Getting the cooling sorted

July 19th 2016

The cooling system has been a bit of a headache. Originally, when I got the car the water pump was in the top hose, which isn't the best idea, and it was also where I wanted to fit an alternator.

As I have shown earlier in the blog, I moved them about, but the only place to put the water pump (it's a remote pump on an Imp) was above the distributor, plumbed into the bottom hose. At least this way it was getting cooler water and pushing it it into the engine, rather than sucking hot water from the engine.

This hasn't worked very well as one of the highest points in the cooling system was the hose from the pump to the engine block. So any air would created an airlock. There were ways around it and I did try converting it to a closed system with an expansion tank from the original open system.

The real answer would be to locate the water pump lower down so that it wasn't get air-locked as easily.

Hunting about I decided to convert to an electric water pump. It seems there are a few contenders but the ones already fitted to modern passenger cars are really just to maintain a flow and assist the engine driven pumps. They don't really push enough water around.
An Australian pump made by Davies Craig (not Craig Davies ... he is a singer, reputedly) seemed to be the job. Available in it's smallest version  with a flow of between 20 and 80 litres per minute, it can be mounted anywhere. In my installation I wouldn't need the electronic controller, which adds £60 to the price. I was just going to run it whenever the ignition is on. That is one option offered in the fitting instructions, so I am not flying by the seat of my pants on that.

I made a dummy of the right size to see if it would fit in any space that I had

It seemed to fit so I ordered one. Here is the kit.

The elbows can go on either the inlet or outlet. Those that come standard are 35mm OD. My hoses are mainly 20mm ID so some reducers were going to be needed.
It was cheaper to make them and buy a silicone reducer hose than to get the alternative 20 mm alloy elbows which where £20 each.

Getting the pump to fit in somewhere was a tricky job. There was one space above the engine mount which seemed a goer. The pump need fitting with a slight incline from the motor to the water pump chamber to - you guessed it - avoid airlocks.

I eventually got it in place and made a small steel bracket from the engine mount bracket to bolt the pump to. The hoses mainly hold it in position, but the bracket was to prevent the pump rattling on the engine and maintain the slight angle needed.

This shows the bracket, The upper hose is a proper reducer hose feeding the engine block. The hose in the centre is cobbled up using other bits of hose and copper pipe. It works OK but now that I have a proper position for the pump I can sort out real reducer hoses to make the installation tidier. The HT leads are just stuck in there at the moment. I can tidy then up later.

This shot from the top shows how crowded it is in there. People using engines without distributors and all the gubbins would have a much neater installation.  

I originally put the expansion tank at the back of the engine bay and had hoses running all over the shop to run the feed back to the "T" in the bottom hose. 

Now that there is no water pump mounted up high I could move the expansion tank to the front and have shorter, more direct hose runs.

Now the hose from the in-line filler neck runs straight to the bottle and the feed from the bottle to the bottom hose drops straight down to a copper plumbing "T" I put in. I did have a plastic "T" from a scrap yard, but it was on a 45 degree bend, which didn't suit the installation.


The other thing I needed to do was to modify the thermostat to allow water to flow even when it is closed. This stops the water pump struggling.
They suggested drilling one or two 5mm holes in the thermostat flange, so I put two holes in, to be safe.
I don't believe in running without a thermostat. The engine can run too cool and the free flow of water doesn't allow back-eddies in the head to scavenge pockets of hot water.

So far it seems to have been successful. As soon as you switch on the ignition the water is circulating and even at low revs it is passing round at a decent speed. It will sit ticking over at about 70 degrees for ever. The thermostat is an 88 degree one so that is not even opening. The by-pass holes are achieving that.

At The Car's The Star demonstration it behaved well. (I once forgot to switch on the fan). Even if it gets up to 100 degrees you can switch off the engine and run the pump and fan and it cools down quickly. The only downside is the enormous amount of heat blowing into the passenger compartment.

Still, on most trials days that would be welcome.

I still have the thermostatic switch to fit into the fan circuit so that I can rely on that to keep the cooling in hand.

Cracked Chassis

Something that came to light whilst I was moving the plumbing about was a crack that appeared in the chassis frame. 

Well, it wasn't a crack, it was a tube that broke away.

In a very strange place as well. For a car that is about 40 years old it seems odd to have just appeared after my first event following a complete re-build. 

The obvious change is that I have replaced the rather floppy alloy plates that held the engine in place with proper steel mounts attached to new uprights in the chassis.

I also fitted a sumpguard which attaches to the engine mountings. 

This must have led to shock-loads transmitting through to the weakest joints which have burst away.

They are brazed in position and since I don't have gas and use MIG for lightweight stuff I had to clear away all the old brazing to get a decent weld.

As the fuel pipe runs underneath that rail I had to take out the bulkhead and the fuel line.

Never easy. is it?

Anyway,that's another little job seen to.

Oil Pressure Gauge

I never learn. In attempt to save money I bought a used oil pressure gauge from a seller on eBay. It's a Mini one so is probably 25 years old at least.

It worked fine at first, but then started being very slow and jerky to gain a reading after starting. This was a worry. 

However it also took a while to fall after switching off the engine, which kind of points to the gauge being at fault.

So I've got a new gauge. What a nightmare getting the right threads to make the connection. Luckily a mate knows a lot about BSP and stuff and managed to create two threads which fitted each other at the engine end of the new pipe, so that looks to be fixed.

So for the moment that seems to have got outstanding problems looked at.

The next instalment may be about fiddling with the steering!