Hi there - just after some FD knowledge, please!

Presumably the oil control rings prevent the oil which is lubricating/cooling the e-shaft and rotors from passing up the side of the rotors, is this correct?

What happens if these fail, can anyone explain the symptoms?
Do you get oil going into the combustion chambers (and therefore lots of smoke), or does it work the other way around, and you get combustion gases leaking past and into the sump?

(I am getting alot of smoke on start, far more than normal, but only after the car has been sat around for several hours after driving. The reason for the above question is, could the oil control rings be leaking? When hot, the engine has expanded and the oil control rings seal properly, hence no smoke on start up if the car is hot. But after it has cooled down, does the engine contract and thus allow for some oil seepage into one or several combustion chambers, and so a large cloud of smoke when the car is started (i.e buring off teh accumulated oil)? Is this scenario possible?)

Thanks!

 

Yes, the seals on the oil control rings can fail. Typically when that happens you have a lot of smoke, all the time as you are burning oil. I have not really seen that cause combustion pressure to go back into the oil system. I've seen the oil system (pan) get pressurized from combustion but from outer seal failures not oil control ring failures.

 

I recently pulled apart a 125k mile original FD motor and the outer oil control rings were cracked and when I tried to remove them they basically fell apart. The motor smoked like Spy Hunter, btw

 

Cheers for the replies!


Hmm..interesting. I don't get any smoke apart from straight after starting. To me it is logical that there is oil accumulating in the combustion chambers and this burns off as soon as the car is started. What I do not see is after this cloud clears (say 20seconds) there is any further smoke. I've even had my wife drive behind me and I've planted the throttle with no obvious smoke. Thanks for the wisdom anyway! Possibly they are leaking very slightly and after a certain time there is enough collected that produces the cloud when starting, but not leaking enough to produce visbile plumes of smoke when driving?

 

You might be leaking, but I don't believe it has anything to do with your oil control rings. Here's a thread with a suggestion in it:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/oil-control-ring-failure-719153/

Also, are you positive it's oil burning?

 

That would be me it really didnt smoke once it was warmed up but on a cold start everything around was a blur but if it was windy it was a good day to drive it since the smoke did not stsy in on place .

 

Rich, how old are you?

 

a lot of the time oil smoke is confused with gas smoke. how does it run when you first start it?

 

Just turned 31 while at DGRR '08, chillin' with herblenny, g's third gen, david jerome, ray crowe and other buds

 

95% sure - blue smoke, and smells oily. Thanks for the link, I have searched, but missed that one.



Starts 1st time every time, hot or cold. Smoke only after it has been sat for several hours, especially over night. Smoke only straight after ignition for say 15-20seconds. It runs perfect apart from the smoke you wouldn't know there was anything wrong with it.


On my long search to try to tie this down, the other main sympton is oil (more than normal) in the compressed air pipework from the turbos to the engine. Its coming from the primary turbo side, since lots of oil is fed back to the airbox via the air bypass valve. The charge relief valve is dry. Had the turbos looked at twice now with new seals and am told they are perfectly fine. There does seem to be oil coming down the air pipe from the oil injectors (that connects to the primary turbo inlet) so not sure if this is meant to happen or not, maybe indicating a problem with one on the oil injectors (i.e. leaking oil into the engine) but can't really see this dumping enough oil in to make it smoke. Then again, i have no idea how little oil is required to cause smoke! I also do not have the pcv line to the throttle body. The only line I have is from the oil filler neck to the primary turbo inlet. In addition, I have run the car with the oil filler cap off, and it really didn't make any difference at all. Best case scenario is a failing diaphragm in an oil injector allowing oil into the primary turbo inlet, and while the car is sat, allowing oil to drip into one of the combustion chambers giving the smoke when started. Personally I don't really buy into that explanation, there just seems too much oil hanging around the place - but again, I do not know how much oil the omp provides, so it could be the cause. So assuming the turbos are actually good, it leaves oil leaking internally, but that doesn't explain the oil in the primary tubby..........a frustrating set of symptoms that aren't easily explained! If it were blowby and crankcase pressurisation forcing oil out of the turbo seals, then why only on one turbo and why is the problem not alleviated when the oil filler cap is taken off? The joys of owning an FD, hey!!

 

there are 2 oil seals in the rotor oil seal.

theres a metal scraper ring that keeps the engine from burning/using oil while its running. and there are o rings in those seals to keep oil from leaking down into the chambers when the engine is not running.

the rotor oil seals last a long time, and they wear gradually. as they wear oil consumption goes up, all the time.

the rotor oil seal o rings, get hard over time, and it lets oil into the engine when it sits, giving you that nice blue cloud when you start it. if you leave one of these o rings out, it'll smoke like a house fire for about 45minutes, then when all the oils burned off, its fine.

FD's are rich on startup too, little puff of blackish smoke is normal