Project Marina, Coolant Flush

Wrapping up the suspension meant I could move onto another small job I needed to attend to; Flushing the cooling system.

The drivers side suspension went together more or less the same as the other side, with a couple of small exceptions. The first was that the trunnion pin would not go through the new bush. The other side was a tight but smooth fit, but this side just would not work.

To remedy this I purchased an adjustable hand reamer and reamed the brass bush out until it was a smooth fit on the pin

I also altered how I applied the epoxy putty on the end. On this one, I used a file to scuff up the metal on the end of the trunnion and left the epoxy a couple of days to set before continuing work. This seems to have worked as it’s far better adhered than the other side, and has set harder. I may have to revisit the other side at some point.

In all its glory, with new bushes and joints.

With that out of the way and the car back on its wheels, I wanted to flush the cooling system. I knew it was pretty grotty from when I removed the heater hoses way back, but other jobs had got in the way until now.

The first task was to disconnect the lower radiator hose and drain the system. Due to the design, this was messy, but I did manage to catch most of it. The fluid that came out was anything but coolant though, it was a thick brown sludge.

I had a replacement thermostat to fit too. Thankfully the three bolts came out easily and with no issues. The old thermostat didn’t have a bleed hole in it and was also very grotty.

With the thermostat removed it allowed me to use a hose to flush the system out. It took a huge amount of water through the system for it to start running clear. The big cutout at the top goes into the head/block and the central tube leads to the waterpump.

This is the waterpump, which I’m lead to believe is a FWD Maxi or Allegro pump as its slightly different to the RWD pump the car should have, hence the creative lower radiator hose.

To gain a bit more access and allow me to flush the radiator I had to pull the radiator out. I pressure tested it when I got the car and it held pressure fine, although looking closer it definitely needs a recore as the fins are all rotting away.

Flushing the radiator took a considerable amount of time. The amount of thick brown sludge that come out of it was horrific. It would start to run clean and then you give it a shake with some water in it and you get another torrent of brown sludge. I think it took about half an hour of constant flushing to get it to run clear.

Before refitting the radiator I cleaned up the thermostat housing. It had some remnants of an old gasket, but it wasn’t in great shape.

The thermostat had been replaced at some point as it was an AC Delco part made in the USA.

The replacement is a Tridon part, with a new gasket. The replacement thermostat has a jiggle valve and a bleed hole which will hopefully make bleeding easier. I placed this at the front as the engine tilts backwards slightly, so that should be a high point.

Finally, before refitting the cleaned up top of the housing I ran a tap and die through the threads of the housing and the bolts. This was a course thread, and I had no replacement bolts that would fit so the cleaned up original bolts were used.

A quick smear of Hylomar, and the thermostat housing was reassembled with the new thermostat and gasket.

Unfortunately upon refitting the radiator I slipped with a screwdriver on one of the nearby hose clamps and punctured the core slightly.

I lowered the coolant level to below the leak, and using my tiny little gas soldering iron turned up to 11, I heated the area with the bare flame first, before using a wide soldering tip to blob some solder over the hole. Its far from perfect, and the radiator really needs a recore now, but it seems to be holding coolant for now.

I ran the car for a few minutes to get some heat into the system and bleed the system and all seemed to be well. The temp gauge didn’t go over quarter, so I need to check that’s working as it should, but it did move.

There are already two positives that I noticed; first, when shut off, the engine didn’t diesel and run-on like it had previously. Secondly, when the engine was shut off it didn’t make the loud popping and banging sounds from deep within the engine like it previously used to. Im guessing all the sludge was blocking passages and causing hot spots around the cylinders.