I have a 95, 5.0, manual, with a/c. I replaced the heater core, therm., radiator, and all hoses. I filled the radiator up and had the enging running with the heater on, while adding water. I finally put the cap on and started reving the engine a little. I noticed the upper radiator hose collapsing. Why is this and what did I do wrong, the temp guage says it is ok, I got heat, and the resevoir tank is full.

 

does the thermostat work? you can test it in the kitchen on the stove in a pot of water. maybe replace the radiator cap.

 

I put a new thermostat and new radiator cap, everything is new except pump. I didn't check the thermostat b4 I installed it.

 

Your radiator cap might need to be replaced. When the cooling system goes go a vacuum, the cap is supposed to unseat and pull coolant in from the overflow tank. If the hose is going flat, the vacuum feature of the cap is not working. That or your upper radiator hose is old and has lost it's rigidity.

Lou Braun

 

do you think I got a bad thermostat? I have heat, and I ran the engine for 45 minutes at idle and it stays cool. Its just when I rev it I notice the hose colapsing.

 

I just bought all new hoses, new radiator, cap and thermostat.

 

Just because they're new, doesn't neccessarily guarantee they're good. You could have a defective cap or stat. Try putting the old cap back on and see what happens. If the problem goes away, the new cap is either defective, or is the wrong one (opens at the wrong point)

 

Umm, sillier question. Are you sure you put the t-stat in right side up? It WILL fit backward, and makes a really nice check-valve if you do. Won't open for spit. The top hose is NEVER rigid. I still have the factory hoses on my '92 with 149,000 miles.(NEVER HAD A COOLANT LEAK, PERIOD). Top one is soft, and always has been. Bottom one's got a coil spring inside it to prevent suction collapse. Bottom one is the suction hose, top is pressure. If the top is collapsing, a vacuum is being pulled in the radiator. Did you make sure the engine was warm enough for the t-stat to open? Chances are, you didn't bleed the system right, and still have air trapped in the heater core and hoses. IF the t-stat doesn't open (engine still cold) and there is air in the heater core and lines, the pump will try to pull coolant out of the radiator and compress the air wherever it is. To properly fill one, take the heater supply hose off the TEE behind the gooseneck (outlet from block to radiator) on top of the intake, where the ECT is also mounted. Fill the system through the radiator spout until coolant comes out the TEE. This will burp the block. Then, start pouring coolant in through the loose hose with a funnel to fill the core and hoses. You'll probably spill some, but should be able to force most of the air out through the water pump then back up to the TEE. You can wait until the coolant cavitates enough to blend the air with the coolant and eventually accumulate in the radiator, but you're risking some heating problems if you do, as well as a LOT of nagging topping off. They will eventually bleed themselves, but you MUST get as much air as possible out when you drain it. Otherwise, you'll get the collapsing top hose syndrome. You may pull some coolant in out of the reservoir, but I wouldn't count on it happening too fast. The vacuum relief feature of the cap is a tiny relief valve compared to the volume of coolant that pump is trying to move. Otherwise, just let the engine idle til it's warm, and check again. If the top hose still collapses, and doesn't get warm, my bet would be a stuck or backward t-stat.