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View Full Version : Fluidyne Radiator Overheating at Installation on '96 Cobra


ProfChaos
09-22-2006, 11:48 PM
My cousin and I just added to my '96 Cobra a Fluidyne radiator (FHP20-96MU), and we also changed all of the radiator hoses. (The thermostat was replaced last Spring, so, we left that in-place.) And, even though we have used with some success a brake bleeding tool on the small nipple at the top of the overflow tank, I think that there might be a large air bubble that causes the car, when it is moving, to heat up in relatively little time (in less than a mile or so).

When the overheating occurred, I was careful to shut-off the car and let it cool briefly before the temperature got beyond the tip-top of the Normal range, but I don't want to have to cycle the car unnecessarily into temperature ranges that make me cringe, so I'm seeking a little helpful advice by fielding a few questions and welcoming ideas:

Question 1: With the Fluidyne dual-core radiator added to a '96 Cobra (that has not had the factory cooling upgrade--original plastic covers over headlights are still in-place), should I change the overflow tank cap to a cap that has a higher pressure rating than the stock 16 PSI?

Question 2: Short of buying an expensive pressure-testing system (which I'd do before risking blowing an engine), what would be the best way to check for and remove an air bubble? (We've already tried running the heater and squeezing the top radiator hose, as suggested in the Haynes Manual. We've gotten the overflow tank to burp and have been able to add almost another gallon of coolant beyond the initial level; however, there still is something wrong, because the car still overheats very quickly.)

Question 3: What in the heck would be the best approach to resolving the issue, while minimizing the possibility of engine damage from overheating?

Thanks for your help.

Professor Chaos

1-QIK-SNK
09-23-2006, 07:47 AM
did you fill it through the cross over tube(top it off)? Also you may want to try this also. i done it to my 96 also and it help out great. it is a high speed fan upgrade.

http://www.svtcobraclub.com/TechApplications/engine_n_tranny/96-98_Cobra_manual_fan_switch.pdf

also if you would happen to pull the thremostat out, drill out about 5-6 1/8" holes in the piece the opens up. that way there is not way for the coolant to get traped before it opens up. it will continue to fill up with not air pockets. that what the guys at kenny bown told me along time ago.

good luck
kerry

ausie
09-23-2006, 09:46 AM
It sounds as if you have trapped air in cooling system. Try filling the system from the cross-over tube. I found that if you use a small plastic bottle (with the bottom removed) that can be screwed into the bleed port on the cross-over tube can be used as a funnel as well as an air bleeder tool. First off, remove the expansion tank fill cap as well as the cross over tube plug. Insert the plastic bottle funnel you made (the water wetter bottle just fits great) into the cross over tube by screwing it in. Only fill the system from the cross over tube until the expansion tank begins to overflow and cap it off. Massage all of the large radiator hoses slowly until no more air bubbles come out from the crossover tube (best to leave it full of coolant when doing this). Add more coolant when the level drops off in the funnel and continue to massage the hoses. When you think you cannot add any more, remove the funnel and cap off the cross over tube. Set the thermostat setting to maximum heat on the console and turn on the fan so that when you start up the motor, the heater core can fill up with coolant. Warm up the motor (monitor the temp guage if necessary) and shut it down once operating temperature is achieved. Let the system cool down a bit. Open up the cross over tube and repeate with the funnel, add coolant and massage the hoses again. Continue until no more air can be pushed out. restart the motor (leave the heater on) and warm up again to operating temp. You may need to do this a couple of times. Once you get all of the air out, the expansion tank may spit out some coolant or you can uncap the expansion tank and push out some coolant by squeezing the hose (after the cooling system has cooled down). Take a short drive and return. Let the engine cool down. Some coolant may be pushed out from the expansion tank when the motor is cooling down. If it overflows alot, you may need to rebleed the system again. Hopefully this will help you. :thumbsup:

ProfChaos
09-24-2006, 12:12 AM
It sounds as if you have trapped air in cooling system. Try filling the system from the cross-over tube. I found that if you use a small plastic bottle (with the bottom removed) that can be screwed into the bleed port on the cross-over tube can be used as a funnel as well as an air bleeder tool.


First off, remove the expansion tank fill cap as well as the cross over tube plug. Insert the plastic bottle funnel you made (the water wetter bottle just fits great) into the cross over tube by screwing it in. Only fill the system from the cross over tube until the expansion tank begins to overflow and cap it off. Massage all of the large radiator hoses slowly until no more air bubbles come out from the crossover tube (best to leave it full of coolant when doing this). Add more coolant when the level drops off in the funnel and continue to massage the hoses. When you think you cannot add any more, remove the funnel and cap off the cross over tube. Set the thermostat setting to maximum heat on the console and turn on the fan so that when you start up the motor, the heater core can fill up with coolant. Warm up the motor (monitor the temp guage if necessary) and shut it down once operating temperature is achieved. Let the system cool down a bit. Open up the cross over tube and repeate with the funnel, add coolant and massage the hoses again. Continue until no more air can be pushed out. restart the motor (leave the heater on) and warm up again to operating temp. You may need to do this a couple of times. Once you get all of the air out, the expansion tank may spit out some coolant or you can uncap the expansion tank and push out some coolant by squeezing the hose (after the cooling system has cooled down). Take a short drive and return. Let the engine cool down. Some coolant may be pushed out from the expansion tank when the motor is cooling down. If it overflows alot, you may need to rebleed the system again. Hopefully this will help you. :thumbsup:

I tried to start the above process, but the plug for the port of the cross-over tube won't budge. (While trying to loosen the crossover port plug, I broke a quarter-inch socket adaptor, and so did my cousin. There might be a tool made specifically for loosening that type of port fitting, but neither my cousin nor I have one, so we deemed it best not to risk fouling-up the port cap.)

All that aside, I have been getting the coolant level to drop a little at a time by massaging the upper hose and following the rest of the procedure that you recommend, as closely as possible, while using also a brake-bleeeding tool connected to the small hose that feeds the expansion tank (coming from the top of the Fluidyne). I simply connect the brake-bleeding tool's vaccum fitting to the small hose, then I block the expansion tank inlet by using my thumb, and then I pump the handle of the manual brake-bleeder's vaccum pump. Since the coolant level is dropping slowly after this process, I'm guessing that the cheesey vacuum pump is slowly having an impact upon the air bubble. Tonight, after letting the car cool for several hours with the expansion tank cap removed, I topped off the coolant level and will let the car sit all night with the expansion tank cap removed. Tomorrow, I'll repeat the cycle several times, until I feel confident enough to take the Cobra for a brief spin down the block to test the cooling system under-load.

My motorcycle is running and the weather is clear, so if I have to take several days of patient periodic cycling to remove the air bubble, I'll be better off than if I were to be impatient, drive off with air bubble still in-place, and then hork the engine. ;)

Thanks for your help.
--Professor Chaos

ausie
09-24-2006, 11:28 AM
The bleed port plug can be extremely difficult to remove. I have broken several small extentions in it myself. I had found that a set of robo-plyers works when it becomes difficult to open along with the 1/4 inch socket and wrench. I had already damaged mine when I used the ratchet directly (not a suggested method). Other issue is that the square notch is metric and I would agree that there must be a special tool for it. May be a hard find. Most extentions have a spring loaded locking ball at the end of it to snap onto sockets, does not make for a good tool for square end caps.

The importance of the bleed port plug is that it is the highest area on the cooling system as well as a direct feed into the heads. When you fill it from that all of the traped air in the heads will escape. You may be surprised as to how much coolant will be needed when filling the system from the bleed plug.

I would highly recommend filling it from the bleed plug. If you are worried about scaring the surface of the plug, you can obtain a new one from the ford parts counter, which is something I need to do sooner or later.

ProfChaos
09-25-2006, 01:06 PM
The bleed port plug can be extremely difficult to remove. I have broken several small extentions in it myself. I had found that a set of robo-plyers works when it becomes difficult to open along with the 1/4 inch socket and wrench. I had already damaged mine when I used the ratchet directly (not a suggested method). Other issue is that the square notch is metric and I would agree that there must be a special tool for it. May be a hard find. Most extentions have a spring loaded locking ball at the end of it to snap onto sockets, does not make for a good tool for square end caps.

The importance of the bleed port plug is that it is the highest area on the cooling system as well as a direct feed into the heads. When you fill it from that all of the traped air in the heads will escape. You may be surprised as to how much coolant will be needed when filling the system from the bleed plug.

I would highly recommend filling it from the bleed plug. If you are worried about scaring the surface of the plug, you can obtain a new one from the ford parts counter, which is something I need to do sooner or later.


I think that I'm getting the air bubble to dissipate, even though I can't get the crossover pipe bleeder port open. I was--empahsis on the past tense--using a brake-bleeding tool (a wimpy little vacuum pump) attached to the small (expansion chamber) hose coming from the top of the Fluidyne radiator, but the pump ingested so much coolant that it no longer pulls a vacuum. Even so, I now have the Cobra to the point where I can drive around the block and bring the car to temperature with the heater blasting. When I do so, the coolant level drops to the point at which the coolant level indicator lamp comes on. I have successfully made this trip around the block twice now, so my guess is that the falling coolant level means that the air bubble is slowly giving way to coolant. (I've been able to add nearly a gallon of coolant since yesterday morning.) I will take it easy and nurse this method along for at least two more trips around the block, letting the car cool a bit and massaging the top radiator hose betwen trips.

Thanks again for your help.
--Professor Chaos

ProfChaos
09-25-2006, 05:18 PM
The air bubble is gone, and Lorena the Cobra is running fine now. In fact, with the combination of the Fluidyne radiator and a bottle of Water Wetter, the car actually runs cooler (with the gauge sitting usually in the middle of the "M" in "NORMAL," as opposed to where it usually sat: mid-way between the "A" and the "L" in "NORMAL").

Thanks for your help, Ausie! :cheers:

--Professor Chaos