Saturn SC2 radiator is leaking from a crack in the plastic near the top of the radiator on the driver’s side. It’s reachable with little trouble, but is it fixable? Online info conflicts: half the people said, “try J-B PlasticWeld (some say WaterWeld)” or some similar epoxy putty product (Permatex’s products get mentioned, too), the other half say, “don’t bother, it only works for a couple of days… get a new radiator”.
What’s the Straight Dope say?
I would try JB first. If it only lasted a couple days, then you replace it.
I was able to fix a BMW radiator with JB, on a broken plastic part. Works fine, even in the extreme desert heat (so far! 
).
Good luck!
I’ve never tried it on a radiator but I have seen JB Weld perform successfully in some very demanding environments!
(Ex-submariner)
Replace it. If the crack catastrophically gives way when someone happens to be standing near it, and they get horribly burned, you’ll wish you’d have replaced it. Even if the patch holds, other parts are probably ready to crack, as well.
ETA: Not to mention that, even if it doesn’t injure someone, it could give way and leave you stranded. Replace it.
Oh, and when you get the new radiator, make sure that you (or others) don’t put your hand on top of the radiator to lean on it when reaching into the engine bay. It’s surprisingly easy to do that without thinking about it, but putting any weight on it is a bad idea. The plastic on radiators will degrade plenty just from the heat cycling - but it doesn’t need any help from hands causing stress fractures.
Another vote for DIY. Along with the JB Weld product, I’ve had stellar success with “epoxy putty”. Find it at your local Big Orange. It comes in a variety of spec, including “marine” and high-temp.
Use the JB Weld to patch the thing until you replace the radiator. You didn’t say what specific year/model car you have, but changing radiators is one of those things that can be an easy DIY project, or a real headache if the transaxle cooler is part of the radiator.
IME, trying to patch a radiator externally with some sort of adhesive is just that - a patch. The last time I did it, the stuff held for about two weeks, then failed catastrophically, resulting in a blown head gasket and about $5,000 in repairs.
A patch might work for an indeterminate amount of time, but you cannot be SURE that it will work for any specified amount of time. It’s a gamble. Feeling lucky?
Keep in mind that the remainder of the plastic radiator tanks, while not leaking now, are as old and stressed as the part that started leaking. Long-term prospects are not good.
My vote is to replace the radiator. Many years ago I had the same problem with an Audi. I patched it externally with fiber glass and epoxy. It broke again a couple weeks later. I ended up replacing the radiator myself. If you do it yourself, plan on replacing the radiator hoses as well. They’re probably old and need to be replaced anyway. Chances are you’ll need to pry them off and ruin them in the process. Scope out what you need to do before starting. If you have an automatic transmission, you’ll likely need to disconnect and reconnected the transmission cooler lines. If you have A/C, see if there’s some way of moving the A/C cooler out of the way. You really don’t want to disconnect the A/C.
A radiator shop may also be able to replace just the plastic part (called a tank) at a reasonable cost if for some reason a replacement radiator is unavailable or too costly ( but I doubt either is the case). I’ve had good luck with all three methods (epoxy, tank replacement, and radiator replacement). I’ve used epoxy on a small leak (crack) near where the overflow tube exits the neck, tank replacement on a radiator which was relatively new enough that I was sure the coil section was good, and replacing the entire radiator when it was old enough that repairing it was probably going to be a waste of money since something else was likely to leak soon. If it’s the original radiator, a Saturn SC2 is old enough to just jump to replacing the entire radiator though.
I would try the DIY method first.
To keep the crack from growing, drill 1/8" holes at the ends of the crack. Then J.B. Weld it or glue it. I have had success with a radiator patch kit from NAPA. It has lasted for four years now in the cold / hot of the high desert country that I live in. A new Radiator is $125 and four hours labor. The patch kit cost $23 and less then one hour labor. You choose. IHTH. 48.
Bar’s Leak too: First nuclear submarine USS Nautilus visits Seattle and crew secretly buys Bar's Leaks on June 3, 1958. - HistoryLink.org
JB worked for my 91 Mustang GT coolant overflow tank, it was made of plastic.
Quite a different thing in that the overflow tank doesn’t have to hold pressure.
Hmmm, thanks all. I’ve been thinking about the effort and consequences of all of the solutions and have decided what to do. I’m gonna do nothing.
Work with me here.
The leak isn’t that large and it’s very near the top of the radiator. When the coolant leaks below the crack, the leak stops. The car is otherwise working fine. Because it’s leaking, the system isn’t pressurized, yet during the insane heat wave recently it didn’t overheat. If I patch it with epoxy and it doesn’t seal, the effort will be wasted. If I patch it and it does work, the system will be pressurized again. That raises the likelihood that a more catastrophic failure, i.e., the radiator could suddenly burst either where the patch is or at some other weak spot. Why invite this if I don’t have to?
I’ve thought about changing the radiator. It’s only $119. I haven’t looked into the labor involved, but I’ve done it on other cars and don’t suspect difficulty. But I dunno how much longer I’m gonna keep the car (165k).
There’s a serious crack in the pipe from the exhaust manifold to the catalytic converter, and the exhaust system from the catalytic converter to the muffler is gone. The crack in the pipe doesn’t look fixable (It’s on a sharp bend), so I’d have to install a complete exhaust system, The parts alone are about $700. I’ve been eying the connection from the pipe to the exhaust manifold, and am dreading the ordeal that is corroded exhaust studs. I live in a townhouse and don’t have a garage. I can’t keep the car up on ramps for several days as I sort it all out. You know the deal: runs to the parts store(s), hunts for tools that might help, stop working if it rains, blah, blah, blah. And I’d have to go it alone. Most friends live too far away.
However…
Am I wrong about fixing the exhaust pipe crack? The pipe comes down, bends sharply, and is attached to the engine with some sort of clamp right before it connects to the converter. The crack is right before the clamp and is getting larger. The presence of the clamp (which is corroded and is unlikely to come off without destruction of itself, the pipe it’s clamped to, or both) and the fact that’s the crack is right next to a sharp bend seems to make repair impossible. Is this true? Anyone ever handle something like this? FWIW, the flexible exhaust pipe available in auto parts stores doesn’t bend sharply enough. If I had to replace the pipe and managed to get it off, I’d pretty much have to replace the converter as well. So, goodbye $700. And it would still have other problems; the rear tires are on their last legs, and there’s still that coolant leak.
But if there were a good solution to the exhaust problem, I’d fix the exhaust crack, replace the exhaust system after the converter (total cost would be more like $300), replace the radiator, and replace the rear tires. For maybe $700-$800, I could drive it for another couple of years. I might even replace the (seriously) cracked left front fender with a junkyard one if I can find one the right color. But I dunno if it’s worth it.
OTOH, the I do like the car. The bones of the car are solid. Oil consumption is low, power’s good, handling/braking are good, tranny’s holding up. The interior is still good, too. And I always wanted to keep a car for either 20 years or 200k (or both!). Bragging rights, ya know…
If there’s no exhaust system shortcut fix, I’ll just live with the noise (it’s actually not too bad), live with the minor leak, keep an eye on the tires, and wait for the car to die.
I was gonna open up a separate thread concerning the exhaust system, be I figured the same people would reply, so I’d try here first.
What say all?
If you really want this, then you must keep up with the maintenance. Surprisingly, this costs money, but it’s usually less than what a new car costs. A newer used car however may make sense.
Have you gotten at least two quotes from reputable muffler shops? Do not guess on the projected cost for the exhaust repairs.
$700 seems a bit high, but what is your life worth to you? Carbon monoxide (CO) can kill you and any passengers. Little kids succumb to (CO) poisoning fairly quickly. If the leak is where you say it is, the likelihood of (CO) getting into the cabin is very high.
In the summer roll the windows down and do not take any long trips with this rig. For the winter, get it fixed!! If you live in L.A. its always summer.
20 years / 200,000 Miles is very possible. I have two rigs that I have put that many miles on. I have owned them for over 30 years. To achieve this goal, you will have to spend some time and $$ on maintenance. As Dag Otto said the time and $$ spent will almost always be less then buying a new car.
If the 20/200,00 goal is not very important to you you might be better off getting a new-to-you car with less miles on the clock and less years of use.
IHTH, 48.