Overheating w Electric Fan

[jaybee]

I don't have it in hand yet but my brother's 2000 Taurus is about to come spend some time in my garage. It has a new overheating issue that he thinks is traceable to inoperative cooling fans (if I remember correctly this is a dual fan setup.)

The car heats up when sitting still, cools off when air is moving through the radiator. It's at its worst when you run the car off the highway directly into stop and go situations, better if you can run a few minutes at surface street speed before stopping. The fan never runs.

My mental check list says it could be bad fan motor(s) or power not getting to the fan(s). If no power it could be bad wiring, bad relay, bad temp sensor, or no power from switch to circuit. I'm not sure if this car gets a signal from the PCM to trigger the fan. Does anyone have tips for troubleshooting this?

[Rrumbler]

Start at the fuses or circuit breakers and work through the system component by component.  A good wiring diagram will help immensely.

[wayne petty]

absolutely...

first thing to check...

the ground wire connections at the top of the core support..

http://i1207.photobucket.com/albums/bb476/waynep712/fordcoresupportgrounds_zps48c74c23.jpg~original

i find so many ford ground wires at the core support in worse condition than these.

http://i1207.photobucket.com/albums/bb476/waynep712/fordbatterytobodygroundwire_zps74c67080.jpg~original

sometimes i find them with only one or two strands left out of 50 strands in an 8 gauge wire to the radiator fans..

also.. the battery negative to the body that has gotten corroded..


before we go ANY FARTHER... dig in the kitchen... find some sandwich wrap..  and a rubber band...  

with a COLD engine...  remove radiator cap... lay sandwich rap across the top of the radiator filler neck..  push down the center slightly.. to leave a depression..  place rubber band around the filler neck to seal the sandwich wrap to the neck.. pinch off the overflow tube or make sure that there is enough coolant in the overflow bottle to prevent air from leaking out..

Crank or start the engine for about 15 seconds...

shut off... examine the depression in the sandwich wrap..

if its still in the depressed position.. GREAT..

if it has inflated.. you have head gasket or cylinder head issues that are NOT unknown in these..


on Taurus .. and a lot of other ford models.. there are radiator cooling fan and other item controller called the CCRM...

constant current relay module..  its a black module usually on the core support.. inner fenderwell.. on the core support on some taurus sable models..

these control one or two radiator fans. the ac compressor.. the fuel pump..

and they burn out ... leaving you without a radiator fan..

but they burn out because of LOOSE... FRAYED .. CORRODED ground wires as that increases the current because of the reduced voltage until they fail..

they have conventional PC mount BOSCH 40 AMP relays inside that are driven by the computer..    PLEASE do not go probing..


after the visual tests...

after a scan tool check for codes.. and a scan tool look if possible at output states.. see if the engine coolant temp sensor signal matches the actual engine temp.. and that when it comes up above 205 or 207 F as i recall.. might be 215.. that the computer commands the cooling fans on...

some scan tools can command them on for testing..

this is done engine off.. in the output state mode.. where for a few seconds.. it turns ALL the driven relays ON..

that proves that both the COMPUTER and the CCRM have command of the radiator fans...

why to NOT probe the wiring.. usually FAN #1 is controlled with a POSITIVE voltage signal to the CCRM to turn Fan 1 on...

fan 2 are controlled by a conventional NEGATIVE signal from the PCM..

if you go probing these with anything other than a LOGIC probe.. you WILL BLOW Out the power transistors in both the CCRM and the PCM...

please... also clean the ground wire connection near the computer plug...


lastly.. DO NOT PLUG IN A RANDOM CCRM..


match the suffex number or the 1 or 2 digit big number on it..


A or B or P something like that..

they are DIFFERENT inside and will DAMAGE your computer.. ford did this on purpose.. to make it harder for anybody but a ford tech to fix...

you will have to trust me on that one.. as its not written.. i studied the wiring diagrams of the various CCRMS a few computers back..

and there are obvious issues if you plug in the wrong one...

let me know what happens with the sandwich wrap....

THAR she BLOWS...   the great white whale of a taurus...

and.. some humor...

if a tree falls on a taurus... does it make any sound..

[wayne petty]

this will be easier..

the 2000 model year does not have a CCRM..

it uses relay in the relay block under the hood..
here are the diagrams for the 2000 model taurus..


http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f8036e1ad


the cooling fan relays have SMALL terminals..

please verify that the insertion force pulling the relay in and out of the socket is enough to transfer current..

you may want to buy at least ONE of these relays...

and rip the cover off the old one leaving an exposed frame...

this allows you to plug it in.. and manually squeeze the contacts shut to see if the controlled device works..

you can also .. operate the car with the bare relay installed.. if you have cleaned the contacts to verify that they close properly..

and  observe the relay.. to see if the computer closes it...

don't throw out this bare frame relay.. as it will be very handy..

if you are careful.. you can remove the relay.cover without a lot of damage..
this allows you to store it loose in the relay box.. or in an verified non wired socket.. to give you an OUT if something else fails..


you will also need the top image from this link...

it shows the under hood relay box. and which relays go where...

the second image shows something different.. the cooling fan brake relay...

that might be used to LOCK the cooling fans to prevent them from windmilling them till the bearings fail...  this is done by connecting both sides to.. probably ground. .i have not printed the diagrams and figured out which way it works..

stops them from creating any current when they windmill.. locks them tight..  kinda like regenerative braking on locomotives..  except locomotives use massive fan cooled resistor wiring..  where is these may run a dead short and prevent much of any rotation at all..


http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f8036e014


wow... thats an ODD circuit..  the radiator fan brake relay..

i will have to think about that.. but please check the relay or replace that relay..

as both fans GROUND circuit goes thru that relay... in the non powered position..  and that can be an issue..

[Rrumbler]

I knew Wayne would have a good write up on this.  Our resident "late model Guru".

[jaybee]

Great information, too bad all my second hand information was wrong. The fans run just fine, it's something entirely different.

I drove the car 70 miles to my house tonight and just got it home. On the Interstate it ran rock steady on the temp gauge. The first time I hit the end of an off ramp it went straight to hot. Back to 55mph for a short hop and it immediately cooled back down. When I got into town proper and stopped at the first stoplight it spiked again, but within a minute or two of constant, fairly slow driving the temp went right where it had been on the highway and stayed there, moving or standing still.

One more little detail that I suspect is probably related. The heater never really warms up. I haven't dug into it very deeply yet, not even enough time to try Wayne's trick with cling wrap over the de-gas bottle neck, but there's no sign of water in the oil. Brother tells me there's also no sign of contamination in the water, but given his track record with describing the behavior of the car I'll want to judge that for myself.

[rooster]

If cooling system is full it sounds like maybe the temp guage is wrong!

To check the fan circuit you could pull the plug from the ECT ( 2 wires) and jump a wire across the terminals (harness side) the fan should start running.

[wayne petty]

the NO heater is an issue..

you have the beginning of head gasket failure..

please... replace the water pump at the same time..

its building air bubbles in the cooling system...

ford installed enough bypass around the thermostat to compensate for some ...

DO you have access to compressed AIR...

do you have one of the 3 hose compression testers...

do you have a remote starter switch/button...

got any sandwich wrap? or a cork... some clear vinyl hose...
so you can observe the level of the cooling system.. filling the hose part way.. so ANY movement in the cooling system will be seen.. like a tubular level gauge...

rig up enough quick connects to be able to hook your compression tester hose directly to the quick connect on the shop air hose...

remove and safely store the valve core from the end of the compression tester hose.. its special.. opens at 4 psi..  

remove ONE spark plug at a time..   install the now open ended compression tester...

use the remote starter button.. usually upside down clamped in your hand.. so you can bounce it off the core support to get TINY movements of the starter that you could never get with your thumb...

bring that piston to TDC at the end of the compression stroke...

charge the line with Compressed air.. 90 to 130 pounds..  and yes.. just like a cylinder leak down test.. which is kinda what you are doing.. look at the level in the radiator .. if it moves when you apply air.. you have a leaker..

why is this different than a cylinder leak down test...

because you are using a compression tester hose.. with the valve core removed...

cylinder leak down tester hoses HAVE a RESTRICTION that this mod does not.. so you can get a LOT more air into the cylinder for testing..

i came up with this mod.. when i was helping out at a shop a bunch of years ago.. they had a early 60s fiat 2100 straight six.. and it kept blowing coolant.. i proved that the new copper head gasket was still not sealing..

so i yanked the head and smeared hylomar on both sides of the head gasket after a proper cleaning..  cleaned both mating surfaces..  the head had been surfaced..   when i reassembled the head.. and ran the car for a while.. then retested. no more leaks...


and since you have a taurus.. with hopefully a pushrod V6...

please invest in a BEAM type torque wrench for the head bolt removal..  you want to note the break away torque.   just for kits.. beam type torque wrenches can be had for 20 bucks..

warning.. the head bolt torque sequence. requires.. 2 different torque wrenches and a big azz breaker bar..  to properly set the bungee bolt head torque...  you will probably want a PAIR of 3/8 drive torque wrenches.. that read foot pounds..  and 3/8 to 1/2 adaptors for each...

the torque wrenches are set to different torques.. for the long and short bolts..

if i had the 8th digit of the vin i could give you exact numbers.. so these are generic numbers...


the bolts all get torqued to one value.. in several steps..

then the first bolt in sequence gets loosened..  then torqued to one of the torque values...  then half a turn with the breaker bar..  i normally go a quarter turn then lift the socket and reset it 90 degrees on the breaker bar and go another quarter turn..  

then go to the next  bolt in the torque sequence..  probably the short bolt.. loosen.. tighten to the other torque wrenches value..  then again switch to the breaker bar and give it a half turn .. a quarter turn at a time..


then on to the next on...

please .. turn your phone off...  put a sign on your back .. do not disturb..

do ONLY one head at a time in this crazy torque sequence.. take a break between the heads.. so you don't go insane...

this is the proper way as i understand it...

i have thought about bringing all the head bolts up to the torque after loosening them..     and once that's done.. then give them all a half turn in sequence..  but that's not how i read the instructions..

why... because i have been here..

and because i have found loose headbolts after a valve job comeback tear down...  somebody answered the phone or went to lunch..  or sneezed.. i did not put that one together the first time..

[jaybee]

DingDingDing!

That's exactly the problem.

I've gotta stop letting him talk me into looking at his cars. They always show up at my place with completely different symptoms (and problems) than he described.

[jaybee]

"The rest of the story" is always the interesting part. Turns out he hired a "mechanic" out of the town where he lives to fix an intake manifold leak. That guy "had to put on a new intake" (who knows if that's true) and put the thermostat in backward. Obviously that led to overheating, which went on for several WEEKS. The 70 mile drive to my place pretty well finished it off, and now it's dead in my garage. Can't wait to find out if he's ruined the heads. Yeehaw.