Datsun HL510 coolant change

[IsaacHeink]

Hi, I have a 1981 Datsun 510 wagon and I am attempting to change the coolant for the first time. I am doing so according to the instructions found in the service manual. In the instructions it says to "remove the cylinder block drain plug," but I cannot find this plug. Can anyone tell me where this plug is or if my model even has one?

Thanks much.

[Doctor510]

Kinda sorta just above the starter...

[banzai510(hainz)]

How about just drain the radiator

 

theres a drain plug on lower corner. Some are reverse threat type if they have a brass tube.

 

Some are just plastic wing nut type looking just loosen left

[IsaacHeink]

You don't think it's necessary to remove the drain plug like the service manual said?

[banzai510(hainz)]

I dont do that. You can if you want but you still going to need to drain the radiaot anyways and hose it out .

 

You can do what you want.

Doc 510 is pretty good. But why risk taking on a plug like that. Its rusted already in there for 25years. But the radiator one might be ezer to tackle

[IsaacHeink]

Yeah, good call. It was pretty rusted so I decided not to bother with it.

Any tips on emptying the reservoir?

[datzenmike]

The coolant recovery container? If everything is correct and working properly it should siphon out when you remove the drain plug on the bottom of the rad. If you already drained the rad with the cap off this wouldn't have happened. Remove the reservoir and empty it.

[DanielC]

I have removed the block plug by the starter, on L-16 521 trucks.  The plug has had an extra decade or so to sit.

To flush the system good, remove the radiator, and remove the thermostat.  I then put the radiator hoses back on the engine.  I push a garden hose in one radiator hose, and and remove the block drain plug.  While the block is filling with water, I hold a finger or thumb over the hole from the block drain.  when the block is full of water, blow compressed air into the block drain hole.  You will be amazed at the amount of rusty crud that gets stirred up by the compressed air, and pushed out of the engine.  let the block fill with water, and blow air into the drain hole again.  Repeat until the water stays fairly clean.

 

Do the same with the radiator.

[IsaacHeink]

DatzenMike, I took the rad cap off before I started draining, so the draining fluid didn't create a vacuum for the fluid in the recovery container. Rookie mistake! But I took the reservoir off and gave it a good cleaning. I also flushed the radiator and replaced the coolant.

[datzenmike]

Kinda sorta just above the starter...

 

On the Z20 the drain plug is on the left or driver's side of the block. The design of the Z series is such that the hot water for the heater exits the right side of the block just above the starter. The head has no outlet for this. Removing the heater hose from the block might be enough to flush with.