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Coolant System Woes

466 views 0 replies 1 participant last post by  Lemurfemur 
#1 ·
A little back-story:

During a pit stop on a cross-country drive, I noticed quite a bit of coolant on the pavement under my 300D. I looked around for leaks but it didn't appear that anything was still dripping. I let everything cool down, topped it off and proceeded down the interstate, taking it a little easy and keeping a close eye on the temp. Started getting a little hot so I pulled off at the next rest stop and jumped out to have a look. At first the pavement was dry, but then whoosh a bunch of coolant was spit out of the little hose coming out the back of the expansion tank. Did a little research and attributed the problem to a leak in the coolant system somewhere, which introduces air which forces out coolant when it gets hot. I discovered that the 25 year-old plastic of the expansion tank was beginning to degrade and the seam between the top and bottom of the tank was coming apart. I sealed around the seam with duct tape, topped it off, and took off. That carried me the final 2000 miles of the drive at 80mph all day for a few more days with just a couple more top-offs, but no serious temp issues.

I get home and I order the new expansion tank. In the meantime, I do some local driving for errands etc. with no problem UNTIL one time I catch the temp gauge going all the way up over 100°C so I pull over quickly. This time the coolant doesn't eject out of the little hose, it's coming out of two hose fittings at the bottom of the radiator. Great. I don't want to touch them and make anything worse so I wait for everything to cool, put in the little bit of coolant in my trunk and all the water from my water bottle and prayed the whole two miles back home. Temp was fluctuating quite a bit, I suspect from all the air in the system, but I made it back. The two hose fittings did not seem to be leaking anymore though, so I supposed it was just because of the high pressure when it was super hot.

The coolant tank arrives in the mail and I replace it. I drain what little is left in the radiator and replace the plug. I pour water into the expansion tank and much to my dismay it starts leaking out of the one hose fitting.

This is the fitting in question:



I inspect it and the fitting is definitely a little loose in the radiator and when I wiggle it the water comes out faster. Then I found a broken collar nut on the ground. I look at the identical fitting on the other side and sure enough it's got that collar nut snugging the fitting to the radiator housing. It must have broken off because of some combination of temp, pressure and age.

Good:


Bad:




Does any one know exactly what to call this and whether it's possible to get a new replacement (rather than picking an old one that will just break again)? It is shown in the image of the radiator above, which is from a parts site, which seems to suggest that they come with the radiator. Also, does anyone know if that brass threaded fitting is supposed to be a little loose in the radiator without this nut and whether the nut will solve the problem?

Thanks so much in advance!
 
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