So much diag and parts replacement - still overheating

[Maryserv]

2007 4.0l 158K miles

I've read through all the posts possible over the last year and a half and have replaced parts based on symptoms. Over the last year, I replaced the fan clutch and thermostat which helped with overheating for about a year. Recently, when overheating started again I have block tested, replaced the thermostat housing, replaced the water pump (after repeated flushes of yuck), replaced the thermostat again (twice), replaced the radiator cap (tested to ensure holding correct pressure), replaced the coolant temp sensor. I've had a Ford-only mechanic look at it and a primarily American engine mechanic look at it. The coolant can get to boiling in the overflow reservoir. I did a prestone clean and flush. The radiator was supposedly replaced before I bought it. The heater core seemed blocked so the place I bought it from did flushes until the heater worked.

Tested the fan today when the engine was hot and off. Fan does move both ways but with some resistance, certainly won't rotate 3 revolutions. The Ford mechanic I'm talking to says that something is stopping the coolant from flowing correctly. The upper hose is very hard when the engine is hot.

I just don't know what else to do. Any ideas? I would appreciate it!

 

[Turdle]

If the lower radiator hose gets too soft, it may collapse and block coolant flow, especially during high rpms. Didn't see that mentioned

 

[Maryserv]

If the lower radiator hose gets too soft, it may collapse and block coolant flow, especially during high rpms. Didn't see that mentioned

I will check that right now, thank you!

 

[Josh P]

A laser thermometer on the upper and lower radiator hoses would tell you how well the radiator is working. If your coolant is 50% antifreeze, the boiling in the reservoir is not a good sign.

 

[J_C]

I'd hook up a scan tool capable of live data and see what temperature is reported.

Was the dash gauge showing hot? Does it still?

I'm throwing a crazy idea out there - Is it possible that your coolant is not so much boiling in the overflow tank but rather that you have a blown head gasket (or warped head) and are getting exhaust into the cooling system? I mean the initial problem might have been overheating but what about now?

 

[Josh P]

I'd hook up a scan tool capable of live data and see what temperature is reported.

Was the dash gauge showing hot? Does it still?

I'm throwing a crazy idea out there - Is it possible that your coolant is not so much boiling in the overflow tank but rather that you have a blown head gasket (or warped head) and are getting exhaust into the cooling system? I mean the initial problem might have been overheating but what about now?

Not a crazy idea. I had an overheating problem once that was a cracked head. Symptoms only appeared when the engine was hot. Harbor freight sells a tester to check for combustion in the coolant. Be worth ruling out.

 

[Maryserv]

I'd hook up a scan tool capable of live data and see what temperature is reported.

Was the dash gauge showing hot? Does it still?

I'm throwing a crazy idea out there - Is it possible that your coolant is not so much boiling in the overflow tank but rather that you have a blown head gasket (or warped head) and are getting exhaust into the cooling system? I mean the initial problem might have been overheating but what about now?

Gauge shows temps creeping up and then hot. I did a block test several times with new fluid showing negative. No other signs of head gasket issue.

 

[Maryserv]

I will plug in tool when driving and check live data. We did check temps on top and bottom hoses and I want to say they were the same which I think is not good and means the radiator isn’t cooling the fluid. I did a clean out of radiator with Prestone, but maybe need again.

 

[Motorhogman]

Based on the temps of the inlet and outlet being the same maybe consider taking the radiator, have it back flushed and flow tested by a radiator shop.

 

[Josh P]

I will plug in tool when driving and check live data. We did check temps on top and bottom hoses and I want to say they were the same which I think is not good and means the radiator isn’t cooling the fluid. I did a clean out of radiator with Prestone, but maybe need again.

Ideal is about a 20 degree temp spread on the inlet and outlet. Less than a 10 degree spread you have a radiator problem.

 

[410Fortune]

The whole cooling stack should be inspected meaning the radiator the ac condenser and any aux coolers
make Sure no fins are plugged the air path is clear

 

[Turdle]

Is it possible to route the serpentine in a way to make water pump spin backward? I'm not sure on your engine but silly as it sounds....

 

[Maryserv]

Y'all have great feedback, thank you. Funny the a/c was brought up, I am about to report something I noticed today. I still drive with the a/c on but turn it off when temps first start to increase. That slows the overheat and I can sometimes drive all the way home without having to blow the heater. I noticed that the a/c temp gets warmer a while before the temps increase on the gauge. Could the a/c compressor be an issue? Causing drag on the belt? I don't know that it was ever replaced - I've replaced so many things that hit the serpentine (alternator, water heater, fan clutch).

I've seen few videos on reverse flushing and some have a tool that is connected to an air compressor. Is this necessary to reverse flush when the radiator remains on the truck?

 

[Josh P]

Lack of airflow through the condenser and radiator would cause this. Dust, dirt, bugs, etc buildup in there and kills the airflow.

 

[410Fortune]

Drag from ac compressor can for sure cause heat buildup however a proper cooling system should be able to compensate

 

[Motorhogman]

Y'all have great feedback, thank you. Funny the a/c was brought up, I am about to report something I noticed today. I still drive with the a/c on but turn it off when temps first start to increase. That slows the overheat and I can sometimes drive all the way home without having to blow the heater. I noticed that the a/c temp gets warmer a while before the temps increase on the gauge. Could the a/c compressor be an issue? Causing drag on the belt? I don't know that it was ever replaced - I've replaced so many things that hit the serpentine (alternator, water heater, fan clutch).

I've seen few videos on reverse flushing and some have a tool that is connected to an air compressor. Is this necessary to reverse flush when the radiator remains on the truck?

Back in the day... long ago when I owned a radiator shop we removed the radiator from the vehicles. Checked the flow using a chart from one of the major radiator mfg companies, ( how many gallons per minute could be flowed before the water built up and started rising in the tank.. ) Then used a combination of compressed air and water to flush the radiator. The biggest reason for removing the radiator from the vehicle was to test it in a tank before re-installing. Sometimes back flushing can make a leak start, especially in older radiators. I don't know if anyone bothers with that today with the replacement part world we live in. Between the cost of labor, water, government restrictions on shops etc,..

I'd say compressed air and water is still a viable way to back flush a radiator if you can find somebody to do it.

 

[Maryserv]

Back in the day... long ago when I owned a radiator shop we removed the radiator from the vehicles. Checked the flow using a chart from one of the major radiator mfg companies, ( how many gallons per minute could be flowed before the water built up and started rising in the tank.. ) Then used a combination of compressed air and water to flush the radiator. The biggest reason for removing the radiator from the vehicle was to test it in a tank before re-installing. Sometimes back flushing can make a leak start, especially in older radiators. I don't know if anyone bothers with that today with the replacement part world we live in. Between the cost of labor, water, government restrictions on shops etc,..

I'd say compressed air and water is still a viable way to back flush a radiator if you can find somebody to do it.

Funny you said replacement part world - one of my mechanic friends said he doesn't backflush, he just replaces it. I did learn how to flush the old-s old-school way from a retired Ford mechanic yesterday so I'll try that either tomorrow or Tuesday. Thanks for all the suggestions and ideas!

 

[Motorhogman]

Funny you said replacement part world - one of my mechanic friends said he doesn't backflush, he just replaces it. I did learn how to flush the old-s old-school way from a retired Ford mechanic yesterday so I'll try that either tomorrow or Tuesday. Thanks for all the suggestions and ideas!

What your mechanic friend says is what we used to call " when in doubt rip out" It seldom ever hit the problem on the nose..

 

[Maryserv]

Update - I did a "rinse" on the radiator only with the garden hose after disconnecting the lower radiator hose. Then I reconnected the lower hose, removed the thermostat, put the housing back on, and disconnected the upper hose from the rad. Ran water from the garden hose while the vehicle on and the heater on to check full flow. I video'd for my mechanic friend who said the flow was good.

I buttoned it all back up and it is still overheating after freeway driving and then going to surface driving. If this was a head gasket issue, wouldn't I have other signs of an issue?

 

[Motorhogman]

Has your mechanic done an HC test. It could be a head gasket, typically you will start popping hoses, gaskets, and even the heater core if it's bad enough. Possible that a minor leak into the cooling system from a head gasket could cause over heating.. This is what shops use to test.
Amazon product ASIN B06VVBSFTF
I'm not sure my link doesn't show.. Go on Amazon and search "block tester"