New to me 77 620

[Stoffregen Motorsports]

Sometimes even dirty door seals will cause them to leak. There is a cleaner and a wax that detail guys use.

 

More likely a bad door seal or the air intake in the cowl is either rusted or has a leaf dam in it.

[Dusten]

On 12/6/2023 at 7:53 AM, Stoffregen Motorsports said:

Sometimes even dirty door seals will cause them to leak. There is a cleaner and a wax that detail guys use.

 

More likely a bad door seal or the air intake in the cowl is either rusted or has a leaf dam in it.

It's not the doors based on where it's wet.  It's wet under the pedals and my tray under my glovebox is wet.

 

The door seals look like they've been replaced.  It hasn't stopped raining for a while.  Basically everything is flooded so I haven't got an chance to look.  

[Dusten]

I got home from running errands and it wasn't raining.  So I pulled the wipers and cowl.  

 

Thanks Mike

 

I took my shop vac to it.  

Sadly it's all remnants from the previous owner.  Nothing in there exists at my house.  

[datzenmike]

They drain down behind the wheel and behind the fenders. Well they should drain. I see pine needles. I get lots of maple keys. You can use fly screen under the louvers.

[Dusten]

Took a drive today.  Trucks been sitting for a week?

I have a coolant leak.  Looks like the radiator.  I was driving and realized I had no heat and the temp was high.  Beat feet back home and when I cracked open the radiator it was about 2/3 of a gallon low.

 

Topped it off and now I either have an air bubble or my new t-stat died.  It won't warm up.

 

Radiator is going to a local shop that repairs them.  I'll get it cleaned and repaired.  I'm going to throw a new fan clutch in it as I realized it's basically free spoiling.  And I'll grab another t-stat since their cheap 

[datzenmike]

Air bubble is impossible. It would work it's way to the radiator and be topped up. Likely over heating messed the thermostat up and it's either stuck in the full open or it's one of those type that fail in the open position.

[Dusten]

5 hours ago, datzenmike said:

Air bubble is impossible. It would work it's way to the radiator and be topped up. Likely over heating messed the thermostat up and it's either stuck in the full open or it's one of those type that fail in the open position.

That was my thought.  But you never know.  I've owned some rigs that take a process to bleed the cooling system

[datzenmike]

The engine always tilts up at the front. The thermostat is the highest point on the engine so all air finds its way there during filling or soon after starting. The thermostat is mounted flat or horizontal so when it opens any trapped air rises up through the radiator hose to the the radiator tank and it can be topped up.

[Dusten]

Finally got off my ass.  

 

Then thermostat was stuck open after being hot.

 

New thermostat and gasket

 

New water pump.  When I was looking over the cooling system the fan spun way to easy.

 

Radiator is at a local shop getting cleaned and leak tested.

 

New lower hose(upper was new recently

 

 

 

[datzenmike]

Clutch fan should spin smoothly by hand but like it's full of thick honey. Give a quick spin and it should stop as soon as you let go. This resistance is what couples it to the engine RPMs. Above about 1,800 RPM fan speeds it's maxed out for moving air and any increase in engine speed simply slips. This saves some power wasted on over cooling as the speed of the vehicle is more than enough to push air through the radiator. In some cases the bearing inside seizes and it is direct coupled and makes a loud roaring sound. In others the silicon oil leaks out and the slip is severe leaving you almost without a fan at low speeds. 15 years ago someone refilled with grease which would work but too thick and would couple too much. Engine oil would be better.

[Dusten]

I know how the fan clutch works.  Ever rig I own has one but my 66.

I could spin the fan and it would rotate 2-3 times before it stopped. That's why I replaced it.  

 

I should have the radiator back Mon or Tues

[datzenmike]

That's more for others that might read this.

[Dusten]

Rad shop called.

 

1 crack.  Several holes.  Needs a core.

He was shocked at the cost.  It's like $655 after taxes.

 

So I'll find an aftermarket replacement 

[Stoffregen Motorsports]

Champion radiators.

 

Also go by Ledfoot racing.

 

And if nothing there, go for a universal radiator from Afco or the like.

[banzai510(hainz)]

On 1/12/2024 at 4:49 PM, Dusten said:

He was shocked at the cost.  It's like $655 after taxes.

Fuck that

these guys can make one or Griffon (USA made) they make Z car rads https://wizardcooling.com/

champion is china but not that bad seen alot of musclecar guys use them. I have one on my 521. need 1/4 spacers to give room off the core support

 

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=datsun+620+radiator+champion&_sacat=6000&_odkw=datsun+620+radiator&_osacat=6000

Edited January 15 by banzai510(hainz)

[Stoffregen Motorsports]

On 1/15/2024 at 7:39 AM, banzai510(hainz) said:

Fuck that

these guys can make one or Griffon (USA made) they make Z car rads https://wizardcooling.com/

champion is china but not that bad seen alot of musclecar guys use them. I have one on my 521. need 1/4 spacers to give room off the core support

 

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=datsun+620+radiator+champion&_sacat=6000&_odkw=datsun+620+radiator&_osacat=6000

Actually no. Champion radiators are made in Texas. At least the ones I buy from them are. They probably use Chinese cores, but they are built in the US.

[banzai510(hainz)]

6 minutes ago, Stoffregen Motorsports said:

They probably use Chinese cores, but they are built in the US.

I did not know that. I swaer I saw China But it works

I used to get the Modine (USA)ones from JC whitney back in the day.

[Dusten]

Champion doesn't list one for the 620

(They list one for older 620s but the rads changed)

I'm not spending time to fab a radiator into the truck because the shop is full.

My daughter's 66 has the cab off while I do cab mounts and floors so I have the frame and body apart.

 

The 620 is on the chopping block for something with a back seat anyways.  So a parts store radiator is going in it.  

Edited January 17 by Dusten

[Dusten]

Well radiator is in.  

Cooling system filled.

 

And it has a misfire/backfire under load.  

 

 

 

So now I get to chase this down 

 

 

 

[datzenmike]

Sounds like it's in the cab.

 

You are there and can hear it better.... Is it actually back firing back through the carburetor? could it a random ping?

 

Back fire

A tight valve can do this.

Burnt or damaged exhaust valve.

 

Ping

Timing too advanced

Combustion chamber carboned up

Dirty plug

Over heating

Too hot a plug

Crappy octane gas

 

 

 

[Dusten]

It's lean popping.  It's not back during through the carb.  You can hear it right under the floor due to the exhaust.  I'm going to pull a plug and verify it's lean then check fuel pressure

 

It's also not random.  It's very easy to replicate.

 

 

It idles and revs cleanly when not under load.  

 

It's definitely not pinging. It's a misfire/pop

Edited January 21 by Dusten

[datzenmike]

Won't be fuel pressure this isn't EFI. If pressure was too low driving it hard would empty the carburetor and the engine would fall on it's face. Lean backfires are usually up through the carburetor.

 

Could still be a tight exhaust valve that's not sealing. Good enough at low speeds but can't contain it when floored

 

You could also pull each plug wire and drive it. If it stops that that's the cylinder causing it.

[Dusten]

53 minutes ago, datzenmike said:

Won't be fuel pressure this isn't EFI. If pressure was too low driving it hard would empty the carburetor and the engine would fall on it's face. Lean backfires are usually up through the carburetor.

 

Could still be a tight exhaust valve that's not sealing. Good enough at low speeds but can't contain it when floored

 

You could also pull each plug wire and drive it. If it stops that that's the cylinder causing it.

 

 

It's only under load which leads me to believe it's fuel pressure.  

It won't empty the carb because I can't stay in it long enough to drain it.

 

The issue is fuel related.  It happens under load and only when a certain amount of throttle is applied.  Light throttle and low load is fine.  As soon as I attempt to get into it, it occurs.  

 

Valves were adjusted like 5k miles ago.  I doubt a single valve has shifted enough since then to cause an issue that is new.  But I can pull the vc and check lash

Edited January 21 by Dusten

[datzenmike]

You have the stock Hitachi Carburetor? It has a sight glass on the front of the fuel bowl. If the float is properly set the fuel level will be in the center. Check and see.

 

If it is, take for a drive and floor it till it acts up. The point here is to see what the level in the float chamber is while it's acting up. So to preserve the fuel level in the carburetor get the clutch in and the ignition off ASAP so the engine stops immediately. Then slow and pull over. Check the fuel level in the sight glass.

[Dusten]

I have a Weber and a redline intake manifold. 

 

Or I can hook up my fuel pressure gauge and read it.