She's a Howler!!!

[69z28]

Just a quick question for the techs out there. My wife's 93 Explorer 4WD just started making a howling sound when the engine is under a moderate load. Not high pitched like a belt squeal. The sound drops off if I put a bit more pedal into it or perhaps changes to a pitch that is not as audible.

I tried to get it to reproduce the sound while parked with the hood up but no luck. I then tried to load the engine by placing it in Drive with the brakes engaged, no luck again. No, I will not have her drive it around with me under the hood!

Thought that it might be a vac line but cannot find one that appears damaged and the engine is running smoothly. Could it be a fan clutch???? How can I test this type of clutch?

Thanks

 

[410Fortune]

it could def be the fan clutch, they get old and lock up and the 4.0L fans are NOISY!!!

Check the vacuum tree at the drivers rear of the upper intake manifold, it could also be a vacuum hose or a missing cap/plug I have seen this many times also

 

[Verno]

On my 94, that sound turned into a loud clunk followed by the sound of a belt going off, and for the remaining 10 miles I drove on battery, no alt fan for cooling, etc. Turned out the bearings on the idler pulley went out, no belt breaking just the idler pulley breaking.

 

[410Fortune]

I replaced an engine in a 95 after they drove for 10 highway miles with no belt because the tensioner failed...

found water in 3 cylinders.....tensioner pulley is $3-20, engine swap cost him $900 and thats friend prices!

 

[marragtop]

It could also be a dirty IAC.

 

[cogs]

since something may have too much pressure on it, make sure the transmission fluid and filter is new, and inspect the tensioner and idler pullies, esp the nut on the idler is tight, and the tensioner housing intact.