Loud whine and some idling problems?

74BOSSK

MEMBER
1997 FORD EXPEDITION
5.4L
V8
4WD
AUTOMATIC
210,000 MILES

When I start the truck, there is a very loud whining or hissing sound coming from the engine bay. After a few seconds of idling, the idling feels almost like a misfire, but straightens out when moving. When accelerating, the high pitch sound gets quieter and lowers in pitch with the load until I let off the gas, at which point it gets loud again. Once I turn it off, the whine seems to wind down and fade out for a few seconds.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,217 POSTS

Based on your description, it sounds like you have an engine vacuum leak. That is the first thing I would recommend looking for.

Here is a link that explains how to locate and repair a leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Try this and let me know if it helps. If you are unable to find a leak, let me know. Also, in the event no leak is found, record the noise and upload it for me to hear. However, what you described is exactly how a leak would react.

Let me know what you find.

Take care,

joe

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Friday, May 26th, 2023 AT 10:44 PM

74BOSSK

MEMBER
2 POSTS

Thanks for responding. I have to say as I've worked with it I think it most definitely a vacuum leak. So far I haven't been able to find where it is, so I'll just have to keep looking. It just sounds like it is coming from everywhere.

Was this

answer

helpful?

Yes

No

Friday, May 26th, 2023 AT 11:39 PM

JACOBANDNICKOLAS

MECHANIC
108,217 POSTS

Hi,

Try using carb cleaner as mentioned in the link I attached. It will cause the engine RPMs to change if you hit the area that is leaking.

Let me know what you find.

Joe

Was this

answer

helpful?

Yes

No

Sunday, May 28th, 2023 AT 1:35 AM