Is my Intake manifold leaking Exhaust gases?
 

I decided I couldn't take the exhaust leak anymore and began removing parts until I found it. After I pulled the exhaust manifold I found no evidence that any part of the exhaust/turbo system was leaking. I did notice what appears to be a ripped intake manifold gasket (see picture). Is the exhaust routed back up thru the intake for some reason? Do I have to pull the UIM to replace this gasket?

http://img156.imageshack.us/img156/3...219acc5.th.jpg

yes it is, but I can't tell you why. Mine was leaking there too. Stupid paper gasket. The new mazda ones are much better. There is a port to the LIM from the rear rotor housing if I remember right. Interacts the the ACV valve for something. You can be sure it has something to do with emissons.

Terry7

soot
 

yes manifold has to come off. Sorry. all that black stuff is blown out by boost. So you can imagine what your losing. I'm sure it allows vacum in too.

Aww...crap, I was afraid of that. Oh well, maybe I'll polish the intake while I have it off. I'd love to remove everything emissions related, it's caused lots of problems for me.

the intake is not causing that. you have an exhaust leak. the lim may be leaking but it is not what caused the black sooty build up

I took the entire exhaust/turbo system off and did not find anywhere that looked like it was leaking. Believe me I want it to be the exhaust since it's already off but I can't ignore the ripped LIM gasket. If the exhaust is routed thru the LIM in the area where it is ripped then that has to be where it is leaking.

is the egr valve leaking??

No, it looks rather soot free. When it was running you could hear the leak real well so it sounded like a big leak.

If I have to take the LIM off is there anything I should check/replace while I have it off?

IF you have a vacuum leak (ripped intake gasket to a good extent, bad vac. lines, etc) you would have noticed it before this. Your turbo spool would be negatively affected, your boost pattern would not be 10-8-10 etc, but lower...

You *cannot* have an exhaust leak thru the intake. It is impossible. But anyhow, while you have the turbos and manifold off..replace everything you can. All gaskets, vac. lines, block off EGR, remove all emissions, etc...you'll thank yourself later. Clean up that engine, too :-)

But yeah..exhaust leak. Crack in the manifold? Turbo hotside? One of your exhaust gaskets may be bad, or maybe one of the bolts was just not on tight enough. Even a *slightly* loose bolt will cause a major exhaust leak.

i would think about replacing the fpd while i was there. maybe the omp lines (not to much more work) if they look pretty haggard. if you do the fpd get new injector grommets for the primaries.

it still looks like an exhaust leak to me from the pics. check the turbo housing under the heat shield to see if they are leaking. did you remove the gasket from the engine and check the other side?

I checked everywhere on the exhaust, turbo, and all the gaskets. I thought for sure it was the exhaust manifold gasket but it looks perfect. I know for a fact the LIM gasket is ripped you can see it in the pic so I was thinking there is a path in the LIM that the exhaust gases are flowing thru, for some emissions reason like sevensheaven said, that is not mixed with the intake charge and is not effected by boost pressure. Car ran perfect before tearing it down I was still getting full boost pressure according to the gauge, which didn't make sense to me at the time. In sevensheaven's pic you can see a 2 rectangular ports one in between and above the exhaust ports and a smaller one to the left of it. My LIM gasket is blown out right below these ports. I think these are exhaust ports going into the intake.

Here I circled them in sevensheaven's pic

Ok, my bad on the loss of boost or vac leak. The areas circled are in the same gasket, but are seperated from the rest of the intank trac.
This is where the exhaust comes from, the irons have ports that match up with the rotor housings. If you look at the small circles below the rotor exhaust ports those small circles port exhaust up through the iron housings the LIM. I have pics of mine when I tore it down at home and will try to post them tonight. I was wondering about these since I had the same exhaust leak my self and changed out the DP gasket several times trying to fix mine.

had the same problem on mine thought simple down pipe leak and turned into major job,there is a small exhaust prt under the lim, right in that corne,r the new gasket from malloy does not have that port open in the gasket and closes it off,that gasket corner wont blow out now!

I pulled the LIM and it was leaking. So anyone with a mysterious exhaust check your intake.

It's great to be able to help! Oh and I figured out why we have those ports. EGR valve!