rx 8 engine failure

bob2 · August 22, 2009, 06:24:24 PM

Hi everyone,

My RX 8 engine failed, so i decided to pull it apart to see whats gone wrong.

Well the bearings are knackered the rotor housing look shot!!! The apex seal\'s are heavily worn!!. One of the rotor housings looks like it has a crack in it by one of the plug holes.

Just looking for opinions on the failure and the causes and what i can do to prevent it.

m1tch · August 22, 2009, 06:53:33 PM

What year car was the engine out of? apparently the early ones only had 2 oil injectors rather than the 3 the newer ones had.

What oil were you using?
How long did you let it warm up for before driving?

HaywardRotary · August 22, 2009, 07:05:47 PM

What is the mileage? and how often was oil changed and what oil used?
Regards
Carl

bob2 · August 22, 2009, 08:11:04 PM

Hi guys

The car (2004 model) did approx 58k always serviced on time and i checked my oil regulaly the most i ever need was 3/4litre to bring back up to max. I used Fuchs XTR 5w-30 for servicing and top up. The only real problem the car has had is a missfire at 45k approx and it ended up needing coils plugs and leads. It never overheated or had any other problems.

Thanks

Grizzly · August 23, 2009, 12:32:04 AM

I don\'t know if it applys to you as your engine looks like its had some oil starvation going on but recently i did an engine rebuild on an FD that had stuck side seals on the front rotor, on examination we found it had similar front Stationary gear bearing damage to yours, it was quite obvious before the rebuild had started the belts had been over tightened some time in its life as the bearings had gone in the Alternator too and we suspect the extra load had not helped. Was odd though that just the front Bearing had gone.

exiled-viking · August 23, 2009, 12:49:09 AM

did you ever use a oil additive in with the fuel

RX-8888 · September 28, 2009, 12:56:12 AM

Sorry to hear about your engine failure, however, I posted many months ago and some here wanted to ignore or not believe what I said..

This is the same Issues to RENESIS I that has occurred ALL over the world, Australia, USA, Japan...and yes the UK.

Apex Seal Wear is lack of oil metering or should I say NO oil metering, I don\'t know why Mazda stuffed up on this one, every other rotary in the past 20 years has had a middle oil injector/dribbler.

ALL Series one RX-8\'s MY 04-08 do not have the middle injector.

Stationery Gear Bearing Wear, goes to prove that either a 5W30 is not thick enough in viscosity...or the bearing can\'t handle the higher RPM\'s, I am certain it is the oil.
As the stationery gear bearings are the same ones used 20 years ago in the 1985 FC RX-7, in fact many of the internal bearings and parts (Oil Pump) are the same as the FC on the RX-8.

There is also the theory that with the Apex Seal wear over time a miss alignment occurs with eccentric shaft and or it\'s bearings... sorry I don\'t believe an overtightened alternator belt will cause this isssue....although they did changed the belts on 09 ~Series II RX-8, but I think this was because of the revised Water Pump Pulleys and E Shaft Pulleys.

Spark Plug hole cracking is also occurring in the US, thought to be Heat related, would not thought an issue in the UK.

So I believe you need to Pre-Mix as it is the ONLY way you can get lube to the middle of the seal, As far as engine oil a 15W40 or even a 20W50 is a better option.

RX-8888 · September 28, 2009, 05:50:40 AM

Hi Bob,
I notice you are/were doing up a 12A RX-3 (S124A), I grew up with these cars as a Mazda Parts manager in Australia, if you are wanting any advice, re Spare Parts in Australia, or Genuine Part Numbers, I am happy to help you.

I also have an RX-3 Factory Parts manual, and lots of Part numbers still in my head.

As you probably know, almost all of the original "new" Mazda Factory parts are no longer available or made.

Mazda Australia had a huge warehouse full of new dead stock which was Auction Off in large lots about 8 years ago, there is a guy here who still sells some of the parts on eBay, but you need to be sure if they are for your model, many of the parts he is selling are not described correctly and are not for the model car he says they are.

Many parts are still available and are interchangeable with later and other Mazda models.

Let me know if I can be of assistance via a PM.

Ash

Will66 · September 28, 2009, 10:07:12 AM

Was that the rear rotor? The engine in mine had issues with oil feed to the rear rotor. It also suffered when the coils died and it overfuelled.

Speedworks · September 28, 2009, 10:30:17 AM

overtightened alternator/waterpump pulleys could be a partial reason for the excentric shaft bearing wear.

A US test on 13B-REW engine with an OEM waterpump/airpump setup compared to a setup with deleted airpump and underdrive pulley kit showed that many peopl overtightened the waterpump/alternator belt in order to keep the waterpump pulley from slipping (reduced touch area due to different setup).

2 60.000 miles engines where stripped and the \'modified\' engien setup showed a lot more bearing wear due to this.

Prof · September 28, 2009, 11:16:43 AM

Out of interest - how do the bearings receive their oil supply ? (that\'s directed to anyone who knows)

Is it possible that you\'ve a blockage or bypass not working correctly and as a result are seeing oil starvation on the bearing ?

gsb876 · September 28, 2009, 12:51:11 PM

One of the reasons i sold my RX8, i bought it thinking the engines would last alot longer without being turbocharged but after reading that the engines actually still kinda fail at approx 60k i sold it with 55k on the engine.

shame as actually really liked the car !!!!

HaywardRotary · September 28, 2009, 01:19:30 PM

What i don\'t understand is that my local dealer has had only one engine failure on an RX8 and now has a considerable number of cars over 150,000 miles with no issues,they have sold over 500 cars.The engine that failed was in a car that was driven out of the showroom and returned on tha back of a truck 14,000 miles later having never been brought back by the owner for any sort of service with no oil on dipstick.Hardly Mazda\'s fault.
Maybe it is poor servicing from some dealers that is the problem?
Regards
Carl

m1tch · September 28, 2009, 01:30:44 PM

There is an RX8 rotor sitting on our mazda dealers front desk, been there for a while, oil starvation due to lack of extra oil injectors caused the failures, its been there for years lol

RX-8888 · September 28, 2009, 10:27:32 PM

What is "Funny" about engine failures??

Bearings are supplied oil from Oil Pump that is jetted through the eccentric shaft to rear bearing, rotors, etc.

I have just learned that your servicing intervals are 20,000 KMS or 12,000 Miles?? is this correct, that is way too far to go on engine oil in any rotary.!!

Australia is half that distance, every 10,000 KMS.