low temp problem

[grassman]

1998 ranger coolant problem 2.5 went bad installed low milage 2.3 swopped all parts engine runs good will not heat up installed manual guage in heater line by sensor runs 140 degrees used heat gun also changed t-stat several times napa /orieleys /even ford parts replaced -water pump ,t sta housing radiator with new shroud ,sensors ,all hoses .bypassed heater hoses glued t-stat into housing put card board in front off radiator changed fan clutch have been a mechanic for a lot of years auto and diesel never have seen this problem before. any help would be great.does not have a converter in exhaust at this time. is exh back pressure needed ? really like truck but cant drive in winter

 

[tomw]

Only thing I can say is get a Stant/Motorcraft/Gates, or any well known brand. When installing, the rubber seal/gasket/ring should be stuffed into the housing tightly so it seats. The legs with the 'flat fee' need to be bent so they rest in the machined groove around the perimeter of the housing. If not, the thermostat can move and lose its seal, allowing coolant to flow when it should be restricted.
The test is to start a cold engine, and let it run at idle, with a hand placed now and again on the upper radiator hose. It should stay COOL, and then, in a very short while, get HOT. If it gets warm over time, the stat is leaking. It should allow close to zero flow until it opens, and should open decisively.
You should not need cardboard or any other external airflow blocker unless you live North of northern Montana, and the temperature is way below zero. The heater should be able to drive you out of the cab when the stat is functional.
tom

 

[Dsetz]

Actually, northern Montana is colder than north of northern Montana! But not quite as cold as east of northern Montana
I've never bothered blocking air flow regardless. I'm slightly out of the N. Montana eskimo zone but we see -20 most winters.

 

[Bgunner]

Have you checked the heat range of your spark plugs? This too will change the engine temps.

 

[Dsetz]

Wow a quick search turns up 6 people in this post having the same problem in the same motors/era. https://www.cargurus.com/Cars/Discussion-t776_ds621795
Someone there mentions radiator cap- which isn't a bad idea. Otherwise....?
Tried a garden hose flush? I like to flush the crap out of them, then run reverse osmosis water over a few cycles to hopefully clean/break things loose, before I refill with anti/distilled. Even after that, my Buick has gummed up again within 2 years. GM dexron, never again

 

[grassman]

have tried several diierent t-stats checked legs for stats ok glued into place. 50/50 mix on coolant. tried long life coolant still same. bypassed heater core .should not half to remove fan to fix problem. will try to pressurize heater core line and block with top hose disconnected to check t-stat for leakage. checked part numbers on water pump for 2.3 and 2.5 seems to be the same. t-stats seem to be the same. t-stat should regulate engine temp at all times no matter what else happens with everything I have changed. does not make any sense. spark plugs ok

 

[Bgunner]

have tried several diierent t-stats checked legs for stats ok glued into place. 50/50 mix on coolant. tried long life coolant still same. bypassed heater core .should not half to remove fan to fix problem. will try to pressurize heater core line and block with top hose disconnected to check t-stat for leakage. checked part numbers on water pump for 2.3 and 2.5 seems to be the same. t-stats seem to be the same. t-stat should regulate engine temp at all times no matter what else happens with everything I have changed. does not make any sense. spark plugs ok

For informational purposes only, if the proper plugs for the motor are not used, the motor can either overheat or not heat up properly. This is caused buy the heat range the plugs were designed for. Because you have changed most things and checked most other things for the cooling system it is time to start looking at what else causes the motor to heat up.

Is the same radiator used on the two different 4 cylinders? I have the 3.0 but know the 4.0 radiator is thicker, this is why I am mentioning this. A larger radiator will dissipate the heat quicker causing it to cool more than it needs to be so then the motor needs to heat it up more to keep the temps up in the 185°-195° range.

 

[alwaysFlOoReD]

Radiator size shouldn't matter if the thermostat is doing its job.
I have nothing else, sorry. I'm interested in what the answer is going to be.
@adsm08
@RonD

 

[Uncle Gump]

Have you tried putting any of your thermostats in a pot of water and confirm their operation?

 

[alwaysFlOoReD]

What he describes would be the stat stuck open. That can be checked visually.

 

[Uncle Gump]

Or… opening way too soon.

It can't hurt to check it...

 

[alwaysFlOoReD]

True.

 

[rusty ol ranger]

Throw a piece of carboard between the radiator and grille.

 

[alwaysFlOoReD]

Throw a piece of carboard between the radiator and grille.

He tried. Its in the first post. Its easy to miss because he doesn't use commas or periods.

 

[Dsetz]

And actually, searching farther, there are endless cases just like this on the net, in Ford Rangers/Explorers, where everything that should be replaced/checked has been. Enough for a TSB.

One common area of trouble was corrosion in the thermostat seat preventing a proper seat.

You never mentioned whether you burped it on filling. A pocket of air won't transmit heat through the system like coolant would.

Here is another burping method from "pawpaw" from a different forum.

"If you think the system didn't burp well after refilling, turn the cabin heater temp control to Max temp/heat, park front end up hill, the steeper the better, or elevate the front end, the higher the better, so the radiator is the high point in the cooling system.
Milk the lower radiator hose about a dozen times to chase any entrapped air bubbles toward the radiator. This works to purge air past the thermostat air bleed valve & back to the top of the radiator. If the new thermostat wasn't a Motorcraft, or a design like it with the air bleed valve, you'll have to wait until the thermostat opens for the air to pass the thermostat & get to the top of the radiator, so this step will have some but not full effect

Make sure the coolant recovery tank is topped up & that the radiator cap is functioning, as it'll burp air out of the system as it cools & automatically top up the coolant from the recovery tank. SO, if you'll mark the tank & check it after it cools down, you can see if the recovery tank level dropped when the system burped.
Top up the recovery tank with a 50/50 mix of distilled water & the specified Undiluted coolant.

Start the engine & let it fully warm up so the thermostat is fully open, the temp gauge peaks & drops back, or the upper radiator hose is too hot to hold. Then increase engine rpm to say 1500-2000 for 30 seconds or so, to chase any air back to the top of the radiator, then shut the engine off & let it completely cool & check the recovery tank mark & if it dropped you know it burped, so top it up.

If it drained the recovery tank you know you had a Large air bubble, so top up the recovery tank & radiator & repeat with the front end elevated, until it stops burping & the system should be purged of air."