'97 Thunderbird Over Heating

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1997 Thunder 4.6 OHV 90k miles

Just two days ago my car started over heating (not to the point of stalling though). It also starts with a rough idle (also started happening 2 days ago). It usually idles around 750 rpms and it's been getting as high as 1500 without settling down to normal. I replaced the thermostat by dumb reaction (no, I didn't feel the radiator hose *sigh*) and that led to no result. The coolant levels are correct at cold level, although I don't think the antifreeze / water mixture is correct. There is more antifreeze in there than water. I hadn't changed my oil for 3500 miles but I don't think that's causing the problem. If you need any more info let me know, sorry but I'm not sure where to start. Thanks in advance for any responses

posted by  GnomeKing

welcome to the forum Gnomeking!

A couple of things to check.Is there a presence of oil on the antifreeze?

Check your motor oil and see if it looks to be milky white.

Are you getting any heat in the vehicle?

Also you can start your vehicle cold with the radiator cap off. Observe the antifreeze as the engine warms and look for bubbles. Some may spill out as the thermostat opens.

posted by  hitchhiker

I changed my oil and it looked on average for the time it's been in there. Nothing white, and the coolant looks the usual bright green diluted look. Car also accelerates in any gear where the RPMs are below 2000.

posted by  GnomeKing

The first thing I would do is to pull the trouble codes. Since the car is a 1997 you will need to get someone with a code reader (Autozone, or some of the other parts places) or a scantool (a dealer or garage) to retrieve the trouble codes. The second thing I would do is to Tee in a vacume gage in a vacume line leading to the intake manifold and do a vacume study, primarily looking for a gross vacume leak indicative of a cracked intake. If you think you have a blown head gasket, a compression test will yeild much valuable info.

The overheating issue is typically not caused by an emmission system and is more than likely a bad thermostat or one installed wrong, a bad water pump or blocked coolant passages in the radiator or the block. Sometimes is can be caused by poor coolant flow through the cross-over passages on the intake manifold or a blown head gasket although I have not heard of the 4.6L being to hard on head gaskets.

Typical issues resulting in eratic idleing or surging in most of the Ford 4.6L built since 1992 include bad IAC valves, clogged EGR valve passages, rotten vacume hoses and blocked PCV valves and cracked PCV lines. Starting with the 1996 model year cracked intake mainfolds have become a problem since the parts are now made of plastic. Occasionally a fuel regulation problem will cause this but it will be tough to diagnose until you are certain of the condition of your intake manifold and vacume lines

I would be interested in knowing what trouble codes you find.

posted by  tbaxleyjr

My dad has a reader but I was unable to find the adapter to plug it into. I looked all around the power distribution box and over the engine in general, and couldn't find anything that looked like it'd be it. Sorry for being young and dumb, but any idea where it's at? (My only other experience was on a 94 explorer, and it had it sitting out in the open

Thanks again for your help.

posted by  GnomeKing

On an OBD2 equipped car (1996 and newer), the diagnostic connector or data Link is typically in the passenger compartment, driver side on either side of the steering wheel under the dash. Some Fords, such as the T-bird, may have the connector on the passenger side, near the center of the car immediately under the dash board (to the right of the console if equipped with a floor shifter). The Data Link connector will be 1 1/2 in long x 3/4 inch wide and shaped similar to a RS232 computer port. Some may have a removable plastic cover. The ones on my 1999 Altima and 2002 Town and Country are not covered with a dust cap.

The documentation with your dad's scantool will tell you if it will work on an OBD2 system and how to run the various diagnostic tests (i.e. KOEO - Key on, engine off, KOER - Key on engine running). If it doesn't, you can find someone to pull the codes @ little or no charge. Dont let them erase the codes until you get your problem located and fixed.

You are right about the pre-OBD2 Fords. The diagnostic connector on those cars and trucks was either under the hood on the driver side firewall or the driver side wheel well.

Once you find the trouble codes and interpret them, a little trouble shooting will be in order before buying a bunch of sensors or parts. The codes tell you which sensors or devices are operating out of spec - not what is the root cause or why. AS AN EXAMPLE FOR TEACHING PURPOSES, on my 1999 Nissan Altima 2.5 L, Lets pretend I got a code P0304 which is number 4 cylinder misfire. I would check plugs, test the plug wires for excessive resistanc and inspect them for cracked insulation, and check distributor cap then if these components were good, I would use a noid light to check the fuel injector, and check for vacume leaks at the intake and fuel injector o-ring near #4 cylinder until I found the source of the problem and fixed it. If I got a code P0300 and P0171, I would clean the MAF sensor, look for vacume leaks @ the intake manifold and throttle body, and If I found none, begin looking into the fuel injection system (including fouled filters)

Hope this gives the general gist of why we need to see trouble codes if any are stored - this gives you a starting point of where to start your trouble shooting.

All of us were young once. The only way you learn is by doing. When I was in my teens, I was fortunate that a friend of my family was a retired mechanic from one of our local Buick dealerships who took the time to teach me much of what he knew before he became too sick to work on cars anymore. Take your time and systematically troubleshoot by testing, reasoning, and elimination. If you dont know something about what you are doing, ask or research in a Haynes manual.

The reason I know a little about the Ford 4.6L is I own a 1992 Crown Victoria. I have seen most of the problems except the cracked intake (the 1992 - 1995 4.6L used aluminum intakes instead of plastic)

posted by  tbaxleyjr

Well, the reader would only blink/beep every 10 seconds in engine off key on setting, and the same with the engine on. No pattern whatsoever, so, it has ended up in the hands of goodyear ( or whatever the service center changed it's name to). Thanks again for your help, I'll let you know what they find.

posted by  GnomeKing

Well, Goodyear ran the test and found out that it was the electric fan motor that had gone bad. I also heard a roar in the front of the car while driving at highway speeds, they said it was the left front bearing going bad.

They wanted:
$165 front bearing
$199 entire fan assembly.
total w/ labor : $864

From a junkyard, I bought:
$65 front bearing
$89 fan motor (Had to cut off the rivots and replace with bolts, not a big issue)

and it turned out to be the RIGHT front bearing, so with that in mind, that would have driven their price to well over $1000. I can hear it now "Oh, ahh.. well, the other side must be bad too!".... jerks.

But all problems have been solved, except the check engine light is still on. Am I correct that if I disconnect the battery, it should remove the check engine light if everything was fixed, correct?

Thanks again for your help.

posted by  GnomeKing

Here's something for you to think about. I could have sold you the parts you needed for about $15 more than you paid, total. Except what you bought from me would have been new instead of used. Now you have the same thing on your car that you took off, used parts with an unknown lifespan. Remember, cheaper isn't always a better value. I will agree that the price they quoted you on parts and especially labor was quite high. I wish I could get that kind of money.

As for your MIL, the answer is who knows? Disconnecting the battery won't reset the light but the important question is why is the light on in the first place. If it illuminated ONLY because of the overheat then it will reset itself in a few drive cycles. On the other hand you may have a different problem and are doing unknown damage to the engine everytime you drive the car. So the choice is really yours, drive the car and take your chances or scan it and find out.

posted by  vwhobo

I appreciate your offer, but the parts weren't used. It's a junkyard that also has a warehouse of new parts that they get from distributors on daily orders from customers. Sorry for not being specific about that.

posted by  GnomeKing

Now that I think about it, I hope nobody would every buy a used fan motor or used bearing.. That'd just be a horrible idea, I may be young and dumb.. but not that damn dumb :)

posted by  GnomeKing

one would be surprised what people would do

vwhobo is right about get the ECM scaned. The bad fan motor will cause the car to overheat but the ECM still needs to be scanned if the light does not go out.

posted by  tbaxleyjr

Would anyone know a cheap place in Minnesota to get an ECM read? Goodyear charged me $90, I'll call around, but does anyone know of a for sure deal? Thanks again to everyone.

posted by  GnomeKing

Some parts chains Autozone will pull the codes for free. Their readers will not pick-up freeze frame data

posted by  tbaxleyjr

I own a 1997 THunderbird with the 4.6L engine that has about 120000 miles now. Recently while driving in traffic to downtown Chicago which is stop and go I started to overheat quickly almost to the point of car stalling out before being able to get to the shoulder. Heres a summary of since then . I found out as long as I keep moving at at least 40 mph constent with no stop and go the car will cool down to regular middle temp gauge but if I stop and go and idle it overheats. It would get to where the coolant was boiling in the overflow tank. I changed the thermostat and gasket (correctly mind you), I replaced the water pump, and I have now replaced the 2 sensors on the manifold belive called thermostat sending units sensors( computer and temp reader). I had also did earlier checks for obvious problems. I had got no check engine lights until overheating but they would leave as the car cooled. I looked for coolant in the oil and found none. I looked for oil in the coolant and saw none there. I have to leaks or coolant lose until boil over. My fan works fine and I get heat when heater is turned on. I also checked all the fuses for blown in the fuse box. I am kind of stumped but recently read online that there is a class action suit against for and some of its cars containing the 4.6 engine (including the 96-97 tbird) because of similar issues caused by crack intake manifolds. Is this where my problem lies or am I missing the obvious fix? Please help with any info you can... Thank You :cussing:

posted by  ThunderedBird

Ford had a program to replace intake manifods on 96 and 97 4.6L with cracks in cetain locations on the intake. This was covered under a warranty program and described in TSBs instead of a recall.
I don't know if there may or may not have been a lawsuit but do know there was some fine print in the replacement terms

posted by  tbaxleyjr

Daft it might be but you might have an airlock in your coolant system, thing to check before you spend lots of cash.

posted by  cinqyg

very true.

are there other signs of manifold leak such as an air side leak causing lean engine condition

posted by  tbaxleyjr

when was the last time you change your antifreeze? you need to have 50/50 or your anitfreeze wont properly cool your engine.. have you change your thermostat? or the theromstat sensor (brass fitting on top of engine behind altinator.wires plug into it.) had you ran a dianogstics test on it.. i have a 95 t-bird 4.6 had a similiar problem.. with 139,300miles. are you runing 5w-30 like your suppose to be running in the engine? anything thicker will cause the oil pump to go bad ..

posted by  brandonhadnot

your fan motor that bolts to your radiator is it working properly? if not will cause the engine to over heat at idle or speeds under 40mph..

posted by  brandonhadnot

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