit it lengthwise and peel it off like a banana to avoid breaking the solder joint.

[banzai510(hainz)]

26 minutes ago, datzenmike said:

If replacing the hose I slit it lengthwise and peel it off like a banana to avoid breaking the solder joint.

Good idea!!!  taking apart the heater in my 521 I ruined the solder joints and it inlet/outlet BROKE