RX8 Project – Part 2

In part two we look at finally getting the engine clear. In reality due to the time I had available this process actually took something like three months. A qualified professional mechanic can remove the engine in an RX8 in as little as three HOURS! Clearly I’m not a professional mechanic!

I didn’t fully document the process as there are any number of people who have already done excellent write ups of this but hopefully I can offer a couple of pointers to anyone trying to do this. Officially the engine should be removed by dropping out the front sub-frame and not being able to do this easily on a driveway has led me to removing the engine upwards. This adds a few minor problems along the way but nothing insurmountable

One thing I found is that you really need to remove the crank pulley to clear the front crossmember. While you probably could yank it past regardless it makes the process notably easier.

RX8 Crank Pulley
RX8 Crank Pulley

With somewhat awkward visibility it can be hard to tell whats going on but it looks like this. You do not need to remove the main bolt – the pulley is just held on by the four small bolts around it (already removed in the photo).

The next major problem is removing the engine mounts. I found it virtually impossible to get at in any conventional way. You can get a ratchet on but they’re quite tight and there’s little room, and a breaker bar doesn’t have room to move. My solution to this was to undo the bolts from the top of the engine bay with a selection of extensions. These need to be 1/2″ drive as my 3/8″ drive ones were starting to flex a bit plus you will probably need a breaker bar. Due to the angle restriction a UJ is also required. While the whole assembly looks a bit bodged it works fine.

RX8 Engine Mount Removal
RX8 Engine Mount Removal

Also the oil line connectors, these are really awkward and are usually corroded solid. Hose them liberally with WD40 and let it stew overnight if they are a problem. If you plan to use them again don’t lose the small retaining wire ring, these can be hard to replace (though can probably be replaced by a snap ring from an engineering supplier).

After another brief pause for another project we started watching some car based youtube videos (Roadkill and Mighty car mods for anyone interested) and after feeling inspired to do car-ish things and pull the engine out.

RX8 Engine Bay Night
RX8 Engine Bay Night

My best advice on this one is – don’t try to remove an engine when it’s dark and drizzling!

RX8 Engine Out
RX8 Engine Out

Next up, rotary engine autopsy! Coming soon!

RX8 Engine Swap Project Intro

So the RX8 project involves making what is effectively a worthless vehicle useful again. For anyone not familiar with the Mazda RX8 they are a fairly high spec 4 seater car which is most widely known because it uses a Wankle rotary engine. This type of engine does not use pistons and so is incredibly smooth in operation and in the higher power (231) version of the car revs to 10,000 RPM as standard.

Sadly for all its good points the engine has a number of down sides. In terms of behavior the engine shares a number of similarities to a two stroke piston engine, one aspect is that it is designed to burn oil in normal operation to such an extent it actually has mechanical components to inject oil into the combustion chamber. This means the oil needs to be topped up frequently and it is recommended to check it every time the fuel is filled, though this isn’t as easy it probably should be and very few people do so. As a result many engines fail rapidly due to lack of lubrication once the oil gets low.

The other common failure is with the o-rings which seal the sections of the engine to each other if these fail water gets into the combustion chamber when the cooling system is under pressure (i.e. once the engine is hot). This is one common cause of the warm start/idle problems and where water gets into the oil you get lack of lubrication failure eventually as well.

The engines are expensive to get repaired assuming the fault is detected early enough and no major damage has occurred. If major damage has occurred then sections or even the whole engine may need replacement. Either way the repair is likely to cost more than the car is actually worth and this seems to happen at something around 60-80,000 miles. The combination of all of this is that these cars are abundantly available for very little money with engines in  varying degrees of failure but with relatively few miles on the clock. This leads us nicely to exhibit A:

Cheap RX8
Cheap RX8

This is a 55 plate RX8 I bought from ebay for grand total of £300 taken on the day I bought it in July 2015. While technically still road legal at this stage the car wouldn’t idle when warm so was not drive-able for any real distance without serious difficulty. In order to collect it I had to impose on a friend who has a van and car trailer for moving his racing car.

My plan for the car was to remove the engine and dismantle it to see how far gone the internals were and if possible repair the engine and reinstall it. Failing that the backup plan was to try to swap in an engine from something else simply because buying a working replacement rotary engine would cost approximately £3500!

So having got the car home the next day we started taking things out:

This may look a little unconventional but in the UK the RX8 was Thatcham security rated. Part of this involved preventing the ECU from being removed because otherwise any wannabe car thief could just swap the ECU for one from a scrap yard for which they have the matching immobiliser chip, then either hotwire it or force the ignition lock like older pre-immobiliser cars. RX8’s from other countries do not have the steel retaining plates as they do not have this rating. Since the retaining bars (gold in the picture) were several mm thick and held in place with any number of rivets the only option (well the only one we could come up with at short notice) was to drill the rivets outs. I recommend centre punching (creating a divot in the centre) the rivets before drilling because they are domed and the drill will skid off. Now technically you could probably remove all the plugs on the engine and leave the ECU in place but we wanted to allow as much room as possible to take the engine out.

Unfortunately in the RX8 the engine is mounted very low and well back with a lot of ancillaries on top of it making removal a little more time consuming:

RX8 Engine Bay
There’s an engine in there somewhere!

Incredibly the back end of the engine is nearly level with the visible firewall and the front is indicated by the alternator! Yes is really is a very small engine and this particular one is the lower power RX8 – so the output of this engine is *only* 192 bhp!

RX8 Engine bay end of day 1

And this was basically where we got to by the end of our first day removing parts. In truth this is only about three hours in as we’d had something of a heavy night and bright sunlight wasn’t helping the situation!

More to follow shortly…