This is my first post on the forums, as I come back into the diesel world... Previously had a 08 6.4 rocket, traded that off for a Camry Hybrid and recently purchased a 02 F-250 w/ 7.3 w/ only 145,600 miles...

Thanks to this forum, I fixed a vacuum leak on the MAP hose last night! Thank you for that!!!

When turning the ignition key to on, my gauges stay down and then I hear a deep grinding noise for a long 1 second when the gauges come up. By that I mean this; if the engine is warmed up but was turned off I can turn the key off and all gauges will be down, but the instant they register I hear a this long deep popping noise...

Any ideas on what this could be?

 

Can you YouTube a vid here?

 

Yeah - I'll try and do that tonight and get it posted...

 

Videos in next post..

 

Video showing when grinding noise occurs, which is when the gauges come on:
Noise from inside the drivers side wheel well:

 

Does your vehicle have any aftermarket stuff? Like maybe airbags and onboard compressor....?

 

The truck does have a salvage title so it could have an aftermarket airbag? Do you know how a person could check on this?

 

Onboard compressor - such as???? I'm not real sure. I'd had to have more information in order to start researching that because I don't really know what I'm looking at.

 

Oops...I meant "airbag" as in suspension supplement....vs passenger restraint.

If you have an onboard compressor, there usually will be an air pressure gauge in the cab with a switch or two. Sometimes those systems have an automatic switch that inflates the load leveling air bags. If the air pressure leaks down quickly, then you will hear the compressor for a brief moment when the key is energized....the sound in your video kinda resembles a compressor of some kind. Another possibility is that sound could be your vacuum pump...it is in the engine compartment right nest to the passenger fender...

 

I have that same noise at the same time. Mine comes from the vacuum pump and I have no vacuum issues so never worried about it.

 

I don't believe it has any type of air "suspension" system on it. I would have noticed that...

As for the vacuum pump - I'll have to look into that and see if someone can turn the key while I try and identify where the noise is coming from.

 

Does this vacuum pump have any control of Shift on the Fly 4 Wheel Drive... I have some horrible tires on the truck right now and it's hard to tell if the 4 Wheel Drive is engaging properly or not, but I know there has to be some slip for it to engage if the hubs are turned to Auto, which they are...

 

There is another thread on this page titled Pump under hood (or something similar...). In there is a photo posted by PaysonPSD of the pump. Unplug that connector and then try the key....if the sound disappears then you found your source.

 

Thanks - that will definitely help and it's also great to know this part has some control over the ESOF 4x4!

God Bless You - Thank you for your help and people like you are why so many love this site!

 

It does, the vacuum pump supplies (you guessed it) vacuum to actuate the heater/defrost/face/feet vents as well as locking in the front hubs for ESOF 4x4 when they are in automatic mode. Are you having any vacuum-related trouble?