'03 F250SD - hiss during acceleration???

ttabol · #1 (**permalink**) 07-05-2008, 04:16 PM

Just got a F250SD with V10. During acceleration from stop, I notice a "hiss" which seems to come from the engine compartment if I'm not either going really easy or pushing hard. It almost sounds like a blow-off on a turbo motor. Any thoughts? Thanks!

Bulldog66 · #2 (**permalink**) 07-05-2008, 09:57 PM

It's that V10 telling you it wishes it was a PSD.

ttabol · #3 (**permalink**) 07-05-2008, 11:15 PM

It might just be! I wish it was but couldn't pass up the deal.

i eat hybrids · #4 (**permalink**) 07-06-2008, 02:19 AM

Does it only do it when it is cold? If so, then ur missing a stud on ur exhaust manifold.

ttabol · #5 (**permalink**) 07-06-2008, 09:03 AM

Actually, it seems to do it more when it is warm. It occurs most often between the 2nd to 3rd shift.

carls 250 · #6 (**permalink**) 07-06-2008, 05:01 PM

Are you sure you don't have a cat. plugging?

ttabol · #7 (**permalink**) 07-06-2008, 11:28 PM

I'm not sure about the cat...there seems to be no performance issues, no over heating, nothing else strange, just the weird noise which is clearly heard from in and outside of the truck. If I back off the gas just a bit or push down just a bit it goes away???

rebelyell618 · #8 (**permalink**) 07-06-2008, 11:40 PM

i'm going to watch this cause my 5.4 did the same thing (or something similar cause i had a high pitched hissing sound) friday. it only happened once when i was doing 60 mph once i pulled off the road the sound went away and hasn't occured since.

wierd thing is i just changed from 5W30 motorcraft oil to 5W20 motorcraft oil on thursday so wonder if that has anything to do with it.. wouldnt think so but the only other new part with me is a goodyear gatorback belt and a carquest air filter. i doubt that is the cause.

ttabol · #9 (**permalink**) 07-07-2008, 08:06 AM

A saw a post via Google that suggests checking out the air filter/assembly. I'm going to try and look at this tonight...
Rebel - maybe it is the air filter?

sportscar · #10 (**permalink**) 07-07-2008, 08:08 AM

My 04 V10 does that...since new, even with a new air filter.

5.4L to Freedom · #11 (**permalink**) 07-07-2008, 09:07 AM

My 5.4 does the same thing, I think it's just the nature of these beasts... just cam noise, fan, tiny exhaust manifolds, and air intake assembly all working together to make a unique sound.

Keep in mind if you have the stock intake you a pulling a reasonable volume of air into that motor thru a relatively small tube, and as the air is pulled into the intake tube it's going to make noise, plus the high velocity of the air over the flex section will make noise too.

I would only get concerned if the hissing all of a sudden stops while it's running

ALSO the alternators make a bit of noise as they age, not to say it's goign bad, but that makes a bit of hissing as well

Crummy 450 · #12 (**permalink**) 07-08-2008, 01:43 AM

I had a small seal not seat correctly on the intake air temp sensor in my Saturn, and it caused that same kind of hiss. I've had a similar issue with my van too, though it was a small crack that formed in the intake tube causing a whistle. Check your intake tract over carefully for any leaks. If you do find one after the MAF, you should sort it out pretty quick, as it may give you grief.

i eat hybrids · #13 (**permalink**) 07-08-2008, 10:43 AM

If it doesnt do it when its cold then u dont have an exhaust leak. Someone on here a while ago mentioned somtnhing about the heat shield on the y pipe movin around. Does this sound plausible?

ttabol · #14 (**permalink**) 07-09-2008, 01:47 PM

Actually, I could be. I call it a hiss but a vibration on that thin metal could produce a similar sound. I'll give that a check. Thanks!