Loud roaring under hood while accelerating | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Loud roaring under hood while accelerating


May 10, 2009
Reaction score
City, State
Year, Model & Trim Level
I just bought an 08 Explorer Eddie Bauer with 17k miles on it. 4.6V8, 6 speed auto, class III tow package w/trans cooler. Yesterday while driving suddenly a loud roaring sound started coming from under the hood when I accelerated from a stop light. At first I thought the trans was slipping and the rpms were running up. I looked at the tach and quickly ruled that out. I pulled over lifted the hood and had the wife rev the engine and the sound was really loud!. It appears to be the cooling fan. The outside temp was 70 degrees and the temp gauge on the dash showed normal. I went to the local dealer and the tech brought his Tough Book and interface and we went for a ride, but the car wouldn’t do it. It was 55 degrees outside that day. He said it may be the fan clutch, but until it happened and I could demonstrate it, he had no answers. It is very disconcerting while driving. This is my 5th Explorer over 20 years. Loved em all, but never experienced anything like this. Any thoughts or guidance greatly appreciated.


Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

Yes, I was running the A/C, but the sound was so loud and was coming from the vacinity of the cooling fan at the front of the engine. Isn't the blower motor in the firewall? I also then turned the A/C off and it still made the roaring sound. There is no way this can be normal.

Everything on the clutch and realated parts seem sound. It's really a puzzler.

Yes, but it is definitely an air noise and it also did it with the A/C off.

Air intake is secure.

Same issue

Hi! I am having the exact same issue with my 07 explorer. Weird. Did you have the fan clutch fixed? I I am bringing it in on Monday to have it checked and want to make sure my guy knows exactly what the deal is. I would love to know the outcome of your own experience. Thanks!!

Sounds like the fan clutch to me. Occasionally they stay "locked" during initial takeoff and then "unlock" as speed increases. If it's an intermittent thing, then I wouldn't get all uptight about it, but if it "locks" and stays locked, then there may be some issues.

FINALLY!!! We figured it out. Bit of a story though. I finally got it to do it at the dealer. The Service Manager, Lead Tech and myself went for a ride. They agreed that the fan clutch was locking up and felt that a simple R&R would fix it. However at the last minute the Service manager decided to call Ford Engineering and he talked to an Engineer who explained that the fan clutch is controlled by the PCM (Module) and that replacing the fan would not solve the issue. He explained that for some reason the PCM thinks the engine is overheating and it is trying to increase air flow through the radiator. Makes sense. However there are no codes showing an overheating problem. Hmmmm…… Upon further investigation it was found that the trans was throwing of an overheat code! I’m not sure why that was not apparent from the beginning. The laptop showed the trans temp at 270!. No way! So up on the lift, and physically check the trans temp and fluid temp. Well, 160 all day long! Turns out that the Thermo Bypass was faulty and was misinforming the PCM that the trans was overheating and the PCM was locking up the fan clutch to pull more air to compensate. Replaced the Thermo bypass and so far problem solved. To do this you must drop the trans pan and remove the valve body as the Thermo Bypass is located in the valve body. Heading up north to Wisconsin camping this weekend, towing my 16’ Aluminum boat so that should be a good test. I think Ford should put out a TSB on this.

That's a good one.

Aloha, Mark

Hi, I just wanted to reply to this post because I have the exact same problem with my 2008 Ford Explorer XLT I have taken it to the Jones Ford dealer and took the mechanic for a ride so he could hear it but he couldn't explain it. So they have replaced the radiator the fan clutch and a bent alt. assembly. but it is still doing it. Help what should I do?

amgreene- take it to Hay Tire in Mt. Pleasant, speak with Greg. They are fixing mine as we speak. I don't know the exact diagnosis as to the problem but they told me it was an easy fix. I will post later today once I pick it up.

Great! let me know when you pick it up what exactly the problem was.

Loud Noise

Same thing is happening to my 06 Eddie Bauer Explorer. When I took it into the dealership, couldn't get it to repeat the problem. Of course it was a cooler day so I'm sure that had something to do with it. I've already had to replace a radiator (big surprise) that was leaking. I want to get this fixed ASAP in case this problem has something to do with causing the radiators to fail. So is replacing the thermo bypass solving everyone's problems? Or would a PCM update calaibration do the trick? HELP!!!

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

Well I started losing a little coolant and it turned out my radiator cap (on my recently installed radiator) was leaking by. I replaced it but the fan kept constantly engaging. Checked the fan clutch and it appeared to be OK (no play and had resistance). My temperature gauge wasn’t showing that high but I did notice it was flickering back & forth real quick, not a huge swing. So I decided to replace my thermostat and that took care of the problem. Drove all the way from Charlotte, NC to Naples Florida with no issues. Went from averaging 17.3 MPG to 19.8 MPG. I’m just wondering why the temperature gauge gave no indication of a problem. Possible a bad temperature sensor.