Datsun 620 battery buzz and light won’t shut off

[Scrapson]

My 79 datsun won’t shut off the buzzer after I checked the battery after a jump and it was fine but the buzzer and light stay on but In 4th gear the buzzer turns off and I do city driving so it’s annoying. The radiator is clogged so it gets hot which could’ve cooked the alternator or voltage regulator I don’t know what happened but it happened right after I got a jump start from a clapped out Mazda B2000 😂

[datzenmike]

What buzzer?

What light? The charge light?... be as specific as you can.

 

Over heating has nothing to do with the charging system. If over heating get this fixed. Here are some causes of over heating. Most are easy enough to check and fix.

 

9 hours ago, datzenmike said:

You can see the gauge but we can't. Anywhere in the 'run range' is ok but just above half to 3/4 of it is better.

 

Did you change the thermostat before the problem? If yes, this is the problem. Your old one may have been wrong or not working and now it's reading correctly and seems high.

 

Don't go to 160⁰ an L20Bs is designed to run in the high 180s and into the 190s for best mileage and over all driving. Replacing the thermostat with something cooler is not fixing the problem as it should be capable of running in the middle of the temperature range even in the desert.

 

Usually two things cause over heating.... lack of air flow or lack of coolant flow.

 

AIR

Spin the clutch fan with your fingers. When you let go, does it continue to spin? 1/4 turn? 1/2 turn? more? The clutch is bad. It should be firm to turn.

 

You should be able to shine a flash light through the rad fins from behind at night. Are that plugged with bugs, dirt, leaves??? are the fins all bent over?

 

Do you have a bush bar, license plate or extra fog lamps blocking air flow???

 

COOLANT

Rev the engine and look at the bottom rad hose. Does it collapse from suction?

 

Take the cap off and drain enough coolant to see the open ends of the vertical rad tubes. Are they covered with hard water scale (lime) deposits?  Drain, take rad out and set face down and fill with a 50/50 mix of CLR to dissolve the scale. Rinse in the morning and refill with distilled water and a good antifreeze. Get a coolant recovery rad cap and direct the over flow hose into a coolant recovery reservoir from an newer truck. When coolant is expelled after driving it's saved and when the engine cools it siphons back and keeps the rad full. With one of these you may only need a cup of water to top up once a year.

 

If your heater is leaking and the two heater hoses are looped together, find some way to block the flow. Put suitable bolts in the hose ends and gear clamp them. This is hot water from the head that is by-passing the rad and fed right back into the engine in a closed loop.

 

 

 

 

OTHER

Are you constantly now adding water to top the rad up? Could be blown or blowing head gasket.

 

Timing was mentioned. Retarded timing allows much of the hot expanding gasses to escape out the exhaust ports and dumps most of it into the water jacket around them instead of doing work pushing the pistons.

 

A lean fuel air mix from a part blocked primary jet. Gas absorbs heat when it fully evaporates in the combustion chamber. Less gas, less heat taken away. Pull your plugs. Lean mixtures are hot and will self clean the plugs so they are very light/white porcelain below the center electrode. Tan light brown is better. 

 

Brakes dragging? front tires toed in? making the engine work harder than it should. Lift and spin the tires and see.

 

Tire pressure at near maximum. Too high is better than too low.

 

 

 

 

[banzai510(hainz)]

Maybe something got fucked during the JUMP process. Hooked up cables wrong at first. Poped a Voltreg in alternator?

is your truck still charging correctly? check the voltage at the battery?

alternator belt tight.

 

these are EZ trucks to fix. Even Bushmen in Africa can handle this ,so hopeflully you can also

 

 

if rad is clogged why you driving this?

[Scrapson]

So yes the charge light is going off, I need to get the alt checked which is hopefully tomorrow. The belt is tight that’s the first thing I checked. I drive it to school and back which is like a 5-7 minute drive but the radiator is definetly clogged. I put the stock 180° thermostat in but the old one was almost seized and I tested the new one by putting it On a stove. The water pump is almost brand new I got it off a block that had 1’000 miles on it with new everything. I’m like 99% sure it is the rad. Where is the voltage regulator on the alt I’m new to this and I’m 16 so still learning lol. I’m going to do the CLR thing this weekend hopefully depends on how things go but if it doesn’t fix it I’ll buy a new aluminum rad

[datzenmike]

The regulator is inside the 'internally' regulated alternators.

Use extreme caution removing old hoses from the rad. It's easy to pull the ends out of the rad. I would undo the hoses where they join to the engine, where you can't hurt anything pulling and twisting on them. If old and needing to be replaced, slit them length wise with a knife to remove rather than twisting on them.

 

I just placed the well rinsed out rad face down with the hose ends up and the rad cap on. Chucked a bottle of CLR in and topped with water. It will slowly fizz as it dissolves the lime scale. Every now and then give a little shake. Like I said I couldn't get back to mine for a couple of days and it's fine. CLR says safe to use on copper pipes and solder. Rinse thoroughly in all directions to dislodge anything loose. Wash away any dead bugs on the outside.

 

If this fixes the problem make sure you drain the cooling system and use distilled water/anti freeze 50/50 mix from now on and for topping up the rad. Scale deposits are dissolved minerals in 'hard' water that are concentrated in the cooling system by evaporation and constant topping up of the rad.

[Scrapson]

So my problem is with the rad is it’s not stock so I dunno if it’s smaller or bigger or what. So the voltage regulator is internal to the alternator in the 620’s for 76-79? I am doing the CLR tomorrow morning through the day to go to work at 6. You said shake it do you mean to like stir it?

[datzenmike]

'78 and up on all Datsun/Nissans are internally regulated alternators.

 

'Rad clogged' is much different from 'not stock so I dunno if it’s smaller or bigger or what."  If too small nothing will help.

 

I would continue with the CLR, it may help. You can't really stir the CLR once in but you can tip it up and down to slosh the contents in side. Just don't fill up the hose ends, just enough to fill the cooling tubes inside. Leave enough room to slosh the CLR around.

[Scrapson]

So the radiator is still 3 core and the fins are blocked to all hell so I think it’s the clogs. I’m amazed at how it didn’t die while I was driving it home on the highway when I got it unless it just developed the problem which it did just randomly get hot and I couldn’t do jack diddly squat. 

[datzenmike]

Outside or inside blocked?

[Scrapson]

Inside of the radiator I ran water through it and it was straight orange brown looking. I just was ripping out my entire EGR shit and it was clear so I know it’s internal. So on 79 model year I need a different alt to replace the voltage regulator. Today it just stopped then came back on I don’t know why but also the buzzer for the charge light shuts off in 4th gear but none of the others. 

[datzenmike]

Orange /brown is rust from the block. I would start with a good cooling system flush first. Pull the thermostat out and take the bottom rad hose off. Garden hose in the thermostat end and flush away. There are brass block drains on the side near the rear that can be removed to allow rust out. Take both heater hoses off and turn the heater to ON. Garden hose in both directions to remove crap in the heater core. While the bottom hose is off flush the rad.

 

When thoroughly flushed, I mean thoroughly flushed, refill with anti/freeze coolant and distilled water.

[Scrapson]

Okay so flush the entire loop like the block and heater. So the last guy that had it I think just shoved water in the thing and I had coolant in it and then it puked it out the next day. So the fittings in the back need to be open or removed? Also what do they look like just know what I’m looking for. 

[datzenmike]

One's  just near the starter on the side of the block and one on the opposite side. I think they are brass and about the size of a nickle. Having then open helps flush debris out because they are very low in the block cooling system.

[Scrapson]

Alright well I have to do it tonight and I cannot put anti freeze in due to the fact that my local auto parts store does not have any but they get it thursday so that should do it. The charge light buzzer shut off the other day for a couple seconds then came back on but I don't know why it shuts off in 4th gear and I can put it in 4th gear anytime and the buzzer shuts off. Could it be the wiring is messed up or something is grounding out when I put it in 4th gear?

 

[DanielC]

I buy antifreeze at the local Walmart mini grocery store.  It is less expensive for Prestone antifreeze, and you can get distilled water in the same store a few aisles over.

If you do not have a container to mix 50/50 distilled water and antifreeze, you can buy one gallon of premixed antifreeze, and once that gallon bottle is empty, use it to mix the full strength antifreeze with water

[datzenmike]

6 hours ago, Scrapson said:

Alright well I have to do it tonight and I cannot put anti freeze in due to the fact that my local auto parts store does not have any but they get it thursday so that should do it. The charge light buzzer shut off the other day for a couple seconds then came back on but I don't know why it shuts off in 4th gear and I can put it in 4th gear anytime and the buzzer shuts off. Could it be the wiring is messed up or something is grounding out when I put it in 4th gear?

 

 

There is no 'charge light buzzer' but there may be a relay that will buzz from low voltage. Can you locate the buzzing sound and tell me where it's coming from????

[Scrapson]

It sounds like it’s in the dash. If a relay is bad how in the world do I get to and fix it because it’s starting to annoy me. I’m gonna test the alternator and see if it’s it

[datzenmike]

There is a seat belt warning buzzer somewhere behind the radio and beside the glove box.

[Scrapson]

Alright well how in world is there a seat belt buzzer because there are no wires that go to the seat belt stuff. I also have two wires hanging from my dash that are red and green stripe and another that has red with yellow stripe I believe or its a blue stripe ill check.

 

[Scrapson]

So update I cleaned out the block the water was a bit brown but it cleared out and it’s crystal clear. I’m going to take it for a rip in the morning.