2001 Grand Marquis Overheating

[grasscutter]

Try it without the thermostat. That's supposed to make engines run too cold.

 

[SwampSurvivor]

Isn't this the one you swapped motors on? I recall something missing a cylinder.

Have you run it w/o the cap? I wonder if it popped a head gasket already.

Bummer.

I don’t believe it’s lost a head gasket or cracked a head. It doesn’t bubble or boil coolant. Or lose any coolant. Any time I’ve seen a head gasket let go it’s made the coolant boil or bubble. I don’t see that

 

[SwampSurvivor]

Try it without the thermostat. That's supposed to make engines run too cold.

I think I’m going to try a 180 and see what happens. If that can get me to work before hitting failsafe mode then that’s the fix

 

[The_Eric]

Get a working infrared temp gun and measure the temp at the t-stat housing. You need actual verification that she's getting that hot.

 

[grasscutter]

I think I’m going to try a 180 and see what happens. If that can get me to work before hitting failsafe mode then that’s the fix

No. Go straight to the no T-stat. Remember it's just a test.

 

[supton]

I don’t believe it’s lost a head gasket or cracked a head. It doesn’t bubble or boil coolant. Or lose any coolant. Any time I’ve seen a head gasket let go it’s made the coolant boil or bubble. I don’t see that

I noticed you hadn't indicated boiling, so it didn't seem right... but I'm at a loss here (no surprise, not a mechanic). There's something stopping flow.

I'd remove the t-stat and see what happens.

 

[SwampSurvivor]

Yep. I think my next step is going to be removing the thermostat. Hopefully I'll get some time this week to try that.

The front axle decided to remove itself from one of the Jeeps while driving on Saturday. So had to try to recover that and fix it today.

 

[JHZR2]

The citrix acid flush scares me. I don't want to eat a 25 year old heater core. That would be the end of the vehicle. I guess I could just bypass it temporarily.

If it’s of reasonable quality it won’t. This gets done on old MB diesels often as part of the FSM recommmendations.

But just watch the ratios.

Maybe I missed something. Have you fully flushed and flowed pressurized water through? Like remove the hoses, remove the radiator, and flow it?

Have you looked at the impeller of the water pump?

Have you verified the sensor is correct?

I wouldn’t count on an IR thermometer for this.

 

[SwampSurvivor]

If it’s of reasonable quality it won’t. This gets done on old MB diesels often as part of the FSM recommmendations.

But just watch the ratios.

Maybe I missed something. Have you fully flushed and flowed pressurized water through? Like remove the hoses, remove the radiator, and flow it?

Have you looked at the impeller of the water pump?

Have you verified the sensor is correct?

I wouldn’t count on an IR thermometer for this.

It's been flushed with pressurized water twice. When I did the thermostat I figured I would back flush both the engine / heater core and the radiator separately. I got a LOT of crap coming out of the radiator when I back flushed that. Nothing of note came out of the engine just some brown coolant. It was the garden hose so I didn't do a full 40 PSI ... that would end the heater core quickly.

When I changed the radiator and water pump a week later I flushed the engine again and nothing came out other than coolant.

The water pump in there is new now. I did verify that the impellers are the same way as the original one. I don't believe ford modular engines had different rotation water pumps, but I know that was an issue in Jeep engines for a while. I think the water pump is working because it has good heat and the heater core is able to extract heat enough to keep temps under control when it goes bad.

This has 2 sensors on it. One for the gauge on the intake manifold and one for the computer / fan on the cylinder head. I guess they both could be bad, but they do both agree with each other when the fan kicks on high and it eventually goes into failsafe cooling.

 

[AdmiralYoda]

I once had a 1993 Jeep Cherokee. I chased an overheating problem forever and put in a new water pump, heavy duty radiator, new hoses, new t-stat, etc. The gauge still indicated that it was running hot. Turned out to be a bad temp sensor. $15 and it was back to running cool. The old temp sensor was indicating a higher temp on the gauge than it actually was operating at.

At highway speeds if you are still running hot you either have poor coolant flow, or poor airflow through your radiator.

 

[SwampSurvivor]

I once had a 1993 Jeep Cherokee. I chased an overheating problem forever and put in a new water pump, heavy duty radiator, new hoses, new t-stat, etc. The gauge still indicated that it was running hot. Turned out to be a bad temp sensor. $15 and it was back to running cool. The old temp sensor was indicating a higher temp on the gauge than it actually was operating at.

At highway speeds if you are still running hot you either have poor coolant flow, or poor airflow through your radiator.

Ironically, I think I have the only Cherokee on the planet that hasn't had overheating issues.

It seems to only happen on the highway or when driving. And as soon as I stop it cools right down.

 

[Chris142]

I'm thinking it's the radiator, it's somehow plugged up, not actually flowing. I wonder if you could get one of those borescopes and see what can be seen in the tanks? but it could be plugged elsewhere.

Warm it up. Shut it down and immediately feel the radiator core. Feel for cold spots.

 

[SwampSurvivor]

Warm it up. Shut it down and immediately feel the radiator core. Feel for cold spots.

While it's running at 230 I can't touch the driver's side of the radiator, but I can touch the passenger (outlet) side of the radiator and it's lukewarm. It does gradually get cooler the closer I get to the outlet.

I don't think it's circulating coolant through either the original or new radiator. Water pump has to be pumping because the heat works.

Depending on how this week turns out for stuff going on, hoping to pull the thermostat out and drive it around.

 

[zzyzzx]

Water pump has to be pumping because the heat works.

Is it the original water pump?
Have you considered the possibility of a worn impeller?

 

[SwampSurvivor]

Is it the original water pump?
Have you considered the possibility of a worn impeller?

It's a new water pump. The old water pump had perfect impeller fins. It unfortunately got destroyed upon removal so I'm only able to use the new pump.

 

[crashz]

The only thing restricting the flow to the radiator would be the thermostat then. Also seems to coincide with the overheating on the highway.

 

[97prizm]

I'm at a loss here. This is my 2001 Grand Marquis , 175K miles on the car ... 160K miles on engine.

I noticed this spring/summer that the fan was running pretty much constantly. According to the torque app, it was running around 225 on the highway. If sitting still, it would cool down.

When I got the car 5 years ago, I'm pretty confident I was the first person to ever change the coolant. Numerous coolant flushes and it still turns brown quickly. But it never had any overheating issues. It always seemed to run right around 200 -210 and I never heard the fan come on unless I turned on AC

This year it's been worse. We had a day last week where it was 100F out and it couldn't keep up. Even with the heat on full blast, best it could do was 235. It kept going into failsafe cooling mode if I didn't have the heat on full blast. That means it was hitting 260... Even when it hit 260, the coolant wasn't boiling but I could tell it was HOT. There's 2 temp sensors - one of the gauge and one for the computer. If they're both agreeing that something hot, I'd be inclined to believe that it's not a bad sensor.

I put a new 195 degree thermostat in. Didn't help. Changed the water pump and radiator and same problem.

It's not boiling the coolant or using any coolant. No milkshake in oil or on the oil cap ... not that oil cap is a good indication on a 2 valve Ford anyway - they always milkshake the oil cap). The weird thing is, yesterday when it was running at 230, I was able to squeeze the upper radiator hose and opened up the cap and it didn't even have any pressure on it?!

There is definitely coolant flow. Heater is blowing hot. Old water pump was perfectly fine. When I pulled the radiator, I back flushed it a bit and got a bunch of crap out of it.

If I put my hand over the new radiator, I can tell it's definitely doing something. Warm on the driver's side, cool on the passenger side.

Try the Prestone coolant system flush. I agree it sounds like you don't have enough coolant system pressure.

 

[mattd]

The panthers can and do blow headgaskets. Used to see int a lot on the crown Victorias once the miles were up there on the police vehicles. This is usually the biggest symptom unless it’s completely ruptured. You’ve replaced and proven everything else from what Ive read JMO. More than likely why the cap failed.

The passenger side of the radiator should be cooler than the driver. That’s the “cooled”
Coolant.

 

[SwampSurvivor]

Update -

It got real hot on the way home from work again. Bummer.

Once it cooled down a bit and opened the cap to bleed off pressure, I drained some coolant off and pulled the thermostat. It was still quite warm - it was running a few minutes prior and the thermostat was closed.

Fun fact ... Dorman intakes can't run with no thermostat. The outlet housing won't seal without one. I thought about cutting one of mine up but didn't feel like dinking around , so I grabbed a 180 degree thermostat.

Waiting for it to do a few complete heat cycles and burp fully, but initially it seems to maintain a cooler temp idling in the driveway. The fan was cycling on and off low speed instead of running up to and staying at 220. We know thermostats set the minimum temperature ... so maybe, fingers crossed ...

Also once the 180 opened I could actually feel warmth on the passenger side of the radiator.

I just ran it up to temperature and let it sit. Seemed to cycle between 200 and 215 (when the fans kick on). That seems a bit more normal. Fingers crossed for how it does tomorrow.