Radiator Hose keeps blowing off
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
Have you tried the radiator pressure testor that was recommended a few posts ago? What were the results? That tool will pressurize the system (you can check your cap too). If there's a problem in the system, it'll ususally show up because the system won't hold pressure (leave it at operating pressure for about 10 minutes if you have to). If you hold pressure fine, check the cap. I didn't see where you mentioned anything about the overflow, so it seems your blowing hoses but you're not having any issues with the overflow. If you're building pressure past 16 or so lbs (I'd think you have to in order to blow a hose) the cap should release and you should get coolant in the overflow. The cap might not be releasing pressure like it should.
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
Right, and by removing the cap, I am elimintaing the possiblity of it being the weak link correct? The pressure will obviously be released because there is no cap correct? The coolant level is about an inch down right now at the fill and I planned on leaving it that way for now. This would let me see that the coolant is being pumped through the system. In theory, the level should rise once the pump works the coolant out of the block and through the radiator...correct? -Neal
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
Have you tried the radiator pressure testor that was recommended a few posts ago? What were the results? That tool will pressurize the system (you can check your cap too). If there's a problem in the system, it'll ususally show up because the system won't hold pressure (leave it at operating pressure for about 10 minutes if you have to). If you hold pressure fine, check the cap. I didn't see where you mentioned anything about the overflow, so it seems your blowing hoses but you're not having any issues with the overflow. If you're building pressure past 16 or so lbs (I'd think you have to in order to blow a hose) the cap should release and you should get coolant in the overflow. The cap might not be releasing pressure like it should.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
Right, and by removing the cap, I am elimintaing the possiblity of it being the weak link correct? The pressure will obviously be released because there is no cap correct? The coolant level is about an inch down right now at the fill and I planned on leaving it that way for now. This would let me see that the coolant is being pumped through the system. In theory, the level should rise once the pump works the coolant out of the block and through the radiator...correct? -Neal
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
Ok, didnt have time to stop at autozone today after work but i did check the plugs when i got home. They dont look like coolant was washing past them and I checked the oil again...all looks normal. I mostly did these things for my own peace of mind. -Neal
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Racer
Joined: Apr 2006
Posts: 340
Likes: 0
From: Warrensburg MO
I would leave the T-stat in place. Take the cap off, crank it up and watch the flow. It will start to overflow until the thermostat opens, and then you should see how the flow is through the radiator. If the flow is normal, then I can't imagine the pressure building up to the point of blowing your radiator hoses off. The pressure tester is a good tool to check the cap pressure, and to check for leaks, but I don't think those are your problems. Your cap should be able to hold the normal pressure during operation. If it needs to open during normal operation, there is another problem; in my opinion. Is your temperature in the acceptable range? Remember that your circulation is from the bottom, and then back in at the top. Check the flow.
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
Update
Ok, I ran the car this evening after work. It idled for 35 minutes and got up to temperature. I left the thermostat in and cap off. This time, NO HOSES BLEW OFF!!!! 
There was no moisture whatsoever coming from the tail pipes, no coolant in the oil, and all the plugs looked great. Would I be wrong to assume that the cap seems to be the problem here? Some coolant came out of the cap location, but that's to be expected when there's no cap on it. It didn't over heat...stayed right at about 195-200 degrees and the hose got hot once the t-stat opened, but never tight or full of pressure at all. Any input? Thanks a lot, Neal
There was no moisture whatsoever coming from the tail pipes, no coolant in the oil, and all the plugs looked great. Would I be wrong to assume that the cap seems to be the problem here? Some coolant came out of the cap location, but that's to be expected when there's no cap on it. It didn't over heat...stayed right at about 195-200 degrees and the hose got hot once the t-stat opened, but never tight or full of pressure at all. Any input? Thanks a lot, Neal
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
That tells that the tstat is working and the radiator is cooling the system adequately at idle.
Now you have to try a known good radiator cap. (see post #9)
If you have no shroud, mist water from a hose over the front of the radiator while idling. You really need a shroud to drive it.
If the new cap blows off coolant, or your hose, then you must test for combustion gas. A pressure tester will not always show it.
If you use the recovery tank, any excess coolant should blow in there.
If not using a recovery tank, then expect it to puke coolant until the level is approx 1 1/2" below the fill neck and then it should stabilize and never blow more.
Be aware that on a cross flow radiator with a slanted cap neck on the tank top, it is almost impossible to see combustion air bubbles in the coolant flow and believe it or not, it is a fairly common problem.
Now you have to try a known good radiator cap. (see post #9)
If you have no shroud, mist water from a hose over the front of the radiator while idling. You really need a shroud to drive it.
If the new cap blows off coolant, or your hose, then you must test for combustion gas. A pressure tester will not always show it.
If you use the recovery tank, any excess coolant should blow in there.
If not using a recovery tank, then expect it to puke coolant until the level is approx 1 1/2" below the fill neck and then it should stabilize and never blow more.
Be aware that on a cross flow radiator with a slanted cap neck on the tank top, it is almost impossible to see combustion air bubbles in the coolant flow and believe it or not, it is a fairly common problem.
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
That tells that the tstat is working and the radiator is cooling the system adequately at idle.
Now you have to try a known good radiator cap. (see post #9)
If you have no shroud, mist water from a hose over the front of the radiator while idling. You really need a shroud to drive it.
If the new cap blows off coolant, or your hose, then you must test for combustion gas. A pressure tester will not always show it.
If you use the recovery tank, any excess coolant should blow in there.
If not using a recovery tank, then expect it to puke coolant until the level is approx 1 1/2" below the fill neck and then it should stabilize and never blow more.
Be aware that on a cross flow radiator with a slanted cap neck on the tank top, it is almost impossible to see combustion air bubbles in the coolant flow and believe it or not, it is a fairly common problem.
Now you have to try a known good radiator cap. (see post #9)
If you have no shroud, mist water from a hose over the front of the radiator while idling. You really need a shroud to drive it.
If the new cap blows off coolant, or your hose, then you must test for combustion gas. A pressure tester will not always show it.
If you use the recovery tank, any excess coolant should blow in there.
If not using a recovery tank, then expect it to puke coolant until the level is approx 1 1/2" below the fill neck and then it should stabilize and never blow more.
Be aware that on a cross flow radiator with a slanted cap neck on the tank top, it is almost impossible to see combustion air bubbles in the coolant flow and believe it or not, it is a fairly common problem.
If the cap was good don't you think it would've let the pressure out before the hose blew off? I have to imagine that 16lbs wouldn't blow the hose off like it did, but I could be wrong. How can I test for combustion gas if a pressure tester doesn't show it? -Neal
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
Several posts back you asked about where to get a lower radiator hose with a spring in it. I got mine from Zip since they are right in my back yard. It cost me about 50 bucks. I know DeWitts also has them for about the same price.
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
I'm not sure this is needed though. I am positive that the lower hose isn't collapsing with the cap on as my hand was on it when the upper hose blew last time and it was full of coolant. I may get it after all is said and done anyway...just for peace of mind more than anything else.
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
This is the cap I will get tomorrow. Should be fine right? http://shop.advanceautoparts.com/web...ci_sku=6091458
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
I don't have any caps other than the one on the car. I sold the last one with a good cap. I'll hit up a parts store at lunch tomorrow and grab the most expensive one I can find and hope it works. I do in fact have an over flow tank in the car and there is a hose hooked up to it.
If the cap was good don't you think it would've let the pressure out before the hose blew off? I have to imagine that 16lbs wouldn't blow the hose off like it did, but I could be wrong. How can I test for combustion gas if a pressure tester doesn't show it? -Neal
If the cap was good don't you think it would've let the pressure out before the hose blew off? I have to imagine that 16lbs wouldn't blow the hose off like it did, but I could be wrong. How can I test for combustion gas if a pressure tester doesn't show it? -Neal
A bad cap not blowing off, can build to a much higher pressure that it would take to blow the hose off.
You can test for combustion gases with a dye kit or with an exhaust gas analyzer that a good shop should have.
I have a car here now with that problem, pushes the coolant into the tank, but no coolant in oil and doesn't overheat. Either bad head gaskets, cracked head, or corroded aluminum head.
Hopefully yours is just the cap. Make sure you get one for a recovery tank and with a spring loaded recovery poppet. The cheap ones have a gravity poppet without the spring.
Don't get the ones with the lever, they are not as reliable as those without.
Thread Starter
Racer
Joined: Jun 2009
Posts: 276
Likes: 2
From: Parkesburg PA
A good cap will blow off at the rated pressure into the recovery tank. Watch the level.
A bad cap not blowing off, can build to a much higher pressure that it would take to blow the hose off.
You can test for combustion gases with a dye kit or with an exhaust gas analyzer that a good shop should have.
I have a car here now with that problem, pushes the coolant into the tank, but no coolant in oil and doesn't overheat. Either bad head gaskets, cracked head, or corroded aluminum head.
Hopefully yours is just the cap. Make sure you get one for a recovery tank and with a spring loaded recovery poppet. The cheap ones have a gravity poppet without the spring.
Don't get the ones with the lever, they are not as reliable as those without.
A bad cap not blowing off, can build to a much higher pressure that it would take to blow the hose off.
You can test for combustion gases with a dye kit or with an exhaust gas analyzer that a good shop should have.
I have a car here now with that problem, pushes the coolant into the tank, but no coolant in oil and doesn't overheat. Either bad head gaskets, cracked head, or corroded aluminum head.
Hopefully yours is just the cap. Make sure you get one for a recovery tank and with a spring loaded recovery poppet. The cheap ones have a gravity poppet without the spring.
Don't get the ones with the lever, they are not as reliable as those without.