[Editor's Note: This blog post is one of our most popular and it has prompted many excellent questions from interested readers. Please take the time to read through the comments at the end of this posting as the additional information may be very useful in your own efforts.]
Saturday, February 19, 2011
When this hybrid electric vehicle ("HEV") was still rather new with about 17,000 miles, it suffered a failure of the electric motor cooling pump. I was traveling through the Appalachians in the middle of Pennsylvania when the "High Motor Temperature" warning came on. Some of you may be familiar with this issue. The display warns you to "Stop Vehicle Safely" and if you fail to do so within a few minutes the vehicle literally shuts down. Although it may be inconvenient, the shut-down is by design; to keep the electric motor and related components from being damaged from the high temperature caused by some failure of the cooling system.
After allowing the motor to cool off, I limped slowly to the nearest Ford dealer. They diagnosed the problem with the Motor Electronics Cooling System ("MECS") and replaced the Motor Electronics Cooling Pump (Part Number: 5M6Z-8C419-A) under warranty.
It so happens that Ford eventually issued a Technical Service Bulletin for this overheating problem. TSB 08-24-5 states that some 2005-2008 Escape Hybrid and 2006-2008 Mariner Hybrid vehicles may exhibit a red triangle light and codes indicating a transaxle overtemp. This condition may result in reduced power as the system activates fail safe operation. Codes P1A0E, P1A0F, P0A3C, P0A3E, P0A7A, P0A7C and P1A0D may also be set.
The first page of the TSB is shown below (the second page contains dealer billing information irrelevant to this shade tree mechanic repair, therefore it is not included).
I never gave the matter further thought since the replacement pump continued to work fine. Then a few weeks ago, I began to notice that the pump was operating rather noisily. I should have used that as a sign to proactively replace the part. However, I was complacent and before I took care of the pending failure I had a repeat of the "High Motor Temperature" and "Stop Vehicle Safely" warning.
Since I had driven another 100,000 miles since the first failure, I cannot really complain. From what I have read of other's experiences, it is not unusual for these components to fail after 50,000 miles.
With the vehicle out of warranty, I decided to see if this was a repair that I could complete myself. First I followed the procedure from the TSB.
[FORD] 1. After verifying the Motor Electronics Cooling System ("MECS") is at the proper level and condition, raise the vehicle on a hoist and with the ignition key in the run position, use a stethoscope to verify operation of the MECS pump.
[Me] The MECS pump cannot be seen from the top of the engine compartment, and is only visible from under the vehicle. It is located behind and below the radiator, just in front of the oil filter as shown in the photo below. Do not confuse this pump with the slightly smaller pump on the driver's side of the radiator. This other pump is part of the cabin heating system.
Well, I don't have a hoist or a stethoscope, but I used some jack stands to raise the front end a few inches and laid under the vehicle. Then I placed a short length of plastic hose between the pump and my ear to determine if it was operating. Nope. No sound from the pump.
[FORD] 2. If the pump is running, verify coolant flow into the MECS degas bottle. If there is no flow, verify hoses are not pinched or twisted and if no issues are found replace the pump with the listed kit part.
[FORD] 3. If the pump runs and there is coolant flow into the degas bottle this Technical Service Bulletin may not apply so follow normal diagnosis and repair.
[Me] Since the pump was not running, these two steps did not apply. And what the heck is a degas bottle? It's just a fancy name for what most of us call the coolant overflow tank.
[FORD] 4. If the pump is not running, tap the housing and listen for the pump to turn on.
[Me] Using a small hammer, I tapped the pump housing a few times and what do you know? After a few grunts and groans, and with a bit of noise, the pump began to operate again. It stopped after a few minutes, but it led me to the next step.
[FORD] 5. If the pump turns on after tapping, replace the pump with new service kit. The kit provides the necessary instructions and hardware.
[Me] There you go; it was time for a new motor electronics cooling pump. After seeing where the pump was located, I decided that the procedure was something that I could do myself. Two compression-type hose clamps, two 10 mm bolts and one electrical connection... just about anyone can perform this repair in the driveway. It would also be much less expensive than the $300 estimated dealer labor cost.
I checked with the local Ford dealer's parts department and they had part number 5M6Z-8C419-A in stock with a list price of $281.98. I also checked online and found it available for much less, as low as $177.37 (from Ford Parts Giant). Mentioning this to the dealer prompted them to drop their price to $225.58 without hesitation. Since I needed the repair completed quickly the discounted dealer price was a good deal for me, so I headed home with the parts to complete the work.
Ford's service procedure for the pump replacement couldn't be much more simple:
1. Remove old pump.
2. Install new pump.
Although Ford's instructions are correct, I would suggest that the steps listed below may be helpful if you are going to do the work yourself.
1. Optional: Securely raise the front of the vehicle using jack stands or blocks. Even a couple of inches makes the work so much easier.
2. Optional: Remove the protective plastic shroud under the engine compartment from the passenger side. There are five 10 mm bolts and one plastic pin. You CAN perform the repair work with this shroud in-place, but taking a couple of minutes to remove it makes the process so much easier.
3. Drain the coolant from the transaxle cooling system. Ford has an official procedure for this, but it seems overly complicated. I placed a clean, small bucket under the pump and carefully removed one of the hose connections allowing the coolant to drain into the container. Only about a gallon and a half or so drained from the system. If you are careful, you should be able to recover virtually all of the old coolant. I moved the bucket aside to reuse the coolant (more on that later) instead of dealing with an environmental hazard disposal issue.
4. After the coolant has drained from the system, remove the second hose connection.
5. Remove the two 10 mm bolts that hold the pump in place.
6. Remove the electrical connector.
The old pump on my vehicle was manufactured by Bosch, while the new replacement was made by Cooper Superior. The new model is obviously a highly modified design as you can see in the side-by-side photo below. The good news is that the new pump is a bolt-in substitute and no changes to the hoses or wiring are needed.
7. Bolt the new pump in-place with the two 10 mm bolts.
8. Connect the two hoses to the pump, and secure with the compression clamps.
9. Attach the electrical connector.
10. Replace the coolant. You may decide to use a new coolant mixture, or reuse the old coolant like I did. To make certain that no contaminants were introduced into the system, I strained the old coolant through a clean cotton cloth placed over a funnel. Ford has an official procedure for the refilling process as well. It includes venting the system at the transaxle; a task not easily done. I found that almost the entire volume of old coolant filled the degas bottle to the original level without a need to vent the system. Save the remaining pint or so that is leftover for the next step.
11. Turn the key to the run position and confirm that the new pump operates. With the pump running, verify coolant is flowing into the degas bottle. The level in the degas bottle should drop enough to allow the addition of the remaining coolant. In my case, the coolant level returned to virtually the same exact level it was before I started the repair.
Your installed replacement should look similar to the following photo.
Your installed replacement should look similar to the following photo.
12. Confirm that there are no leaks and that all connections are secure. Reattach the protective plastic shroud and carefully remove the vehicle from the jack stands or blocks.
Wasn't that easy? I'm not certain if I will still own this vehicle for another 50,000 or 100,000 miles. But if I do, I will be prepared to confidently complete this repair once again. Hopefully, these instructions will help you to do the same.