fabfoes87 Posted December 30, 2010 Share Posted December 30, 2010 Had a wierd one yesterday. Cust comes in says he has a very loud and annoying whistle noise coming from the engine compartment when driving. At first I alone heard nothing but after a 2 mile drive with the customer, noise made itself clear. It sounds like a turbo spool on psd, but will go away when throttle is adjusted slightly. So I droped the customer off and B man and I made another drive to figure it out. We could get the noise to happen when slowly taking off and heading up a hill. Noise creeps up and is most prevelent in third gear. Very high pitch whiste. So back in shop, decided to smoke intake and maybe find any type of leak that may be causing noise. Smoke test ok, no leaks. Upon a more in depth visual, I found that RS Exhaust manifold had 2 broken studs on cyl 4. Our theary is that exhaust gasses leaving cyl, and causing the gasket to act like a reed valve causing noise. Ordered manifold and hardware, day off today but hopefully tommarow Customer will have a quite truck. I know it's late to ask now, but has anyone heard of this type of noise before? Thanks guys. Quote Link to comment Share on other sites More sharing options...
Adam_Dodson Posted December 30, 2010 Share Posted December 30, 2010 I know the alternators like to make a metallic squeal when it's cold out. Replaced the alternator in my truck a few winters back which only fixed the noise for about a month then the replacement started to make the same noise...now I just live with it.. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted December 30, 2010 Share Posted December 30, 2010 What Adam said.... and yes, we only ever see it in the winter. Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted December 31, 2010 Share Posted December 31, 2010 Yea, working on an 04 e350 5.4 with a noise at idle- think it's refered to as whooping or hooting and caused by the iac snorkel getting cracks on the inside or somthing-seen this on towncars. Also this bus has 240+ miles on it and there's 1 busted stud on the exaust manifold and i'm leavin it alone. I've done them on expeditions and navis and there pretty easy but never did one on an eseries and it looks pretty tight to do plus all that milleage on it. Quote Link to comment Share on other sites More sharing options...
cbriggs Posted January 7, 2011 Share Posted January 7, 2011 I've had broken exhaust studs on a 6.4 create a reed effect with the gasket, sounds like yours, only squeal on slight accel,at exactly the right load, usually after a long coast down. Quote Link to comment Share on other sites More sharing options...
fabfoes87 Posted January 19, 2011 Author Share Posted January 19, 2011 Sorry for the long awaited update. Exhaust manifold was installed on my day off and tech said he heard nothing out of the ordinary. Of coarse I was concerned because he had no idea how to recreate the noise, but I was optimistic. A couple weeks go by and customer had not been back. Well on monday customer returns and says noise is still present. I had been anticipating this and was planning to atack the alternator first. I hooked up the chassis ear directly to the alternator and the intake. Go on a test drive and recreate noise. Through the headphones, can hear noise gradually come up and intensify about 10 seconds before noise enters cab. The noise was always heard through channel 1 which was directly on the alternator itself. Nothing from the intake. Back at the shop installed new Alt. and test drove again. Could not get noise to return. This concern seems to be poping up all around our shop. Another tech has the same noise on 5.4. I would like the members of DTS for their input, becaue before I posted this topic, I had no direction to take after the exhaust manifold. Thanks for the help fella's. Quote Link to comment Share on other sites More sharing options...
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