cooling system issue

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  #1  
Old 10-22-13, 03:59 PM
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cooling system issue

My brother-in-law was telling me about this cooling system issue he's having with his '97 Ford F150.

"It only happens when it's warming up from sitting overnight. It's strange. It starts to warm up normally, heater starts blowing warm air, then all of the sudden the heater blows cold air and the temp. needle drops way down. Then, when I get on the highway, the needle will spike all the way up to hot (pegs the top of the meter), so I usually pull over, the needle goes back down to normal, and then it's fine from then on."

He says he took it into a good reputable shop where they replaced the thermostat and did a backflush of the cooling system, but none of that helped.

Any comment/ideas what might be a likely cause of the issue as he describes? Thanks.
 
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Old 10-22-13, 10:47 PM
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There are only two things I can think of.... a sticking thermostat or air in the system.

The thermostat was replaced and the system was flushed.
You would have thought that the air would be purged out but maybe it's not.

I've been reading around on the Ford forums. One re-occuring problem I saw over and over is the water pump impellers dissolve.
 

Last edited by PJmax; 10-22-13 at 11:11 PM. Reason: additional info
  #3  
Old 10-22-13, 11:50 PM
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But this problem had started before and had continued after the thermostat was replaced and the system flushed. But yeah does seem like it could be air in the system causing the problem, coolant not circulating properly.
He said he "did smell coolant coming from under the hood, and saw what looked like coolant spray around the overflow tank. But the needle spiked so fast, like in 2 seconds from normal to pegged."
Another person suggested maybe the fan is not working right. It has a clutch fan but he said the mechanic said that was fine. But I'm not sure if whether a clutch fan not working would cause the heater to blow cold air and the temperature needle to go down then up erratically like he said. I don't think so but I'm no mechanic.

Another suggestion was that the water pump may be on the way out. Water pump impellers dissolving -- that sounds like an odd thing to happen.

He said he's not gonna guess around anymore and just have it diagnosed by a professional. Should be interesting to find out what it is.
 
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Old 10-22-13, 11:57 PM
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You could check inside the radiator for good flow when the vehicle is up to heat. That would tell you if the pump had an issue.
 
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Old 10-23-13, 12:01 AM
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How would you do that PJ? Can't really look inside the radiator when the radiator is full of hot coolant??
 
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Old 10-23-13, 12:04 AM
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You should see it flowing across the top..... especially when you hit the gas.
 
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Old 10-23-13, 10:14 PM
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Update: So my brother discussed it with his mechanic over the phone. Mechanic said he's familiar with the symptoms and sounds to him very likely due to a blown head gasket, the type of failure that causes combustion gases to enter a coolant passage and the gases will displace (push) coolant out of the cooling system.
 
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Old 10-23-13, 11:12 PM
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Yes....when I was reading at the Ford sites.... head gasket was also mentioned with that engine.
 
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Old 10-28-13, 11:02 PM
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i've seen these same issues and it was a blown head gasket, you can rent a gas tester at most autoparts stores that will tell you right away if there's exhaust in your cooling system.
 
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Old 10-29-13, 12:09 AM
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i've seen these same issues and it was a blown head gasket, you can rent a gas tester at most autoparts stores that will tell you right away if there's exhaust in your cooling system.
Yep. The shop he ended up taking it to used some kind of tester or equipment that showed he had hydrocarbons in the coolant, which to them seemed to indeed confirm a blown head gasket. His truck is an eight cylinder. So far he's got a couple of estimates for the repair job, from 12 to 18 hours labor plus parts. One independent shop quoted him $2300. A dealer quoted him $1945. He doesn't want to try to fix it himself, doesn't have the time.
 
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Old 10-29-13, 07:49 PM
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be cheeper to replace the engine. with the over head cam setup with this engine he could have the engine replaced with less labor and almost match the price if not beat the price of replaceing the head gaskets. also would be better off if the truck has more than 150,000, because then you have a big chance of the bottem end going out a few months down the road.
 
  #12  
Old 10-29-13, 11:09 PM
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be cheeper to replace the engine
Maybe. Something to look into anyway.

if the truck has more than 150,000
It has 105,000
 
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