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-   -   328i RADIATOR OVERFLOW TUBE NIPPLE TOO SHORT -- advice needed (

bmw4ed 11-03-2012 10:07 PM

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THe screwdriver in the photo points to the problem area. THe radiator overflow tube nipple is way too short, and it has no barb to keep the tube from falling off with heat and pressure.

A shop had replaced the radiator in my sister's car. I don't know if this problem existed all along. After a year, I noticed the overflow tube area was wet. I removed the tube from the radiator tank and noticed the nipple is too short (only about 1/4-inch long, and no barb to keep the clamped tube from falling off). I clamped it tightly, but during a long trip the tube fell off and I had to pull over and make a quick fix.

In the photo, you see how I added an extra length of tube, clamped the tube to the very short nipple, and clamped the tube to the radiator large outlet hose clamp (to apply a constant force which kept the overflow tube from falling off for the remaining 400 miles of the trip).

I want to make this a permanent repair. I found overflow nipple repair kits for BMW and MBZ cars that tell you to tap a hole in the tank and install a metal barbed fitting. Some say this repair won't last b/c the metal and plastic tank have different thermal expansion rates and the repair eventually works itself loose. Also, I don't see a kit for my 1997 E36 328i.

Someone said they used a mag-wheel-style tire stem and inserted it from inside the radiator tank, and tightened the nut down from the outside. Mag style tire stems have a nut and rubber grommets to seal from both sides of the radiator tank. Bicycle valve stems come in smaller diameters, but I'm not sure if I have clearance inside my radiator tank to install a tire stem from the inside of the tank. I'm also not sure what to do with the threaded part of the tire stem. Plus, a normal car tire stem is too big a diameter for the overflow tube.

Anyone tried the metal BMW overflow tube nipple repair kit? Results good or bad? Do these repair kits come with a plastic barbed fitting, for a closer thermal expansion to the plastic radiator tank?

Anyone have other ideas, besides replacing the radiator. They're not expensive, nor hard to replace, but mine is fine other than the overflow tube nipple is too short.

dc_wright 11-04-2012 04:46 AM

The radiators (as well as the rest of the cooling system parts) need to be replaced on these cars about every 60K-70K miles. On the radiator the plastic gets brittle with aging and you can get sudden catastrophic failure at the key connections like the main coolant hose connections. If you do some searching you can find all metal radiators for the same or less than an OEM plastic/metal replacement. Bonehead Performance has Mishimoto radiators at a pretty good price.

petriej 11-05-2012 11:34 AM

I heard if you get it cold, the nipple gets bigger?

hornhospital 11-05-2012 03:20 PM

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ZeGerman 11-05-2012 03:41 PM

The short answer is that the radiator is broken, and needs to be replaced along with any other cooling system component which has not been replaced in the last 75-100k miles.

dc_wright 11-05-2012 06:10 PM


Originally Posted by petriej (Post 7177019)
I heard if you get it cold, the nipple gets bigger?


petriej 11-06-2012 09:21 AM

Heather Graham! She's the best.

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