I have a 1999 F-350 V-10 4x4 auto that I bought new. I few years back it started making a squealing noise when pulling hills with the engine revving over 4,000 rpm. The noise sounded like a tea kettle starting to boil, it would start out low and work its way up to a high pitched squeal, but the instant the engine dropped below 4,000 rpm it would go away. I replaced the idler pulley, tensioner pulley and belt, but no change.

I noticed a little fluid leaking out of the fan clutch and felt a little movement, so I figured that must be it. I went to the Ford dealer and purchased a new fan clutch that looked exactly the same, but it had no effect on the noise. With the new fan clutch the fan no longer came on and ran for a while like it used to, it now cycles on and off ever couple of seconds at high rpm, causing the truck to jerk back and forth constantly.

I finally figured out that the alternator had some play in the shaft so I took it in and the rear bearing was bad. The shop rebuilt it and that cured the noise, but obviously not the jerking. The next several trips were fine, but this weekend I was towing again and it developed a very loud squeal between every cycle of the fan at high rpm. The fan roars for two seconds then kicks off, then a very loud squeal appears for two seconds, then it goes away when the fan cycles back on. This went on over and over and my wife swore it was some sort of warning alarm because it was so loud.

I finished the trip with no problems but I cant figure out what can be causing this noise. I took the belt off and spun everything, but all sounds and feels normal, and the fan clutch has no play and is not leaking.

Anyone have an idea where I should look?

Thank you, Rick

 

Do you still have the old fan clutch?

The '99 V10, I believe had a 6-rib belt, versus the later years with 8, or was it 8 and 10? Not sure.

Anyway, the '99's belt wasn't wide enough for the fan and the accessories.

That fan clutch cycling so much sounds like something else is up - is the radiator and AC condensor nice and clean of leaves/dirt/crud? Thermostat OK?

It shouldn't cycle like that. Which is why I asked if you still have the old clutch - you might want to try putting it back on and seeing what happens.

Other than that, I dunno... You sure the bellhousing cover isn't hitting the flywheel?

 

Unfortunately I chucked the old fan clutch when I changed it, I figured that since I had to rent the tool to change it there was no point in keeping it for a spare in case of a breakdown. My engine has the wide belt and its the same as the one that came off. The radiator is not blocked and the coolant was changed in the last year, but I do need to change the thermostat. I bought one at the dealer to change when I did the coolant, but when I took it out the new one had a much smaller coolant hole. I went to the dealer and learned they only stock the V-8 thermostats. He claimed they use them in everything and don't have a problem. I figured the V-10 had a larger coolant passage for a reason so I put the old one in. The coolant gage never shows any sign of overheating so I figured it was good, but I'll give that a try next.

The noise only occurrs at high rpm while towing. If I'm running down the highway pulling a grade in 2nd gear at 55-60 mph (4,000-4,200rpm) in hot weather the noise starts after a while, and it's crazy loud, but only between the fan cycling. Once I get back into 3rd gear it goes away, and on cool days I never hear it. It makes the noise if the A/C is on or off. It seems directly related to the fan, but then again I don't know for sure.

 

Its crazy that you posted this cause my truck is doing the exact same thing and im stumped, and my dads just started doing it as well.I have a 02 v10 and he has a 2000 v10. We just got back from a camping trip pulling our trailers up some very steep grades, and my truck would make the high pitched squeal for a few seconds and then go off for maybe 30 seconds. It felt like I would loose a little power when it would start squealing. I have had my truck since it was nearly new and this just started recently. Earlier this year I replaced the belt with a gates one and so did my dad. All pullies seemed to be tight and spinning free. I wonder if swapping to a ford belt would change anything?

 

Try the "cog" style belts, I know Dayco makes one, and Goodyear of course.

Could it be an idler pulley bearing?

 

I also thought about a idler pulley, but I thought if it was a bearing wouldnt it do it all the time? The noise is intermittent. Doesnt seem like the fan clutch either cause it only comes on for a few seconds at a time. It definatley loads the motor more though. I will try the cog belt and let you guys know how it works.

 

I was looking on the Ford Parts website and I searched for parts by entering my VIN. They list two different fan clutches, one is $173, and the other is $312, but there is no description or explanation for the price difference. When I bought a new fan clutch a couple years back it was right around $200, so I'm not sure which one I bought, and I didn't know there was a choice. I know that sometimes the snow plow packages come with a special fan clutch, but my truck doesn't have a snow plow package, so I'm confused why there are two different parts for my truck.