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Old 09-30-2014
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3.0 cooling system problems

Hi everyone. This is my first time posting to this site, thanks in advance for any help. I apologize for the length, but I wanted to provide as much information as possible. Here are the details:

I have a 1995 Ford Ranger with the 3.0 v-6. The truck had a blown head gasket and was forcing air/coolant into overflow tank and blowing it all over the engine bay. The head gaskets were replaced along with the thermostat and all gaskets. The system was thoroughly flushed and cleaned. Here are my questions:

1. How can I tell if the water pump is doing its job? The heater works great but the bottom radiator hose never seems to get warm even after driving. The engine temperature hangs at just above middle on the gauge. I noticed it will drop quickly with an rpm increase.

2. How hard should the coolant hoses be? I replaced the radiator cap with a new unit (16lb) and the hoses got very hard after the thermostat opened. No swelling that I could see, but I couldn't squeeze them very much. When cold the hoses are soft and easily squeezed.

3. I have had to add coolant several times now, but there are no external leaks. I don't see any white smoke except for when I first start it, but it is more of a mist typical of a catalytic converter when first starting. The engine oil looks good, the coolant looks good.

When running with the radiator cap off I see no bubbling of the coolant but I am afraid that there might be a crack in the block or head. The engine runs perfectly smooth and so far has not overheated.

My main concerns are having to add coolant twice, the hard upper and lower coolant hoses when warm, and the cold lower coolant hose.

Thank you very much.
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Old 09-30-2014
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Above 1/2 on the temp gauge seems a little high, I would expect just below 1/2.

Lower rad hose should be approx. 15-20degF cooler than upper hose.

Pressure in the cooling system comes from the coolant expanding as it is heated, so there should be no pressure until engine gets close to operating temp, about 190degF.

Thermostat should be rated as 192-195degF
Upper rad hose should not get warm until thermostat opens, that takes 5 to 8 minutes for driving, just idling maybe a little longer.

After thermostat has opened if temp goes down with increase in RPM your rad could be getting clogged up.
Have someone rev engine to 2,000rpm and hold it there, then feel(squeeze) upper and lower hose, if lower is alot softer then rad is clogged.
Coolant flows into the top of the rad and is sucked out the bottom by the water pump.
If lower gets soft that means water pump is working OK but rad can't pass the coolant fast enough to keep up.
If lower stays as hard as the upper then water pump blades may be getting worn out, and increasing the RPM puts circulation back up where it should be at idle.

Could also be the fan clutch, common sign of failing fan clutch is lower temp while driving then temp rises as you sit at a stop light.
On cold engine spin the fan, it should spin.
After engine/rad is warmed up spin it again, it should not spin, should be tight.
Fan clutch tightens up from Rad heat not engine heat, so a clogged rad(in the center) will not warm up the fan clutch as much so............

yes, new rad cap with coolant change is a good idea.

Where are you adding the coolant?
in overflow or rad?
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Old 09-30-2014
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Thank you very much for this reply. I was working on the truck earlier trying to bleed the system of any air. I had a long funnel stuck in the radiator opening. As the truck got warm the level of the coolant rose to about 10" in the funnel. I didn't see any air bubbles so I shut it off and let the level drop, took a very long time. I put the cap back on and let it come back up to temperature and had the same problem with the hoses above. It seems like a lot of water vapor is now coming out of the exhaust too, but it was getting dark.

I will do your tests tomorrow and post my results.
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Old 09-30-2014
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I decided to go try the tests before I went to bed. I couldn't feel a difference between the upper and lower hose at higher rpm, they are both pretty tight. I tried to spin the fan and it only went about a 1/4 turn so the clutch seems to be OK. I did notice that the temperature dropped significantly when the engine was held at the higher rpm. Does it sound like the water pump blades are getting worn? How much vapor should I see coming from the exhaust? There is a small puddle gathering at the tailpipe and it is wet inside, but it is pure water. It doesn't have a hint of green and smells only like exhaust.
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Old 09-30-2014
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There will always be water in the exhaust, when you combine air("O"xygen) and gasoline("H"ydrocarbon) then ignite it, one of the by-products will be H2O.
This is why exhaust systems always rust from the inside out.

If the outside air is humid there will be more water in the exhaust, because the air being pulled into the engine has more water in it.

Yes, water pump seems to be lacking circulation in lower RPMs.
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Old 10-01-2014
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One other thing to check is a small, almost undetectable leak if you are having to add coolant into the overflow container; if you have an automatic transmission, check the fittings on the drivers side of the radiator (automatic transmission fluid lines) for tightness.

RonD may remember I posted a few months back that I was constantly adding coolant into the overflow container of my 2000 3.0 Ranger. It's water pump was just replaced by the Ford dealer I purchased the truck from, along with a radiator removal/cleaning.

I discovered that one of the fittings that the transmission coolant lines threads into was loose going into the radiator; I was installing an electric fan (I can't stand the "roar" of the clutch fan!), and I saw a very fine spray mist coming out of the upper fitting. I tightened it down, and viola!, no more having to add coolant into the overflow.

As RonD educated me on, any leak will cause the radiator to not overflow to the overflow tank, but rather this leak is the point of least resistance, so under pressure, the coolent goes to the leak rather than to the overflow tank. Makes sense.

Also, the pressured system will not draw from the overflow tank, but rather will draw in "air" from the loose fitting (my case).
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Old 10-01-2014
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Thanks for the replies guys. I don't see a bit of moisture on the ground, but a fine mist wouldn't really leave much of a puddle.

I ran the truck for 10-15 minutes last night and when I checked the coolant level today it was over a quart low in the radiator. The overflow tank level won't change at all and the lines are clear, I tested that. But it is consistently low in the radiator. I assume it should be full to the top when I crack that cap since there should be no air in the system.

I am really afraid that I have a crack in the block or head because of all the pressure building up in the hoses and the loss of coolant. If it was burning coolant would the exhaust smell pretty heavily of antifreeze?
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Old 10-01-2014
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Could be the rad cap, overflow hose or a small leak in the system.

Rad cap has two valves, the 16lbs valve and a smaller return valve that allows coolant sent to overflow tank on warm up, to return to rad as coolant shrinks when it cools off.

If there is a small leak in the rad/engine system then it won't release much coolant until pressure builds up, and if it is warmed up it may just evaporate as it leaks leaving no coolant on the ground.
As engine cools down that same leak point will suck in air.
So overflow tank level never changes, but coolant leaked out and air was sucked in.

I had a leak on my overflow hose, it ran on top of the rad and that's where the leak was, it only leaked when overflow hose was used, so coolant was hot and so was rad, so no sign of a leak.
Same issue as above, coolant leaked out and air was sucked back in, so overflow tank level never changed, just ended up with air in the rad when I checked it.


If rad hoses are getting hard when engine is just warming up then yes you do have a cylinder to cooling system leak.
They shouldn't get hard until coolant gets hot, that is what builds the pressure in the system.
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Old 10-01-2014
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You can remove the spark plugs, one at a time, to see if you have a head gasket failure between a water jacket and cylinder. The spark plug will be very clean compared to the others, as the water/coolant will act like its steam cleaning the spark plug. This would be an easier fix then a block crack, as just that head would need to be removed, checked for "flatness" by a machine shop. Any slight warpage can be handled, and then a new head gasket can be used to replace the head.
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Old 10-01-2014
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Is a cracked head or a cracked block more likely to happen? I know the truck was driven a while with a bad head gasket before I bought it.

To be clear, when I pull the plugs if I find a steam cleaned one that would mean head gasket and not a cracked block? Is it possible to have a crack in the block or head and it cause the same problems? I am just trying to avoid removing, replacing/re-working the heads only to find out the block was bad.

Thanks again for all the help, I have learned a lot already.
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Old 10-01-2014
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Cracked block would leak coolant onto the ground or into the oil, and it wouldn't be subtle, you would know for sure.

Cracked head and blown head gasket present the same symptoms, white exhaust smoke all the time, too much pressure in cooling system causing overflow tank to fill up, even on cold engine.
Bubbles in the rad cap opening at first start up and then surging coolant, flowing out of rad cap opening as engine heats up and air builds up in the head and is then purged.

Cracked head won't cause coolant in the oil
Blown head gasket can cause coolant in the oil but only if it has blown near an oil drain or passage, so maybe 10% of the time on newer engine, on older engines it was 50/50
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Old 10-01-2014
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I am replying with my phone, I hope it works ok. I started the truck tonight with the radiator cap off and within seconds the coolant level went from so low I couldn't see it to spewing out of the radiator. I quickly put the cap on and the top hose started to puff up and get hard. The thermostat hadn't even opened yet. Never did any coolant go into the overflow and I don't understand that. There is clearly a lot of pressure. I tried the brand new cap and the old cap let the hose get hard but nothing. I expected an explosion of coolant into the overflow. I can blow bubbles into the overflow tank so the line is clear. Any ideas?

Pretty sure I am dealing with a cracked head. Wish I had them checked before replacing the head gaskets. Lesson learned.
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Old 10-02-2014
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The reason there is no coolant going into overflow is that the pressure in the cooling system, with cap on, is pushing coolant into cylinder on intake stroke, and exhaust stroke.
It is actually a common occurrence.
It can also be because the head gasket has blown between two cylinders, this tends to equalize in and out pressure.
In either case if you let engine run long enough it can get an "air" bubble in the head's coolant passage.
If the head temp in that bubble reaches 270degF(above coolant boiling point with 16psi pressure), then it will flash to steam and THAT will increase pressure above 16psi and blow coolant or air, whatever is at the top of the rad, into the overflow.

There is a simple way to test which cylinder has the leak, and it does read like you have a leak, from cylinder to cooling system.
Remove rad cap, cold engine
Get a balloon, condom or latex glove.
Place it over the rad cap opening, for glove use rubber band to seal it to rad opening
Remove overflow hose and plug the opening
Cooling system should now be sealed

Unplug coil connector, we want a no start
Crank engine
Balloon, condom or glove should bounce each time the leaking cylinder is on it's compression stroke.

Now remove one spark plug at a time, and crank engine, when glove stops bouncing last spark plug removed is the cylinder with the leak, put spark plug back in to confirm.

In the case of a dual cylinder leak you will see glove have a smaller bounce, continue to next cylinder to test that.


Heads usually crack between the valve seats, it is a weak spot.
Heads crack from being overheated and the metal expands too much.
Similar to why head gaskets blow, the metal ring on the head gasket seals the cylinder, if overheated the head metal expands more than usual and crushes that metal ring, allowing a breach.
Moral of the story, if temp gauge is going up DO NOT try to make it home, let engine cool off, and make trip home in short hops, cooling down in between, add water/coolant if possible.
If you spend two hours limping 10 miles home and save $600 because you only have to replace a water pump or hose, and not head gaskets, that's like making $300/hour, without really working, lol.

Last edited by RonD; 10-02-2014 at 12:39 AM.
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Old 10-02-2014
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Nice write up. Also like the statement on how to turn a "limp home trip" into making money
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Old 10-02-2014
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I really appreciate all of this help, thank you Ron. I will try the glove test after work. Number 6 was the bad cylinder when I replaced the head gasket. If I were to bet, that is most likely the one with the crack in the head.

If I fail the glove test, which is likely can you recommend the best place to buy replacement heads? Some of the internet shops get some bad reviews that make me nervous. There is a local machine shop that sells a set that are fully tested and ready to install for $425 and I think he gives them a 1 year warranty. I just don't want to get a set that will crack again in a year.

Thanks again.

Eric
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Old 10-02-2014
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Good read here on 3.0l: Ford Ranger II 3.0 liter Engines

They speculate 25% of the 3.0l heads crack, I think that number is a bit high, but........

It might not be a cracked head, may be a head gasket didn't seat correctly.
I have been wrenching for 40+ years and I am not 100% on head gaskets, lol.
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Old 10-02-2014
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Oh man, don't tell me that. I am 0 for 1 and I need to improve my record immediately. Do you have any tips or advice to help me get this right this time? Here is my check list so far:

-Have heads tested for flatness and cracks
-New head bolts...again. I assume the ones I just used are tty and can't be reused.
-All new gaskets...again.
-I am replacing the water pump and radiator this time as well even though both seemed
to be working.
-All new hoses.
-Thermostat is new.
-New radiator cap.

What am I missing? Any tips that will help me with the install would be greatly appreciated. I can't be 0 for 2, I need this truck running. And thanks for the link!
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Old 10-02-2014
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If final tightening of head bolts is a "degree", i.e. 90deg, then yes they are TTY and should not be re-used.

Yes, cleaned, machined and pressure tested would be what to have machine shop do.
I assume Valve Guide seals were already replaced, machine shop will do that also, the seals usually come with the head gasket sets.

Don't buy new heads just because............if one is cracked just get one, not two.
Machine shop can swap over valves and springs to new head as needed.


Just pull water pump and inspect it, compare to new one if you want, return new one if not needed, although water pump failure is usually the main bearing seal which you can't see/inspect.

Pull out radiator and do a "flip test" on it.

If rad core lines run side to side, which I think they do
Place rad on its side, so core lines are running up and down, make sure drain is tight, and rad cap on.
Put your hand over lower hose outlet
place water hose in upper hose outlet and fill rad with water
Stop filling when full(remove water hose)

remove your hand from lower hose
water should rush out, rad should be drained in a few seconds, tilt it a bit to get the last of the water out.

NOW THE TEST
Flip rad over, upside now downside...........
If ANY water comes out it could only come from blocked core passages
If little or no water comes out rad is OK

You can repeat test in the other direction just to be sure.

Last edited by RonD; 10-02-2014 at 03:36 PM.
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Old 10-02-2014
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Thanks Ron. I will do the glove test and try to figure out which cylinder or cylinders is causing my problem.
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Old 10-03-2014
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I think this was mentioned (indirectly) but you should also use new head bolts, as the old ones will be strectched. Run a tap in the block that the new head bolts go into, to make sure the torque readings are exact and precise; any dirt or ? in the thread holes can alter the torque readings.
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Old 10-03-2014
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Thanks a lot for the help guys. I didn't catch the radiator test before. I will do that too. I ran out of daylight yesterday but I plan to do the glove test today. If I fail that hopefully I can find the suspect cylinder and start tearing things apart this weekend. I will be sure to run a tap in the block when I get to that point.

Eric
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Old 10-03-2014
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I just thought of question I don't think I asked above. Why do I not see any bubbles in my coolant, but have a lot of pressure build up? Assuming I do have a head gasket or cylinder head crack, should I see bubbles for sure or is it possible to build up pressure like mine is without seeing any bubbling of the coolant?

Grasping at straws...

Thanks again.
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Small breach in cylinder to coolant passage will make bubbles in coolant areas BUT you would only see them after thermostat opened because the bubbles stay at the top of system, so behind t-stat in intake/head area.

Pressure in cooling system just after cold startup can only be a cylinder leak, there is no other pressure source in an engine, a water pump isn't really a "pump", it has no valves like a Fuel "Pump", it is a circulater, like a ceiling fan in your house, it doesn't cause any pressure changes.
Oil pressure might do it(never heard of that before) but you would have a milkshake on the dipstick, and the 10psi at idle from oil pressure wouldn't do much in the cooling system pressure wise, the 160+psi from cylinder compression will, and when engine is running there would be 1,000+ psi but some of that is equalized by intake stroke having more suction than when just cranking engine, which is why the "glove test" works better with cranking vs running engine.

Last edited by RonD; 10-03-2014 at 11:23 AM.
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Old 10-03-2014
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Hey guys. I ran home at lunch time and tried the glove test. Amazing what you have to do when you have two boys who take up all of your time. Anyway, the glove did not move at all. I really expected to see some movement. I noticed the coolant was just at the top of the coils inside, maybe and inch or so below the cap. While I was there I figured I would start it and do the hose test again. This time it didn't really start to get hard until it got warm (I am just asking for a dirty joke with this talk). I squeezed the upper hose as hard as I could and hit the throttle and the hose became a little easier to squeeze. Not night and day different, but definitely easier. This is the test Ron had me do early on, but at that time I didn't try to keep constant pressure with my.

Based on these results it almost seems that I have a clogged radiator. However, I can't explain the coolant loss. Is it possible that I could have had some areas in the radiator or even the block that were clogged and they are now taking coolant? I have not found a drop of coolant on the ground or in the engine bay. If it is a leak it is a very small one.

Also, I didn't see any smoke today.
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Old 10-03-2014
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Great news with the glove test
It is a pretty definitive test.

Only need to pull the rad hoses and move shroud back then 2 bolts to pull the rad.
Unless you have an automatic then you have those leaky PITA cooling lines at the bottom or side.

Then do the flip test
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