cruiser

What happens to engine internals when an apex seal goes because of running too lean ? Does the seal bend, does it break and it scorches the housing, does it fly through the exhaust port in the turbo ?

My engine went yesterday I think. Car has lumpy idle, 10psi of vacuum at idle and smokes black under boost - symptomps of a blown apex seal, right ?

What can I expect when I take out the engine and pull it apart ?

Thanks !

cruiser

Hmm... I was able to drive the car home and it could still go to like 90mph. Weird thing is that the car was fine until I spun on the track (hit the brakes when the slide was past 45degs) and I went over the cerb. Could it also be my MAP sensor ? Car puls OK, but under boost it just smokes black smoke.

cruiser

One more thing, the vacuum is quite stable at 10psi, it used to be around 20psi before at idle. When driving, it is at 20psi again.

So is it the apex seal or should I look for problems elsewhere ?

Can a compression be done on an FD with an ordinary compression gauge ?

cruiser

Anyone ?

BoOsTin FD

I think you should check the hose to the map sensor, it's known to crack and give you same sympthoms of blown engine.

I don't think you can check compression with the regular tester because it needs to have 3 numbers for every rotor. I may be wrong though.

rajeevx7

iTrader: (11)

yes, sounds like that vac hose behind your throttle body is disconnected. boost spikes can cause this. similar thing happned to me.

raj

GarageBoy

You cannot do a leakdown test like a normal piston engine. (so I've heard) Depending on what brand/type of seals, it can do many things when it breaks

Rotarius

I do compression test on rotary engines with a regular compression gauge. The one I have has a small relief valve on the base to bleed down pressure. What you do is remove a plug hook up the gauge,disconnect the fuel pump and coils have someone step on the gas and crank over the engine. The needle should jump 3 times per rotor revolution, if it only jumps once every crank then you defenetly blew a apex seal. Also you can do all the above without an comp. gauge an listen to the swoosh sound coming out off the spark plug hole; it sh ould be 3 even swoosh sounds , if you get 2 low ones an 1 loud one then it is a sign of trouble.

911GT2

When I blew an apex seal i couldn't get my car above 40. Getting moving took a lot of clutch slip, and about 4000 rpms. It didn't idle, at all. I had to hold the revs at 1500+ to keep it running. Black smoke and violent UIM shake are also good indicators of blown apex seal.

That being said, your issue sounds more like a MAP sensor than an apex seal. Possibly a cracked seal though, not completely blown.

cruiser

Hmm... why would my vacuum show only 10psi ? It used to show 20psi before.

BoostedRex

Don't you mean 10 in/Hg in vacuum. If you are holding 10psi at idle you have MAJOR issues. Plus, 99% of the blown apex seals I've seen the car WILL NOT hold an idle on it's own. That is one of the biggest indicators. So, it sounds like the line going to your MAP sensor to me as well. Definately check that one out. Best of luck to you. Laterz.

Zach

cruiser

Don't know the exact unit, the autometer boost gauge shows 10units of vacuum when it used to show around 20units before. I will definately check that line to MAP sensor ASAP. Thanks for help guys !

cruiser

And the idle it jumpy between 300-1000rpm, and then it usually settles at 900rpm. Weird thing is that there is power before positive boost but when the boost hits there is just black smoke and the car sputters. Oh well, gotta check the MAP sensor when I get home on weekend.

BoostedRex

That's what it sounds like. What I was talking about a blown seal not holding an idle is it won't stay running at all without you giving it gas. Plus the engine will sound very different. Kinda hollow and alot like a weed eater! My friend blew his 13B-RE and it sounded just like a weed eater. The sound is actually pretty funny, until it's your car making it.

cruiser

It indeed was a disconnected MAP sensor !!
I'm so happy, and also a bit angry of myself for not seeing it before (I was looking at the cables instead of the hose).
Anyway, everything is cool. Even the plugs are fine and idle resettled right after the engine got warm.
Took it for a spin and everything is fine

Thanks a lot !!