1988 F250 Custom - Highway Noise
 

In short, when I'm traveling over 55-60 mph the motor sounds very labored. Almost like the motor is sucking in too much air or there's something that doesn't close.

Once in a while it sounds like something closes and the labored noise becomes quiet.

Any suggestions on where to start looking for the problem would be a great help.

Thanks in advance

Just a guess but i would check your clutch fan if you have one. The clutch is staying engaged at highway speeds. That would lug your engine

The trucks an automatic. I get a high pitched (metallic) squeak right before the noise happens. If you have other suggestions that'd be great

he means that the engine fan is staying engaged via it's clutching mechanism ... but that would not be noticeable in terms of power . my GUESS is the catalytic converter is becoming randomly blocked/unblocked due to internal corrosion.

it's been years but i did have a vehicle years ago that did something similar to what you are describing. it was the clutch fan engaging (or not disengaging) properly. the clutch was worn out. The squeaking sound you referenced reminded me of it but in my case, it was the clutch trying to grab hold of the fan again at higher road speeds and once it did, the air noise coming from under the hood was tremendous.

changed the clutch, problem resolved.

"The trucks an automatic" BUMP

HI tykebe,

the transmission type of the vehicle is not relevant. I think there is a miscommunication.

the clutch is literally on the fan itself unless the stock fan has been replaced with an aftermarket flex fan. the image link below shows an example. Check to see if you have this on your truck.

http://www.2carpros.com/forum/automo...999_tool_6.jpg

If so, this is what I'm referencing in my post. Hope this helps.

Correct terminology is "fan clutch" not clutch fan.......

Doesn't matter whether the truck is manual or automatic, you still have a clutch fan, that is attached to the engine cooling fan.

I agree that it sounds like the mechanical clutch fan is hanging up. Pop the hood and spin it. How easy does it spin?
Now grab it and try moving it up and down and side to side. Notice any slop? If you do, change it before it destroys the water pump or before it gets bad enough to wobbling that it turns into shrapnel.

joey2fords I should have considered such a possibility. I had a similar noise in a old jeep. When I slow my speed it seems like the debris "dislodges" and the motor runs normal. The noise I'm hearing must be the backed up exhaust.

timbersteel I'll check the fan and give an update.

Thanks 93Ford4x4...that does help. I'll make note to check for the fan clutch