Thread: What happened to your D3/D4 today?

Originally Posted by BradC

I don't, but it's still lying around around somewhere. My son likes playing with it. I followed the heater hoses. On mine the water leaves the coolant outlet in the vee, goes through the fuel burning heater and then back into the heater, so I isolated it where it leaves the coolant outlet on one end and leaves the heater core on the other. Where the pipe leaves the heater core it joins a hard line about half way down the engine, so I isolated it there and that's where I started backflushing from.

There are 2 ends. From memory the heater hoses are 3/4" One end is the one you can see in the background. It's a tee with 2 ball valves. One on the garden hose and the other on the compressed air. The other end is a 3/4" to 1/2" host adapter that went into the soak well with a clear hose so I could see the grunge as it came out.

I first used air to blow pretty much all the water out of the core and lines, then air off, water on to put a little slug in the hose, then water off and air on to push it through as fast as possible. I used all sorts of techniques just playing with the valves, but that was the most effective. A couple of goes like that, then just water on to flush it all out thoroughly. Kept going in one direction until it didn't loosen any more up, then reverse the connections and go back the other way. Repeat until no more colour comes out. It took a lot of flushing.

Next time I think I'll disconnect both hoses from the hard pipes.

Thanks. Can’t imagine a little bit of radiator flush or similar wouldn’t help soften it a little to start off. Blow out existing fluid first then start (or end) with this.

Originally Posted by PerthDisco

Thanks. Can’t imagine a little bit of radiator flush or similar wouldn’t help soften it a little to start off. Blow out existing fluid first then start (or end) with this.

I did the full 2 hour drive then fresh water rinse with Cummins Restore prior to starting and it didn't touch it.

I got the idea from the D3 list in the UK where someone figured out how to rig up a pressure washer to the heater core. I have a pressure washer but couldn't figure out how to make it work. By the time the water had made its way down to the core it was pretty much back at mains flow.

The problem is the heater core is the lowest part of the system, so all the grunge just settles there. It's almost like a filter.

Originally Posted by PerthDisco

Thank you for this tip. Do you have a better photo of the connection to heater pipes and how you added air?

Found it.
IMG_2130.jpg
Just cobbled together from bits I had lying around at the time.

Originally Posted by BradC

Found it.
IMG_2130.jpg
Just cobbled together from bits I had lying around at the time.

So you let in some water, then close off the water then let in the compressed air, repeat?

Originally Posted by DiscoJeffster

So you let in some water, then close off the water then let in the compressed air, repeat?

Precisely. Blow it clear with compressed air until most of the water is gone, shut the air off, introduce a slug of water and then blast it through with air, then run the hose to flush it out, lather rinse and repeat.
Mine was pretty blocked, and it took quite a few attacks from both directions over an hour or so to get it clear.

Once I'd done that, I then used it to blow most of the rinse water out of the cooling system.

To be honest I was kind of expecting either damage to the core or a blown seal with the pressure, but it all stood up ok. I think the trick is the water is belting the passenger side of the core. As soon as the water runs past the inlet of the core the excess air pressure just bleeds off through the drivers side of the matrix, which is clear. So there's no real build up of pressure, it's the inertia of the water doing the work.

I got the idea from an expensive widget I saw somewhere on the net that has an automated valve that blasts pulses of water using compressed air, and I figured a couple of ball valves would do the same thing, if not a lot slower, and I had enough bits floating around to cobble something up.

I also have a 2.5HP belt drive compressor with >200L of air receiver, so I have plenty of air on-tap.

Originally Posted by BradC

Precisely. Blow it clear with compressed air until most of the water is gone, shut the air off, introduce a slug of water and then blast it through with air, then run the hose to flush it out, lather rinse and repeat.
Mine was pretty blocked, and it took quite a few attacks from both directions over an hour or so to get it clear.

Once I'd done that, I then used it to blow most of the rinse water out of the cooling system.

To be honest I was kind of expecting either damage to the core or a blown seal with the pressure, but it all stood up ok. I think the trick is the water is belting the passenger side of the core. As soon as the water runs past the inlet of the core the excess air pressure just bleeds off through the drivers side of the matrix, which is clear. So there's no real build up of pressure, it's the inertia of the water doing the work.

I got the idea from an expensive widget I saw somewhere on the net that has an automated valve that blasts pulses of water using compressed air, and I figured a couple of ball valves would do the same thing, if not a lot slower, and I had enough bits floating around to cobble something up.

I also have a 2.5HP belt drive compressor with >200L of air receiver, so I have plenty of air on-tap.

At least with the valve you can regulate a little on the air side. A shop vac on blow would do fine for pushing out water but not creating a hammer.

Also on water side could create a hammer with the tap in this configuration. All bases covered.

Afterwards can prime the system with fresh coolant and reconnect hoses.

A valuable tool for WA Disco owners.

Originally Posted by PerthDisco

Afterwards can prime the system with fresh coolant and reconnect hoses.

I don't bother with that. Since I moved to doing a vacuum fill, there's no need to prime nor bleed.

Saw this a couple of days ago. It’s not everyday that the D4 gets to see little red riding hood with her wolf