I had my radiator flushed and new fluid put in a few months ago...no problems...the indicator goes to normal temp and stays there and I just drove to Utah from Virginia with no problems.

But this morning I had the hood up before startup and noticed that the top radiator hose was partly flattened out...as if it had no fluid in it!

Once the engine was started and it warmed up (and I asume the thermostat opened) the top hose got round and warm and it was obvious that antifreeze was circulating.

But am I right in thinking that the system is low on fluid? Even though the external plastic tank level is basically unchanged (I think it dripped maybe a quarter of an inch in the weeks after the flush).

ANybody else feel like their top hose is empty when the engine is cold?

 

It's either a bad hose/faulty radiator cap or both. The radiator cap maintains the same pressure throughout the cooling system. When the engine cools, the antifreeze cools it creates a vacuum which takes your antifreeze from the resevoir and sucks it back into the radiator.

If the radiator cap is bad, it won't regulate the pressure and the vacuum ends up collapsing the top radiator hose. When is the last time the hose was replaced? I'd probably go ahead and do both.

 

If there is air in the cooling system and the cap isn't allowing the siphoning that might collapse the hose. Saw a post a few weeks ago talking about burping the air out of the cooling system.

 

Do you mean the reservoir cap might be bad? I don't even see a cap on the radiator itself.

 

Mine is an 03 so I can't comment on the '99. But There seem to be many things that haven't changed. I don't believe I have a "real" radiator cap but the cap on the recovery tank is the rad cap now. Mine is a screw-off cap that has a "click-click-click" when it's tight. 99ExpyProblems is right about the function of the cap. As the engine/coolant cools off the pressure in the system goes down and the system will suck some more coolant from the recovery tank. If the cap can't vent then it's not going to suck any coolant into the rad. I think that air in the cooling system is causing the big changes you are seeing. Water doesn't change volume very much with change in temperature and I doubt that the antifreeze does either. So I think some air is in the cooling system, plus you reported the coolant was recently changed.
There's probably a way to test the cap but I'm not sure, maybe AutoZone or one of the other parts houses. I haven't priced a replacement cap but if it's not much $$ it'd be a cheap way to tell if the cap is bad. No more hose collapse. The hose could also be getting weak from age (it's happening to me) and may need replacing as well. New cap is easier than the hose to replace and probably cheaper too. At the end of the day I still think some air is trapped in the cooling system as well.

 

I double checked at a Ford dealer in Salt Lake City today and there is no cap other than the remote reservoir cap...so I bought a new one...it was only about $11 bucks, so no major wallet damage.

But I think you guys have helped me understand that the folks who swapped out the fluid left some air in the system.

Of course it adds to my embarassment that my sister (the real technician in the family), after just now listening to me describe the situation, simply said..."sounds like the idiots didn't burp it."

Apparently this a teachable moment...for me!!

I would have swapped out the hoses while I was here in Utah, but I tried several dealers and could not come up with both hoses. So I am going to get a little more fluid in the system and deal with new hoses back in Virginia. A good time to swap out the serpentine belt and check the water pump too. I have 185,000 miles and last replaced the belt at 95,000.

I am hoping to make it to 250,000 on this beast and then replace with it with something powered by a "Mr. Fusion" unit. 1.21 jigowatts, right?

 

My friend, learning and sharing tips and info is why we are all here! The correct mixture of anti freeze should have all the lubricating properties that your water pump needs. If it's going to fail, then it's going to fail regardless.

I love the fact that your getting this kind of service out of your 4.6L, what a fantastic little engine and Ford is throwing away.

Tim

 

Curious if your sister is also a mother. Every mother knows after feeding baby better burp 'em.
Hope it's just air, that's my guess.

 

If replacing the cap doesn't solve the problem, then there's a pretty good chance that it's time to replace the hose.

 

This post also from today: https://www.ford-trucks.com/forums/8...cuum-leak.html
Read the 3rd post.
Do we have a cooling system bleed screw? All years?

 

When I flush my cooling system on the Expy, I intend to replace every coolant type of hose, T-stat and the recovery tank cap.

I recently flushed my Taurus and 2 months later the bottom T-hose burst without warning. The pastic T on the hose just let go and I lost all of my new coolant.

Tim