Hello all and thanks in advance. 1997 f-150 4x4 4.6l
I have no heat or very little heat coming out of the vents or any other setting for that matter. I was told to change out my thermostat first. Iam in the process of doing that now. I figure if I have to drain the coolant to do this I might as well flush the thing while i was at it. What do you all think? Any way if this doesnt fix my heat problem can the heater core be flushed if it is still on the truck. And I have done a good bit of reading about the blend door problem thinking that is my problem but am unsure. Any help or incite would be greatly appreciated.

 

I'm sorry I don't have intimate knowledge of this particular vehicle yet, but I do have info for you.

First of all, before replacing the tstat on a wild stab, does the temp gauge indicate that it is getting to operating temperature. If it is, then replacing the tstat will not improve anything.

That said, flushing the cooling system and replacing with fresh coolant is a very good thing to do on engines with aluminum components as yours does. To flush the heater core thoroughly while doing all this flushing, find the two heater hoses where they go into the firewall and rig up a way to attach a garden hose. If you can, figure out which way the coolant circulates through the heater core and flush it backwards.

If antifreeze is not changed every couple of years you can easily get into a situation where corrosion will actually cause serious problems. I have seen aluminum heads actually corroded through from the water jacket to the combustion chamber. This requires a new head or in some cases, the head can be removed and welded up. Either way it is a bid and expensive process.

Keep that cooling system clean and full of fresh coolant.

Good luck,
Doc

 

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Hello all and thanks in advance. 1997 f-150 4x4 4.6l
I have no heat or very little heat coming out of the vents or any other setting for that matter. I was told to change out my thermostat first. Iam in the process of doing that now. I figure if I have to drain the coolant to do this I might as well flush the thing while i was at it. What do you all think? Any way if this doesnt fix my heat problem can the heater core be flushed if it is still on the truck. And I have done a good bit of reading about the blend door problem thinking that is my problem but am unsure. Any help or incite would be greatly appreciated.




Well folks I changed my tstat today with no improvement in heat. I did however reach up and feel the heater hose while truck was warmed up the one on the right was warm and the one on the left was cold. I was hoping someone could direct me as to what I need to do next. thanks

 

You have a hard to explain situation. Usually you either have flow of hot coolant through both hoses or not. It could be you check so early in warmup that the return line wasn't hot yet. Maybe. Just to be sure, fully warm up the truck, say 15 minutes. If both aren't hot now you either don't have coolant flow or the hoses or core is plugged. Cores rarely plug, they usually leak if anything. You can test this by partially draining (about 1-2 gallons) your coolant (drain plug is lower passenger side of radiator), removing the heater hoses from the front of the engine, putting your water hose in one of them and seeing if it flows freely out the other one. If not, try a fair amount (not all) of pressure from the hose first into one heater hose and then the other to see if you can flush it out. If not, good luck. Ugly job. Shop time for remove and replace is 5.9 hours. It would take most of us twice that.

If a garden hose flows through the heater hoses and core, then you don't have circulation. One of (1) water pump isn't doing it's job, (2) you have low coolant, (3) you have an air bubble left from a drain and refill, or (4) a head gasket is putting exhaust into the coolant making an air bubble.

Let us know if you get this far and we can help narrow it down.

But if both hoses are warm after full warmup.

Some vehicles have a valve that limits the flow through the heater core. Mine ('97 4.2L XCab) does not. The core has hot water always passing through it. There is a blend door, fairly easily accessible from below the glovebox. Or at least the actuator is. The blend door determines how much of the air in the cab goes through the heater core vs. how much goes around it to control the heat. It is exactly what is controlled by the red/blue **** to the far right. If warm/hot water is flowing through the heater core (both hoses warm) this would be where to look.

 

Another simple check,
The plastic temperature adjustment **** (blue to red), pull it off and look for a crack on the back where it receives the post. Mine was cracked and that was all it was.
Don

 

I had the same problem, ie 1 hot hose (right side) and the other either warm or cold. The problem ended up being the water pump flowing a very minimal amout of water due to the blade behind the pump was spinning freely on the shaft.
If you take the left hose off at the engine, put about a 10" hose on where that one came off and connect the two with a clear tube I think you will be able to see if you are getting any flow from the pump.
Hope you get her fixed.
Joe

 

I'm having somewhat similair probs on my 2002 XLT 5.4 FX4. My temp gauge reports that I'm not even making it to normal operating temperature. The gauge remains very low, no matter how long I operate the vechile. This results in not very warm air being pushed into the cab.

Mind you, it's like -35 Celcius every day here right now (-50 with windchill). Maybe that's just the prob?

 

I would venture to guess that your thermostat is the problem by not cutting off the flow of cooling fluid to the engine when the engine needs to get warmer by blocking off the flow from the radiator.
My 2 cents anyway,
Best off luck with your issue,
Don.
PS also if its THAT FRIGGIN COLD I would also recommend covering up a portion of the radiator from the front with a piece of cardbord or something to limit the cold air to the radiator coils. buddy, That is COLD!!!! Here north of Seattle we were close to 60degF today, 2 days ago it was 20degF. God is having a good time here messing with our heads..