2011 Lincoln MKZ (Fusion) Hybrid Issue - MECS Pump

[jaymunone]

I bought a 2011 Lincoln MKZ Hybrid in September. I've wanted one for a long time.  The MKZ has 110k miles and I want to run it to at least 300k. Runs great. However, an issue crept up about 3 weeks ago.  Whenever I am stressing the engine and I've been on the highway a while, I get the dreaded MIL wrench and soon thereafter, Stop Safely Now. Upon pulling over and turning off engine, an immediate restart resets the alerts and I'm back on the road. If I stress the engine further, it happens again.

 

Prior to this issue, I've already had the MKZ from PA to FL and back, 2000 highway miles at 75-80 mph without issue. I love this vehicle, but this is an issue I need to resolve before my next long trip in March. Driving to work and back or around town, it's all good.

 

My initial research had me convinced it was the throttle body, but it's not. I believe it's the MECS pump. I plugged in an OBDII reader and got the MKZ to replicate the problem. Using FORScan, I got the codes which relate to MEC over temperatures and likely a faulty pump (P0A7C and P0A3E).

 

I was able to get my hands on some YouTube videos and I bought an MKZ hybrid workshop manual, and first pinpoint test is to physically check the MECS pump and to tap it if it doesn't sound like it's running.  It appears my vehicle has the older model Bosch MECS pump and by the looks of it, might even be the original.  I can see the MECS pump when I open the hood, but can barely reach through area between grill and engine to tap the MECS pump lightly with hammer to see if it runs when I hit it.  I'm hearing a subtle clicking coming from that area when I turn on vehicle but I am not seeing movement of coolant in the degas bottle. To be clear the sound I'm hearing is a constant subtle click, not a whirring indicative of an operating pump.  To be more clear, I'm not sure the slight clicking sound I'm hearing is coming from the pump but the sound is coming from that area.

 

I am a novice, but I'm learning more about vehicles and I'd like to use this vehicle as a DIY and would like to change out the pump myself if that is what is required.  The newer model MECS pump made by Cooper is $116 on fordpartsgiant.com and I'm sure going to a dealer, between diagnostic and replacement, will be at least $600, which I'm not looking to spend.  I have enough knowledge now through days of researching and reading that in order to charge that pump out, I'll need to get the MKZ up on jack stands in my garage, then it's two 10mm bolts, an electrical plug and two hose clamps, along with a clean bucket to capture coolant once I remove hoses. There might be a shield too. The workshop manual explains how to refill and bleed system too.  I really think a novice can do this and would like to try on my own, if necessary.

 

Should I be trying something else first?

 

Any advice would be greatly appreciated. Thank you in advance.

Edited January 15, 2020 by jaymunone

[lolder]

There is a TSB 11-7-31 for this that increases the RPM for this pump. If it was not working at all it wouldn't be intermittant.  The TSB was for older cars but it may be the same solution for newer ones. I wouldn't try doing it yourself as working on the motor/electronics cooling system requires a lot more than novice skills. Try Ford first.

Edited January 15, 2020 by lolder

[jaymunone]

I made an appointment with local dealer to flash the PCM this Friday pursuant to TSB 11-7-31 before I start tinkering under the hood.  The TSB says it's only a 0.3 hour job, so shouldn't cost more than $75.  I'll keep the post posted.  Thank you for the suggestion; that TSB came up in initial research so I had been thinking about getting Ford to flash the PCM first before doing anything physical to the car.

Edited January 15, 2020 by jaymunone

[jaymunone]

Well, it wasn't the TSB.

 

And it wasn't the pump either.  I replaced the pump last night.  After doing so, I filled coolant degas bottle per the service manual, opening the bleed screw on the DC/DC until coolant bled from it.  Problem.  No coolant bled from it.  At all.  Removed hose connection at DC/DC coming from radiator.  No fluid.  So either the radiator is all gummed up, one of the hoses is gummed up or something's gummed up in the transaxle.

 

Ugh.  I'm going to remove the hose connection at the radiator, coming from the transaxle to the radiator.  If that's flowing at the radiator, I've got to believe it's the radiator and I'll replace it next.

[jaymunone]

Well, I'm an idiot.  I took the entire front end off, cleaned out front pipes and radiator, and the same issue.  Nothing was gummed up; turns out I just needed to prime it a bit.  Got a little antifreeze in my mouth while priming the old fashioned way but it's definitely running through the whole system now!  Now I have to put the whole front end back together and hope I've solved the problem! ?

[jaymunone]

Put her all back together (those pin retainers are a pain to put back) and ran it on the interstate about 20 miles at about 75 mph.  The outside temp was about 35 degrees.  The MECS temp warmed up a bit but not much; temp sensor was pretty steady around 3.30V (guessing around 70 degrees).  I didn't push it harder, but when the pump wasn't operating, after about 40 miles and putting strain on engine/motor (going up steep inclines at high speeds) the MECS temp sensor would get to about 1.43V (guessing around 135 degrees) before I would get either the MIL wrench or the Stop Safely Now.  Will run it hard Sunday about 60 miles and see what happens.

 

On a sidenote, my vehicle did not have the older model Bosch MECS pump. The faulty pump I replaced is the newer, smaller Cooper MECS pump.  I'm not sure if the newer Cooper MECS pumps were OEM on 2011 MKZ Hybrids or if the one I replaced was already a replacement.  The vehicle has 113K miles so it's possible the original MECS pump on the vehicle was a Bosch and had already been replaced once in the last ten years.  At least I know how to do it myself should it fail again, rather than pay the local dealer $600-700.

Edited January 28, 2020 by jaymunone

[jaymunone]

Ran it hard yesterday--it was interesting to see the temp slightly go up when drafting, then go back down when driving open or in left lane.  Typical baseline was 3.30V (around 70 degrees fahrenheit) when on the highway. New MECS pump running great and I believe problem solved.  End of topic.

[etrain]

So what was the culprit? The mecs pump? I have the same problem, i think. My red triangle came on a few times yesterday but the radiator fan was going full tilt during the whole ride. My pump has a ticking noise, not what I thought it would sound like. How did you prime it?

 

 

On 1/28/2020 at 9:13 AM, jaymunone said:

Put her all back together (those pin retainers are a pain to put back) and ran it on the interstate about 20 miles at about 75 mph.  The outside temp was about 35 degrees.  The MECS temp warmed up a bit but not much; temp sensor was pretty steady around 3.30V (guessing around 70 degrees).  I didn't push it harder, but when the pump wasn't operating, after about 40 miles and putting strain on engine/motor (going up steep inclines at high speeds) the MECS temp sensor would get to about 1.43V (guessing around 135 degrees) before I would get either the MIL wrench or the Stop Safely Now.  Will run it hard Sunday about 60 miles and see what happens.

 

On a sidenote, my vehicle did not have the older model Bosch MECS pump. The faulty pump I replaced is the newer, smaller Cooper MECS pump.  I'm not sure if the newer Cooper MECS pumps were OEM on 2011 MKZ Hybrids or if the one I replaced was already a replacement.  The vehicle has 113K miles so it's possible the original MECS pump on the vehicle was a Bosch and had already been replaced once in the last ten years.  At least I know how to do it myself should it fail again, rather than pay the local dealer $600-700.

 

 

Edited August 10, 2020 by etrain

[ibbanez]

I'm having this same exact problem.  The previous owner said he took it to PepBoys and they said simply the ECU needs to be replaced.  Now I'm wondering if its this.  However, mine seems slightly different, but I don't want to hijack your thread and will make a new one.  Can you confirm if this solved your issue.