radar502

I drove my 93 yesterday 20 miles and this morning looked to make sure my new coil I installed a few days back had not fell off and I noticed the top radiator was sucked in ,anybody know what causes this I had a hose off and had and lost some coolant so had to put in some antifreeze at the same time as the new coil install .. I think I got all the air out of the lines .. I don't have a clue .. Thanks ..

CorvetteRules

Did you check the hose to make sure it just doesn't need to be replaced. On your drive was it running hotter then normal? What steps did you take to get air out of system after you added additional coolant?

Krusty84

Adding coolant to the brim while the car is warm/hot will cause this. If there is no air in the system and you fill it completely up, the coolant will contract when it cools and suck the hose in.

mic575

I had a car do this once. Turns out the shop I took it to for service installed the thermostat upside down. This was not on an sbc though and it doesn't sound like it is your problem based on your description. Just thought I'd throw it out there.

radar502

I might need a new hose this one may be ORG . witch would make very old ,looks Ok for what that's worth and yes I might have put in the antifreeze wile the motor was a little warm , I took the cap off and it tried to suck me in never seen that much vacuum in the system before .. I think I will replace the hose and go from there . I let the pressure off and with new hose give it another try .. Thanks ..

Hot Rod Roy

You may need a new radiator cap. As the coolant cools, the fluid in your reservoir should be drawn back into the radiator. There shouldn't be so much pressure differential that the hose would collapse

.

radar502

NO have been driving it for awhile NO problem .I added coolant wile it was warm might be that coolant contracting deal or the hose might be old ..

radar502

I did notice that the NEW cap leaver was kinda asque it is new I replaced the whole cooling system not long back with ALL new parts and the cap .I need to check the leaver it may be broken and letting water in .. I did not replace the hoses .. Ok new hose and probably and new cap .. That should work . Never had this problem before .. How hard to fix should it be RIGHT ..

Krusty84

I didn't give any advice.

radar502

My system may have be too sealed ,when I released the cap I have never seen or heard so much vacuum it was like for 10 sec. sucking in air it had one hell of a vacuum on the cooling system .WHY ??? This what I did ,removed the top radiator hose off and a heater hose off replaced them lost a little coolant ran it for a few minuets bleed the system at the top of the thermostat bleeder deal .. was not hot turned it off it off took cap off was a little low . cup- pint ? of distilled water cranked it back up rechecked the coolant level replaced cap drove it 20 miles last night ,rechecked it this morning and the hoses were sucked together ,released the cap and it did the vacuum deal ,, I just put a new cap on it rechecked the coolant and bleed it got it hot 200% seemed to be fine now ,have not driven it will later .. I think it was the vacuum on the system that sucked the hosed in ??? why it had so much on it .. ???? I will drive it and see what happens .. Thanks for all the input ..

Hot Rod Roy

Originally Posted by Hot Rod Roy I'm sorry Krusty, but this is bad information. Today's cooling systems are designed to be filled 100% full. As the coolant expands when the engine is hot and flows into the reservoir, any air in the system will be expelled, too. As the engine cools, coolant should be drawn back into the radiator from the reservoir, with no air in the system. A good radiator cap will have a good seal in the top lip of the cap to seal the cap against the neck of the radiator. The valves in the cap assure the proper pressure during operation, and the good return of coolant to the radiator during cool down.

radar502

I don't really give advice myself . I just say want I did and how I did it and this and that might be the deal ,someone can take from there .. Been working on these sweet little rides ( RIGHT) scene 1964 14years old so I think I have seen it all NOT .. Something new every day .. Go to love it ..

gpierce

Last time I had a car with collapsed hose like that it was a bad radiator cap.

radar502

The one on it now is new the one it was new ,new parts now days don't mean you got a good part .. I think they are like $14-$15 or more bucks , The one I took off had 500 miles on it . I will see if the new well the newer one fixes it .. It seems to be working right now will take it out in the morning and see what happens ..

383vett

I'd bet on the cap. The cap is designed to hold pressure to 15 or 16 lbs or so, depending on your cap. After that pressure, coolant enters the reservoir. As the motor cools, the vacuum within the system allows the fluid in the reservoir to reenter the radiator. If the cap didn't allow this, the hose would collapse. Filling the system when warm as someone mentioned won't cause a hose to collapse.

drcook

just for ha ha's and may not have any bearing, but check the tube into the plastic overflow tank. mine was plugged solid from, I guess the "pills" gm used to put in the coolant or just the coolant itself. this was with maybe 15,000 miles on it. I discovered this while putting in a DeWitts radiator in 2017. (mine probably plugged from sitting so much before I bought it in 2016). It was plugged solid and did not allow the system to function as intended. I had to run a wire down through it to get all the junk out.

0Tom@Dewitt

All LT1 engines utilize a special 2-way acting full bypass thermostat. This means that the thermostat regulates coolant flow both in to as well as out of the engine, while the bypass portion of the thermostat circuit supplies the water pump with a full flow of liquid coolant at all times. This is unlike a conventional engine thermostat, which only regulates coolant flow at the engine outlet, and which does not allow full flow through the water pump when the engine is cold and the thermostat is in bypass mode.

Both sides of the 2-way thermostat used in the LT1 are linked together, and a single wax pellet actuator operates the spring loaded mechanism at a pre-set temperature. When the designated temperature is reached, the wax pellet expands, opening the dual acting valve. All current LT1s come from the factory with a relatively low 180 degree temperature thermostat. Most conventional engines today use 195 degree thermostats in order to meet emissions specifications at the expense of power, durability, and reliability.

It is important to note that the 2-way thermostat is unique to the Generation II LT1 and is not interchangeable with older Chevrolet smallblock engines. This is particularly important if you decide to change to a colder 160 degree thermostat, make sure it is the proper dual acting type required by the modern LT1.

radar502

Thanks Tom for the info . All was good till I removed the hoses and added a little coolant ,the new system has worked well ( all the new parts ) have worked together for about I say 500 miles so thinking adding coolant and removing the cap some how started all the problems . Over the years working on the C-4 s have noticed that adding coolant to these C-4s is a by the numbers deal for sure number one step two Etc.. and if not done right can cause all kinds of problems . I am thinking it was the cap it felt funny as I took it off something just didn't feel right about it so now its got a Super- stat one it now and is heavy duty for sure . I think it was the vacuum deal like I said when I removed the cap it drawled in air like a heavy duty shop vac. I never seen one do this over the years most of the time it blows air out not suck it in . To me I am thinking I did ( sounds weird but we the C-4 owners know the deal ) not respect the coolant filling procedures with the LT-1 . Going for a spin and will see what happens .. The old new cap is in the can another new part in the can starting to see a pattern here buy new parts don't work put then in the can go get another part . I seem to be doing this more and more .. Will let you know the outcome ..

radar502

Update : After a 20 mile drive no problems .. I don't know what I did to cause this but will never do it again . Thanks for all your input for real Corvette people like myself ( first Corvette 1961 in 1965 ) input really helps and advice really helps as well if nothing else advice can be a test of ones knowledge . ..

SJW

The radiator cap is a bit more complex than most people realize. There is a spring-loaded plunger that seals the filler port until system pressure exceeds the spring pressure, at which point the plunger lifts, allowing hot coolant to escape into the recovery tank, thus limiting system pressure to a designed set-point. There is also a smaller valve that allows coolant to return to the system from the recovery tank after the system cools, and system pressure drops below atmospheric pressure. If this return valve fails to operate, system pressure will drop significantly below atmospheric, which will lead to collapsed hoses. As noted in an earlier reply by drcook, in order for coolant to return to the system after cool-down, not only must the return valve in the cap be functioning properly, but air must be permitted to enter the recovery tank to replace the returning coolant. If the air vent line is plugged as it was on drcook's car, the symptom will be the same as if the return valve in the cap is inoperative (collapsed hose).

Live well,

SJW