[nUcLeArEnVoY]

So as I walked back to my storage unit to close the door after pulling the T/A out yesterday to go on a drive to class, I noticed there was the same small puddle of coolant (less than even an ounce or so) located in the same spot that resulted in an entire heater core; heater hose; and heater outlet nipple fitting replacement job last June. I was able to verify the leak occurred since I could see wet coolant on the big fender bolt behind the front passenger tire; the frontmost bolt that uses the speed nut, not the rearmost one near the pinch weld. The leak drips from that area of the fender onto the ground. Couldn't tell if it occurred when I started the car for the day or after I shut it down at operating temp a couple days prior.

Thought I had this leak fixed for good, since the last time it happened which resulted in the heater core replacement, I was able to catch the leak live and could see coolant was running from behind the heater core box and running down the very corner of the passenger footwell and out the fender in a trickle effect; but even before I did the heater core replacement job, the leak was very intermittent - as in, would only occur months apart. Really weird, and it only occurred after shut down at operating temp when the system pressure rises temporarily due to no more flow.

So yes, last June I replaced the old heater core (it was still the original Harrison unit and I honestly couldn't find any obvious holes or leak points in it when I took it out) with the new copper/brass unit from Ames, I replaced all the heater hoses, I replaced the heater hose nipple fitting at the rear passenger cylinder head (later style with the rubber restrictor), AND for good measure I put an additional in-line aluminum 0.250 restrictor into the inlet heater hose for extra restriction. I'll be REALLY freakin' pissed if my brand new heater core failed after less than a year considering all the measures I took to prevent it from failing. It's not like my cooling system is under extremely high pressure - the car runs very cool, and even after shut down when the pressure rises, yeah the upper radiator hose feels firm to the squeeze but by no means is it rock hard.

I'm starting to think it's not the heater core this time (possible it never was!), but rather the inlet heater hose connection. I would think a heater core failure would give me the classic "puddle of coolant in the passenger floor inside the car" symptom, and not drip out EXTERNALLY behind the passenger tire - the only culprit that makes sense that I can think for my type of leak would be the heater hose connection, specifically the inlet that you can only get to by removing the inner wheel house. Thus my question...

When I did the heater core job, I replaced the clamps with repro Wittek tower clamps for originality; but I've learned that they're not quite the best, plus like worm gear clamps they do not account for thermal expansion and contraction of the hose (cheapo worm gear clamps were what was on the old hose before I did the heater core job). Since nobody will ever see the inlet heater hose connection to the heater core anyway, I figure I could instead opt for something with function over form, which leads me to constant tension spring clamps as they apparently work better and are used almost exclusively on most modern cars.

Has anyone used constant tension spring clamps for the heater hoses? If so, what size did you get? I know the inlet heater hose is 5/8" INNER diameter, but the outer diameter is more important for me to gauge what type of spring clamp I should get.

I'll also be replacing the radiator cap for good measure just in case the issue is my radiator cap intermittently failing to release pressure due to some fault.

Thanks.

[hgerhardt]

Spring clamps are great. On my Sling A/C project, I just went through this exercise. You measure the OD of the hose (in the relaxed state, not over a nipple), and get that size clamp. For 5/8" Gates hose I used 15/16" clamps which were the right size. For 3/4" hose, you'll have to measure.

McMaster: https://www.mcmaster.com/7329K48/
Amazon also has these. https://www.amazon.com/Constant-Tens...dp/B0040CYVSG/

[nUcLeArEnVoY]

Originally Posted by hgerhardt

Spring clamps are great. On my Sling A/C project, I just went through this exercise. You measure the OD of the hose (in the relaxed state, not over a nipple), and get that size clamp. For 5/8" Gates hose I used 15/16" clamps which were the right size. For 3/4" hose, you'll have to measure.

McMaster: https://www.mcmaster.com/7329K48/
Amazon also has these. https://www.amazon.com/Constant-Tens...dp/B0040CYVSG/

Just the answer I was looking for! Thank you.

I'm thinking I may have overtightened the Wittek Clamp, too. I just didn't want to take the wheel liner off again so I figured the tighter the better but since they don't apply even pressure I may have ovaled out the hose. Hope I didn't warp the heater core tube.