Coolant Pump Leak

[Groover]

I had a leaking coolant pump a year ago and it was replaced. Now I have overheating problems again. Does this picture indicate another leaking coolant pump? If so can any experienced eyes tell if that mark/stain is fresh or at least a year old?

Thanks!

 

[Trainmaster]

Doesn't look like a year-old leak to me. The system should be pressurized and if the pump's leaking you'll get a drip from the pump. A tool to do that job's $40. Not always easy to find a leak. That tool is very helpful.

But a leak wouldn't cause overheating unless it substantially reduced the coolant level. How's the level in the reservoir? If the level's fine and you're overheating and you don't have air in the system from running low, check (or replace) your thermostat...

 

[Groover]

Thanks Trainmaster. It was at the bottom of the cold fill range so I topped it up to the top of the range. Yesterday I drove it 375 mi and I had some overheating but it was manageable. I checked this morning and the coolant level has not dropped.

Would a faulty thermostat throw a trouble code? I checked and there are no codes, pending or otherwise in the system. I just found this in the FSM:

The thermostat monitor is a function of the PCM and is designed to verify correct thermostat operation.
The monitor executes once per drive cycle and has a monitor run duration of 300-800 seconds. If a
malfunction occurs, DTC P0125 or P0128 sets, and the MIL illuminates.

 

[Trainmaster]

My experience is that a faulty thermostat would not give you a code but substantial overheating would. The "thermostat monitor" function you reference is news to me, and you'd have to research the parameters that would set the code. I suspect that in some situations it may not indicate the defect.

A new thermostat in less than $10 and changing it only takes a few minutes. The symptoms you describe would point to a faulty or sticking thermostat. Less likely would be a faulty fan clutch, but that would usually give you a code.

 

[99WhiteC5Coupe]

My experience is that a faulty thermostat would not give you a code but substantial overheating would. The "thermostat monitor" function you reference is news to me, and you'd have to research the parameters that would set the code. I suspect that in some situations it may not indicate the defect.

A new thermostat in less than $10 and changing it only takes a few minutes. The symptoms you describe would point to a faulty or sticking thermostat. Less likely would be a faulty fan clutch, but that would usually give you a code.

GM has a diagnostic code for a slow engine warmup, which usually indicates an engine thermostat that is “stuck open”.

I’m not sure if Ford does, but always thought that all modern manufacturers of ICE vehicles did?