Alright guys, here I am again. Been super busy lately so I have been away for a while. And now, I have a major problem once again.

99xk8 has a horrible idle. Loud hissing from intake manifold; sounds like the sound is coming from the inside. Being my paranoid self, I took the valve covers to make sure my cams were still aligned after I did my tensioners a while back, and while they are damn close, they are not perfect, but I don't think that miniscule of a difference would cause problems.

So, I'm driving over to my "Semi-friend"/mechanic and get there as he is closing up his shop. I caught him right before he left, and it seemed like he wanted to get home and get rid of me, so he quickly popped the hood, heard the hissing and said I have an internal crack in the intake manifold!? WTF? He advised me to bring it back in the morning and he can have a better look. I told him my cams were not 100% lined (as in I took a straight edge and placed it over the two cams and they were very slightly off. He said that would not make a difference and there was some tolerance in the timing

So, anybody heard of an internally cracked intake manifold? I sprayed carb cleaner everywhere around the vicinity of the leak, but no change in idle. I know it is not the intake manifold gaskets because I just replaced them 2k miles ago, and again, when spraying carb cleaner around the gaskets, no change in idle. Really actually does sound like it is coming from the inside.


ANy experience? Help? BTW, I havnt driven my car for a few weeks; my cousin has been driving my car while his is in the shop, and he is telling me it happened out of nowhere. Unforunately, I can only go off what he is telling me.

 

There have been reports of cracked manifolds, especially on the R. Apparently caused by a back fire into the intake. No details, just memory of reading posts.

 

I am not sure what sound, if any, an internal crack in the manifold may make; however, the hissing sound around the intake typically is air being pulled in or escaping from outside the designed air induction system. Since you have recently pulled the cam covers for tensioners and replaced the intake manifold gaskets, possibly a gasket or grommet slipped, was "pinched", or defective when reassembling, resulting in an air leak. I would be inclined to check the torque on the intake bolts. If the hissing persists, you may have to remove the intake again, inspect all contact points between intake and engine, possibly buy a new gasket set, and reassemble making sure all torque specifications and sequences were, once again, met. You made the comment you sprayed around the leak. Did you isolate the leak? Is it near a gasket, grommet, or where a hose may be fitted? Sometimes, with engine running, one can slightly loosen intake bolts one at a time and isolate the leak.
Hope I have, at least, provided some thought starters.

 

I have to ask this, did you check all the bolts, to make sure they are tight?
It is not unheard of, for bolts to back out or for gaskets to compress after insstall and allow leaks.
Did you use lock-tite and recheck all bolts after install of gasket?

 

thanks for all the advice. I was unable to isolate the leak with the carb cleaner. Made no difference anywhere, and I did spray absolutely everywhere. Checked all the obvious points of bolts being tight, fitted properly, etc. It is obvious that the hissing is coming from inside the manifold (sounds like a regular vacuum leak, but inside the manifold). Anyhow, I went to my mechanic this morning who thought he had a spare manifold for my car to test if this was the problem, however his was from a 98, and apparently the design changed in 99. Bummer, now I am on my hunt to locate an intake manifold cheap. I'll let you guys know if this was the problem.