When the car was getting checked over last month by the mechanic he noticed that it was leaking a bit of coolant. This was a bit strange as I hadn't noticed this before, and the level in the coolant tank had been consistent over the last few months and not needed to be topped up. The next time I drove it I noticed a little puddle forming on the ground under the front side of the engine when the engine was hot and the car was off. After a bit of looking around I was able to see a consistent drip going onto the timing cover from the water pump/bypass hose area. Once I got back home it was making another puddle, but the leak stops once the engine cools down, so I'm guessing it's a pressure related leak from the water pump seal. I ordered up a new water pump this week and it's ready to be installed
While I have the radiator out it will give me a chance to install my new speedo drive gears. My speedo was reading perfectly prior to me changing the engine and diff ratio, so we started with the following matching combination:
The stock 850 speedo is 1408TPM (turns per mile)
My kph 850 speedo is 880TPK (turns per km) which is just 1408 divided by 1.6
Diff ratio was 3.76
Speedo gears were the standard 6/17 combination
At 100kph on the speedo the road speed would be 100kph - all good
Since I changed to a longer 3.44 ratio (exactly 10% longer) and had kept the standard 6/17 gears it has been reading low by 10%
At 100kph on the speedo the road speed would be 110kph - not good!
The BMC method of adjusting for this was to change the speedo, so going from a 3.76 diff to a 3.44 the speedo would go from 1408TPM to 1280 (or 880TPK to 800). This wouldn't work in my case as I wanted to keep the silver 140kph speedo I have already. This meant I would have to get a reduction gearbox for the speedo or try and find some alternate speedo drive gears for the gearbox end.
There is a handy calculator here which can calculate what parts you need to make the speedo read correctly:
http://www.guess-works.com/Tech/ratio.htm . I put all my numbers in and it suggested I would need an unusual combination of 7/18 gears.
These took a couple of months to get into stock and get shipped, but they are finally here
I decided to give it all a go last night after work. Starting on the inside of the car, the gear lever needed to come out so that the engine would lift up high enough to get the radiator out. The carpet, starter button, accelerator pedal all needed to come out too
Next up the lower 2 engine steadies and the top one near the master cylinders (plus the breather on the top of the flywheel housing)
I managed to drain the entire radiator without spilling a drop - the funnel right here did the trick. Of course I spilled an awful lot of coolant later when I pulled the pump off
I followed Matt Read's easy-out radiator method, jacked up the engine and just undid the 2 bolts at the bottom and it came right out.
Next up the engine mount bracket came out and also the alloy block
I was able to have a look under the water pump, and yes it was definitely leaking!
The speedo gears live under these covers, so these were taken out too
Old vs new parts here
New pump in with a new bit of hose
New speedo gears in too
The day nearly ended in disaster at this point, when I dropped a washer into the breather on top of the flywheel! Luckily I was able to get it out with a magnet
A couple of things left to put on, hopefully all done tomorrow
![Image](https://i.imgur.com/QpVVsLfh.jpg)