cygnusx1 Posted July 18, 2007 Share Posted July 18, 2007 Last night I was driving around with a slightly modified tune in the MS. Nothing major just a little richer in the cruise range. The car was running very well. I started hearing a faint psstt psst pssst pssst under light and medium engine load. It was so faint it was probably half as loud as ping. Then it started to get louder and sound more like a peep peep peep peep, now it's an all out squeal squeal squeal at the frequency of the engine under load. It only does it under light to moderate loads. I didnt try it at full throttle because I didn't want to damage whatever it is any further. It sounds like a loose belt or a rubber ducky squeek when I load the engine or rev it in neutral. It almost sounds like a dry bearing squeal or a bird caller. Any ideas? It sounds like it's coming from the left side of the motor down low around the turbo area. Wastegate? Intake gasket? Exhaust Gasket? I checked all the hoses already because that was my first guess. I will try to get a recording of it tonight. http://album.hybridz.org/data/500/Mouse_in_the_Z.avi Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted July 18, 2007 Share Posted July 18, 2007 Are you running A/C? Not sure about what could be making that turbo noise... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 18, 2007 Author Share Posted July 18, 2007 Yeah the car has AC. But it's definielty an engine load related sound...or maybe something metal that is loose which vibrates and squeaks with engine vibration. It's weird. I have heard exhaust manifold leaks before but I never heard one that chirps. The noise is not the belts but it's a similar squeak. Have you ever heard the WRC cars squeak when they go by...that's sort of what it sounds like. Here: have fun watching this...lisen for the squeak. Thats what mine sounds like only mine squeeks under load all the time. http://www.youtube.com/watch?v=hMSBNm4mmQs Quote Link to comment Share on other sites More sharing options...
Warren Posted July 18, 2007 Share Posted July 18, 2007 I'm gonna go out on a limb here and say "idler pulley bearing"...probably wrong, but often overlooked. Warren Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 18, 2007 Author Share Posted July 18, 2007 Good guess. That crossed my mind too but it's definitely not coming from the front of the motor. It's more under the intake manifold towards the firewall. Tonight I will scope it out with a piece of hose and my ear. I wonder if a stuck wasegate puck could whistle like that? I will try to manualy move the wastegate tonight. The problem is that I can only make it chirp three or four quick chirps by reving the motor in neutral. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted July 18, 2007 Share Posted July 18, 2007 I have the same sound! Sounds like a bird, have no clue what it is. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 19, 2007 Author Share Posted July 19, 2007 OK Here is a video of the squeaking. The engine sounds a lot noisier in the video. It's actually a very quiet motor with the hydraulic head. The squeaking sounds like it's from under the intake manifold. http://album.hybridz.org/data/500/Mouse_in_the_Z.avi Any Idea? Quote Link to comment Share on other sites More sharing options...
rags Posted July 19, 2007 Share Posted July 19, 2007 Dave, where is the BOV? Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted July 19, 2007 Share Posted July 19, 2007 Cygnus, I dont know if you are running a new turbo that is larger than before your upgrades, but I had a similar noise once when I changed to a larger turbo. The compressor housing was only a 1/32 of an inch away from the exhaust manifold when mounted. I let it run as is and it would squeak when I drove it. Turns out the cast iron manifold expanded enough when warm to just barely rub the compressor housing causing the "tweety bird effect". A 3/8" stainless turbine housing spacer cured it. When I removed everything the to inspect what the noise was, the right side of the compressor housing was polished to a near chrome finish from the rubbing. Just a stab..... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 19, 2007 Author Share Posted July 19, 2007 The BOV is way up front on top, it's quiet. I thought of listening to that also. I have had the TO4B compressor on there for over two years and the squealing just started yesterday. Could be, but it sounds a little more related to engine pulsations. Quote Link to comment Share on other sites More sharing options...
strotter Posted July 19, 2007 Share Posted July 19, 2007 You know, rod bearings make a chirp-chirp-chirp sound before they completely fail... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 19, 2007 Author Share Posted July 19, 2007 I hope that's not it. I want to finish off the Summer driving the Z. It only squeaks under particular load conditions. You can hear from the video as the MAP approaches atmosphere it squeaks. I need to do some more test driving and I will pull the pipes off the turbo, spin it by hand and feel for play in the shaft. If that's not it, I guess I will start removing things one at a time until I see something strange. I also thought it might be a loose injector seal passing air but that wasn't it either. Miffed!!! Quote Link to comment Share on other sites More sharing options...
jt1 Posted July 19, 2007 Share Posted July 19, 2007 All the spark plugs OK? edit- Probably not, wrong side of the motor. jt Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 19, 2007 Author Share Posted July 19, 2007 What's the consensus? Does it sound like an air leak or a mechanical squeak? I can't seem to pinpoint this. Knowing the difference would make attacking the problem different. Maybe I will put my foot on the tailpipe to see if exhaust pressure will make it squeal. Although my gut feeling is still either a wastegate leak or intake leak.... I stood on the otherside of the motor and the noise is definitely coming from the manifold side towards the middle rear of the engine. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 20, 2007 Author Share Posted July 20, 2007 OK I think I got it. I tightened down the bolts under the intake manifold and the last one, the easiest one near the firewall was pretty loose. I also checked the turbo flange bolts and the intake port blocking plates I made. I wiggled the wastegate to make sure the puck was seated and started the engine. The noise was no longer there. I let it warm up and reved it pretty hard a few times and I can barely hear a tiny faint sound. So basically, what sounded like a squeaky metal part, I think, ended up being a leaky exhaust manifold gasket. I cant drive it tonight because the roads are a mess from all the rain we had. Hopefully, the gasket makes it through the Summer and I will rebuild the whole motor over the Winter. Quote Link to comment Share on other sites More sharing options...
strotter Posted July 20, 2007 Share Posted July 20, 2007 Thank goodness it was a gasket noise! I was dreading opening this thread this morning ... when you described the noise early in the thread, I had that cold-in-the-gut feeling you get when some huge problem looms - and the "chirp chirp" thing reminded me so much of bad noises I've heard under my own hood. Glad I was wrong about the bearing! Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 20, 2007 Author Share Posted July 20, 2007 Yeah, I never heard any gasket leak that sounded like that. Usually it's more like a steam train or a knock sound. This was clearly a squeal. Quote Link to comment Share on other sites More sharing options...
zcarnut Posted July 20, 2007 Share Posted July 20, 2007 Yeah, I never heard any gasket leak that sounded like that. Usually it's more like a steam train or a knock sound. This was clearly a squeal. Fairly common to have a vacuum leak which "squeals". At the engineering lab where I work the techs find vacuum leaks with an ultrasonic detector: http://www.uesystems.com/why_up_apps_leak_detection.asp Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 20, 2007 Author Share Posted July 20, 2007 Ultrasonic? Maybe that's why I never heard them before.... I learn something new every day. Thanks. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 20, 2007 Author Share Posted July 20, 2007 OK update. I went for a test run this afternoon and the squeek is still there but not nearly as loud. That tells me that the gasket is shot and/or the manfold is warped enough to leak. One of the hydraulic lifters began intermittently ticking again, and there is a tiny tiny bit of oil smoking off the turbo center section. All in all, it's running great but I am not sure for how long...the engine pull and rebuild has just gotten much higher on my list of priorities. It's about a year sooner than I wanted, but I can make it happen this Fall. Quote Link to comment Share on other sites More sharing options...
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