I seem to have a leak Front Passenger side, drips on the horn, sometimes does sometimes doesn't. Minimum loss of fluid, no overheating to speak of. Checked hoses etc. Question is : I understand it is a plastic radiator (!!!) can this be fixed with Prestone or similar stop leak. It seems to have worked but I have a 4 hr drive next week and would appreciate anyones experience with these plastic rads.
Aluminum radiator CORE with plastic tanks. Standard method of manufacture these days, unfortunately.
can this be fixed
The inevitable can be DELAYED with stop-leak, but I don't trust what stop-leak does to the rest of the system. Bars-Leaks brand is pretty innocuous, but even it probably reduces the heat exchange capacity of the system a bit. Some of the more aggressive stop-leak compounds are also known as "heater-core plugger compounds" for good reason.
The plastic/aluminum tanks actually hold up remarkably well. My wife has (knock wood....) almost 250,000 miles on her '93 LH on the original radiator. It has a pinhole leak right in the top of one of the tanks, which I've just been keeping my eye on. Its so tiny that it doesn't even drip, just makes a crusty spot where the coolant evaporates. The danger is that once you have a crack in the plastic, the pressure cycles might make it grow very fast and very suddenly. If you can see the leak and are fairly sure its a pinhole type leak and not a crack with visible extent, then I wouldn't worry much about a short 4-hour trip and back. Carry a jug of water to be on the safe side.
Have you tried a dab of Right Stuff?
Hmmm... no. But that could work- with the system cold and no pressure, just "grind" it into the pinhole with a thumb.
If practical, for a pinhole leak take a piece of wire that is longer than from the hole to the nearest radiator opening. (Obviously out of the vehicle.)
Strip the insulation off the wire and throw the wire away.
With a SMALL drill, enlarge the pinhole. Then feed the insulation through the enlarged pinhole and out opening. Now put a 'tack' into the insulation tube. Smear a bunch of goo you want to use to seal with on the underside of the tack and carefully PULL the tack into the radiator till the spike sticks out the hole. (The hole you drilled MUST be large enough for the tack with the insulation over the spike to fit the hole!) Let it set/cure.
When it's almost set, but not 'hard set' clip off the external spike.
The advantage of this is you now have a 'compression' fix against radiator pressure, not a patch that can be 'blown off' by radiator pressure.
Although I'm leery of putting a 'tack' in my radiator...
If possible, I'm much more comfortable with enlarging the hole to where I can use the same trick to feed a small 'bolt' with a big washer on it, even rubber washers if possible, from the inside of the radiator and once it's in place then put a washer and nut on the outside with even more goo to 'pinch' the radiator tank body. Then when I'm satisfied, I much up the exposed threads of the bolt so there's no way the nut could come loose.
I understand where you're coming from on that, but I've got to question the ultimate wisdom of that practice. I guess the idea is to put a ceiling on the max. system pressure for moderate temporary pressure spikes. My concern would be a situation of moderate to serious overheating in which the 15 psi cap may (not guaranteed, but may) at least prevent flash boiling and reduce the chance of engine damage, whereas in the same situation, the 7 pound cap will possibly totally let loose in a flash boiling suddenly leaving critical overheated parts that are accepting even more heat from even hotter other parts unsurrounded by liquid coolant.
I guess there are different but real increases in risks either way, but I would think the right way is to do preventive maintenance (use the right coolant, change it before it on a realistic scehdule) and replace any and all weak parts (certainly old hoses, any radiator showing signs of age, etc.).
The 7 psi cap seems like a bandaid to me. The primary goal is to protect the engine - not to protect weak parts in the coolant system that need to be replaced. Again - the 15 psi cap may prevent flash boiling (and engine damage) in a situation in which the 7 psi cap would not.
IMO...
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
I am sure that you all saw that post a few weeks ago that contained a link to a picture of radiator that had blown out part of it's tank. I would be hesitant repairing the tank after seeing that picture. I don't every remember every seeing a brass tanked radiator doing that.
-KM
I don't think there's ANY way that a Chrysler LH will run with less than
12-14 psi of cooling system pressure. These cars, like most modern cars, operate at significantly higher temperatures than older cars for better fuel efficiency, lower emissions, and (although it isn't intuitive) less wear. You can run a '49 Plymouth with NO radiator cap and at most a small waft of steam will come out the radiator neck. If you just *idle* an LH car to get it up to operating temperature without a cap, coolant will boil in the cylinder heads and send a geyser out the neck. Heck, even my '66 Dodge *needs* a 12-14 psi cap to avoid pushing too much coolant into the overflow tank, and that's just with a 180-degree thermostat, not the 195 or 210 thermostats like modern engines use. Even if you can run the car at lower pressure, you can be sure that you are having "microboiling" going on in the heads creating steam pockets that result in hot-spots, and cavitation that erodes metal from the inside of the cooling passages. Lowering cooling system pressure is ONLY a reasonable option if you do something like convert to one of the waterless coolants like Evans NPG. And then you give up some heat transfer capacity in the process.
No, I've never seen a brass tank radiator fail quite like that (big chunk gone out of the tank). HOWEVER, I definitely HAVE seen a brass tank radiator fail by having the tank blow completely off the core at the solder joint. Different failure mechanism, but just as sudden and just as complete. :-/
Mechanical design and materials selections always have tradeoffs, and even though my first reaction also was "Ewww! PLASTIC?!?!?" I've come to realize that "plastic" tank radiators aren't so horrible after all. Harder to fix when broken, but they do have some advantages.
That's that flash boiling I was talking about. That just means temperatures are rising well above the boiling point (the low boiling point that accompanies little or no pressure), after which, once that water flash boiled, there's *nothing* to moderate the temperatures soaking thru from the even hotter metal immediately surrounding the combustion chamber.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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