coolant overflowing

[shand dill]

After several burp prcedures. Purchase of new caps and thermostat, the sytem continues to overflow reguardless of cool to hot. Attached is simple drawing of the sytem layout.
Most of the time within minutes of starting the system starts pucing on the ground from from the main catch can. Can catch from t-filler is 1/3 full at cold. Can catch from radiator is OEM and 1/2 full with cold.
What am i missing?

[Bob Cowan]

That usually means too much pressure from a bad head gasket.

Don't guess - know. Go down to Autozone and borrow a coolant system test kit. They'll charge you $80, and you get that back when you return the kit. It comes with instructions.

[FFR5452]

Did you recently rebuild the engine?

[Beal]

In your diagram it appears you have 2 pressure relief caps and 2 tanks. Why? Are you sure your not emptying one tank out during cool down and when hot sending fluid to the other tank which would overflow.

[Frank Messina]

Your plumbing looks okay but you don't need an overflow to the ground if everything is working right. Do what Bob says and pressure test your cooling system. Sounds like a blown head gasket to me.
Frank

[shand dill]

To all,
If bad head gasket would i not see some water in the oil? Yes to rebuild, six months ago. The two tanks are independant of each other. Raditor tank has the float/electrical low fluid indicator, however i don't have the indicator light on the dash. Should i just plug that the port and just use the top filler overflow only? seeing the filler cap is 14lbs?

additional Q, just read another post about the t-filler cap not seating correctly due to machining of the oval, the brass disk doesn't seat or sit inside correctly. I would assume that if this happening then as the coolant heats up, the caps is not holding pressure and therefore blows out into the overflow....

[BigLeo69]

too much pressure can get your WP seal to leak and wick out the weep, meaning cap my not be working.
i would still pressure test the system like was stated earlier

should have a cap only one place too, and overflo works as a closed system.

[d42davis]

You should have only one point where water exits under excess pressure and returns under vacuum.. Plug the radiator fill and vent connections with a permanent plug. Use the t-filler for all vent and return service.
A system pressure test with a test kit is good insurance that all connections are leak free, but won't test the performance of your T-filler/cap seal. However, those parts must seal correctly for the system to hold 14-16 # pressure, and return fluid from the overflow when the system cools and goes to vacuum.

[shand dill]

d42davis; copy that. In looking for a permanent plug, please advise to type of cap.
Thanks everyone who has shared their ideas too, to this nightmare.i'll do the system pressure test as well.

A little freaked out on the head gasket issue, causing the issue. I have had this motor out and in so many times and the final time built by reputable engine builder and now head gasket failure, the fun of this project is lost.

[xsive]

RE: "Water in the oil?"

Depends on where the gasket has failed. It's possible to blow between the cylinder and water passage, and not leak into the crankcase. If so, you would see bubbles at the T filler. Not saying this is the problem, just a possibility. HTH

Don H

[5.8Cobra]

Probably not a blown head gasket... You could run a higher pressure cap on the radiator and the standard 14psi cap at the filler. Also on the capacity of the aftermarket overflow, if its too small, it will over flow when the car gets hot and then suck empty when it cools off. I think you need around 2 quarts of capacity. What if you bypassed the aftermarket overflow and used just the OEM one, connecting your red line to the factory tank. Try the whole burping thing again and see what happens. Does it overheat? Is the thermostat in the correct way? It helps to drill an 1/8" hole at the 12 o'clock position on the thermostat to help with air elimination. What thermostat are you running and are you carbed or EFI. Keep us posted.

Mike

[ROADRACER83]

It's certainly possible to have a blown head gasket and not have water in the oil. Since the oil pressure is usually higher.

It is not correct that you cannot have two pressure caps in the system, although it is not absolutely necessary. My system is identical to yours and works fine, but I have a 20# cap on the upper radiator "T" cap location, a hose from the "T" to the BOTTOM of the expansion tank, and a 16#cap on the expansion tank and an overflow hose from above the 16# cap to overboard The expansion tank doesn't need the pressure cap, but it keeps the water from evaporating in the tank as an open system would. Both caps have the small valve that allows water or air to flow back into the system when it cools.

Ron

[d42davis]

Using a much higher pressure cap at the radiator is a solution, but only if you incapacitate the vacuum function of the cap. If not, the system could pull a vacuum at either. You need to insure the system only pulls from the cap with the dedicated overflow tank.

[acth4347]

I noticed in your original post you said it starts to overflow very soon after starting. It sounds like your system is not able to pressurize. Can you do a pressure test from one radiator cap and then the other? You may be able to tell if the inline filler T cap is sealing that way.

[shand dill]

Ok here we go, I have 20lb cap on the radiator connected to an OEM sytle overflow that houses the float system with the "fill if low" OEM plastic cap. On the t-filler i employee a 14lb lever action cap. The overflow goes into the bottom of the container that holds around 1 qt+ on the radiator overflow tank it holds1.5qts so says the liturature. Purchased from a racing parts store. THE BIGGEST ISSUE, the system works and then it doesn't. I have noticed that cooant has drawn from the radiator overflow due to the peep line level.
I have installed a new lever cap at t filler and as indicated it appers it might not seat at at the brass disk into the filler.inside of tfiller it is oval rather than round like another post is talking about too.this imperfection may be causing the system "NOT TO Pressureize" as acth4347 spectulated. AND YES is has shown overheating, however when i use alazer thermometer it reads 146 degrees at sensor, thermostat housing.
So with that said i fully understand the only one canister and plug off the overflow too.
I do so appreciate everyone's input. I'll do further investigation and report back.

[Dually]

my engine started life as a Ford Racing 347 - 450hp. After initial startup I noticed that pressure remained in cooling system even after several days and there was a small amount of coolant weeping from water pump. Quickly diagnosed issue by putting a pressure tester on where rad cap goes and saw pressure start to build immediatly upon startup. Worked a deal with Ford and took engine to a highly recommended builder. Found some issues with deck machining which was allowing combustion pressure back into cooling system. Tore mtr down and started over with a complete blueprint. No signs of bad seal and engine ran fine, no water in oil. I would check to see if you are bleeding combustion gas back into the cooling system.

[CraigS]

D24 davis has an interesting point about the cap on the radiator. i put a new rad in my car a few months ago and tried to plug off the rad cap area but that plug popped out. Obviously the wrong thing but my easiest solution was to buy a 20# cap. I screwed it on and have been running that way ever since w/ a 16# cap on the T-filler. No problems so I will leave it as is but plan to double check that 20# cap when I have the system open next.

[Cone Basher]

Is it possoble you have the wrong water pump? Check to make sure you have the correct one, they come in two variations.
Just an idea;
HTH
CB

[shand dill]

cone basher; yes sir checked correct W/P. Craig S, i too have a new 20lb cap on the radiator. Thinking 20lb on the t- filler. however thats 4-6 lbs greater than recommended. Dually, i have run out of motor money two motors ago. i do appreciate your thoughts. i'm just going to start with the t-filler oval issue. pressure check and if no improvements then i'll take her back to the engine builder see what they say, maybe some additional diagnoses. Again thanks to all for your thoughts.

[jlkendri]

I had a problem with mine overflowing and it ended up being the t-filler. i don't remember what brand it was, maybe moroso. There were others who had this problem. The machining on the t-filler did not seal with the radiator cap. I bought a different t-filler and never had another problem.