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Coolant leak

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07coupegt

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Last winter, the rad on my blazer began leaking, so I replaced it with a new one. After installing the new rad, I noticed cooland leaking the around the upper hose where it clamps onto the rad, so I replaced both hoses. After doing this, it still leaked a little but eventually stopped. After driving around all summer with the overflow resevior almost empty (The hose had stopped leaking) I decided to refill it last week. Ever since filling the resevior, both hoses have been leaking. I tried tightneing the clamps, but it still always leaks in at least one spot. Any ideas why? Rad cap? head gasket? the truck isn't overheating or burning any coolant. It seems like there is too much pressure in the rad.
 
Might try the rad cap first. Not sure what PSI its supposed to be but I had a similar issue last year with one of my Burbs. New rad cap fixed it and its the cheapest/easiest thing to start with.
 
My radiator started leaking around two of the three nipples off the radiator. I pulled the radiator and took it to the local shop where they re soldered the nipples back on. Easy cheap fix.
 
It's definately not the rad that is leaking, Its the hose connections. I replaced the rad cap, hopefully it'll fix the problem. If that doesn't help, I am going to borrow a guage to check the pressure in the rad. I don't see any bubbles comming up in the rad when the engine is running though (with the rad cap off) so I doubt its a headgasket.
 
there's also a test kit I think you can buy that will test for exhaust gases in the radiator. I think, unless I dreamed all that up. Someone might know more :)
 
Try some sealant, I believe the stuff I'm thinking of is permatex form-a-gasket. It's kind of a tar looking type stuff, it will seal if the problem is simply a slight gap that is still there.

If the problem is a head gasket it will push right through whatever you put in there anyway, in general.
 
Look for some Goodyear "Pliobond" in the gasket maker section of a good parts store--that works great on rubber to metal connections like radiatir hoses,and wont be a pain to remove later on,like Indian Head Gasket Shellac,if you want to WELD a rubber hose to a metal fitting,I'd use that stuff!..RTV sliicone is a poor choice as it'll let the rubber possibly slide off eventually,as silicone is prety slick stuff..

You can have a repair garage use their exhaust gas analyzer they use to do emission tests to "sniff" the radiator after opening the cap,and running the engine,put the probe in the neck of the radiator (dont submerge it!),and any hydrocarbons escaping from a leaking head gasket will be detected by the probe...I'd guess you have original head gaskets that were steel shim type,and they are probably rotted thru in one tiny spot and its letting compression sneak into the radiator...cracked valve seats can do it too..intake gaskets leak often on newer engines too,but cant pressurize the radiator..
 
Well, looks like the rad cap didn't help. If there is any coolant in the overflow tank, it will leak at the hose connections. Tightening the clamps just makes it leak at another connection. It seems to leak the worst when the truck is shut off before it is ran long enough for the thermostat to open. The other day I drove 5 minutes to the gas station, and when I came back out, there was a puddle of coolant under the truck that had leaked from the upper rad hose. Time for head gaskets? My friend is a mechanic, so we may try a leakdown test.
 
Do you still have a brass radiator? I've had the solder get the smallest pinhole leak once everything gets hot and expands and creep up the hose itself. Kind of looks like the hose is leaking until you start flexing things around while its under pressure.

Something must be wrong, my hoses don't leak even when I accidentally pressurize the whole cooling system to 90psi cuz I forgot to adjust the regulator on the compressor :whistle: lol
 
try a coolant system pressure test.. way quicker than a leakdown.. pretty sure most of the parts stores rent em.,...
 
First I would check the overflow hose its self. Not likely, but its the easiest suggestion I have.
It just seems strange that filling the overflow makes it leak. Makes me wonder if there is something stopping the overflow hose up.

Next, I would pull one or both of the radiator hoses off and make a really close examination of the nipple.
I've got a bad feeling that they might be so thin that they warped or partially collapsed when you first tightened the clamps.

If its not too bad, the sticky sealer mentioned by the others might fix it as long as you don't tighten it too much and warp it more.

As for checking for head gaskets, most radiator shops have the tester.
Its a glass bottle with some liquid in it and a hand vacuum pump.

They put in on the radiator in place of the cap and suck some of the air out of the radiator through the liquid, which turns blue if you have exhaust gas in the water.
 
Radiator seems fine, and the hoses are new. Both hoses leak at both ends, which pretty much rules out a rad problem. The hose going to the overflow seems fine, since coolant enters the tank when hot, and drains back into the rad when cold. The truck is now leaking much worse. I drove the truck for about 10min this morning, and when I came back out there was a large puddle on the ground under each rad hose. Any idea where I can get an exhaust gas tester. I went to 3 stores and none of them have heard of it. Napa has nothing.
 
I was going to buy one, but the cheapest one I found in town was $100, and I didn't want to spend that on a tool that will likely only be used once.
 
As mentioned before, it is not the rad nipples. It also leaks where the hoses clamp onto the thermostat housing, and the water pump. At this point I am 90% certain it is head gaskets
 
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