Boilin' Over!

[1shot]

I got a 92 Ex 4.0 V6 Auto Eddie B with 200K. It OVERHEATS BAD, but ONLY ON HIGH SPEEDS.
okay I done some work on it but im starting to pull my scalp offa my head.
so far i have:
-New H2O Pump (Proven - from another truck with less than 10K)
-New T'stat (tried 2 a used one from a another truck and the new one)
-New Heater Core (a proven new core from another truck)
-New hoses throughout. (ALL new)
-New Aftermarket Radiator (on the truck for <20,000k)
-Replaced Clutch pack and 10 blade plastic fan from known truck
-OLD H2O temp sensor and gauge (but have been verified correct)
-truck shows steam at rad and resivoiur but no bubbles in rad.
-Coolant flow appears strong.
-truck shows NO steam or white smoke out of tailpipe.
-truck runs 100% with no rough idle or acceleration regardless of temp shown.
-plugs are all norm light brown. no white plugs.
-Using infra red temp gauge shows rad same temp across face.

NOW FOR THE DETAILS...

If I start and drive around town it works fine, gauge shows temp comes up as quickly as should, heat comes out of vents quickly, hot and before gauge shows temp deflection.

I can drive around city and stop at lights etc, with no problem for hours.
I can idle in driveway till tank is empty - stays inside of normal range - ie m in normal.

BUT BUT BUT if i get onto a highway within a few miles/KM it climbs up and gauge shows high (1 letter per km on standard gauge...(C BAR space N O R M A L space BAR H)) and it overheats and spits out coolant out of overflow tube to resevour. It especially!!! heats up quickly if i try to go up a hill. I can drive all day on flat slow speeds but instantly overheats on highway or going up a slope.

Now since I put new parts into it, it has improved slightly, but same problem persists. Driveable in city but overheats badly on hwy speed, night or day, hot weather or cold.

I'm figuring I'm down to a plugged new radiator or a very small exhaust gas leak thru a cracked head or gasket.

Any comments?

 

[Turdle]

Clogged catalytic converter?
High rpm's? (torque converter not locking?)

 

[1shot]

hmmm, well...

as fer clogged cat - it just went thru "AIR-CARE" in Feb which is our dyno testing smog test for lisence in our parts - and she passed - so I'm sure it isnt that cause it drives / feels the same - really seems to breath fine. (As well i've done new air filter and cleaned the MAFS as well) And fer trans.. well she locks up really fine...She dang near picks her front wheels off of the ground... LoL - (she is much STRONGER than her sister, my other '92 4.0)

OK so I have heard from a local mechanic that if yer buggy overheats at low speeds it's more likely that it is a head or head gasket or similar source,
and,
that if it overheats at highway speeds it is more likely to be the rad, plugged or otherwise similar causes...I would have thought the other way around - so I do not know which way to test next...

 

[trucku]

maybe you have a bad coolant cap that won't hold pressure and allows coolant to boil over. Test the cap.

You can also do a back flush on your radiator. It would only help.

 

[mawrazen]

Go to a boneyard and pull a radiator. Try a lower temp Tstat, Check your fan clutch, check or replace rad cap, try "Water Wetter" or the other product next to it where you drain the system and add it instead of antifreeze. (Says to stop overheating by reducing temp by 25 or 40 degrees depending on which can you buy $20-25 for 40 degree and $15 for the 25.

Also if you have too much antifreeze instead of water you are not transfering heat as effectivley. The more H2O the better.

My 1994 Ex w/ 230K + miles usually is below N with water wetter, gets to OR only when towing up the mountains.

Hope this helps.

 

[BrooklynBay]

Check my thread on cleaning out the cooling system: http://www.explorerforum.com/forums/showthread.php?t=162848

 

[jonafer]

Replace lower intake gaskets and use RTV around water passages.

 

[gijoecam]

This may be a dumb question, but it has to be asked : Are you running a 50/50 micture of antifreeze and water? Straight coolant can do exactly what you describe.

I would second the radiator cap. Have it pressure tested or just buy a new one (or swap it out with one from another vehicle if you can).

What's the lower intake gasket got to do with overheating on a 1st gen?

-Joe

 

[1shot]

maybe you have a bad coolant cap that won't hold pressure and allows coolant to boil over. Test the cap.

You can also do a back flush on your radiator. It would only help.

tried a new cap (stant 13 lb) and a old tried and true cap off of my other truck.

Cap holds except when engine is very hot...


but thanks fer the suggestion

 

[1shot]

Go to a boneyard and pull a radiator. Try a lower temp Tstat, Check your fan clutch, check or replace rad cap, try "Water Wetter" or the other product next to it where you drain the system and add it instead of antifreeze. (Says to stop overheating by reducing temp by 25 or 40 degrees depending on which can you buy $20-25 for 40 degree and $15 for the 25.

Also if you have too much antifreeze instead of water you are not transfering heat as effectivley. The more H2O the better.

My 1994 Ex w/ 230K + miles usually is below N with water wetter, gets to OR only when towing up the mountains.

Hope this helps.

WELL... I aint got NO antifreeze in it right now - it burps out too much to try with antifreeze.
I know H2O is a better heat transfer medium than glycol so i have not tried antifreeze yet - got to get it to stop overheating before I add the exspensive stuff.
Fan Clutch is good because I swapped a known good 10 blade fan and clutch into it but it still overheats.
I'll look for water wetter as well... but if I cant drive it on highway on a cool day with straight water - then it still has a problem...Like I said - I can drive around all day at low speeds (ie <60km per hour ) but as soon as I get on highway it overheats quickly...

 

[1shot]

Next Days Events

Okay, This morning I drove it to Dealership - The Service Manager (Friend of mine) came out to greet me with his temp reader gun in hand...

I had driven aprox 25 Km on highway to this point and the needle was showing at L on gauge.

Temps aprox were...

220 at base of tstat housing
180 at base of rad hose in
< 140 at output rad hose
140 at inoput to heater core
100 at out of heater core.

All of these temps appear normal for a fully warmed up motor... He shook his head and looked at me quizzically and said that it looked normal...

however my gauge was at the L and 2 blocks later at my office I turned truck off and it then spit up about 2 liters (1/2 gallon) of steam and water back through the overflow tube into the resivour.

 

[1shot]

So after work I drove 1 mile to brothers house - attached a flush kit and flushed the dang thing out for 1 hour.

Then I drove home but temp kept crawling higher evertime I went up a hill or gave it enough gas to get to highway speed. So I kept to the back roads - kept it at 60kph or less and made the 25 km trip home and it did not spit up any water when I got home but it was at the L on the gauge on the verge of boiling over...

So once again I am confused - cause the sun had gone down by the time I went home and the air was MUCH cooler...

 

[trucku]

tried a new cap (stant 13 lb) and a old tried and true cap off of my other truck.

Cap holds except when engine is very hot...


but thanks fer the suggestion

I thought it was supposed to be a 16lb cap?

Flush it with concentrated radiator flush not just water.. fill her with water and flush (take thermostat out so your getting constant flow and heater on full hot). Driver around a bit as long as you can keep her from overheating. The engine speed will help the flush break debris loose.
Maybe you have some kind of blockage inside the engine. The thermostat free environment might allow enough pressure to circulate around and free the blockage.

Did you Backflush the radiator. Disconnect the hoses and then maybe the pressure of the water in the opposite direction will push out the blockage.


Wow sorry for the heat gremlins
Good luck

 

[jonafer]

Water passage in lower intake blocked.

 

[gijoecam]

Good news about the water.

Oh, I've got two dumb questions: First, did you install the thermostat with the bleeder hole facing up? Second, did you install it facing the right direction?


The only other thing that comes to mind would be a bad gauge or sending unit, but that wouldn't explain the puking coolant when it gets hot. That's a sign that it's being allowed to boil.

What was the temp of the block at the thermostat housing when it was boiling over?

The only other thing that comes to mind is a leaking head gasket allowing combustion gasses to over-pressurize the system. Have you tried doing a compression check? I doubt it's the problem, but we have to rule it out...

Here's something else you could try: Yank the thermostat out all together and take it for a drive. If it's a coolant flow issue, it will continue to overheat. If it's a thermostat issue, it'll run cool as a cucumber.

 

[aldive]

I put it into boiling water in the stove at 195 degress C and

.... and duck.

I think you got the Cs and Fs confused. It should read 195 F.

By the was 195 C = 383 degree Fahrenheit

 

[trucku]

use that temp infrared temp guage and monitor the water temp as it climbs. see when the T-stat starts opens and when it is fully opened.

 

[shamaal]

How frustrating this must be!

The stuff you listed as replaced in your first post pretty much covers all my suggestions. I was thinking a collapsed lower radiator hose but I see that has been done, Also the fan has been replaced, I'm not sure if a ten bladed fan is right, I would think that might impede air flow at highway speeds but without measuring airflow I couldn't say.

I don't think your problem is that the water isn't wet enough or the t-stat is wrong although putting in backwards merits a look. A blocked heater core would have no effect either. The numbers from the radiator look like I would expect a working radiator to look like although the engine (220F) seems hot. It's not the first time a tstat has been installed backwards.

We are absolutley certain, when the engine is cool, that there is no water being lost? If I was grasping at straws I would recommend a simple cylinder pressure test a block cooling test. At this point the problem sounds like a blocked water passage in the block not allowing removal of enough heat or a cracked head/cylinder adding more heat than the cooling system is designed to remove.

FWIW there are two temp sensors, one goes to the engine computer and one goes to the gauge. Both have the same resistance at temp. The spitting water kind of validates the gauge reading though.

Sorry I couldn't be more help.

 

[1shot]

okay day 7 of this escapade... LOL~!

Ok. I talked to a Ford Dealer Service tech today and he says he is the Original owner of a 91 EX with the exact same symptoms allthough not quite as bad. He says he got his RAD flow tested and it was bad...He says he plans to replace his rad in the next few weeks.

SO - ARMED with that info - I went back to my brothers and bought the heavy duty rad flush solvent. Flushed and flushed and flushed.

I verified that my tstat was in correctly with the pellet into the block but I removed the tstat for tonights flushing. Then replaced it again.

I ran the truck hard for close to an hour with the flush in the system, then flushed, and flushed and flushed.

Then I drove myself home (about 15 miles of highway = 25 kilometers) and it still overheated, allthough not as bad or quite as fast. It did not spit any water out - but... it WAS at the L of normal and smelled a bit hot but didnt boil over.

--------------------------------------------------------------------
SO Today I bought a new HD 2 core Rad. IMa gunna try it tommorrow.

Shamaal, thanks again fer yer input...

Oh and additional info: I removed all but the number 6 plug and they are all normal soft tan/brown colour - no white or extra clean plugs. Lower Rad hose is not collapsing, temp sensor shows normal temp when tstat opens, and I can see the deflection of the dash gauge flicker when it reaches the R in normal, so I can tell thats when tstat opens...

And GIJOEcam, the truck overheats without tstat installed, I tried that also...

SO I figure I might have a poorly built rad that allows for limited flow, so ima going to install a new one tommorrow.

 

[trucku]

The damn radiator.....jeez.

Glad you may have found the problem...

I bet the flush made the coolant passages nice an shiny inside. At least you won't have to do that again in the hear future.

If you want absolute coolant safety, buy a spin on style coolant filter.