What's wrong ?!?! .....I 'test' drove the '68 for the first time since my radiator swap. It's now a 'closed' system with an expansion tank unlike before the swap. After getting home, there was a slight over-heating problem & I lost about 2 cups of water through the overflow hose.

5 min. later - both upper & lower radiator hoses COLLAPSED !!! :eek:
What caused this ? -I know there's a vacuum & I'm thinking that there was "air" in the system.

Also, I filled the radiator through the upper hose inlet & filled the exp. tank 1/2 full. Is it possible that the engine had an air pocket ? :confused:

 

Does the tube/hose (into your expansion tank) extend to near-bottom of tank ... so it can draw from near-bottom of tank?

Is there smutz in tank bottom? Is tube too close to tank bottom? Could that tube have a clog? ... or a kink? ... or a collapse under vacuum? ... restricting free-flow back to rad?

BTW, I have Stant pn 331 LeverVent rad cap (16 lb) ... works great with my overflow tank.


[Modified by jackson, 12:34 PM 10/17/2002]


[Modified by jackson, 12:58 PM 10/17/2002]

 

Not an expert here, but the overflow tank is designed to catch the overflow (neat, huh!) when the system is warm. As the engine cools, the excess coolant is drawn back into the system by way of vacuum. If the hose does not extend to the bottom of the tank, you would suck in air.

 

you need a special cap that allows the coolant to be drawn back into the rad on cool down and if the cap does not do this it will collaps the hose. :chevy

 

Crap, crap, crap......you're right - something is majorly wrong - O !!! :crazy: :eek:

Ok....back up.....I've installed an expansion tank from a '66 vette - shouldn't matter, right ?.....ok - maybe I'm the "Dummy" :troll :conehead :hat

So, I 'reversed' the lines ? ....The cap is up, and the line from the rad. feed from the top - Oh :mad :cuss :mad :cuss :cuss ....my fault :nonod:

YIKES !!! I swapped the lines & this just added to my running hot prob., right ?

 

Sounds like your radiator cap is not working properly.

It should allow the excess coolant (from expansion as it heats up) to flow out to the overflow tank, then as it cools down it should open again from the vacuum created by the cooling to allow that fluid to go back into the radiator (as long as the pickup tube in the coolant tank goes to the bottom, otherwise it will suck air). It sounds like your cap is opening just fine under pressure, but is not opening to allow the coolant to move back into the radiator.

 

The expansion tank shouldn't matter. It is simply there to collect fluid. Any bottle, can, etc will do that. The cap does matter (did not think of that) because the system is pressurized. The cap has to allow for pressure equalization to create the vacuum to draw back in the coolant.

Not sure on the reversed lines, but the system is designed to move the coolant one way, and the flow was affected, it would add to overheating.

 

In my case - the cap is "brand new" and is working good enough to pressurize the system........Where I screwed up is the line - my rad. line come in at the top - DOH ! :eek:
So it sucks air instead of water :cuss - but I'll post a re-cap since I'm going home for lunch, I'll see what I can do ! :cheers:

 

Even if your cap is suckin in air,the hoses shouldnt collapse.That would just mean that you get more air in the system and the hoses should be intact.
My .02 is on the cap..As i see it its the only thing that could cause this type of probelm.. :cheers: :smash:

 

:cheers: Jackson found 1 of my problems.....it's -fixed-......hoses are in the right places now & everything "appears" to be working properly.

However, I'm not ruling out the possibility of a 'defective' rad. cap. Also, I notice that this time I over-filled the system since it leaked a little overflow this time.......

BUT - it's not running near as hot & my oil pressure is where it should be ! :cheers: I'll keep posting updates & check that cap again !!! - this forum rocks. :yesnod: :chevy

 

Some of the the hoses are spring loaded. Others are not. The spring loaded don't collapse, the others do.

Bob

 

Recap ... sorry, no 'pun' intended ! :lol:

The cap was A-ok - 16lbs. of pressure......BUT - :eek: - .....my radiator wasn't completely full ! :cuss

These closed systems are harder to fill than I thought.....so, I took off the upper hose at the neck & held it up while adding water until water squirted out the pass. end at the top 3/8" outlet to the exp. tank.

Now it's full and seems to be working. There might be other issues dealing with heat. :mad .....anything to look for ??? :confused:

I'm checking the following :
* Timing advance (could 'cause engine to operate warm)
* Carb. setup (hafta do this every mo. since it's a Holley :lol: )
* Oil deposits in the water system
* Water pump impeller blades {hafta pull it - last resort}
* Thermostat ? (doesn't have one right now)
* Anything else ???

 

I just replied to a thread above. The engine water spaces are full of air. Run the motor without the cap on, but don't let it overheat. It should not overheat unless there is a blockage somewhere. If a vacuum develops, you must eleviate it. Most times, the upper hose collapses due to suddenly cool air tyying to pass where there should be hot water. Squeeze the darn thing. If air bubbes thru, let it keep coming. No rocket science here. If you want to bleed all of the air out of your cooling system before you start a new engine, do what we do at NASCAR. Run cold water thru the sucker until it comes out clear.. No air, no problem. And while I'm here...you all know never to run pure water thru your Vette engines, don't you Run a 50-50 mix...and this means you Bubba.

 

Paul/Verskel:
Virtually all cars should run a t'stat ... or some means of restriction. The restriction is needed to create the backpressure ... without that the pump impellor may not pick up properly. Either put a good t'stat back in ... or you can take a junk t'stat & snip out-gut the center section. A gutted t'stat will provide the needed backpressure with no possibility of a fail-in-closed-position condition. Yea, I know ... there are also t'stats that only fail in open. My point is that some restriction needs to be in the t'stat housing.

Also, you noted that both rad hoses had collapsed ... proving lower hose can collapse. When running, upper hose has pressure and lower hose has suction (pump draws from lower hose). When running you don't want lower hose to collapse as that can restrict flow and cause overheat. Make sure you get a lower hose with a spring in it to prevent collapse. Also, if you have room, double-clamp both ends of both hoses. When running, a pressure leak at top will loose water ... but a vacuum leak at bottom can allow air to be sucked in & that too will cause overheat.

Straight distilled water don't provide corrosion inhibitor nor lube for pump ... 50% antifreeze don't cool so good. So, if you're not in danger of freeze-up ... a good mix is 20% antifreeze:80% DH2O ... that's enough AF to nix rust & lube pump and will elevate boiling point ... BUT it also elevates freezing point.
bubbajack


[Modified by jackson, 2:31 AM 10/20/2002]


[Modified by jackson, 2:31 AM 10/20/2002]

 

Thanks for the tips guys.....! :cheers:

I "re-filled" the radiator again leaving the pass. side expansion hose off......and I'm in the process of installing "new" hoses as well. IT's frustrating trying to work out all the bugs :boxing when you're in a "hurry" to see results ! :crazy: :eek: .....ok, deep breath..... Here in TX it doesn't get very cold all too often & I'm sure a 20-30% anti-frz. mix will work just fine......I'm also planning to use a bottle of Redline 'Water-Wetter' ! ;)