My 2000 F250 has 170k miles on it. It's all stock except for aftermarket air filter and air box. I was on the hiway at 65 mph today when suddenly the engine noise got about 20% louder then usual. I was going up a slight hill, but not enough for the auto trans to kick down out of overdrive. I hit the gas and the turbo pressure gauge jumped to about 12 psi, which is normal, so I don't think I blew a turbo boot or pipe.

Got home and popped the hood and stuck my head in the engine compartment. There is definitely a louder noise then usual. On the driver side engine compartment there is a hollow, low noise, which sounds like it's part of the exhaust noise. Can't really hear it on the passenger side. I checked the turbo boots and they seem tight and intact. I felt around and couldn't feel any exhaust "wind" caused by a cracked exhaust.

Any ideas what I should be looking for?

Thanks!

 

Noises have a funny way of sounding like they are one place when they are some place else. Is it a whiring noise? How does your fan clutch feel?

 

Where are you located...as temps started warming up this week. Forgive the silly obvious question, but are you sure it wasn't the big fan just kicking in for the first time this year? Mine hasn't ran all winter, but I know when it does it's an obvious boost in noise.

 

Thanks for the ideas. I'll look around closely, even where I don't hear the sound. The sound isn't whirring, it doesn't sound rotational. More like a booming type sound. My first impression is a low pitch exhaust related sound.

How should the clutch fan feel?

sawaxeman - good idea on the temps, I suspect you are located in the cold part of the country. I'm in California and it's been a very mild winter - been in the 60's a good portion of the "winter".

Another site suggested up pipes and/or donuts, manifold bolts and ebpv. I'll check all this stuff out when I get home tonight.

Thanks!

 

I'm in Indiana where we just got out of a two month DEEP freeze. So no fan kicking in for me, haven't seen the truck truly warm up a single time this winter, and got the hear the EBPV a LOT! But she does start like a champ in sub zero temps without being plugged in so I'm pleased with that.

 

Maybe an up pipe gave out? If it's exhaust noise the damage should be visible, just gotta lay down some cardboard and roll around awhile.


Also inspect the air filter. What kind is it?

 

Well, I looked closely for soot around the up pipes and on the firewall and saw nothing. Hooked up a pressure cap for the turbo and didn't find any leaks. Looked closely all over the exhaust manifolds and saw no problems. Crawled around under the truck with a bright light and saw nothing unusual in the exhaust. Unhooked the EBPV wire and made no difference. Fan seems to spin about right - when I shut off the engine it will slowly come to a stop. Now I'm wondering if I'm just imagining things! I don't notice any loss of power.

These trucks are loud, and I could have sworn it suddenly got a bit louder - kind of like my ears popped, but I wasn't changing elevation. I guess I'll just put some miles on the truck and see if I notice any problems. Glad I don't have to mess with the up pipes - sounds like a challenging install!

Thanks for the suggestions.

 

V-clamp still tight on the down pipe? And is there any soot around the weld for the flange on the downpipe? My cousins 97 cracked out around the weld for the flange and it started makin a pretty good bit of racket at 60-65 mph.

 

Your description still sounds like the cooling fan spinning up to me. It's quite a noticeable difference in volume when it is engaged. For me....I may or may not notice when it happens. All depends on how "zoned" my mind is or is I am cranking the tunes. Could be why it was a strange sound to you that you haven't heard before - or in a while? Just speculation on my part.

 

Do you have a scan tool that will tell you your oil temp? Your timing will change depending on oil temp. If the truck thinks the oil temp is too low your truck will suddenly get louder. It has happened to me a couple times. Scared the crap out of me.