Hi everyone,

I have a 97’ F150 5.4L 2-Valve.

thanks to this forum I was able to replace my trucks heater core. However when I cut the heater core out I didn’t see any noticeable signs of leaking. I talked to another ford owner and he mentioned how the inner linings of the heater core hoses start to deteriorate after a while and that tends to clog the heater core.

When I replaced my heater core I was only able to replace one of the hoses. If you are familiar with this process you know that getting to the back hose is almost impossible due to the fire wall.

Anyway I had a co-worker recommend I flush my engine and my maybe even my radiator. I have been looking into how to do it and it’s not so cut and dry.

My truck has over 200,000 miles and for the last 3-4 years it has rarely been driven. Any advice or recommendations would be greatly appreciated. I plan on keeping this truck running long enough to one day pass it on to my kid.

This truck was my Dads old work truck. My older brother had it but didn’t take the time to take care of it. We lost my brother only 5 months ago and fixing this has been the best form of therapy I could ask for.

 

Everybody has a method
I learned from reading a can of Ford flush
Put that stuff in there and drive it ten miles
Come back to the shop and open the petcock on the radiator
Hot coolant will come shooting out under pressure
Grab your garden hose and put it on trickle and in the radiator cap
By now you should be able to remove the cap and put the garden hose in there
So, run the engine at idle with the hose in the radiator and the petcock open
About 20 minutes of that and you will have clean water coming out both the petcock and the top of the radiator
Shut off the hose and the engine, let it drain, add coolant to get the mixture correct at 50-50
have fun

 

I would pressure test before wasting any new coolant. You say there was a leak but the core didn't show it. I have had a leak where a heater hose attached to the core's nozzle and dripped into the passenger compartment.
'When you flush, I would remove the thermostat to flush, reinstall or replace the thermostat (OEM), refill and test.

 

How do you know if you even need a flush?
I think you should have flushed before doing the heater core?
Unless there is a way to get around flushing it thru the heater core.
On my 99 I broke the water pump outside connection when putting in a camshaft sensor,so I had to replace the water pump.
This is a around a 23 year old water pump,look how clean it is.
The inside on my engine looks as clean, I never flushed the engine or radiator since new.
I wouldn't even flush unless needed. If you do remove the thermostat. And maybe the heater hoses?
Original water pump.....23 years old, look how clean it was when I replaced it.
This is how it looked when I removed it, no cleaning was done to it before the pictures.

 

Only neglected cooling systems require flushing.
Mines 21 years old.... Has never needed flushing

The older trucks that used green glycol ...need that changed every year... and most people don't... Some never do
Hence the cooling systems that are filled with rust and need to be flushed

Or even worse.... Somebody ignorantly mixes incompatible coolants purchased ... And what's in their cooling system resembles thick mud.....

These are just some of the reasons I never purchase a used vehicle owned by somebody who doesn't appear to have the money .... or the attitude...to have maintained it well.... cough cough... students... someone that lives in a trailer park.... Certain stereotypical individuals..... You know what I'm talking about.

The ones using the long life 5-year gold coolant... Well most people can get around to changing their coolant once every 5 years. I do mine about every 2 -3 yrs

 

When I figured out that my heater wasn’t working. I opened up my hood and saw that the 2 heater hoses coming from the heater core were cut. So I figured a mechanic just bypassed it. Why did they do that I do not know.

so when I took out the old heater core I tried running water thru it and it was clogged so I pushed air thru it and whatever was stuck came out.

I don’t want this problem to happen again to the new heater core so I thought that flushing the engine/radiator would help prevent that.

 

Thy probably cut them instead of fixing the problem?

 

I looked for my trucks radiator cap but I don’t see it.

in videos I’ve seen them just spray water into the coolant reservoir.

 

Ill most likely replace the thermostat, what temperature do you recommend?