Operating Temperature Range (when reading an OBDII Scanner)?

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Brian Mifsud

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Hi All,

A puff of steam from the coolant recovery tank last week has me concerned about my 2004 Thunderbird's cooling system. I had been eyeballing the engine compartment for another reason and saw that the recovery tank seemed almost empty. I've since seen the "Max" line is very near the bottom of the tank, so levels were probably fine, but I'm guessing I did not tighten the cap tight enough when a day later I saw that steam. Gauge on dash showed dead normal between "H" and "L", but when I hooked up my code scanner and drove around, the live data feed for coolant temp was fluctuating between no lower than 206F, and sitting most of the time at 228F! When fan kicked on, I'd see it dip. This is while driving around at about 40MPH in cold weather. My fan had been running like a Freight Train the last several months of summer, and my aux. coolant pump has recently been running for quite a long time after shutdown (just had to replace battery, I guess the pump killed it). After I did the drive and saw the data, I was very concerned. Aux Pump was still running five minutes after shutdown, so I put my charger on the battery so as not to kill the new one.

After reading everything Google could find for me, I decided I had a bad thermostat, or broken/disconnected plastic impeller in the water pump. I pulled the thermostat and pump yesterday. Impeller is plastic, in perfect shape, and I checked to make sure it was still firmly attached to the shaft as one YouTube video I've seen for a Lincoln LS owner showed it slipping due to cracks in the plastic. The thermostat cover has no visible cracks. There are no signs of obvious leaking anywhere. I will put the thermostat in boiling water tonight to see what it does, but I'm kinda stumped.

The 228F water temp seemed to point to water not circulating. Could it simple be the thermostat? It's a heck of lot of work to take the thermostat out and reassemble everything just to see if temps go down. I'm planning on replacing the pump with one with a metal impeller just so I don't need to ever touch it again.. any suggestions on a Ford/Lincoln/Jaguar part number where the impeller is metal?

Thanks

Brian
 
I found another useful thread and this may explain why faulty plastic can lead to problems:


"If anyone is running around the 230 mark... That usually means there is an issue with the thermostat and or the housing, the coolant mixture, or it has air in it from a leaking plastic part that is failing.

If it's not the middle of summer... And the cooling fan sounds like a jet engine even if the gauge is showing normal... Then the vehicle is overheating due to one of the aforementioned issues."

Sucking air can make a pump cavitate and reduce its flow rate. I have foaming in my Coolant Recovery Tank when its running and that seems to me to be caused by air in the line. I've done the air bleed process a few times, but a crack in the plastic would reintroduce air on the fly.
 
may pay dividends to inspect the radiator core fins for dirt/bugs/vegetation blockage. got to have airflow to work. check the radiator outflow hose for inner jacket separation. that could block fluid flow and cause pump cavitation. assure the thermostat is properly installed. try to stay with the motorcraft pump if you can. it's a great pump. assure the aux pump flow is there. even with the pump motor running, it may be blocked. with all the extra cooling systems parts the car has, stick with the basics of cooling. in as much you are going to drain everything to change pump/thermostat now would be an excellent time to check everything. in this day and age, it is not outside the realm of possibilities that today's car owners ignore periodic maintenance because they think everything is disposable. trust nothing.
 
Brian Mifsud said:
I found another useful thread and this may explain why faulty plastic can lead to problems:


"If anyone is running around the 230 mark... That usually means there is an issue with the thermostat and or the housing, the coolant mixture, or it has air in it from a leaking plastic part that is failing.

If it's not the middle of summer... And the cooling fan sounds like a jet engine even if the gauge is showing normal... Then the vehicle is overheating due to one of the aforementioned issues."

Sucking air can make a pump cavitate and reduce its flow rate. I have foaming in my Coolant Recovery Tank when its running and that seems to me to be caused by air in the line. I've done the air bleed process a few times, but a crack in the plastic would reintroduce air on the fly.
Click to expand...
 
sounds like time for a cooling system pressure test is overdue. only way to get "air" into a pressurized closed system is to have a source of gasses that has a higher pressure, like a cylinder head gasket leak from cylinder to cooling jacket. just my take on it.
 
capt fast said:
sounds like time for a cooling system pressure test is overdue. only way to get "air" into a pressurized closed system is to have a source of gasses that has a higher pressure, like a cylinder head gasket leak from cylinder to cooling jacket. just my take on it.
Click to expand...

I was not even considering the head gaskets.. I'm really hope you are wrong... but Yes, that is the right way to check it
 
General repair info isn't your friend with this car. Checking for radiator blockage is a basic thing that does apply here, but pump or thermostat failure is relatively unusual but not unheard of

Head gasket failure on an AJ engine is extremely rare. The most common way for air getting into a sealed cooling system is from the system no longer being sealed. Failed/rotted plastic pipes/tanks/housings is extraordinarily frequent here. Loss of pressure allows for vapor pockets to form in the head due to the lowered boiling point, causing localized overheating. Any plastic parts that have turned brownish red are getting ready to burst and likely have intermittent leaks. Pressure testing is notoriously ineffective on this chassis.

195-205 is perfect. Up to 220 seems normal for older cooling systems. Staying 220+ is bad and getting ready to overheat. 230+ is overheating. The gauge is a borderline liar because it's buffered and non-linear. The gauge stays dead center from 190-240.
 
Well, I'm going to change out all the plastics as I have quite a bit of it already pulled apart. Good time to check radiator for coolant flow blockages and air flow. All the coolant system parts are still way cheaper than an engine rebuild.
 
Brian Mifsud said:
Well, I'm going to change out all the plastics
Click to expand...

Other than FDR's recommendations... that is probably the wisest advice you could give yourself. It's actually the recommended procedure on this forum.

If you've been hearing your cooling fan since summer... it's been overheating since then. Do NOT buy aftermarket parts. They don't last! Buy everything from the dealer... but be prepared to spend around a grand $$$. Add another $500 if you also do the DCCV... aux coolant pump... and water pump.

The radiator is probably clean inside... but the passenger side tank on the radiator is known to crack exactly opposite where the hose connects. If it's bad... that will be around another $300, (Motorcraft through Rock Auto).
 
Brian Mifsud said:
Well, I'm going to change out all the plastics as I have quite a bit of it already pulled apart. Good time to check radiator for coolant flow blockages and air flow. All the coolant system parts are still way cheaper than an engine rebuild.
Click to expand...

Agreed. One difference of opinion (somewhat experience based) is that I'd put the old water pump back on before I would replace it with aftermarket.
Same on the plastics. Go OEM or Jaguar only, aftermarket has been problematic on this car. I'll bet that your degas bottle has lots of cracks on it.
 
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