2016 Ford C-Max; Noise when switching from Elec to Gas Engine

[Telerisk]

2016 Ford C-Max....love the car; hate a few annoyances... 

 

About 2 months following Purchase I began to hear a Thud\perhaps more like a thump from the rear Right Cargo area.  Paying close attention when I hear this noise I have pinned it down to when I pull from a stopped position at a slow speed where the Electric engine is powering the Car and quickly accelerate were it hands off to the Elec Engine I hear the Noise. If I watch the instrument Panel I can see the Blue Band, hear the noise and see the White appear....(Elec handing off to Gas).  If, I slowly start, see Blue Bar about 1/3rd up and than accelerate and Elec takes over, I don't hear the Noise.  Also, all coasting speeds......switching from Elec to gas, I never hear any noise.  So I hear this noise only at a slow startup with a quick acceleration to change from Elec to Gas.  Obviously there are solenoids/relays or whatever the part must be called in this rear Cargo area that is handling the Change-overs, charge the battery, Battery running elec engine, etc.....and it would be a guess on my part, this part is the cause of the Noise.  Can't think its normal because 1) I don't recall this noise until several months following purchase 2) it only makes the noise with a slow startup and fast acceleration 3) a friends C-max...never makes the noise.

 

Anyone else with any year C-max experienced this Noise?  Yes, eventually I will take this into my dealer but although the noise is annoying, the C-Max is running great with 42MPG is a Very busy loaded with Traffic lights community.  

 

The other annoyance is a HISSING sound coming off the brakes, again, other then the noise is annoying, the brakes are great...anyone experience this noise?

 

 

 

 

[ptjones]

Have the service adviser seat in the back seat and duplicate the issue with you driving. :)

 

Paul

[SnowStorm]

So it sounds like the thump only happens when the ICE starts and goes quickly to high torque which would put a sudden twist on the engine mounts.  Perhaps an engine mount is bad or there is something loose in the exhaust system that feels the jerk when the ICE starts and is making the noise.  Pure conjecture on my part.

 

I have heard what might be described as a hissing sound when the friction brakes first engage after the car has been sitting and (I think) a bit of rust has formed on the rotors.  It seems to happen only when first driving off in the morning.  They also tend to grab a bit at this time.  With efficient braking, the friction brakes may get almost no use for a while and some rust might build up.  Some folks here have suggested an occasional hard stop to help keep the rotors clean.

[plus 3 golfer]

So it sounds like the thump only happens when the ICE starts and goes quickly to high torque which would put a sudden twist on the engine mounts.  Perhaps an engine mount is bad or there is something loose in the exhaust system that feels the jerk when the ICE starts and is making the noise.  Pure conjecture on my part.

 

I have heard what might be described as a hissing sound when the friction brakes first engage after the car has been sitting and (I think) a bit of rust has formed on the rotors.  It seems to happen only when first driving off in the morning.  They also tend to grab a bit at this time.  With efficient braking, the friction brakes may get almost no use for a while and some rust might build up.  Some folks here have suggested an occasional hard stop to help keep the rotors clean.

My vote.  OP, with the exhaust cool, grab the muffler and shake in all directions. It should move a good bit but with no banging / thumping.

Edited September 30, 2017 by Plus 3 Golfer

[plus 3 golfer]

2016 Ford C-Max....love the car; hate a few annoyances... 

 

About 2 months following Purchase I began to hear a Thud\perhaps more like a thump from the rear Right Cargo area.  Paying close attention when I hear this noise I have pinned it down to when I pull from a stopped position at a slow speed where the Electric engine is powering the Car and quickly accelerate were it hands off to the Elec Engine I hear the Noise. If I watch the instrument Panel I can see the Blue Band, hear the noise and see the White appear....(Elec handing off to Gas).  If, I slowly start, see Blue Bar about 1/3rd up and than accelerate and Elec takes over, I don't hear the Noise.  Also, all coasting speeds......switching from Elec to gas, I never hear any noise.  So I hear this noise only at a slow startup with a quick acceleration to change from Elec to Gas.  Obviously there are solenoids/relays or whatever the part must be called in this rear Cargo area that is handling the Change-overs, charge the battery, Battery running elec engine, etc.....and it would be a guess on my part, this part is the cause of the Noise.  Can't think its normal because 1) I don't recall this noise until several months following purchase 2) it only makes the noise with a slow startup and fast acceleration 3) a friends C-max...never makes the noise.

 

Anyone else with any year C-max experienced this Noise?  Yes, eventually I will take this into my dealer but although the noise is annoying, the C-Max is running great with 42MPG is a Very busy loaded with Traffic lights community.  

 

The other annoyance is a HISSING sound coming off the brakes, again, other then the noise is annoying, the brakes are great...anyone experience this noise?

The hybrid battery is connected to the electronics upon startup and remains connected.  There is no switching of power components on / off via relays.  The inverter, the dc/dc converter, the power to the electric motors, and so forth are always connected. Torque control is seamless during ramping up / down of ICE.  That's the beauty of the planetary gear set that connects ICE,  the electric motors, and the drive shafts. If the noise is in the rear, then the transmission and associated components (mechanical and electrical) are not the source of the noise.

 

The only things I can think of in the rear that are related to ICE ramping up quickly that might cause a thump are the fuel pump and exhaust system.  The fuel pump is operated as a dual speed fuel pump.  Upon startup, you should hear the fuel pump run for about one second. It's located under the right rear seat. When ICE is not rotating, the fuel pump is off.  Under normal ICE operation, the pump runs at a slower speed.  My guess is that when high ICE torque is required, the pump runs at high speed.  You may be hearing the pump coming on from an off position to a high speed position.  Perhaps it's failing.

Edited October 1, 2017 by Plus 3 Golfer

[Telerisk]

I am in no way questioning your response, you certainly must know the mechanics of the 2016 C-max just based on your reply.  I thought mostly all Fuel Pumps were located inside gas tanks?  The C-max positions the Fuel Pump separate from the Fuel tank and under the right rear Seat.....odd place to place and run Gasoline......Its accessed by removing the seat?  Underneath the Vehicle?  Your explanation sure points as the cause because I hear this same noise 8 out of 10 times when I push the Start Button and like you wrote, the Fuel starts as soon as the vehicle is started..... Try to do a Google search for how to replace the Fuel Pump, or, see a picture of where it is located, but could not find anything.......

[plus 3 golfer]

I am in no way questioning your response, you certainly must know the mechanics of the 2016 C-max just based on your reply.  I thought mostly all Fuel Pumps were located inside gas tanks?  The C-max positions the Fuel Pump separate from the Fuel tank and under the right rear Seat.....odd place to place and run Gasoline......Its accessed by removing the seat?  Underneath the Vehicle?  Your explanation sure points as the cause because I hear this same noise 8 out of 10 times when I push the Start Button and like you wrote, the Fuel starts as soon as the vehicle is started..... Try to do a Google search for how to replace the Fuel Pump, or, see a picture of where it is located, but could not find anything.......

The fuel pump mounts to the top of the tank and is thus inside the tank.  To get to the fuel pump one must drop the tank and then one can remove the fuel pump.  The reference to "located under the right rear seat" simple means that's where you will hear the sound coming from not how one gets to the fuel pump.  If you look under your car from just in front of the right rear wheel well, you can see the bottom of the tank (which is pretty much under the right rear seat).  :)

 

The fuel system pressure needs to be relieved and the tank drained before removing the tank to get to the pump.

[plus 3 golfer]

I looked at the service manual and this is how one removes the fuel pump:

 

1) Depressurize fuel system - disconnect electrical connector to fuel pump, start ICE and run until it stalls, try to start ICE again to ensure system is depressureized.

2) Drain fuel tank -  insert tube down filler pipe and drain as much fuel as practicable.

3) There appears to be some sort of disconnection of the filler pipe to the tank but I can't tell what from the pics.  They show what looks to be pliers and a clamp that connects the filler tube to the tank.

4) There are several shields and a cross member underneath that need removed and the exhaust system apparently needs to be lowered by removing hangers and it appears it also has to be disconnected from the converter, and another shield removed.

5) Fuel tank can now be lowered using a jack for support and removing several screws. 

6) The fuel pump and sender unit can now be serviced.

 

It's hard to tell how difficult the job is from the pics but the car will likely have to be lifted a good bit to do the job (perhaps more than just jack stands). This is one job I'd leave to a mechanic with a lift. :)

[Telerisk]

That sounds like some serious tear down....and honestly, I doubt it will all go back like it was from the Factory.  May just live with the occasional thump....All else is good; great mileage...40+ mpg in Florida where AC is running all the time.  This might be one of those things that you are better leaving as is.