hey all,
i've got a '99 Lariat Supercab w/ the 5.4L engine and 78,000 miles. just recently, i have noticed an excessive whine coming from the engine compartment. i opened the hood and the noise seemed, but i am not for sure, to be coming from the intake manifold area or near the serpentine belt. any suggestions?? i am driving here in southern texas where the temperatures are a cool 100 degrees, but i get the feeling something may be giving up on me. thanks for any help you can give.

 

Sounds like it could be your alternator, mine gave out and i found it makes quite a bit of noise.

 

get a new PCV, that should solve the problem. What you are hearing is back pressure from build up of HCO. Your PCV is either stuck or defective. Let me know how it goes with it...

 

Oh and could just be the belt too, they do that sometimes.

 

thanks guys for the quick and helpful responses. took the alternator to get tested and it seemed to be fine (13.97 volts charged back to battery). PCV valve i will replace, and i will check the belt too. thanks again.

 

Does the whine seem to change with RPM's (does it get higher pitched as the RPM's climb?) . . . I've noticed a smiliar noise on mine and was wondering what it was as well. You can hear it in the cab but it doesn't sound like it's coming from the alternator. Only noticeable at low speeds . . . haven't really noticed anything wrong with driving, charging, etc.

Maybe I'll check out the PCV valve on mine as well. Mine is a 97 4.6.

 

mechanics stethoscope, very useful tool.

 

Check the power steering. Mine has a slight leak and it whines. Turn your wheels from lock to lock a few times to bleed the system. That may cure it for a while.

Regards

Jean Marc Chartier

 

if the noise disappears when you hit the gas and only noticeable at idle, try replacing PCV. I had this problem for 2 weeks until I repalced it then noise was gone. During this problem, I replace plugs, check COP's, replaced air, fuel filter. The idle is great too, when you have defective or bad PCV, all those extra HCO has no place to go but to leak out via gaskets, or injector port. This is what I think you are hearing (irregular hissing/buzzing noise at low rpm or idle condition--along with little rough idle). This problem will not result in engine light either. Anyway good luck.

 

Maybe the idler/tensioner pulley?

 

Hey man, I have a 2000 F150 4x4 with a Triton 5.4L and mine has 68111 miles, and my dads has 113,000 miles, and ours dont whine when they hit any amount of RPMS, but my brother has a 99 modle 5.4 and his will whine when he hits about 3000+RPM's. THere is nothing wrong with your truck, it is just the 99 modle engine

 

I wholeheartedly disagree.

 

My 98 5.4 w/ 74k whines between 2350 - 2475 RPM. I have tried to reproduce with the hood up, but I can't hear it. I will try the PCV, but I am guessing it is something to do with the intake. (IAC, MAF, etc.) I've never cleaned any of that stuff, but the IAC was replaced about 1year ago... PLEASE let me know if you solve the problem, or if you think we have the same problem.

Thanks,
Jim

 

My whine was the fan clutch. I found it because every time I turned the engine off I would hear the whine for a second or so after the engine shut down. I could see the engine stop turning but the whine cycled down for a second. The only thing still spinning for a second after the engine stops turning was the fan clutch. I took it off and it was shot. I replaced it with 2 different brands of replacement fan ($70.00 each). Both were locked up most of the time and I could hear the fan really blowing loud and there was a lot of power being robbed. I bought a junkyard clutch for $35.00 and returned the other 2. No problems with the junkyard clutch.

 

hey davet, im not to familiar on the fan setups, how can you tell if the clutch is working or not?