I need Advice From a Car Mechanic

[Avi 12]

Today i challenged myself to change the radiator on my '01 grand caravan, as it looks like now i did the job right the heat is working and car is running without overheating. however i noticed something weird and wondering whats causing this (i didnt drive it yet) whenever i give it throttle the upper hose collapses as if its sucking and get all the air or water sucked out when i let off the throttle it goes back to normal. what do i need to do? thanks much

[pjd832 146]

I'd think Bad/soft hose...first check the small hose going to overflow tank for blockage ....I'm not a mechanic...but those are a couple issues I've gad that caused that issue....

[67gtonut 847]

Hmmmm......  usually a Lower Hose issue. In most coolant systems, Coolant is flowing TO the radiator thru the Upper Hose.  

 

My only thought is the system is not full enough, and when you rev the motor the waterpump is drawing down the level  enough to cause a vacuum at the top of the radiator.

[Howard 538]

You might have air entrapped in the system.  I have not done this in about thirty years, but you might try starting it up with the radiator cap off to allow the air a place to exit.  I vaguely recall having to do that once, but many many moons ago

[FLHX 1]

You might have air entrapped in the system.  I have not done this in about thirty years, but you might try starting it up with the radiator cap off to allow the air a place to exit.  I vaguely recall having to do that once, but many many moons ago

I think but am not a mechanic but I remember someone starting with the cap off and then shutting it off and the radiator fluid shot out of the radiator where the cap should of been. I could be wrong  as I am buy no means a mechanic, but i think I did learn something that day when the guy got burnt. So if you start the car with the cap off don't shut it off until putting the cap back on. Could be wrong don't I don't want to test it.

 

Howard do you know or anyone?

[67gtonut 847]

Depending on the cooling system......  yeah, I have seen systems "purge" themselves pretty well on shutdown or when letting off throttle if revving engine to burp the system.

 

If you are a novice.....  better to have the cap on..... 

[vjf915 456]

You might have air entrapped in the system.  I have not done this in about thirty years, but you might try starting it up with the radiator cap off to allow the air a place to exit.  I vaguely recall having to do that once, but many many moons ago

This was my first thought as to what the cause is.  If the system was completely filled with the coolant, it should prevent the hose from collapsing.  Sounds like air in the system.

[tony357 386]

It does sound like it is air bound.

 

Is the radiator the highest point of the cooling system ?

[JT Custom Guns 958]

Try running the vehicle (in the driveway) with the heat on and the rad cap off.

This will circulate the water through the complete system and with the cap off

should help eliminate the trapped air quicker.....................

 

Good Luck!

[djg0770 481]

which engine in the GC avi?

 

When I have emptied coolant systems in the 2.4 I4 engines and the 3.6L V6 engines I have had to rev the engine while adding coolant for several minutes to ensure that all of the air comes out of the system.  Did you just fill the radiator and put the cap back on and go?  If so, your system probably has purged much of the air and is looking for more coolant.

[junkmanted 54]

did you change the T stat ? sounds like its backwards or stuck closed 

[Babyface Finster 45]

Some Chrysler engines have a bleeder up high like on the intake manifold or t-stat housing. Check for one. If yours has it you will need to open it while filling the reservoir when cold.

[NJKen 23]

If it did this with the radiator cap (or pressure cap on the coolant reservoir) you may need a new cap.  A lot of newer cars are reverse flow cooling systems.  In other words, the coolant enters the engine through the upper hose to cool the heads first.  In theory this promotes a more uniform temperature across the engine allowing use of much more aluminum since the expansion and contraction rates are equalized a little bit.  If ther is air in the system it will compress under pressure prom the water pump.  If you compress the air and more coolant cant get in one of the hoses will colapse.  Chances are that you have done nothing wrong and only have a little air trapped in there somewhere.  As long as you have heat and the engine is not overheating you will probably be fine.  Drive it a little bit, let it cool, and then top it off.  It will most likely not do it again after that.

Ken

Added on edit:

Like above, look for a bleeder on the highest part of the engine.  It will look just like a break bleeder and most likely require a 5/16 or 8mm socket to open.  They can be on a steel coolant line as well so dont limit your search to just engine parts.

[Avi 12]

Thanks a million guys i will try out all the good advice and report back

[Dan_G 0]

If that doesnt work and there is no bleeder, try parking the car on an incline or putting ramps under the front wheels that way the rad cap is definitely the highest point. Then take the rad cap off and bleed.

Also I like to burp my hoses when filling with coolant. Basically grab and release the upper hose a couple times, you will see the level drop as you forced some air out of the system.

[djg0770 481]

Also I like to burp my hoses when filling with coolant. Basically grab and release the upper hose a couple times, you will see the level drop as you forced some air out of the system.

 

I forgot about that though I've done it a bunch of times.  Good advice.

[millsan1 3]

There may have been a spring inside the hose.  That is there to prevent collapse.  Did new hose come with the spring or did the old hose have the spring?

[Smoke Eater 0]

I think you don't have enough fluid... and an air pocket in your radiator. Fill and give it throttlw with the radiator cap off. Keep adding fluid until its full and doesn't disappear. My 2004 sebring I had to do this to do to a hose collapsing

[Porthole 15]

What did you change besides the radiator? A radiator change with any mileage on the vehicle is best done with new hoses.

 

 

Filling the cooling system cold, putting the cap on and then doing a start - warmup run and there is a good chance you still have air in the system.

 

Engine cold, remove the cap and squeeze the hose, it should not feel spongy. If you are not familiar with how the hose should feel, best advice is try a new hose, get an idea of strength.

 

With the engine cold, remove the cap, top off with 50/50, wait, top off again until the radiator is full. This could take some time to allow the air to purge past the t-stat.

If you have any doubts about your radiator cap, replace it, and I would recommend a dealer cap as opposed to one of the universal part store caps. Price will probably be the same anyway. Once you can no longer add fluid put the cap on and leave it.

 

A properly operating system "should" purge air through the coolant recovery tank. One of the reasons the recovery hose is at the highest point in the cooling system (under the radiator cap)

 

Is your coolant recovery tank and hose in good condition? Does the tank have ANY sludge build up? Clean top to bottom?

Pull the recovery hose off and make sure it is clear.

 

Once you get a closed system filled you should only add coolant to the recovery tank, to the marks on the side (hot or cold line)

[Avi 12]

What did you change besides the radiator? A radiator change with any mileage on the vehicle is best done with new hoses.

 

 

Filling the cooling system cold, putting the cap on and then doing a start - warmup run and there is a good chance you still have air in the system.

 

Engine cold, remove the cap and squeeze the hose, it should not feel spongy. If you are not familiar with how the hose should feel, best advice is try a new hose, get an idea of strength.

 

With the engine cold, remove the cap, top off with 50/50, wait, top off again until the radiator is full. This could take some time to allow the air to purge past the t-stat.

If you have any doubts about your radiator cap, replace it, and I would recommend a dealer cap as opposed to one of the universal part store caps. Price will probably be the same anyway. Once you can no longer add fluid put the cap on and leave it.

 

A properly operating system "should" purge air through the coolant recovery tank. One of the reasons the recovery hose is at the highest point in the cooling system (under the radiator cap)

 

Is your coolant recovery tank and hose in good condition? Does the tank have ANY sludge build up? Clean top to bottom?

Pull the recovery hose off and make sure it is clear.

 

Once you get a closed system filled you should only add coolant to the recovery tank, to the marks on the side (hot or cold line)

Thanks guys you nailed it my mistake was i filled the radiator in shot a gallon and half and didnt give a chance for the air to escape i should have filled it slowly. with you advice i let the car run with the cap off and let all the air escape now its fine. yes i changed new hoses with the job i was also going to change the thermostat but the dealer was closed and all i had was sunday to do it thanks again everyone you really helped me out

[bry@n 195]

Avi,

 

You can always find a shop manual in digital form. Usually give you capacities for coolant etc.