Fix4Dirt '98 XLT

[Josh P]

A laser thermometer would rule out blocked airflow with the radiator. Did you bypass the trans cooler in the radiator, or is it inline with the Hayden cooler? How often do you use a garden hose to get the dust out of the radiator fins?

 

[410Fortune]

Or it’s got trapped air and the sensor is reading high because it’s steam not water

The little pin is a weep hole, as John said it must go up … but in a sohc there is no up lol the thermo lays flat

You might just have some trapped air
With a laser thermometer you can read temps on both sides of thermostat see when it opens

Check the hose between coolant res and radiator.. not blocked

Likely just an air pocket they can be a ***** to bleed out….

Had air trapped in a 77 bronco the other day… holly sniper new install…bronco been in restore for 4 years so this 77 302 has been dry for years

the gauge kept climbing 217 218 219 220… then shut engine off. Water is still cold, only thing hot was lower intake. It’s trapped steam, the water is not actually 220 the sensor is reading hot air/ steam

Took a few runs and some major burping to get the air out… then once the air pocket goes away the temp started dropping like a stone…. 220 down to 190 and then finally back to 200 steady

You can tell a lot by feeling the upper radiator hose and the heater core hose.. the heater core gets water direct from waterpump so it the first thing to get hot
The upper rad hose won’t get hot until thermo opens
Try to find a high spot where you can release some air… without getting burned

See the mess? Coolant everywhere


I know you like the Earl bronco stuff so I figured you would like to see this

Rangers Explorer the 4.0 cooling system can be a ***** to burp
I have used a few methods over the years
Park truck with front end 2’ in the air lol
Pour boiling hot water down the upper rad hose to force the thermo to open
Or just run it a bunch knowing that’s air on the sensor and not actual water temp, the air should work its way out the overflow reservoir

A infared thermo really helps with diagnostics on cooling system.. you can see where is hot and where is still cool
An air bubble behind the thermostat/ lower intake can basically stop the flow/ reek havoc …..until you release it

 

[Fix4Dirt]

Pin goes on top to let air bubbles escape.

Double check for maybe a shop towel or rag got slipped in between radiator and condenser somehow. It could happen. All your symptoms combined point to blocked airflow thru radiator, slowing airflow on the the trans cooler in the process.
Edit
If the trans lines still go to radiator, and radiator overheats, trans fluid will rise to that temp.

Good idea to check lower radiator hose. If it feels at all flimsy when squeezed, it's fired!!!

In other words, the high trans temp might be a by product if overheated coolant.

Edit edit. Do you have a factory fan?
How does the shroud look?

Lower rad hose feels solid to me

I think so- I can get the truck to get hot without the trans getting hot (when I first start driving it)

Yes! Factory fan shroud looks fine

Check what you changed before the symptoms occurred. An easy way to check a thermostat is to put it in a pot of water on the stove with a thermometer. See if it opens when it's supposed to open.

Check the new housing, it's possible it's blocked?

Stop throwing parts at it. It's something to do with the thermostat or housing.

I did check the thermo & also put another known good one in that I had around. Most of the parts Ive changed were either known good I had around or should be changed because age (like WP)

I did take it all apart already once and the housing felt smooth no blockage nothing I could see or feel...

 

[Fix4Dirt]

Or it’s got trapped air and the sensor is reading high because it’s steam not water

The little pin is a weep hole, as John said it must go up … but in a sohc there is no up lol the thermo lays flat

You might just have some trapped air
With a laser thermometer you can read temps on both sides of thermostat see when it opens

Check the hose between coolant res and radiator.. not blocked

Likely just an air pocket they can be a ***** to bleed out….

Had air trapped in a 77 bronco the other day… holly sniper new install…bronco been in restore for 4 years so this 77 302 has been dry for years

the gauge kept climbing 217 218 219 220… then shut engine off. Water is still cold, only thing hot was lower intake. It’s trapped steam, the water is not actually 220 the sensor is reading hot air/ steam

Took a few runs and some major burping to get the air out… then once the air pocket goes away the temp started dropping like a stone…. 220 down to 190 and then finally back to 200 steady

You can tell a lot by feeling the upper radiator hose and the heater core hose.. the heater core gets water direct from waterpump so it the first thing to get hot
The upper rad hose won’t get hot until thermo opens
Try to find a high spot where you can release some air… without getting burned

See the mess? Coolant everywhere


I know you like the Earl bronco stuff so I figured you would like to see this

Rangers Explorer the 4.0 cooling system can be a ***** to burp
I have used a few methods over the years
Park truck with front end 2’ in the air lol
Pour boiling hot water down the upper rad hose to force the thermo to open
Or just run it a bunch knowing that’s air on the sensor and not actual water temp

A infared thermo really helps with diagnostics on cooling system.. you can see where is hot and where is still cool
An air bubble behind the thermostat/ lower intake can basically stop the flow/ reek havoc …..until you release it

Ill check tonight! It seems that when it heats up it cools back down reslly fast. We have a cap by the heater core for flush/bleed thats always worked fine in the past. That said Ill check again & also look at temps

 

[Fix4Dirt]

A laser thermometer would rule out blocked airflow with the radiator. Did you bypass the trans cooler in the radiator, or is it inline with the Hayden cooler? How often do you use a garden hose to get the dust out of the radiator fins?

Oops, forgot to respond

It's inline with the rad

Did it a few weeks ago, and again when the rad came out. There was a ton of mud, but it didnt change the symptoms.

I do have the winch on it, but thats never been an issue with cooling.

 

[BKennedy]

Now that I've had some time to think about it, it could be trapped air like a few posted above. Find yourself a very steep incline and drive up on it and let it idle for a minute, it's always worked for my Explorer.

 

[Fix4Dirt]

Im going to try looking for hot/cold spots & burping it again!

 

[Fix4Dirt]

Didnt see anything alarming in terms of hot/cold spots, and burped it a few times, no bueno. Tried on a steep incline. Ive got about 100 miles on this distilled water, so any bubbles shouldve worked their way out by now... but even still burped and no bueno.

Flushed out the system backwards forward, everything, still no bueno. Flow seemed fine to me as measured by my hand Used combustion gas tester and it came up negative, I dont see any smoke/smell, so theres no good evidence of a head gasket leak. Theres a little soot or something I saw in the system, hopefully it came out with the flush. Tested the tstat everything seems fine, no defects that I can tell in the housing...... Im going to try to seal the housing even better to make sure theres no air coming through there.

 

[Turdle]

While the engine is " overheated" pull over real quick, engine running open hood, pull throttle to rev engine, watch lower radiator hose. See if it sucks collapsed while revving engine.

 

[Fix4Dirt]

While the engine is " overheated" pull over real quick, engine running open hood, pull throttle to rev engine, watch lower radiator hose. See if it sucks collapsed while revving engine.

Got it, Ill take a look next time I run it. When it wasnt getting hot, the hose didnt collapse at all. THis was when it was at operating (192). If I let it idle, it never gets above 192. And when I lug it it doesnt heat up as quickly. Heats up faster at lower speed, but at high speed it still heats up just not as quickly.

 

[Fix4Dirt]

The only thing I can think of that explains everything is a tiny hairline crack in the gasket or something that isnt showing up in the gas tester0 ie small enough that at idle when hot it wont show up, but when you raise the pressure & load it starts to show up?

Forgot to say its not runnign rich or lean, no CEL, LTFT is within +-5%

I will definitely check the hose again though... this one's a stumper at least for me.

 

[CDW6212R]

How far below the top is the coolant when you remove the radiator cap? If there's any air in there, it won't be filled to the top. If there is air in there, that's a problem, but hopefully it's a coolant leak, and not a consumption of it past the head gaskets.

 

[410Fortune]

Went back a re read
Almost seems like a slipping trans? You said trans pan temp got up to 190… that is pretty dang hot for a trans… I mean usually I see 180 in the pan when it’s hot normal operations 150 is more like it

Could be slipping converter causing rapid water temp rise on hill

However 212 degrees is within the coolant operating range, it’s not till 220-225 I start to worry. Coolant operating temp is usually 15-20 degrees above thermostat opening temp, ours are fully open at 198 (we hope) so 210-215 is still in “normal” operating range. I don’t like running at 215-220
But ford would tell you “within range”

Could be fan clutch, heard you mention that a bit

I had the catalyst inside one of my
Converters break loose years ago… all was fine until I get on a steep hill then it would fall to the back of the converter housing and plug on the exhaust… big loss of power, engine would heat up, took me a bit to sort that one out

 

[Josh P]

Harbor freight has a tool for using an air compressor to put the coolant into the engine, works great for getting all the air out.

 

[Fix4Dirt]

Went back a re read
Almost seems like a slipping trans? You said trans pan temp got up to 190… that is pretty dang hot for a trans… I mean usually I see 180 in the pan when it’s hot normal operations 150 is more like it

Could be slipping converter causing rapid water temp rise on hill

However 212 degrees is within the coolant operating range, it’s not till 220-225 I start to worry. Coolant operating temp is usually 15-20 degrees above thermostat opening temp, ours are fully open at 198 (we hope) so 210-215 is still in “normal” operating range. I don’t like running at 215-220
But ford would tell you “within range”

Could be fan clutch, heard you mention that a bit

I had the catalyst inside one of my
Converters break loose years ago… all was fine until I get on a steep hill then it would fall to the back of the converter housing and plug on the exhaust… big loss of power, engine would heat up, took me a bit to sort that one out

When I watch the trans and water temps, I can get the water temp to spike when the trans is still running at a consistent 100 (like when its still colder). Which leads me to believe its the engine cooling overwhelming the trans cooling?

Really? Huh Ive never had it do that before. It would always stay rock solid at 192 even towing the boat up Grapevine (for the non SoCal folks basically longer steep hikl) and the trans would stay pegged around 175. Dunno, I feel like it still rises faster than Id like to hope. Since if I go up the 14 itll keep going past 210 if I let it but by then I put the heater on

 

[Fix4Dirt]

How far below the top is the coolant when you remove the radiator cap? If there's any air in there, it won't be filled to the top. If there is air in there, that's a problem, but hopefully it's a coolant leak, and not a consumption of it past the head gaskets.

I dont see/smell any coolant leaking on the ground or puddling by the engine

It stays about where it normally is. It went down slightly because I refilled it last night and ran it a bit to push some air out. But nothing out of the ordinary that I can tell. Id have to put a hundred miles or something on it to know probably.

 

[410Fortune]

210 climbing in so cal and putting the heater on.. I agree something is wrong! Not normal

Keep going! You’re doing a good job
If it was easy we wouldn’t have anything to talk about

 

[410Fortune]

Infared thermo
They are cheap!
Very useful
Can check each cylinder temp at manifold
Can check various temps throughout the cooling system
Could be a miss? Lean fuel? Things that cause an engine to run hot

One more thing how does she roll? Any drag in the brakes or drivelines?

 

[Josh P]

Check the radiator inlet and outlet hose with a infrared thermometer to see what the temperature spread is.

 

[sandsprayer]

A laser thermometer would rule out blocked airflow with the radiator. Did you bypass the trans cooler in the radiator, or is it inline with the Hayden cooler? How often do you use a garden hose to get the dust out of the radiator fins?

Seeing that Fix uses the truck on a fair share of trails, yes to the garden hose from the back side. Mud, dust and fine fine gravel are enemies.
I even just remove the radiator and use a pick every 20k-there is a lot to be mined from it.