Hi folks, I'm in a bind and here's what's happening.

2006 Mercury Mariner (FEH)
Mileage: 106,000. Non carb state

Symptom: 20-30 mins and stop safely now message appears

One message read : motor overtemp

Diagnosis:
1). Front punctured radiator. Coolant leaked out.
Action: Used bar's copper permanent fix and leak stopped. Topped off fluid
Results: Problem persists

2). Seemed like a likely mecs pump issue. I did not diagnose it well
Action: replaced mecs pump. Topped off fluid. Ooops, air trapped. Had dealer flush electronic cooling system.
Results: Problem persists

3). Hybrid diagnostic run.
Bad dc/dc converter.
Part cost:$1600 (Doh!!). I found a salvage yard that had one. $150. Just arrived and dealer techs done for the weekend.

Question: can I throw the service switch to cut high voltage and swap it out myself? Seems straightforward.
Tech said the new coolant pump didn't seem to have much flow. I'm hoping a bad dc converter may be causing a blockage and swapping it out will remedy that too. Any ideas re: troubleshooting coolant flow for an idiot like me?

Thanks so much for any and all help folks!!! I've learned a lot from lurking here, grateful.

-Rob

 

Secondary note: AC is not very cold at all. Not sure if this is related

-Rob

 

Wth, life is short...winging it.

Old dc converter out...going to fill with antifreeze externally and put the salvage replacement in. Very little coolant loss from hoses so far.

Dear god I hope this is it...

 

Craptastic. Stranded on hwy again. Bad dc converter swapped and problem persists.
So new pump, coolant flush, replaced dc converter which tested damaged. Any ideas welcomed!

-Rob

 

Seems like the overheating in the motor electronics cooling is still happening. Maybe when the coolant leaked out the DC/DC converter was damaged because your 12V battery was bad or there was a short in the 12V system. If the DC/DC converter had to work extra hard because of a bad 12V battery or a short on the 12V, it would easily overheat.

I would be concerned that after putting in the new pump that the technician still said the flow was low. Maybe the stop leak gummed up something in the motor cooling system. I would chemically flush the motor electronics loop and then see if the flow improves. The radiator leak might return but if the flow improves the answer might be a new radiator and not stop leak stuff. If it doesn't improve even after that then there is probably a blockage that the flush can't get rid of. Don't know how you could fix that, though.

 

What temperature is the MECS running at?

 

With the key turned to on but the engine not started, do any of the hoses in the motor loop look like they're collapsing or even puckering together a little? Maybe a power flush with the garden hose and an adapter can clean the path out to get the coolant flowing properly.

 

Something similar just happened to my 2020 Ford Escape Hybrid: got a bunch of "electric energy reserve on see manual" warnings, followed by another random "put car in neutral to start (while traveling at over 50MPH). Pulled over, couldn't get car going again, had it towed. Turned out, the DC converter literally MELTED according to the dealer. I was charging a phone while driving - cause or contributor, don't know, but in any event it ought not to have happened and I'm glad the car didn't catch on fire. Anyone else have this problem with the Ford Escape Hybrid?