NewmanFirstgen

Well my car started making this terrible noise yesterday. Broke something in the motor, what is weird is it seems to go away at higher rpm's, and it still idles fine and has no loss of power.. I will be checking compression this weekend but I think it may be a stationary gear tooth that broke off??

Anyone seen this? I was told if you break an apex seal it will probably not idle anymore and you will notice loss of power..



What else could it be besides a seal? am I going to need to replace my housings after this? if it were a stationary gear tooth that broke. are there any other parts prone to failure?

dazed and confused.

Aviator 902S

Check your spark plugs. If the business ends of all of them are dry and the usual tan or grey color your apex seals are ok. Likewise if the car idles fine.

If both plugs for any one of the two rotors are wet and oily-looking (fuel-soaked), and the car sounds like a lawnmower on start-up and won't idle at any setting under 1500 rpm it's likely that an apex seal has been unceremoniously spat out the exhaust port. This would have also wrecked the rotor housing and rotor. You'll also notice a huge reduction in power and an increase in fuel consumption.

I've never seen the results of one stationary gear tooth parting company with the engine but if one did others would be soon to follow. (assuming of course that the departure of one tooth didn't immediately take out others and cause the rotor to go out of its orbit). Said gear tooth would likely damage the engine on the way out the exhaust, and it wouldn't do the apex seals any good either. When more teeth get broken the engine will crater in hand grenade fashion and completely sieze.

lovintha7

If the gear broke, then the rotor gear is probly screwed. You'll probly end up replacing the side housing (s), and possibly the rotor housing depending on what the piece of the gear was wedged against, or scraped against. Of course all this depends if the gear even broke.

It may be easier to diagnose if you had a sound clip.

You may have possibly spun a bearing on the eshaft inside the rotor. I'm sure this would produce a horrendous noise. Either way, you're going to need a rebuild.

MosesX605

Yeah, we definately need a sound clip. It's weird that you have good idle conditions and no appreciable loss of power, both of which lead me to believe that there is something else going on aside from a failure in the internals. Anything that would produce a noise would also severely effect power and idle quality I'd think.

NewmanFirstgen

When i bought the car the prvious owner stated that he thought he broke an apex seal.. Upon test driving it for the first time he said it felt ok, he didn't think anything had happened.. This guy isn't the smartest person when it comes to cars in general. But he is a friend

I'm wondering if he didn't break the tooth from the gear, and it get wedged into the interior of the rotor, the little cut out's going around the interior walls of the rotor... and me driving it alot since then, jarred it loose..

it idles fine at 800-900 just like it always has, still feels as powerfull as it did before the noise, although i only drove it a 1/4 mile home after i heard the clanking. I am just hopefully optimistic that the housings are still good..

anyways isn't the stationary gear and rotor gear sealed with the side plates and rotor, wouldn't the broken tooth stay within the rotor assembly itself.. if i am correct in my thinking of how the motor pieces go together then the tooth would be floating around on the interior of the rotor, since the rotor and side plates are sealed with the oil ring.

well, we will se upon breakdown what it is, and this will be my first teardown of a rotary... wish me luck..

Rx7carl

Well check the compression, but from what you said I doubt you popped a seal. What kind of noise? In all gears? Is it definately RPM related? Even sitting still in neutral? I would think that the tooth would end up floating around in the rotor cavity and not make any noise, but I dunno for sure.

SparkienSuggah

*sparkie wanders over to the spare, half assembled engine in his bedroom*
well, if you broke a tooth on either the stationary gear or the rotor, the loose tooth would stay between the housing and the eccentric part of the E shaft.. it CANT get into the rotor itself because the casting cavities are on the other side. BTW: if you DID break a gear, the shards should snag in there pretty damn quick. i would hazard a guess that you didnt, cause your baby still runs.

Furthermore: a broken apex seal sounds like ball bearings being sucked into a shop vac... just for reference

NewmanFirstgen

when i first got the car it had a faint "dunk dunk dunk dunk" sound that cleared up after it warmed up, and it sounds the same as this just a little louder, in fact at idle it still makes the sound and gets louder with rpm until about 2.5k when it goes away.. it's weird .At first i thought it was a rotor touching the housing but the motor only has 20k on it, The previous owner did over rev the engine, thats when he thought he threw a seal, but i also have seen people saying that hardened statiionary gears are essential to a motor being taken to its rpm limits, and if it doesn't have hardened gears, which i pretty sure it doesn't. would also point toward a gear broke.. i will know more this weekend

kenn_chan

sounds more to me like the teeth that engae the stationary gear "walked" loose from the rotor and contacted the side houseing, or chewed them selves on the stationery gear. (thats why we measure the width of the rotor at the gear teeth when assembling a motor, to determine if the ring gear has moved).

it is held in place by the roll pins, and if one of them comew loose the ring gear slowly works its way loose from the rotor and moves outboard into the stationary gear teeth eventually chewing them up as well as the side housing.

kenn

Aviator 902S

All true. I don't know how I managed to miss that one. Of course any shredded teeth would have been contained inside the rotor.

But I'm now wondering if the thrust bearings may be toast? I've never had this happen to any of my 1st gens so I don't know what this would sound like.