Loud rev at startup, intake leak?

[mdisalvo]

My explorer has been revving pretty loud lately at startup, it quiets down after it gets warmed up, but it seems unusually loud to me. Also my mileage seems to have taken a dip in recent weeks. Is this symptomatic of a leak in my intake somewhere? I was going to try the propane thing around the vacuum lines nad intake, but thought I'd see if there were any common causes for htis first. Any advice?

 

[Number4]

Could be a bad fan clutch is all.

 

[mdisalvo]

I don't think it's the fan clutch because I replaced it last summer when it was getting stuck on on the highway. It's the same sound but it's only at startup...

 

[turborich]

I would also take a look at the fan clutch. On some vehicles the fan clutch will be engaged for the first few seconds of cold start up.

Open the hood, have somebody start the engine while you feel for air flow, if the air flow reduces when the sound stops then that's it. Doesn't necessarily mean it's bad though.

A vacuum leak would be constant you would think, not just at start up.

 

[Number4]

Yeah, my 05, 4.0 roars like a lion at cold start, then when it drops below 1k RPM, the sound goes away.

 

[mdisalvo]

I'll probably try the propane trick just in case, but sounds like I was worrying about nothing, thanks for the info.