I own a 97 f150 4x4 w/ the 4.6 and auto trans. Under normal driving conditions the truck does fine. When I am pulling a trailer, it pushes coolant past the reservoir cap. The load never exceeds 4000lbs. The coolant gets all over the driver side wheel well and frame. I replaced the cap and it does the same thing. Any suggestions???

 

I would install a water temp gauge and see what the temps are. The stock gauge measures the cylinder head temperature...not the water temp. Does the stock gauge move any when towing?

 

To quote my '98 F150/250 Owner's Guide (page 14) under: "Engine coolant temperature gauge"

"Indicates the temperature of the engine coolant."
"This gauge indicates the temperature of the engine coolant"

The gauge face graphic shows a thermometer in liquid.

Haynes describes the "Engine Coolant Temperature (ECT)sensor" as a traditional looking brass threaded plug/probe, requiring plumber's Teflon tape to seal threads. I presume this wet 'sender' is for the temp gauge.

Haynes also briefly describes the "Cylinder Head Temperature (CHT) sensor" as affecting the operation of the entire FI system, no mention of sealing threads, or any reference to "gauge".

Are you sure "The stock gauge measures" the CHT signal?

97dave shouldn't have coolant "all over the driver side wheel well and frame". The 1st problem that comes to mind which "pushes coolant past the reservoir cap" is cylinder head faults. Failing head gaskets or cracks in the head fizz combustion gases into the water jacket, displacing coolant to the overflow tank. This tank has a 16 PSI cap & is designed as an expansion/overflow tank. The abnormal pressure of combustion gas leaks easily exceeds 16 PSI & the volume of the 'bubble' is added faster under heavy load. It doesn't take a lot of displaced coolant to overfill the overflow tank, where it gets forced out.

 

hey club wagon after speaking w/ a few mechanics and also noticing little bubbles in the reservoir at idle, i am betting it is a head/head gasket problem. i'm a little surprised at this b/c the truck has been very well maintained (owned it since new) and for a 12 yr old truck has relatively low miles at 140k. is this a common problem w/ this model year? ford wants between 2-3k to fix the problem, but also told me if it acts fine under normal driving condition it may be more financially feasible to leave it be. they also said b/c of the mileage they recommend a new motor @ around 5k.

 

I'm pretty darn sure. My Haynes manual doesn't state which one the cluster reads from, but do a search on here and the general consensus is yes.

https://www.ford-trucks.com/forums/6...mp-sensor.html

 

Bubbles or foaming in the overflow tank, and a gas/exhaust smell, can be a dead give away. However occasionally a marginal water pump seal can slowly create an air pocket that displaces coolant.

In 12 yr & 140k how many times has the antifreeze been replaced?
FORD veterans accustomed to all iron motors, were frequently resistant to get onboard w/regular antifreeze changing after aluminum heads were introduced. Old, depleted antifreeze doesn't just loose it's anticorrosive properties, those compounds are consumed. The byproducts of these reactions can actually become corrosive w/o really effecting freeze point. IMO its common for aluminum heater cores to fail b/c of internal corrosion resulting from failure to change antifreeze. OEM head gaskets have thin steel that will readily rust, especially if left with just water for coolant. Head gasket failures are harder to pinpoint b/c of the extremes of temp & pressure, as well as the difficulties of expansion between iron block & aluminum head. The tradition of retorquing head bolts has been lost. Loss of coolant & overheating can easily crack heads. These faults often lead to rough running, especially misfire when started after sitting b/c some coolant will leak into a cylinder. In this case pulling & comparing the plugs can tell you which cylinder is leaking.

Shop around. In this economy it shouldn't be hard to find a mechanic who'll do this job for well less than "2-3k". Option 3 may be better than "leave it be" that is to try one of the Snake Oil remedies. Many swear by stuff like BarsLeaks, be aware many curse them too. I saw a product specifically claiming to seal leaking head gaskets.

 

Haynes links the CHT to FI computer. FORD's owner's manual says of the "cluster" temp gauge: "This gauge indicates the temperature of the engine coolant".

If you're still "pretty darn sure" FORD is FOS, please post your idea what "the general consensus is" regarding the function of the "ECT" then? Haynes note: Some engines may have more than 1 ECT sensor.

I'll stick w/the "general consensus" of FORD's technical writers & editors AND those at Haynes. "I'm pretty darn sure" enough not to even test it by simply unplugging the "ECT" to confirm it's role as sensor for the "cluster" temp gauge. Suggest you try it & report back, so we can test the veracity of the "general consensus...here" since you obviously distrust my input.

 

You still "pretty darn sure"?

My '98 4.6 is 1 of the motors w/more than 1 Engine Coolant Temperature sensor.

 

"Pretty darn sure" comes from the dozens of posts and posters (some are Ford employees) on here that confirm my statement. I gave you a link...

It's raining pretty heavily today, I'll do my own tests and get back to you.

 

I'm "Pretty darn sure" you're missing a key fact. Your "link" is about mdeerslyr's '02 F150 5.4. This thread is about 97dave's '97 F150 4.6.

The CHT "link" within the "link" is also about later model year ('01?) & its common knowledge FORD made changes.

"I gave you" verbatim out of a '98 owner's manual & direct positive observation of 2 ETC sensors on my '98 4.6.

I'll still take that over your allegation the "link" & the exaggeration "dozens of posts....confirm" this "statement" in your response to 97dave's: "I own a 97 f150 4x4 w/ the 4.6"

ATC Crazy: "The stock gauge measures the cylinder head temperature...not the water temp.

Your posts fail to address "the general consensus" . Surely a majority of the millions of '97-'98 vintage F150 owner's (right or wrong) would've accepted FORD's "This gauge indicates the temperature of the engine coolant" from the manual provided w/every single pickup?

 

Ah...now I didn't know about any changes in the temp. sensors between the '97/'98's and the '99+'s. That would be news to me, as I've never heard/read about that.

I just assumed the temp sensor/sender/gauge was the same throughout the years (of course, you know what they say about someone who assumes things...)


...At least I won't be completely wrong...

I'm still going to try it on my truck when I get the chance (if I can get to the CHT sensor easily enough).

 

I know my 01, the dash gauge reads head temp, but I don't think this was the case back in 97.

 

"Would be news"? The writing IS on the wall & has been for over a decade. "What they say about someone who assumes" applies when 1 person's false assumption is believed by another.

[quote=ATC Crazy;6095670] (of course, you know what they say about someone who assumes things...)

...At least I won't be completely wrong... quote]

I'm not sure & it doesn't apply to 97dave's inquiry anyway, but I think FORD may have used the ECT until '01. If so, the change might not have come w/"'99+'s" as you stated. Have you confirmed this or is it your assumption?

Through this exchange:

97dave: "I own a 97 f150 4x4 w/ the 4.6"
ATC Crazy: "The stock gauge measures the cylinder head temperature...not the water temp."
FORD: "This gauge indicates the temperature of the engine coolant."

its clear your "statement" was & is "completely wrong". Sorry, too late to "assume" otherwise. What you "never heard/read about" happened to be something I was aware of. No getting around the fact "u" were on your own & must leave "me" out of it.

 

My trucks guage definitely measures cylinder head temperature but, my owners manual states that it read coolant temperature.

 

Thanks, looks like another instance where FORD literature is in error. FORD changed the design, but didn't update the manual? Wonder if they edited it in later years?

You aren't suggesting that 97dave's '97 & my '98 don't use ECT sensors to accomplish FORD's: "This gauge indicates the temperature of the engine coolant."? Are you?