The hum maybe the vacuum pump. It is on the drivers side, on top of the wheel well... That will happen if you have a vacuum leak. Yes just fill it. you may need to do it a coupe times. Hopefully it will work out any air??

 

Fixed! Yep, it was air. Mechanic vacuumed it and refilled the coolant with pressure to take out any air gaps. Good to go!

No leaks on the fuel cooler reservoir or lines, wonder why it was low. Maybe when they replaced the radiator they forgot to top it off? Thanks for your reply.

 

When you did your radiator did you go wth an oem? Did you check your cab bushings?


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Yes, OEM radiator. Took it to mechanic, and didn't ask if he checked the bushings.

3 days of running around, checked if this evening and it's still topped off. Assuming no leaks.

 

Take a look at your cab bushings, they're a known reason (besides poor design) why the oem radiators sprung leaks. As they wear, the rad support becomes the flex point weakening the crimping that hold the end tanks on...


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So the vacuum pump is not supposed to make the humming sound? My vacuum pump (drivers side wheel well) is extremely loud. Does this mean there's a leak somewhere? How do I check for leaks?

 

It should not run all the time. If it does you have a leak some where. The tank that the pump goes to is under the drivers side battery. you can get to it thru the fender liner. Just take it out. Then there is a bunch of fitting sticking up in front of the degas bottle. The line from the tank to that connection is the one that broke on mine.

 

The vacuum pump is used to actuate the four wheel drive. I believe it provides vacuum for something else as well, but I can't recall what it is at the moment. The pump will run at start up, and when it has a demand. If there is a leak, the pump will run more than it should. Trace the vacuum lines and check them for cracks. Make sure they are connected at each end. This should be a simple fix.

 

It also runs the vent actuator for the cab if I recall. Mine doesn't run all the time. I've just noticed it runs when I have the key on to change tunes and it's loud. So I always put a charger on to keep the batteries charged while waiting on the files to load.

 

As long as it shuts down you should be OK? As long as everything is working? 4X4 autoloc, , vents work.

 

It does not have anything to do with vents, starting in 08 all of the vent controls are electric. On 6.4 its only there for the auto hubs.

 

ok, good to know. Thanks guys.