Under cooled. Overheated. I don't get it.

[koldcustoms]

The story so far...

Bought an '87 Ranger with a 2.9L last August. The truck was purchased from a friend in Tucson Arizona. At the time the temp gauge was reading high. The P.O. told me it had been doing this for a while. Over the passed 2 years he had replaced the rad, pump, thermostat, and sending unit for the gauge to try and remedy the problem. Nothing worked, but he was curtain the motor was not running hot.

About a month after purchase, the truck overheated during a trip from Phoenix to Tucson. I was able to make it to an auto parts store where I changed the cap (after cool down), and replenish with bottled water. It was enough to get me to Tucson.

The next day I flushed the cooling system, replaced the thermostat (180 degree) and added a bottle of Water-Wetter to the coolant mix. After warm-up, the temp needle read square in the middle of the gauge. Okay, problem solved. A day later, the temp gauge refused to work; the needle never came off 'C'.

In December, I used the truck to tow a car and about 500lbs of tooling from Tucson to my home in Ontario Canada. By the time I reached Oklahoma City it was cold enough to need heat inside the cab. There was nothing coming out of the vents. I changed the thermostat again (190 degree this time). Nothing. At my next fuel stop, I placed a piece of cardboard over the grill. Nothing. Despite being nearly overloaded, climbing over dozens of hills and mountain passes, the truck would not heat up. At one point I used 4WD through a snow storm. Still nothing. Aside from this, I had no problems with the truck during the trip.

It is now registered in Canada. I have been driving it without heat since my return last December. This evening, I finally found the time to troubleshoot these issues. During a short drive to my shop, I noticed the throttle response was sluggish. The temp gauge then spiked toward 'H'. I pulled over, shut it off and popped the hood. The radiator had sprung a leak and was probably overheated. Did I mention it was -15C at that point, with a wind-chill of -22C; I had just herd to the weather report before stopping! WTF is going on!!!

I waited for it to cool down, topped off the rad with windshield washer fluid (the only thing I had that wouldn't freeze overnight), and nursed it back home. Still no F***ing heat in the cab, of course.

At least I know my engine temp and the intermittent indication problems are not related. What is strange is that both hoses to the heater core are warm despite the engine temp. It seems I have 3 separate problems.

Tomorrow: flush coolant, new rad, new thermostat (for the forth time in 6 months), probably a new temp sender, fresh coolant (without Water-Wetter) and a close look at the heater core and ducting.

Am I forgetting something? Any suggestions?

Thanks

 

[IMenriched]

Have you replaced the the Heater core?? a plugged one would cause no heat in the cab. If it is leaking a bit might also be the reason for the inconsistant temp.

BTW factory sending units for the guage cluster are not very reliable..best bet is to get a good set of mechnical guages.

If your still worried about loosing coolant...there is a die you can put in the coolant nad see where it is going

 

[0ldman]

Do the Rangers have a heater core cut off valve?

 

[JoshT]

Did you bleed the air out of the system last time you changed the T-stat? Are you sure, it can be tricky sometime. I don't recall where the T-stat is located on a 2.9, but on my 2.8 it's down on the bottom in the front. What I did to help with the bleeding is drill a (IIRC) 1/8" hole in the top center of the T-stat's flange, this allowed air to pass and made the job easier, and quicker.

Now you said when you didn't get heat you moved to a higher temp T-stat? That was the wrong move, you needed to go lower, if not stayed at stock. By putting in a higher temp T-stat it required the truck to get hotter before the valve would open and let warm water through to the radiator and beater core. What you needed there was a lower temp to allow the warm water coolant to flow sooner, not that it sounds like it would help in this situation. As for the heater core have you checked to ensure that it's not clogged? If the heater or lines going to it are logged the heater core will never warm up therefore no heat.

 

[Tedybear]

2.9's are located at the top. The thermostats normally have a "jiggle pin" that gets positioned at the top when installed to aid in 'burping' the system out. (yeah...it works like crap too)

I've always burped the system after replacement of parts by filling the radiator within about 3-4" of the top, starting the engine with the cap off and letting it warm up. It'll kinda spurt a bit when the thermostat first starts to open up..then you'll see the coolant level spike up a few inches---and within a few seconds? It'll drop like a flippen rock. When it drops? You want to add the 50/50 mix in the radiator somewhat slowly. Too much and it'll kick back at you...(not to mention pouring in coolant into HOT coolant? If the radiator heats up to quickly doing this--can stress it) Once the coolant level is returned to about 3" from the top of the neck--Let it warm up a bit more, feel the heater hoses and upper hose to ensure coolant flow. Slowly add a bit more until it's below the neck a bit, and install a new radiator cap. Set the amount of coolant in the side juggy about mid-way.

Should be good to go afterwards. That initial surge/drop can be messy, and dangerous if you have to much coolant installed at first. (it sputters out and can splash around..and it's flippen hot).

In regards to the heater? I agree it is very possible the core itself is plugged. When it's at temp, feel free to feel both heater hoses. If both hoses are hot? The heater core has flow. (if one hose is stone cold...or pee-warm..and the other is hot? It's restricted) I'd also recommend checking the air mix door, and cleaning the buildup of crap that loves to restrict air flow through the heater core. Thankfully this style heater core is pretty easy to get to, and just as easy to verify it's operation. You can frankly pull the cover off, run the engine..and watch the core for leaks...and feel along the fins for heat.

S-

edit: Normally when replacing the thermostat I also replace the thermostat "neck". It's not to expensive, and it's shocking how badly pitted up that little part can get. Might also pay off to remove the hoses to the heater core, (do this while cold) and point one end into a bucket...and hit the other end with a stream of clean water from a hose to flush it out. You'll know pretty quick if it's plugged.

 

[90B24wd]

One fast way to bypass the heater, is to run a short piece of heater hose on inlet & outlet nipples in the front .

 

[koldcustoms]

Yes, I burpped the system when I changed the thermostat in Oklahoma. I drove the front wheels onto a curb in a parking lot to aid the process.

The factory shop manuals I have state that the 195 degree thermostat is the correct spec. It was suggested by the P.O. that I use the 180 degree (as he had) because of the extreme heat in southern Arizona, and as piece-of-mind due to the indication problem. It was my intention to solve this issue and go back to using the 195. I know a lower temp unit has been recommended on this site. However, I don't subscribe to the idea; the engine's computer is programmed to manage fuel consumption between a specific temperature range.

Anyway...

I replaced the rad with a new unit for a '92 Explorer, and swapped in another 195 thermostat. I haven't yet repaired the indication problem. When I find the time, I'll take IMenriched's advice and install an aftermarket guage. For now, I've rigged up a calibrated thermocouple used for aircraft diagnostics. Water temp doesn't go above 208F degrees in the city, and I now have some heat in the cab. The engine also idles at a lower RPM when warmed up (which I expected).

Thanks for your replies.

 

[UnderMedikated]

Sounds like the start of a cracked head.
Do you lose any antifreeze?
Does the system hold the correct pressure?
2.9's eat heads like Rush Limbaugh eats Democrats.

 

[UnderMedikated]

At least on your Ranger you can replace the heater core easily. The new ones are a F$$king B$tch. Automotive engineers need to be slapped into oblivion. Nothing like getting F'd for 800$ to change one at the dealer.

 

[koldcustoms]

Yes, the system holds pressure and I'm not detecting any loss of coolant. I suspect the heads were replaced by the original owner. This is the second time it has overheated, yet I don't notice any reduction in power. I'll perform a compression check and an oil change this weakend to determine if any further damage has occured. I'll also be replacing the heater core.

Can anybody tell me where the casting numbers are located for Ford's revised 2.9L heads?

 

[Natedog]

Do the Rangers have a heater core cut off valve?

A physical cut-off valve....NO. They are full-flow all the time.

I'd check that the dash lever cable is actually hooked to the proper flapper door and functional....this flapper (mixer) door is what controls the cabin air temperature....NOT any type of water flow control valve.

Replace the GUAGE temp sending unit (NOT the EEC sending unit, although I'd replace this too if it's original), check that the wiring to the guage is intact with a DVM.

Use the FACTORY temp thermostat....192F............the engine is designed to run at this temp....lower is not better....it will result in lower fuel mileage, faster engine wear and increased exhaust emissions.

2.9's are located at the top. The thermostats normally have a "jiggle pin" that gets positioned at the top when installed to aid in 'burping' the system out. (yeah...it works like crap too)

I've always burped the system after replacement of parts by filling the radiator within about 3-4" of the top, starting the engine with the cap off and letting it warm up. It'll kinda spurt a bit when the thermostat first starts to open up..then you'll see the coolant level spike up a few inches---and within a few seconds? It'll drop like a flippen rock. When it drops? You want to add the 50/50 mix in the radiator somewhat slowly. Too much and it'll kick back at you...(not to mention pouring in coolant into HOT coolant? If the radiator heats up to quickly doing this--can stress it) Once the coolant level is returned to about 3" from the top of the neck--Let it warm up a bit more, feel the heater hoses and upper hose to ensure coolant flow. Slowly add a bit more until it's below the neck a bit, and install a new radiator cap. Set the amount of coolant in the side juggy about mid-way.

Should be good to go afterwards. That initial surge/drop can be messy, and dangerous if you have to much coolant installed at first. (it sputters out and can splash around..and it's flippen hot).

In regards to the heater? I agree it is very possible the core itself is plugged. When it's at temp, feel free to feel both heater hoses. If both hoses are hot? The heater core has flow. (if one hose is stone cold...or pee-warm..and the other is hot? It's restricted) I'd also recommend checking the air mix door, and cleaning the buildup of crap that loves to restrict air flow through the heater core. Thankfully this style heater core is pretty easy to get to, and just as easy to verify it's operation. You can frankly pull the cover off, run the engine..and watch the core for leaks...and feel along the fins for heat.

S-

edit: Normally when replacing the thermostat I also replace the thermostat "neck". It's not to expensive, and it's shocking how badly pitted up that little part can get. Might also pay off to remove the hoses to the heater core, (do this while cold) and point one end into a bucket...and hit the other end with a stream of clean water from a hose to flush it out. You'll know pretty quick if it's plugged.

Great advice.

 

[Natedog]

Yes, the system holds pressure and I'm not detecting any loss of coolant. I suspect the heads were replaced by the original owner. This is the second time it has overheated, yet I don't notice any reduction in power. I'll perform a compression check and an oil change this weakend to determine if any further damage has occured. I'll also be replacing the heater core.

Can anybody tell me where the casting numbers are located for Ford's revised 2.9L heads?

Under the valve covers....here's the numbers and the two styles of 2.9 heads from the Tech Library on this site.

http://www.therangerstation.com/tech_library/2_9_Page.html

http://www.therangerstation.com/tech_library/index.php

 

[AllanD]

Do the Rangers have a heater core cut off valve?

No.

I was having suprisingly similar symptoms from my 4.0 on a return trip from wyoming... in early January of 2008...

it was all of 11degF and my truck was "overheating"

What the problem turned out to be?

When I DISASSEMBLED the radiator (I.E. TORE the end tanks off of it) I discovered that of the 80-some tubes in the radiator, 8 (EIGHT!) were entirely clear and an additional four or five would allow partial flow.

That's the radiator at <10% of it's rated capacity.

Your 2.9 radiator (unless you've put a 4.0 radiator in it)
had HALF the capacity...

A NEW 4.0 radiator is only about $130
and living whre you do retrofitting in a 4.0 A/T
Radiator would be an excellent idea...

as for the lack of heat? some of the crap blew out of the radiator and clogged my heater core making me replace it just before that december/january trip to wyoming.

There was still enough crap in the system after I flushed it
to kill a second heater core the following september.
(thank Advance Auto Parts for a lifetime warrantee

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