Loud roaring under hood while accelerating

I have a 2006 Explorer (Eddie Bauer) and I have visited the dealership 7 times. The first two visits resulted in a replaced radiator and then I had to return because they did not replace the thermostat. That was 5 visits ago. The last visit was last week which resulted in a new viscuas fan. I have 51K miles and I juat cant beloeve that the roaring noise that I have been hearing is normal. I have been told that the noise is the fan, I assume this fan is also called the viscus fan or fan clutch, this fan is clicking on to cool down the engine. The funny thing is that it only clicks on when the air or defrost is on and hot outside. It is so loud! It sounds like an air plane taking off. After it shifts to second gear, the noise stops. But, once I stop at a light and accelerate, it roars up again. I am so discouraged right now. I had a 2002 Explorer and had no problems, so I bought another one, but I bought this one used.
Are there any suggestions as to what I should do?

Good luck with that! I have been told numerous fixes for this problem. I had the same issue. When it firsts started I was losing coolant so the radiator was replaced (at 36k miles). Then it started up again a few months later. I decided to replace my thermostat and that took care of the problem for me. You're right, mine sounded like a jet taking off!

Loud roaring under hood

I too just purchased a 2008 Eddie Bauer 4.0 with 41,000 miles, and I am also having the same roaring problem. It only does it in the heat of the day. In the mornings, evenings and night I don't have any problem. However, in the middle of the day idling through a parking lot, or taking off from a red light it roars bad. Once I'm out of low gear it's fine. I have no coolant leak and the temp gauge stays in the normal range. I have not taken it back to the dealer yet. Think it's worth trying a thermostat first?

Thanks! Bill

I have had this exact same problem for several years with my 2003 XLT V8. Only does it during the hot summer 70-90 degree outdoor temp with the A/C on. Or cold start up. Dealer can't find anything wrong. What was your final outcome Lessor2 on the camping trip?

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. Problem solved.
Dave

LESSOR2 said:

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. Problem solved.
Dave

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Is this a fairly simple procedure, to replace the thermo bypass?

I believe they dropped the trans pan, removed the trans filter. Not sure if they had to remove the valve body. For me it was under warranty so I didn't pay to much attention to the details.
Good luck,
Dave

Loud roaring under hood while accelerating -potential to mis diagnois

Here is a little updated info for anyone who may have this problem or hear of someone that does. It can indeed be the fan clutch. Most overt the counter manuals tell you when the engine is cold (vehicle off) the fan should turn easily 1 to 1 1/2 turns if the fan clutch is good, and with the vehicle warm (vehicle off) the fan will turn with more resistance. I found THIS NOT TO BE NOT TRUE. I went to the auto parts and tried to turn a new one and it was as stiff if not stiffer than the one that was on my truck. Because this noise occurs from take off to about 30 mph I took my belt removal / replacement tools out into a parking lot, removed the belt, started the truck and made a QUICK test drive that lasted about 30 - 45 seconds (do not overheat your vehicle). There was no noise at all. I replaced the fan clutch and the problem is solved. I would not rely on the statement that the fan should spin easily when the engine is cold as an indicator of weather this part is bad or not. If I had relied on this information and not dismissed it based on checking the new fan clutch at the auto store I would still have a truck that sounds like a fighter jet or freight train when taking off from a stop light.

SNO...

So ultimately, you replaced the fan clutch and the belt, and it stopped?

Yes, that is correct. I got a new fan clutch from the auto parts ($62.00) R&R'ed it and put my belt back on. The whole job took about 45 minutes total including getting out and putting back the tools. This is a very simple repair.

Good luck,
Sno

Thanks for all the info in this thread. I just got a used '06 XLT with 36,500 miles. It started doing this same noise and I immediately started searching for an answer.

This is all great information- I just don't know which avenue to pursue. I'm not sure if I should take all this info to a deal and have them check it out or what. I don't have any warranty so it's all on my dime.

If I knew what it was, I'd have no problems doing it myself. Going into the tranny would be a first for me but I think I could handle it.

I hope it's not the tranny overheating though!

I would start by checking the fan. It was a difficult diagnosis. I do not know you level of expertise but you could start with a cold engine, remove your fan belt and start your car for a very short time, about 45 seconds then you should be able to tell. I quickly drove down my block to verify. I am not reccomending that you drive because I dont know your circumstances, but in any case do not put your engine at risk of overheating! If the noise stops when you do this you know its the fan.

Sno

snorida said:

I would start by checking the fan. It was a difficult diagnosis. I do not know you level of expertise but you could start with a cold engine, remove your fan belt and start your car for a very short time, about 45 seconds then you should be able to tell. I quickly drove down my block to verify. I am not reccomending that you drive because I dont know your circumstances, but in any case do not put your engine at risk of overheating! If the noise stops when you do this you know its the fan.

Sno

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Thanks- I like to think I'm pretty good.

However, I'm not sure if your situation was different than mine, it sounds like it might have been. Let me explain further and we'll see if we can meet in the middle. It sounds like you have a good method to troubleshoot, but my problem is intermittent. I guess I failed to mention that, however I believe others seemed to. Was yours constantly making the F16 takeoff noise? Mine has only done it a few times. I'm not sure if it was temp related, but it met the other parameters described- low speed, stopped after 2nd gear, scared the crap out of me, etc.

So unfortunately at this point I don't believe that removing the fan belt will help, unless it gets worse and happens reliably... Though I could be wrong!

Thanks again!

Mine was more regular- not intermittent, however the funny thing was that it stopped all together for about 2 1/2 months after I towed at high speed and high load. This really confused me. Once it started again I vowed to fix it, and so my test and success. I do agree that if you can wait until it exhibits the behavior you can be satisfied that you have found it. Let me know how you turn out.

Well good news or bad, I have more data. I don't think it's heat related. It was 28 degrees this morning and happened in the first 5 miles of my commute (after warming up though). Oddly enough, it was at 40 mph, so I'd think it was out of first gear. I have the 4.0L 5 speed tranny btw.

It happened a couple times, then stopped. Was fine for the reaming 30 miles.

Ford has tsb 07-10-12 for pcm update for various concerns including fan noise on startup and during ac operation. Printable View (48 KB)
TSB
07-10-12 VARIOUS DRIVEABILITY AND A/C PERFORMANCE QUALITY SYMPTOMS - 4.6L 3V 6R60 EQUIPPED VEHICLES ONLY

Publication Date: May 14, 2007

FORD: 2006-2007 Explorer
2007 Explorer Sport Trac
MERCURY: 2006-2007 Mountaineer


This article supersedes TSB 06-23-11 and 07-2-8 to update the Service Procedure.

ISSUE:
Some 2006-2007 Explorer/Mountaineer and 2007 Explorer Sport Trac vehicles equipped with the 4.6L engine and 6R60 transmission may exhibit various driveability and A/C performance quality symptoms.

ACTION:
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

Apply reprogram to 2006-2007 Explorer/Mountaineer and 2007 Explorer Sport Trac vehicles that may exhibit the following symptoms:

SYMPTOMS

Cold hesitation/surge
Long crank
Engine fan noise on cold start and A/C operation
High idle during warm up (cold engine)
Inaccurate Message Center average fuel economy estimation
Overheat indication at idle in gear in high ambient temperatures
A/C shutoff at idle in gear in high ambient temperatures
Lower than desired RPM during long deceleration
Install IDS or equivalent and ID the vehicle.
Update the PCM and TCM calibration using IDS release 48.13 and higher or 49.2 and higher. This new calibration is not included in the VCM 2007.5 DVD. Calibration files may also be obtained at www.motorcraft.com. Since the TCM cannot be reprogrammed alone, reprogram the PCM/TCM together to ensure that both engine and transmission calibrations are updated to the latest level simultaneously.

WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.

OPERATION DESCRIPTION TIME
071012A 2006-2007 Explorer/Mountaineer, And 2007 Explorer Sport Trac 4.6L Engine, 6R60 Transmission: Reprogram PCM And TCM (Do Not Use With 12650D) 0.6 Hr.

DEALER CODING
BASIC PART NO. CONDITION CODE
recal 04

--------------------------------------------------------------------------------

NOTE: The information in Technical Service Bulletins is intended for use by trained, professional technicians with the knowledge, tools, and equipment to do the job properly and safely. It informs these technicians of conditions that may occur on some vehicles, or provides information that could assist in proper vehicle service. The procedures should not be performed by "do-it-yourselfers". Do not assume that a condition described affects your car or truck. Contact a Ford, Lincoln, or Mercury dealership to determine whether the Bulletin applies to your vehicle. Warranty Policy and Extended Service Plan documentation determine Warranty and/or Extended Service Plan coverage unless stated otherwise in the TSB article. The information in this Technical Service Bulletin (TSB) was current at the time of printing. Ford Motor Company reserves the right to supercede this information with updates. The most recent information is available through Ford Motor Company's on-line technical resources.

Copyright © 2007 Ford Motor Company

swetrid said:

Ford has tsb 07-10-12 for pcm update for various concerns including fan noise on startup and during ac operation.

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...

swetrid said:

4.6L 3V 6R60 EQUIPPED VEHICLES ONLY

Click to expand...

Thanks for this information swetrid! Unfortunately for me, I'm not included in the lot since I have the 4.0L and 5 speed. :roll:

Looks like I'm back to on my own- I felt very hopeful when I saw your post come in on my phone- ironically while driving home from work and having the fan blasting.

mine hadnt made the noise for about 2 months, until i heard it today. weird... i dont know what to do. i ran my car for about 5 mins and then turned it off and by hand tried to move the fan and it was turning quite easily.

the information on how easy or hard it turns is very subjective and deceptive. I tried this method several times over the course of a couple of days... tried turning with a cold engine first thing in the morning before driving. Tried turning it after driving the vehicle and letting it sit... as well as any other combinations i could think of. There was never enough difference in the feel for me to make a conclusion.

good luck

jakesc7 said:

mine hadnt made the noise for about 2 months, until i heard it today. weird... i dont know what to do. i ran my car for about 5 mins and then turned it off and by hand tried to move the fan and it was turning quite easily.

Click to expand...

And oddly enough, mine did it again- it was 54 degrees, and I was going above 65MPH. So it's another data point, but it's an outlier I'm not sure what it means.