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Heat goes hot and cold, mechanic doesn't know what's wrong

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Old Jan 21, 2011 | 09:03 PM
  #1  
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Heat goes hot and cold, mechanic doesn't know what's wrong

Hi, i have been having some problems with my heat and anti-freeze overflowing out my resevoir now for about a month.
I have a 2000 Ford Ranger XLT with about 60,000 miles on it. I originally took it in because the heat would only work about 50% of the time.
The water was really dirty so i thought that was it. They flushed it real good and i brought it home. Next day there is fluid on my garage floor. I took it back and they said it was leaking from the radiator, so they replaced the radiator, another flush cause my block is making my water dirty. They stated i was good to go.
3 weeks go by and my heat still only works 50% of the time. When it works, it works great, gets real hot. Also, in the 3 weeks time, when i shut it off water will push out through the resevoir and leak all over my garage floor.
So i take it back in for another appt., they did another pressure check over night and said pressure is freakin great. They replaced the thermostat, 2nd one in 2 yrs. time, new radiator cap. After all this, same problems.
They told me they do not know what is wrong.
So, i drive it home only to have heat for about 5 minutes, turned cold, pulled in my garage, turned it off and again fluid pushing out through the resevoir on my freakin floor!
Someone PLEASE HELP ME! This **** is driving me crazy!
 
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Old Jan 21, 2011 | 11:43 PM
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Ok, common problems can sometime show up as an uncommon issue. The first thing I would suspect is that you have the wrong thermostat. I have through personal experience learned that an genuine Motorcraft thermostat is the only way to go. The aftermarket ones are NOT designed specifically for your truck. They do not bleed the air properly, which can lead to strange thing as trapped air can prevent the coolant from flowing correctly. A Motorcraft thermostat does not cost significantly more than any other brand, but they work properly, and they are made for your specific truck.

Same situation with radiator caps. I see a lot of radiator caps that can test good, but do not hold the proper pressure in the real world. If it won't hold pressure, that coolant will force its way into your reservoir and push it all out.

But the last thing, is that sometimes when the water pump fails, it can cause lots of erratic behavior. On some vehicles, Ford actually designed a new water pump to address coolant flow problems involving sudden pressure surges.

I suspect that trapped air is a large part of the problem. You can build pressure, which then escapes through a leak or a bad radiator cap, then as the coolant cools down, the pressure drops, causing air to enter through a leak. Next time more coolant is pushed out and more air gets in.
 
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Old Jan 22, 2011 | 01:02 AM
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Did you have this spitup problem before the repairs????

What temp range thermostat was used???

Is the engine temp gauge staying in the normal range after it warms up????

If so, it kinda sounds like the cooling system didn't get burped good & it might have an air bubble causing it to spit up after shut down.

Did they install a Motorcraft thermostat, or one like it, with an air bleed valve in it????

If so, park with the engine up hill, the steeper the better & with it warmed up & the in cabin heater temp control at max heat, let it idle in this position for 15 minutes or so & listen for air causing gurgling sounds in the heater to stop & air in the block to be routed to the radiator via the open thermostat, or it's bleed valve if you do this with the engine cold & the thermostat not opened up.

Turn the engine off, check the coolant recovery tank level & top it off if need be & note or mark it's level.
Let the engine completely cool off & recheck the recovery tank cooant level. If it's dropped, the system had air in it & the radiator cap has let it burp, to let the air out & automatically top the system coolant level up.

Try driving it again & if need be repeat the burping process until it stops spitting up.

Again, is the engine temp gauge staying in the normal range after it warms up???? If not, with the condition of the coolant you reported, you may have other problems, like a blockage, or pump vane erosion, causing weak coolant circulation troubles.
 
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Old Jan 22, 2011 | 04:57 AM
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Hi, no the temp. gauge is not staying normal, it fluctuates up and down when there is no heat. When i have heat it is normal.
I tried removing the cap and letting it run to remove the air, but i can't the anifreeze pushes out the radiator.
 
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Old Jan 22, 2011 | 05:01 AM
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+ on Khan and pawpaw.........you should add the engine, tranny, 2wd?, your location?, etc to your vehicle profile
 
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Old Jan 22, 2011 | 05:06 AM
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Originally Posted by mayhem69
Hi, no the temp. gauge is not staying normal, it fluctuates up and down when there is no heat. When i have heat it is normal.
I tried removing the cap and letting it run to remove the air, but i can't the anifreeze pushes out the radiator.
THIS IS THE 3RD TIME YOU ARE BEING ASKED.............WHAT BRAND AND DEGREE T-STAT DID YOU INSTALL?....................................

if you let the engine cool you should be able to take the rad cap off without any issues.....
 
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Old Jan 22, 2011 | 06:58 AM
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Originally Posted by powersmoked
THIS IS THE 3RD TIME YOU ARE BEING ASKED.............WHAT BRAND AND DEGREE T-STAT DID YOU INSTALL?....................................

if you let the engine cool you should be able to take the rad cap off without any issues.....
First off, WHY THE HELL ARE YOU YELLING AT ME! I didn't install the t-stat and today is Saturday, they are closed. I will let you know when i find out.
 
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Old Jan 22, 2011 | 07:03 AM
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The heat comes and goes because there is intermittent flow of coolant through the heater core. Likely the same thing causing the temperature gauge to indicate shifts in temperature.
With the system cool, you should have a full radiator, and squeezing on any of the hoses under the hood should cause the level to rise where at the filler neck. You should also have coolant in the overflow near to the 'full cold' or similar line. When the engine warms, the coolant expands into the overflow tank, raising the level to near the 'full hot' line. When the coolant cools, it will contract, and air pressure will force the coolant back into the cooling system, [radiator] lowering the level in the overflow tank.
High pressure can be caused by 1) a blown head gasket or 2) the wrong radiator cap or 3) the wrong thermostat causing the temperature to be higher than normal, however, the radiator cap should release the over pressure in all cases except #2.
I suspect that your mechanic needs to go to school on 'burping' cooling systems. You can borrow, possibly, a pressure gauge that mounts to the radiator filler to determine if you have an overpressure situation, to test the radiator cap release pressure, and pressurize a cold system to find leaks. I suspect that you have air trapped in the system.
tom
 

Last edited by tomw; Jan 22, 2011 at 07:12 AM. Reason: add
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Old Jan 22, 2011 | 07:13 AM
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Originally Posted by mayhem69
First off, WHY THE HELL ARE YOU YELLING AT ME! I didn't install the t-stat and today is Saturday, they are closed. I will let you know when i find out.
don't bother letting me know I don't give a crap about your truck. Drive it off a cliff for all I care.........I was yelling becasue 2 members(very competent members) that are helping you for FREE asked you what T-stat you used.........you did not even spend the time to read their posts and respond accuratly......these forums only work if you provide details.......we are not mind readers.................bring it back to the mechanic and get hosed.........CYA

* a competent shop will provide a receipt. on the receipt it should show the brand and part # that was used. .....
 
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Old Jan 22, 2011 | 07:36 AM
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You can check for the presence of air in the system and bleed it out yourself. With the engine cold park it on an incline so engine is higher than rear. Set heater on full heat setting, open radiator cap and run engine till fully warmed up as indicated by temp gauge. If air is in system you should see the bubbles rise to the top of radiator or overflow (if you don't have a cap on radiator). Once air is burped out replace cap. If you still have problems more troubleshooting needs done to rule out head gasket.
 
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Old Jan 22, 2011 | 07:42 AM
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Leaning towards head gasket or broken head bolt. There is a test for exhaust gasses in the coolant.
 
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Old Jan 22, 2011 | 09:45 AM
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Hey, powersmoked. Take it easy. Mayhem has only made a few posts to FTE. Your responses can discourage him from using this site for help in the future. In addition, he has not made enough posts to add truck details in his signature. Of course, I agree that it would be a good idea to list truck information in the post - it usually helps helps. In this case I don't think it would make any difference.

Mayhem,

Don't be discouraged, the suggestions Pawpaw and Kahn made are good ones. When you are able, follow up on them. Keep us posted on what you find.
 
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Old Jan 22, 2011 | 05:02 PM
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The closed cooling system which as already mentioned refills the block and radiator from the coolant reservoir as the engine cools, providing everything is tight and the vacuum valve in the cap works. Over my many years working fleet maintenance I took a liking to the spring type hose clamps. I felt they could expand and contract on the hose as the necks of what ever grew or shrank according to temerature. I began to have a heater problem as you discribed this fall. Every time I would check the coolant it was down in the radiator maybe a half a cup. I looked for leaks and began to really think about the
problem. Since we need vacuum (low pressure in the radiator) to pull the coolant back which has been pushed out to the reservoir during the heating cycle I knew I had a leak somewhere. I found it apparently the spring type clamps on the upper hose had relaxed
enough to seep a very slight bit when cold. Replaced and the problem is gone. My suggestion is check all your connections and get the system tight before replacing anything else. kotzy
 
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Old Jan 22, 2011 | 06:38 PM
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Is it a 4.0L engine? Any knocking or thumping noises? The fluctuating temps could indicate steam is building up in the cooling system, or an uneven flow of coolant caused by a bad water pump.

See: https://www.ford-trucks.com/forums/2...ng-system.html
 
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Old Jan 23, 2011 | 12:04 AM
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Hi Mayhem,

I got nosey and and looked at your previous threads. Two things caught my attention:

1. does your truck have the 3.0 L engine? An earlier thread indicated this. If that is the case, the posts that refer to cooling problems with a 4.0 L engine may not apply to you. I'll retract my earlier comment that engine size may not apply in this situation.

2. In a couple of your earlier posts, you mentioned more detail about your truck - engine size, drive info, etc. It is a good idea to include that information in your initial post. Also, please include that information in your next update to this thread. It will help.

Good luck in getting answers to some of the questions asked in earlier replies.
 
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