Divebou-UK

Hey All,

So after owning a brand new RX8 in 2004 for 6 months I've been given the opportunity to have another. This one a bit cheaper at £700.

The issue is it has just started to have hot start issues.

My plan is to pull the engine and replace the Apex seals. Is there anything else I need to look for.

I've also just stripped a 192ps that had the bits missing from my 231ps and plan to strip that engine for practice before attempting the real one.

MincVinyl

Assuming you already did compression checks on both motors and also ruled out other variables like plugs, coils, clean sensors etc. If the compression is so bad that you are experiencing hot starts, I'd be willing to bet that your rotors are going to have their tips bent due to extremely worn down apex seals. From experience I would suggest just buying a mazda reman motor in the end it will highly likely cost less and be 10x faster than rebuilding yourself.

To rebuild yourself you will need to tear apart the motor and then really inspect all your components individually, assuming you only owned an rx8 for 6 months I would advise against this. The apex seals are not the only seal/surface that wears.

Divebou-UK

Thanks, great reply. I've rebuilt many piston engines., and raced a few in BTSCV comps. But I want to try my hand at RX8s, having had one and loved it.

From a engineering point if view, I do feel like I'm starting from scratch. But the drive and feel is awesome and I'm not allowed a motor bike 😁😁

Loki

iTrader: (1)

If all you replace is the apex seals, you're wasting your time. You don't rebuild your engine, you build an engine out of known good parts. Since you've already stripped a couple engines, have a look at their housing surfaces. You might find flaking chrome, chatter marks, cracks, etc. You need 2 housings without those problems, and rebuilding with problem parts is pointless.

If you want a project you can buy new or known good housings. If you just want a running car, it's infinitely easier and cheaper to buy a complete rebuilt engine.

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Divebou-UK

Absolutely no fun in that.

Clearly if a part was bad I wouldn't use it.

schm1347

Looks like I am resurrecting this thread. To rebuild an engine you will likely need the following:

1. New apex and side seals of course (stick to OEM unless you know seals well)

2. New housings. Some rebuilders will reuse housings that have minimal flaking of chrome on edges with low wear on chromate, but new housings will give the best sealing.

3. New coolant and oil seals. You take the engine apart then you need to replace these.

4. You will have to inspect rotors for wear and also bearings. End plates will need to be inspected for unusual wear on surfaces and ports but in all but extreme cases these should be reusable.

of course you will need to check clearances, dimensions, etc of all the parts as you are very well aware.

Im not an expert but I’ve researched engine rebuilding quite extensively in the process of thinking about how I might have my engine rebuilt when the time comes. Right now I’ve got low 90psi for compression with no hot start issues. So my engine is still going but I’m monitoring and preparing for when that time comes.

schm1347

anyways, how did your rebuild go?