2000 Taurus heater

[jaybee]

You might remember I talked about my brothers 2000 Taurus 3.0L OHV having a blown head gasket a while back. It sat until I could get into it, and now that job is done, but the car still doesn't run right. Good news is, it doesn't puke coolant. Bad news is, it still has a couple of symptoms it had when I picked it up.

Still has a BAD stumble on idle. Not a dead miss, but it won't idle steady and sometimes hunts for idle speed and when you run it up it'll hang sometimes on the way down...reminds me of a vacuum leak that the EFI is trying to compensate for.

Still absolutely zero interior heat. I assumed the lack of heat was due to the heater circuit being blown out of coolant by the head gasket leak. Now I think it has an inoperative heat control valve...maybe it's unhooked and the source of the vacuum leak? So far I can't find the valve so I don't know.

There's now a pinhole leak in the EGR tube, where it was broken previously and welded back together. Will this affect idle?

So far it isn't throwing a CEL.

Does it sound like I'm on the right track?

[wayne petty]

Still absolutely zero interior heat. I assumed the lack of heat was due to the heater circuit being blown out of coolant by the head gasket leak. Now I think it has an inoperative heat control valve...maybe it's unhooked and the source of the vacuum leak? So far I can't find the valve so I don't know.

i don't recall or even see a heater control valve when i searched it out at motorcraft.com  i have done a few taurus heater hose sets.. i don't recall any valves... do you have an infrared temp gun??  measure the inlet and outlet temps of the hoses.. is it hot on one side.. and not on the other?? could be clogged core..   this is with the heater fan on.. temp set to hot.. turn the system off and see if the temp gets warmer on the outlet.  you could have a lot of sediment in the core.. reduced airflow will allow heat to work its way thru without loosing it to the airflow ..

have you a radiator pressure tester.. can you pump up the cooling system  if it takes more than 2 pumps.. you have air pockets in the system..

check all the other hoses.. and did a new thermostat get installed?

use your temp gun to see the various coolant segments picking up heat and cycling as the thermostat cycles..

~~~~~~~~~~~~~~~~~~

There's now a pinhole leak in the EGR tube, where it was broken previously and welded back together. Will this affect idle?

depends if its still leaking..  got an OBD2 scan tool.. get it into live data.. O2B1S1 and O2B2S1.  both upstream.. select one then the other .. when you get one highlighted.. push enter. take it into graph mode..  slowly take the RPMs to 2500 and let it stabilize there.  using all your foot and leg muscles.. hold your foot totally still.. no movement of the throttle.. do you get a nice clean sine wave.. 0.01 to 0.9 volts.. /\/\/\/\/\/\/\/\/\/\  without any drop outs.. or do you get /\/\/\------___________ indicating issues. with dilution..

let it back to idle.. the pattern should be similar.. but spread out slightly.. / \ / \ /\ / \ / \ / \  if you loose the pattern at idle..  look for vacuum or exhaust leaks..

do the other oxygen sensor..  the harbor freight scan tools do this really well for cheep.. i just got the new one 60694.. have just barely started to use it.. man it does graphs really well..

http://www.harborfreight.com/can-obd-ii-professional-scan-tool-60694.html

i got it as it can command the vapor control system on some cars that the 98614 does not..

~~~~~~~~~~~~~~~~~~~~

Still has a BAD stumble on idle. Not a dead miss, but it won't idle steady and sometimes hunts for idle speed and when you run it up it'll hang sometimes on the way down...reminds me of a vacuum leak that the EFI is trying to compensate for.

check that all the spark plugs are properly plugged in..

if you have a scope.. you might be able to look at the snap throttle coil voltage test.. you have to go thru each wire at a time..

you can turn the coil over.. and check for cracks on the bottom in the potting compound.. if so.. replace..

this is DIS.. 3 individual sets of coils.. spark comes out of one terminal.. down wire.. jumps plug.. thru head, block other head jumps spark plug going other way.. up wire return to other coil tower..

when the coil high voltage leaks inside the coil.. it can take a short cut to ground  or into a different set of coil windings and cause a misfire thats hard to spot in most cases.. once in a while you can move a good timing light around the various wires and spot a double flash.. where all the others were a single flash..  throw a coil on it.. look for one with a long warrantee..

you can test some vacuum hose with your ohm meter to make sure its conductive.. make six little stands of vacuum hose to extend the wires up..  fire the engine up.. and touch the individual vacuum hose sections with a conventional test light probe thats properly grounded.

open circuit testing.. with a wire off can cause issues.. of th high voltage looking to get back to the starting point.. sometimes right across the low voltage Cmos circuits in the computer.

you might be able to try individual wires on one of the adjustable gap spark output tester..

[rooster]

[quote="jaybee

Still has a BAD stumble on idle. Not a dead miss, but it won't idle steady and sometimes hunts for idle speed and when you run it up it'll hang sometimes on the way down...reminds me of a vacuum leak that the EFI is trying to compensate for.



So far it isn't throwing a CEL.

Does it sound like I'm on the right track?[/quote]

If you had the battery cables disconnected there probly some relearning going on! Might take abit of driving to see CEL again.

Might try reverse flowing the heater core see if you can get some of the crud out of it.

I thought maybe you TPS sensor might have a glitch!

Sounds like you have been given a handful of problems to figure out!

[jaybee]

Sounds like you have been given a handful of problems to figure out!

Can't disagree with that. IMO he's been developiing issues over time and it all just came to a head.

[river1]

Your lack of heat MAY have something to do with the idle problems.

I believe the temp is something the computer reads to adjust the idle.

Hopefully this gets figured out

later jim

[wayne petty]

on many fords... there is a coolant pipe that comes up out of the intake really close to the thermostat housing..  the coolant temp sensors are usually screwed into the side of this.. there is also at least one heater hose or bypass hose that comes off this...

on the top is a bolt.. 14MM hex head.. might be 15MM..  there is usually a plastic disc under the bolt with some writing.. this is actually the cooling system bleeder screw...

on other fords.. i have had to not only take the bleeder bolt/screw all the way out.. and clean the passages from the center and out thru the side of the threads. but i have also had to replace the plastic disc with a proper fitting nylon drain plug gasket...

the plastic disc fractures slightly over the years.. tiny drips of coolant come out but get boiled away on the top of the motor.. the issue is... when the engine cools off..  instead of it pulling coolant in from the overflow bottle.. it sucks a little bit of air into the engine thru the leaking plastic cap.. so the engine has an air lock every morning..


i also wonder if the impeller blades on the water pump have eaten away and are not pumping the water with enough force to push it thru the heater core.. .?


these are just waking up thoughts for an early saturday morn..

[rooster]

If all else fails, this dont look to bad of a job!

this one looks like a shortcut

Do you have a scan tool?

[Crosley.In.AZ]

Buy one of those 12 volt dash defroster deals... plug it in, and run with it

[jaybee]

As an update;

I got the pinhole leak in the EGR tube stopped, but there's still an exhaust leak. Looks like the manifold to cat converter gasket slipped out of place at the last minute and there's a major leak at that point. I feel pretty confident that there's air getting to the O2 sensor (it's right there, after all) and the idle problem will clear. It's drivable but rough when stopped and threw a CEL right before I shut it down the last time. I'll fix the problem I already know is there before getting into that because I'd expect a light under the circumstances.

Doesn't seem like a plugged heater core at this point. Both inlet and outlet get nice and hot, and it doesn't make little heat, it makes ZERO. I'm leaning toward a bad heater blend door motor or broken heater blend door, both of which also seem to be common Taurus issues.

[rooster]

As an update;

Doesn't seem like a plugged heater core at this point. Both inlet and outlet get nice and hot, and it doesn't make little heat, it makes ZERO. I'm leaning toward a bad heater blend door motor or broken heater blend door, both of which also seem to be common Taurus issues.

might be something here! Your getting closer!

http://www.heatertreater.net/videos.html#taurus

[jaybee]

Regarding the heater blend door, I would not have thought to come up with the repair procedure "cut a big hole in the side of the heater box that you will later put back together with hot glue and duct tape" but I guess when you're trying to save $1,000 on a repair compared to what the dealership will charge all options are on the table.

No kidding, that's how the repair works...cut a hole big enough to get the blend door out and back in. Even at that I had to cut the old one in half while it was hanging part way out in order to clear the dash bracing. The new one from Dorman comes in two pieces so it goes in more easily, though it does need to be assembled by reaching through that same hole.

[jaybee]

OK, I'm stumped. I've been driving the car for the last couple of days doped up with Prestone radiator flush (instructions say that's acceptable). During that period any and all indications that the car would try to overheat went away, temp was dead stable. Today while it was above freezing and I could run a garden hose I drained, flushed, and refilled the system. It's worth noting that I did see some particulate matter in the drain pan.

I refilled, let it idle in the driveway until warm and everything stayed cool. Time to call brother and let him know I'm bringing back his car. Fifteen minutes through town and the temp needle was nudging hot. Let it cool down, poured a gallon of water in and headed for home. It started to do it again. It doesn't try to blow the water out like a head gasket, but it won't stay cool all at once.

What the...?

[chimp koose]

Big air bubble?If you had to add a gallon before going home I would think there was air trapped in the system when you first left on the trip.

[jaybee]

Big air bubble?If you had to add a gallon before going home I would think there was air trapped in the system when you first left on the trip.

Hmmm, maybe. I warmed the car with the nose down, parked outside so I could sweep out the garage. When I filled it last it was nose up on jack stands.

[jaybee]

OK, I've about got this one nailed down...down to one issue, slowly overheating at extended idle or stop & go traffic. You can basically drive it forever if you don't stop, but once the whole system is heat soaked it'll start to climb at idle and drop right back down when moving again.

The cooling fans on this car are 2 speed and they never switch from low to high. That includes when the a/c or defroster are turned on, which should automatically engage high speed for the fans. I've been around the internet and see lots of complaints of the fans not coming on, none that quite match my issues. Anyone have thoughts for diagnosing this one?