Every so often it sounds like its trying to flush itself. it makes a slight noise and you can see bubbles

Oil is getting into the combustion chamber and igniting ....dont try starting it again...

This sounds like wind noise. Try to find the air leak by mixing up some really soapy water , start your car and turn on the heat on high. Wash the car with the soapy water paying close attention to areas around doors and windows. If you see air bubbles growing, or foaming this is most likely your air leak.Check the seals around this area for cracks or damage.

This sounds like a HOUSE plumbing issue. Is the line porperly vented? Bubbling sounds like the line needs venting. If you cannot go through the roof, they now make local vents that work.

sediment build up is usually causes thumping and noises from tank. it needs flushed out. models, where the heat source is beneath the tank. The burner heats the water under the sediment, leading to a build of steam. The steam finally escapes as bubbles, which can cause the sounds.

have a good day !

Have you checked it out for any blockage in the toilet or drain line.

You could try a 6ft auger to try to remove blockage from toilet.
If it is a drain issue it is either blocked somewhere or the vent is not working correctly causing it to get air bubbles.

Check you tank for proper water fill level up to marked line. Also make sure fill line from fill valve is connected to overflow pipe to fill bowl up correctly.

Not enough water in tank will affect the flush.

Your coolant level is low, and you hear the coolant taking up the vacant areas....bubbling...due to low coolant.

Sounds like to much water pressure.  Try turning the shut off valve off.  Flush the toilet.  Then slowly turn the valve back on until it makes the noise again.  When the noise is heard, turn the valve back a little bit untill the sound stops.

I forgot to ask if the noise was front or rear and stationary or moving so I will cover both.

If the noise is while the truck is stationary and the noise is from the front I would have to say the power steering pump. I have been changing several lately for similar concerns.

As far as the rear if the noise happens while making sharp turns and makes a whirring/growling noise while in motion its the rear differntial. What you can do yourself to be sure is find an open lot and drive in rather tight circles for about a minute, then noise should stop. This action flushes the clutch disks and stops the noise. If the noise goes away you will need to do a rear diff flush.

The fluid is very expensive so be sure this is your problem first.

In order to do the flush drive in tight circles for 5 minutes in each direction and then drain and fill the rear diff with the new Versatrak fluid.

Good Luck

sounds similar to mine. Find the source of the bubbling noise (defrost timer at the bottom), remove the cap and advance the timer with a screwdriver. If you fridge starts working, your defrost timer is faulty.

I would certainly take the unit back cause that noise could be the tracking or focus coils making that noise as they are being overdriver. This could cause the unit to fail prematurly. Its not an adjustment that you can do your self, it takes special equipment and disc