Thought I would make a thread here since nobody goes on the mazda forums anymore.
About a year ago a friend and I went halves in an old Mazda 626, owned by a friend of my mum's since 1998, with a full service history at the Mazda dealer all its life. It's a 1995 GV wagon, basically the same car as an AT/AV Telstar and 626 GD (they replaced the GD in the early 90s but kept it going in wagon form with a facelift called the GV).
Had a bunch of fun with it until a few weeks later the head gasket went, my brother was driving it and didn't notice it overheat so it completely cooked the head to the point of being beyond repair. We pulled the head off and the internals weren't in the best shape either so we decided to find a replacement engine.
Searched for ages for a new engine with no luck until a turbo version from an 1989 MX6 came up for $250. We snapped it up and the guy even threw in an XR6 intercooler which he reckons can be made to fit.
We pulled the auto box off the new motor and decided to do some work on it before putting it in the car. Glad we did because the head gasket on the new one was probably going to go soon due to age.
Not long after this an opportunity came up to buy a GD wagon for $100. It needed a couple of things but my dad was in need of a car at the time so he drove it around for a couple of months before it also blew the head gasket (yes it's very common on these motors). So it's now going to be a parts car.
We pulled the sump and took the pistons out, removed the rings and cleaned them up (it can be common for the rings to sieze up especially if driven sedately with an auto). They weren't too bad but it was good to learn as I'd never done anything like that before. Of course I ended up snapping a couple of rings so had to pull some out of the old motor which was a pain as it's almost impossible to get the sump off with the engine still in the car.
Pistons back in
The hardest part about this whole job was scraping all the old gaskets off everything (sump, top of the block, etc) - extremely time consuming!
Sump back on
We also did a bunch of work on the head - took out the rockers, cam etc and did the valve stem seals and lapped the valves. Also resurfaced the head using sandpaper and a thick sheet of glass which worked perfectly (look on youtube if curious)
Before and after:
Reassembled the head and put it back on the block etc (new seals, gaskets etc everywhere of course)
Also painted the valve cover.
(Not pictured, the part where I forgot to put sealant under the end camshaft caps and had to take the head apart again)
Put on the thermostat housing, new thermostat etc
Pulled the old motor out of the car and separated the gearbox. We will be using this gearbox even though it's not as strong as a turbo gearbox but it's all we've got (unless we want to go auto which is not an option)
The new engine was missing the alternator so we swapped over the one from the old engine. We also swapped over the power steering pump and AC compressor as they were known working, plus the power steering connections were different.
We then swapped over the timing gear onto the new motor (the old one had invoices for it all being replaced only 20k ago) and fitted a new timing belt.
(Not pictured, the part where it took us about 3 hours to undo the crank bolt from the old engine.)
That's where it's at currently. Need to install a few other things like intake manifold, accessory belts etc then we can take it off the stand, put the clutch and gearbox on, and think about putting it into the car.
The biggest challenge we have to overcome is working out the fuelling for the turbo engine. We have part of the engine loom for the F2T (turbo engine) so we'll probably have to use parts from the F2 (NA). Out options are:
a) Run the F2 ECU, injectors, wiring, sensors etc - from my research this is possible, but we'll need to find a way to give the engine extra fuel under boost.
b) Get an F2T ECU and run the turbo injectors - the problem with this is that there would still be a ton of wiring to do. There's also another problem because there are "A spec" and "B spec" cars that use a different ECU, wiring and injectors. The engine is an A spec one (pre 1990) and the car is B spec (post 1990). So to get the correct ECU for the engine, the dash wiring for the car won't plug into it.
c) Run an aftermarket ECU - the problem with this is cost, and my inability to do the tuning for something like that.
At the moment the preferred option is a), and either run an extra injector and injector controller to deliver more fuel under boost, or run a rising rate FMU which will increase fuel pressure under boost.
If anyone has any ideas about how to do this please let me know.
There's an outside chance I may be able to get the whole lot (ECU, wiring etc) from a guy on the Ford Telstar facebook group but he's not 100% sure yet.
Anyway I've probably made it all sound much easier than it was by leaving out all the details of where we messed up but it's been a fun project. Happy to take criticisms and suggestions etc!
