I recently acquired a 89' f 250 5.8 a/t 2wd.
One problem I'm currently having is I have very little heat after driving couple of miles I have no heat.

​​​​​​The cooling system was basically a chocolate milkshake so I removed and resealed lower plenum also r&r'd and resealed front cover and replaced stat, water pump, radiator and heater core and hoses.
while the w pump was off I flushed and back flushed the block through the pump passages.

I've checked and repaired a couple of vacuum lines, went back and rechecked my work including making sure I clipped the temp blend door cable.

I'm at a loss.

 

1st time posting here....
So I've aquired a low mileage 79000 mile
f 250 351w c6 that I've been struggling to resolve a low/no heat concern.
Initially I've resealed lower plenum, front cover, replaced w pump, radiator,heater core and t stat, all because of leaks and the cooling system has appeared to have been jammed full of stop leak.
While the w pump was off I thoroughly flushed the block through the w pump coolant ports.

I've repaired a couple of vacuum lines and verified temp blend door is workingworking.At idle it will only warm up but quickly cools off once driving.

How difficult can this be ? Lol
Thanks in advance

 

Here's a simple check:

Using your hand, feel the inlet and outlet of the heater core hoses. Are they hot? Only one hot?

Instead of using your hands, you can also use a digital temp gun to measure it to see how hot it's getting. You can even shine it at the heater core itself to see how hot it is.

I think you have air in the system.

 

Possibly the wrong t-stat. What temp is the replacement t-stat in terms of temp?

 

I had to get away from this thing for a while.

I do now have a ray tech thermal gun.

The stat is a new 195*.
i spose just cus it's new doesn't mean it's any good .I'm hoping the block isn't full of bars stop leak.
I'll get back to it in a day or so.

 

Bricker, I combined your two threads since they concerned the same problem with your truck. Please keep any new posts on this issue confined to this thread. If you start new threads on this, you'll get conflicting, possibly erroneous advice due to incomplete information in the new thread that, if followed, can waste your time and cost you extra money and aggravation.

- Jack

 

i didn't realize 1st post went through

 

How are you making out on this?

 

I hope I'm wrong but currently am leaning towards a block full of stop leak.
will remove and test/ replace thermostat.
Oddly enough this has very suddenly developed a connecting rod knock (hopefully a set of main and rod brgs will fix that)
The temp have have never gets past the "m" in normal but it acts like it's over heating. I say that because as I pulled the dipstick out it smoked a little bit.
I may be splitting hairs which is why I need to start with inspecting the (new) thermostat 1st.
Thank you for asking, stand by

​​​​​​​

 

I have since been unable to get back to my little project soon to return.

It's gonna be something weird, perhaps a block full of stop leak.

I will be removing and replacing stat first.

Thank you and stay tuned!

 

I will be returning to me lil project.
Thank you and stay tuned

 

I agree, air in the system. If there's a blockage that could exacerbate the issue. Other than that, the heater core still needs to burp.